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rust/rust/af2ca5267d62cc3a9f77458e4fca17d9140c29bb/./compiler/rustc_metadata/src/rmeta/encoder.rs
blob: 8481db9d3c52343d47f1b86e98e7cfab05e6877e [file]
use std::borrow::Borrow;
use std::cell::RefCell;
use std::collections::hash_map::Entry;
use std::fs::File;
use std::io::{Read, Seek, Write};
use std::path::{Path, PathBuf};
use std::rc::Rc;
use std::sync::Arc;
use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
use rustc_data_structures::memmap::{Mmap, MmapMut};
use rustc_data_structures::sync::{par_for_each_in, par_join};
use rustc_data_structures::temp_dir::MaybeTempDir;
use rustc_data_structures::thousands::usize_with_underscores;
use rustc_hir as hir;
use rustc_hir::attrs::{AttributeKind, EncodeCrossCrate};
use rustc_hir::def_id::{CRATE_DEF_ID, LOCAL_CRATE, LocalDefId, LocalDefIdSet};
use rustc_hir::definitions::DefPathData;
use rustc_hir::find_attr;
use rustc_hir_pretty::id_to_string;
use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
use rustc_middle::middle::dependency_format::Linkage;
use rustc_middle::mir::interpret;
use rustc_middle::query::Providers;
use rustc_middle::traits::specialization_graph;
use rustc_middle::ty::AssocContainer;
use rustc_middle::ty::codec::TyEncoder;
use rustc_middle::ty::fast_reject::{self, TreatParams};
use rustc_serialize::{Decodable, Decoder, Encodable, Encoder, opaque};
use rustc_session::config::mitigation_coverage::DeniedPartialMitigation;
use rustc_session::config::{OptLevel, OutputType, TargetModifier};
use rustc_span::def_id::CRATE_MOD_ID;
use rustc_span::hygiene::HygieneEncodeContext;
use rustc_span::{
ByteSymbol, ExternalSource, FileName, SourceFile, SpanData, SpanEncoder, StableSourceFileId,
Symbol, SyntaxContext, bug, span_bug, sym,
};
use rustc_structures::CrateType;
use tracing::{debug, instrument, trace};
use crate::diagnostics::{FailCreateFileEncoder, FailWriteFile};
use crate::eii::EiiMapEncodedKeyValue;
use crate::rmeta::*;
pub(super) struct EncodeContext<'a, 'tcx> {
opaque: opaque::FileEncoder<'a>,
tcx: TyCtxt<'tcx>,
feat: &'tcx rustc_feature::Features,
tables: TableBuilders,
lazy_state: LazyState,
span_shorthands: FxHashMap<Span, usize>,
type_shorthands: FxHashMap<Ty<'tcx>, usize>,
predicate_shorthands: FxHashMap<ty::PredicateKind<'tcx>, usize>,
interpret_allocs: FxIndexSet<interpret::AllocId>,
// This is used to speed up Span encoding.
// The `usize` is an index into the `MonotonicVec`
// that stores the `SourceFile`
source_file_cache: (Arc<SourceFile>, usize),
// The indices (into the `SourceMap`'s `MonotonicVec`)
// of all of the `SourceFiles` that we need to serialize.
// When we serialize a `Span`, we insert the index of its
// `SourceFile` into the `FxIndexSet`.
// The order inside the `FxIndexSet` is used as on-disk
// order of `SourceFiles`, and encoded inside `Span`s.
required_source_files: Option<FxIndexSet<usize>>,
is_proc_macro: bool,
hygiene_ctxt: Rc<RefCell<HygieneEncodeContext>>,
// Used for both `Symbol`s and `ByteSymbol`s.
symbol_index_table: FxHashMap<u32, usize>,
}
/// If the current crate is a proc-macro, returns early with `LazyArray::default()`.
/// This is useful for skipping the encoding of things that aren't needed
/// for proc-macro crates.
macro_rules! empty_proc_macro {
($self:ident) => {
if $self.is_proc_macro {
return LazyArray::default();
}
};
}
macro_rules! encoder_methods {
($($name:ident($ty:ty);)*) => {
$(fn $name(&mut self, value: $ty) {
self.opaque.$name(value)
})*
}
}
impl<'a, 'tcx> Encoder for EncodeContext<'a, 'tcx> {
encoder_methods! {
emit_usize(usize);
emit_u128(u128);
emit_u64(u64);
emit_u32(u32);
emit_u16(u16);
emit_u8(u8);
emit_isize(isize);
emit_i128(i128);
emit_i64(i64);
emit_i32(i32);
emit_i16(i16);
emit_raw_bytes(&[u8]);
}
}
impl<'a, 'tcx, T> Encodable<EncodeContext<'a, 'tcx>> for LazyValue<T> {
fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
e.emit_lazy_distance(self.position);
}
}
impl<'a, 'tcx, T> Encodable<EncodeContext<'a, 'tcx>> for LazyArray<T> {
fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
e.emit_usize(self.num_elems);
if self.num_elems > 0 {
e.emit_lazy_distance(self.position)
}
}
}
impl<'a, 'tcx, I, T> Encodable<EncodeContext<'a, 'tcx>> for LazyTable<I, T> {
fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
e.emit_usize(self.width);
e.emit_usize(self.len);
e.emit_lazy_distance(self.position);
}
}
impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for ExpnIndex {
fn encode(&self, s: &mut EncodeContext<'a, 'tcx>) {
s.emit_u32(self.as_u32());
}
}
impl<'a, 'tcx> SpanEncoder for EncodeContext<'a, 'tcx> {
fn encode_crate_num(&mut self, crate_num: CrateNum) {
if crate_num != LOCAL_CRATE && self.is_proc_macro {
panic!("Attempted to encode non-local CrateNum {crate_num:?} for proc-macro crate");
}
self.emit_u32(crate_num.as_u32());
}
fn encode_def_index(&mut self, def_index: DefIndex) {
self.emit_u32(def_index.as_u32());
}
fn encode_def_id(&mut self, def_id: DefId) {
def_id.krate.encode(self);
def_id.index.encode(self);
}
fn encode_syntax_context(&mut self, syntax_context: SyntaxContext) {
let idx = self.hygiene_ctxt.borrow_mut().get_syntax_ctxt_encoding_index(syntax_context);
idx.encode(self);
}
fn encode_expn_id(&mut self, expn_id: ExpnId) {
if expn_id.krate == LOCAL_CRATE {
// We will only write details for local expansions. Non-local expansions will fetch
// data from the corresponding crate's metadata.
// FIXME(#43047) FIXME(#74731) We may eventually want to avoid relying on external
// metadata from proc-macro crates.
self.hygiene_ctxt.borrow_mut().schedule_expn_data_for_encoding(expn_id);
}
expn_id.krate.encode(self);
expn_id.local_id.encode(self);
}
fn encode_span(&mut self, span: Span) {
match self.span_shorthands.entry(span) {
Entry::Occupied(o) => {
// If an offset is smaller than the absolute position, we encode with the offset.
// This saves space since smaller numbers encode in less bits.
let last_location = *o.get();
// This cannot underflow. Metadata is written with increasing position(), so any
// previously saved offset must be smaller than the current position.
let offset = self.opaque.position() - last_location;
if offset < last_location {
let needed = bytes_needed(offset);
SpanTag::indirect(true, needed as u8).encode(self);
self.opaque.write_with(|dest| {
*dest = offset.to_le_bytes();
needed
});
} else {
let needed = bytes_needed(last_location);
SpanTag::indirect(false, needed as u8).encode(self);
self.opaque.write_with(|dest| {
*dest = last_location.to_le_bytes();
needed
});
}
}
Entry::Vacant(v) => {
let position = self.opaque.position();
v.insert(position);
// Data is encoded with a SpanTag prefix (see below).
span.data().encode(self);
}
}
}
fn encode_symbol(&mut self, sym: Symbol) {
self.encode_symbol_or_byte_symbol(sym.as_u32(), |this| this.emit_str(sym.as_str()));
}
fn encode_byte_symbol(&mut self, byte_sym: ByteSymbol) {
self.encode_symbol_or_byte_symbol(byte_sym.as_u32(), |this| {
this.emit_byte_str(byte_sym.as_byte_str())
});
}
}
fn bytes_needed(n: usize) -> usize {
(usize::BITS - n.leading_zeros()).div_ceil(u8::BITS) as usize
}
impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for SpanData {
fn encode(&self, s: &mut EncodeContext<'a, 'tcx>) {
// Don't serialize any `SyntaxContext`s from a proc-macro crate,
// since we don't load proc-macro dependencies during serialization.
// This means that any hygiene information from macros used *within*
// a proc-macro crate (e.g. invoking a macro that expands to a proc-macro
// definition) will be lost.
//
// This can show up in two ways:
//
// 1. Any hygiene information associated with identifier of
// a proc macro (e.g. `#[proc_macro] pub fn $name`) will be lost.
// Since proc-macros can only be invoked from a different crate,
// real code should never need to care about this.
//
// 2. Using `Span::def_site` or `Span::mixed_site` will not
// include any hygiene information associated with the definition
// site. This means that a proc-macro cannot emit a `$crate`
// identifier which resolves to one of its dependencies,
// which also should never come up in practice.
//
// Additionally, this affects `Span::parent`, and any other
// span inspection APIs that would otherwise allow traversing
// the `SyntaxContexts` associated with a span.
//
// None of these user-visible effects should result in any
// cross-crate inconsistencies (getting one behavior in the same
// crate, and a different behavior in another crate) due to the
// limited surface that proc-macros can expose.
//
// IMPORTANT: If this is ever changed, be sure to update
// `rustc_span::hygiene::raw_encode_expn_id` to handle
// encoding `ExpnData` for proc-macro crates.
let ctxt = if s.is_proc_macro { SyntaxContext::root() } else { self.ctxt };
if self.is_dummy() {
let tag = SpanTag::new(SpanKind::Partial, ctxt, 0);
tag.encode(s);
if tag.context().is_none() {
ctxt.encode(s);
}
return;
}
// The Span infrastructure should make sure that this invariant holds:
debug_assert!(self.lo <= self.hi);
if !s.source_file_cache.0.contains(self.lo) {
let source_map = s.tcx.sess.source_map();
let source_file_index = source_map.lookup_source_file_idx(self.lo);
s.source_file_cache =
(Arc::clone(&source_map.files()[source_file_index]), source_file_index);
}
let (ref source_file, source_file_index) = s.source_file_cache;
debug_assert!(source_file.contains(self.lo));
if !source_file.contains(self.hi) {
// Unfortunately, macro expansion still sometimes generates Spans
// that malformed in this way.
let tag = SpanTag::new(SpanKind::Partial, ctxt, 0);
tag.encode(s);
if tag.context().is_none() {
ctxt.encode(s);
}
return;
}
// There are two possible cases here:
// 1. This span comes from a 'foreign' crate - e.g. some crate upstream of the
// crate we are writing metadata for. When the metadata for *this* crate gets
// deserialized, the deserializer will need to know which crate it originally came
// from. We use `TAG_VALID_SPAN_FOREIGN` to indicate that a `CrateNum` should
// be deserialized after the rest of the span data, which tells the deserializer
// which crate contains the source map information.
// 2. This span comes from our own crate. No special handling is needed - we just
// write `TAG_VALID_SPAN_LOCAL` to let the deserializer know that it should use
// our own source map information.
//
// If we're a proc-macro crate, we always treat this as a local `Span`.
// In `encode_source_map`, we serialize foreign `SourceFile`s into our metadata
// if we're a proc-macro crate.
// This allows us to avoid loading the dependencies of proc-macro crates: all of
// the information we need to decode `Span`s is stored in the proc-macro crate.
let (kind, metadata_index) = if source_file.is_imported() && !s.is_proc_macro {
// To simplify deserialization, we 'rebase' this span onto the crate it originally came
// from (the crate that 'owns' the file it references. These rebased 'lo' and 'hi'
// values are relative to the source map information for the 'foreign' crate whose
// CrateNum we write into the metadata. This allows `imported_source_files` to binary
// search through the 'foreign' crate's source map information, using the
// deserialized 'lo' and 'hi' values directly.
//
// All of this logic ensures that the final result of deserialization is a 'normal'
// Span that can be used without any additional trouble.
let metadata_index = {
// Introduce a new scope so that we drop the 'read()' temporary
match &*source_file.external_src.read() {
ExternalSource::Foreign { metadata_index, .. } => *metadata_index,
src => panic!("Unexpected external source {src:?}"),
}
};
(SpanKind::Foreign, metadata_index)
} else {
// Record the fact that we need to encode the data for this `SourceFile`
let source_files =
s.required_source_files.as_mut().expect("Already encoded SourceMap!");
let (metadata_index, _) = source_files.insert_full(source_file_index);
let metadata_index: u32 =
metadata_index.try_into().expect("cannot export more than U32_MAX files");
(SpanKind::Local, metadata_index)
};
// Encode the start position relative to the file start, so we profit more from the
// variable-length integer encoding.
let lo = self.lo - source_file.start_pos;
// Encode length which is usually less than span.hi and profits more
// from the variable-length integer encoding that we use.
let len = self.hi - self.lo;
let tag = SpanTag::new(kind, ctxt, len.0 as usize);
tag.encode(s);
if tag.context().is_none() {
ctxt.encode(s);
}
lo.encode(s);
if tag.length().is_none() {
len.encode(s);
}
// Encode the index of the `SourceFile` for the span, in order to make decoding faster.
metadata_index.encode(s);
if kind == SpanKind::Foreign {
// This needs to be two lines to avoid holding the `s.source_file_cache`
// while calling `cnum.encode(s)`
let cnum = s.source_file_cache.0.cnum;
cnum.encode(s);
}
}
}
impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for [u8] {
fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) {
Encoder::emit_usize(e, self.len());
e.emit_raw_bytes(self);
}
}
impl<'a, 'tcx> TyEncoder<'tcx> for EncodeContext<'a, 'tcx> {
const CLEAR_CROSS_CRATE: bool = true;
fn position(&self) -> usize {
self.opaque.position()
}
fn type_shorthands(&mut self) -> &mut FxHashMap<Ty<'tcx>, usize> {
&mut self.type_shorthands
}
fn predicate_shorthands(&mut self) -> &mut FxHashMap<ty::PredicateKind<'tcx>, usize> {
&mut self.predicate_shorthands
}
fn encode_alloc_id(&mut self, alloc_id: &rustc_middle::mir::interpret::AllocId) {
let (index, _) = self.interpret_allocs.insert_full(*alloc_id);
index.encode(self);
}
}
// Shorthand for `$self.$tables.$table.set_some($def_id.index, $self.lazy($value))`, which would
// normally need extra variables to avoid errors about multiple mutable borrows.
macro_rules! record {
($self:ident.$tables:ident.$table:ident[$def_id:expr] <- $value:expr) => {{
{
let value = $value;
let lazy = $self.lazy(value);
$self.$tables.$table.set_some($def_id.index, lazy);
}
}};
}
// Shorthand for `$self.$tables.$table.set_some($def_id.index, $self.lazy_array($value))`, which would
// normally need extra variables to avoid errors about multiple mutable borrows.
macro_rules! record_array {
($self:ident.$tables:ident.$table:ident[$def_id:expr] <- $value:expr) => {{
{
let value = $value;
let lazy = $self.lazy_array(value);
$self.$tables.$table.set_some($def_id.index, lazy);
}
}};
}
macro_rules! record_defaulted_array {
($self:ident.$tables:ident.$table:ident[$def_id:expr] <- $value:expr) => {{
{
let value = $value;
let lazy = $self.lazy_array(value);
$self.$tables.$table.set($def_id.index, lazy);
}
}};
}
impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
fn emit_lazy_distance(&mut self, position: NonZero<usize>) {
let pos = position.get();
let distance = match self.lazy_state {
LazyState::NoNode => bug!("emit_lazy_distance: outside of a metadata node"),
LazyState::NodeStart(start) => {
let start = start.get();
assert!(pos <= start);
start - pos
}
LazyState::Previous(last_pos) => {
assert!(
last_pos <= position,
"make sure that the calls to `lazy*` \
are in the same order as the metadata fields",
);
position.get() - last_pos.get()
}
};
self.lazy_state = LazyState::Previous(NonZero::new(pos).unwrap());
self.emit_usize(distance);
}
fn lazy<T: ParameterizedOverTcx, B: Borrow<T::Value<'tcx>>>(&mut self, value: B) -> LazyValue<T>
where
T::Value<'tcx>: Encodable<EncodeContext<'a, 'tcx>>,
{
let pos = NonZero::new(self.position()).unwrap();
assert_eq!(self.lazy_state, LazyState::NoNode);
self.lazy_state = LazyState::NodeStart(pos);
value.borrow().encode(self);
self.lazy_state = LazyState::NoNode;
assert!(pos.get() <= self.position());
LazyValue::from_position(pos)
}
fn lazy_array<T: ParameterizedOverTcx, I: IntoIterator<Item = B>, B: Borrow<T::Value<'tcx>>>(
&mut self,
values: I,
) -> LazyArray<T>
where
T::Value<'tcx>: Encodable<EncodeContext<'a, 'tcx>>,
{
let pos = NonZero::new(self.position()).unwrap();
assert_eq!(self.lazy_state, LazyState::NoNode);
self.lazy_state = LazyState::NodeStart(pos);
let len = values.into_iter().map(|value| value.borrow().encode(self)).count();
self.lazy_state = LazyState::NoNode;
assert!(pos.get() <= self.position());
LazyArray::from_position_and_num_elems(pos, len)
}
fn encode_symbol_or_byte_symbol(
&mut self,
index: u32,
emit_str_or_byte_str: impl Fn(&mut Self),
) {
// if symbol/byte symbol is predefined, emit tag and symbol index
if Symbol::is_predefined(index) {
self.opaque.emit_u8(SYMBOL_PREDEFINED);
self.opaque.emit_u32(index);
} else {
// otherwise write it as string or as offset to it
match self.symbol_index_table.entry(index) {
Entry::Vacant(o) => {
self.opaque.emit_u8(SYMBOL_STR);
let pos = self.opaque.position();
o.insert(pos);
emit_str_or_byte_str(self);
}
Entry::Occupied(o) => {
let x = *o.get();
self.emit_u8(SYMBOL_OFFSET);
self.emit_usize(x);
}
}
}
}
fn encode_def_path_table(&mut self) {
let defs = self.tcx.definitions();
if self.is_proc_macro {
for def_id in std::iter::once(CRATE_DEF_ID)
.chain(self.tcx.resolutions(()).proc_macros.iter().copied())
{
let def_key = self.lazy(defs.def_key(def_id));
let def_path_hash = defs.def_path_hash(def_id);
self.tables.def_keys.set_some(def_id.local_def_index, def_key);
self.tables
.def_path_hashes
.set(def_id.local_def_index, def_path_hash.local_hash().as_u64());
}
} else {
for (def_index, def_key, def_path_hash) in defs.enumerated_keys_and_path_hashes() {
let def_key = self.lazy(def_key);
self.tables.def_keys.set_some(def_index, def_key);
self.tables.def_path_hashes.set(def_index, def_path_hash.local_hash().as_u64());
}
}
}
fn encode_def_path_hash_map(&mut self) -> LazyValue<DefPathHashMapRef<'static>> {
self.lazy(DefPathHashMapRef::BorrowedFromTcx(self.tcx.def_path_hash_to_def_index_map()))
}
fn encode_source_map(&mut self) -> LazyTable<u32, Option<LazyValue<rustc_span::SourceFile>>> {
let source_map = self.tcx.sess.source_map();
let all_source_files = source_map.files();
// By replacing the `Option` with `None`, we ensure that we can't
// accidentally serialize any more `Span`s after the source map encoding
// is done.
let required_source_files = self.required_source_files.take().unwrap();
let mut adapted = TableBuilder::default();
let local_crate_stable_id = self.tcx.stable_crate_id(LOCAL_CRATE);
// Only serialize `SourceFile`s that were used during the encoding of a `Span`.
//
// The order in which we encode source files is important here: the on-disk format for
// `Span` contains the index of the corresponding `SourceFile`.
for (on_disk_index, &source_file_index) in required_source_files.iter().enumerate() {
let source_file = &all_source_files[source_file_index];
// Don't serialize imported `SourceFile`s, unless we're in a proc-macro crate.
assert!(!source_file.is_imported() || self.is_proc_macro);
// At export time we expand all source file paths to absolute paths because
// downstream compilation sessions can have a different compiler working
// directory, so relative paths from this or any other upstream crate
// won't be valid anymore.
//
// At this point we also erase the actual on-disk path and only keep
// the remapped version -- as is necessary for reproducible builds.
let mut adapted_source_file = (**source_file).clone();
match source_file.name {
FileName::Real(ref original_file_name) => {
let mut adapted_file_name = original_file_name.clone();
adapted_file_name.update_for_crate_metadata();
adapted_source_file.name = FileName::Real(adapted_file_name);
}
_ => {
// expanded code, not from a file
}
};
// We're serializing this `SourceFile` into our crate metadata,
// so mark it as coming from this crate.
// This also ensures that we don't try to deserialize the
// `CrateNum` for a proc-macro dependency - since proc macro
// dependencies aren't loaded when we deserialize a proc-macro,
// trying to remap the `CrateNum` would fail.
if self.is_proc_macro {
adapted_source_file.cnum = LOCAL_CRATE;
}
// Update the `StableSourceFileId` to make sure it incorporates the
// id of the current crate. This way it will be unique within the
// crate graph during downstream compilation sessions.
adapted_source_file.stable_id = StableSourceFileId::from_filename_for_export(
&adapted_source_file.name,
local_crate_stable_id,
);
let on_disk_index: u32 =
on_disk_index.try_into().expect("cannot export more than U32_MAX files");
adapted.set_some(on_disk_index, self.lazy(adapted_source_file));
}
adapted.encode(&mut self.opaque)
}
fn encode_crate_root(&mut self) -> LazyValue<CrateRoot> {
let tcx = self.tcx;
let mut stats: Vec<(&'static str, usize)> = Vec::with_capacity(32);
macro_rules! stat {
($label:literal, $f:expr) => {{
let orig_pos = self.position();
let res = $f();
stats.push(($label, self.position() - orig_pos));
res
}};
}
// We have already encoded some things. Get their combined size from the current position.
stats.push(("preamble", self.position()));
let externally_implementable_items = stat!("externally-implementable-items", || self
.encode_externally_implementable_items());
let (crate_deps, dylib_dependency_formats) =
stat!("dep", || (self.encode_crate_deps(), self.encode_dylib_dependency_formats()));
let lib_features = stat!("lib-features", || self.encode_lib_features());
let stability_implications =
stat!("stability-implications", || self.encode_stability_implications());
let (lang_items, lang_items_missing) = stat!("lang-items", || {
(self.encode_lang_items(), self.encode_lang_items_missing())
});
let stripped_cfg_items = stat!("stripped-cfg-items", || self.encode_stripped_cfg_items());
let diagnostic_items = stat!("diagnostic-items", || self.encode_diagnostic_items());
let canonical_symbols = stat!("canonical-symbols", || self.encode_canonical_symbols());
let fake_doc_items = stat!("fake-doc-items", || self.encode_fake_doc_items());
let native_libraries = stat!("native-libs", || self.encode_native_libraries());
let foreign_modules = stat!("foreign-modules", || self.encode_foreign_modules());
_ = stat!("def-path-table", || self.encode_def_path_table());
// Encode the def IDs of traits, for rustdoc and diagnostics.
let traits = stat!("traits", || self.encode_traits());
// Encode the def IDs of impls, for coherence checking.
let impls = stat!("impls", || self.encode_impls());
let incoherent_impls = stat!("incoherent-impls", || self.encode_incoherent_impls());
_ = stat!("mir", || self.encode_mir());
_ = stat!("def-ids", || self.encode_def_ids());
let interpret_alloc_index = stat!("interpret-alloc-index", || {
let mut interpret_alloc_index = Vec::new();
let mut n = 0;
trace!("beginning to encode alloc ids");
loop {
let new_n = self.interpret_allocs.len();
// if we have found new ids, serialize those, too
if n == new_n {
// otherwise, abort
break;
}
trace!("encoding {} further alloc ids", new_n - n);
for idx in n..new_n {
let id = self.interpret_allocs[idx];
let pos = self.position() as u64;
interpret_alloc_index.push(pos);
interpret::specialized_encode_alloc_id(self, tcx, id);
}
n = new_n;
}
self.lazy_array(interpret_alloc_index)
});
// Encode the proc macro data. This affects `tables`, so we need to do this before we
// encode the tables. This overwrites def_keys, so it must happen after
// encode_def_path_table.
let proc_macro_data = stat!("proc-macro-data", || self.encode_proc_macros());
let tables = stat!("tables", || self.tables.encode(&mut self.opaque));
let debugger_visualizers =
stat!("debugger-visualizers", || self.encode_debugger_visualizers());
let exportable_items = stat!("exportable-items", || self.encode_exportable_items());
let stable_order_of_exportable_impls =
stat!("exportable-items", || self.encode_stable_order_of_exportable_impls());
// Encode exported symbols info. This is prefetched in `encode_metadata`.
let (exported_non_generic_symbols, exported_generic_symbols) =
stat!("exported-symbols", || {
(
self.encode_exported_symbols(tcx.exported_non_generic_symbols(LOCAL_CRATE)),
self.encode_exported_symbols(tcx.exported_generic_symbols(LOCAL_CRATE)),
)
});
// Encode the hygiene data.
// IMPORTANT: this *must* be the last thing that we encode (other than `SourceMap`). The
// process of encoding other items (e.g. `optimized_mir`) may cause us to load data from
// the incremental cache. If this causes us to deserialize a `Span`, then we may load
// additional `SyntaxContext`s into the global `HygieneData`. Therefore, we need to encode
// the hygiene data last to ensure that we encode any `SyntaxContext`s that might be used.
let (syntax_contexts, expn_data, expn_hashes) = stat!("hygiene", || self.encode_hygiene());
let def_path_hash_map = stat!("def-path-hash-map", || self.encode_def_path_hash_map());
// Encode source_map. This needs to be done last, because encoding `Span`s tells us which
// `SourceFiles` we actually need to encode.
let source_map = stat!("source-map", || self.encode_source_map());
let target_modifiers = stat!("target-modifiers", || self.encode_target_modifiers());
let denied_partial_mitigations = stat!("denied-partial-mitigations", || self
.encode_enabled_denied_partial_mitigations());
let root = stat!("final", || {
let attrs = tcx.hir_krate_attrs();
self.lazy(CrateRoot {
header: CrateHeader {
name: tcx.crate_name(LOCAL_CRATE),
triple: tcx.sess.opts.target_triple.clone(),
hash: tcx.crate_hash(LOCAL_CRATE),
is_proc_macro_crate: proc_macro_data.is_some(),
is_stub: false,
},
extra_filename: tcx.sess.opts.cg.extra_filename.clone(),
stable_crate_id: tcx.stable_crate_id(LOCAL_CRATE),
required_panic_strategy: tcx.required_panic_strategy(LOCAL_CRATE),
panic_in_drop_strategy: tcx.sess.opts.unstable_opts.panic_in_drop,
edition: tcx.sess.edition(),
has_global_allocator: tcx.has_global_allocator(LOCAL_CRATE),
has_alloc_error_handler: tcx.has_alloc_error_handler(LOCAL_CRATE),
has_panic_handler: tcx.has_panic_handler(LOCAL_CRATE),
has_default_lib_allocator: find_attr!(attrs, DefaultLibAllocator),
externally_implementable_items,
proc_macro_data,
debugger_visualizers,
compiler_builtins: find_attr!(attrs, CompilerBuiltins),
needs_allocator: find_attr!(attrs, NeedsAllocator),
needs_panic_runtime: find_attr!(attrs, NeedsPanicRuntime),
no_builtins: find_attr!(attrs, NoBuiltins),
panic_runtime: find_attr!(attrs, PanicRuntime),
profiler_runtime: find_attr!(attrs, ProfilerRuntime),
symbol_mangling_version: tcx.sess.opts.get_symbol_mangling_version(),
crate_deps,
dylib_dependency_formats,
lib_features,
stability_implications,
lang_items,
diagnostic_items,
canonical_symbols,
fake_doc_items,
lang_items_missing,
stripped_cfg_items,
native_libraries,
foreign_modules,
source_map,
target_modifiers,
denied_partial_mitigations,
traits,
impls,
incoherent_impls,
exportable_items,
stable_order_of_exportable_impls,
exported_non_generic_symbols,
exported_generic_symbols,
interpret_alloc_index,
tables,
syntax_contexts,
expn_data,
expn_hashes,
def_path_hash_map,
specialization_enabled_in: tcx.specialization_enabled_in(LOCAL_CRATE),
})
});
let total_bytes = self.position();
let computed_total_bytes: usize = stats.iter().map(|(_, size)| size).sum();
assert_eq!(total_bytes, computed_total_bytes);
if tcx.sess.opts.unstable_opts.meta_stats {
use std::fmt::Write;
self.opaque.flush();
// Rewind and re-read all the metadata to count the zero bytes we wrote.
let pos_before_rewind = self.opaque.file().stream_position().unwrap();
let mut zero_bytes = 0;
self.opaque.file().rewind().unwrap();
let file = std::io::BufReader::new(self.opaque.file());
for e in file.bytes() {
if e.unwrap() == 0 {
zero_bytes += 1;
}
}
assert_eq!(self.opaque.file().stream_position().unwrap(), pos_before_rewind);
stats.sort_by_key(|&(_, usize)| usize);
stats.reverse(); // bigger items first
let prefix = "meta-stats";
let perc = |bytes| (bytes * 100) as f64 / total_bytes as f64;
let section_w = 23;
let size_w = 10;
let banner_w = 64;
// We write all the text into a string and print it with a single
// `eprint!`. This is an attempt to minimize interleaved text if multiple
// rustc processes are printing macro-stats at the same time (e.g. with
// `RUSTFLAGS='-Zmeta-stats' cargo build`). It still doesn't guarantee
// non-interleaving, though.
let mut s = String::new();
_ = writeln!(s, "{prefix} {}", "=".repeat(banner_w));
_ = writeln!(s, "{prefix} METADATA STATS: {}", tcx.crate_name(LOCAL_CRATE));
_ = writeln!(s, "{prefix} {:<section_w$}{:>size_w$}", "Section", "Size");
_ = writeln!(s, "{prefix} {}", "-".repeat(banner_w));
for (label, size) in stats {
_ = writeln!(
s,
"{prefix} {:<section_w$}{:>size_w$} ({:4.1}%)",
label,
usize_with_underscores(size),
perc(size)
);
}
_ = writeln!(s, "{prefix} {}", "-".repeat(banner_w));
_ = writeln!(
s,
"{prefix} {:<section_w$}{:>size_w$} (of which {:.1}% are zero bytes)",
"Total",
usize_with_underscores(total_bytes),
perc(zero_bytes)
);
_ = writeln!(s, "{prefix} {}", "=".repeat(banner_w));
eprint!("{s}");
}
root
}
}
struct AnalyzeAttrState {
is_exported: bool,
is_doc_hidden: bool,
}
/// Returns whether an attribute needs to be recorded in metadata, that is, if it's usable and
/// useful in downstream crates. Local-only attributes are an obvious example, but some
/// rustdoc-specific attributes can equally be of use while documenting the current crate only.
///
/// Removing these superfluous attributes speeds up compilation by making the metadata smaller.
///
/// Note: the `is_exported` parameter is used to cache whether the given `DefId` has a public
/// visibility: this is a piece of data that can be computed once per defid, and not once per
/// attribute. Some attributes would only be usable downstream if they are public.
#[inline]
fn analyze_attr(attr: &hir::Attribute, state: &mut AnalyzeAttrState) -> bool {
let mut should_encode = false;
if let hir::Attribute::Parsed(p) = attr
&& p.encode_cross_crate() == EncodeCrossCrate::No
{
// Attributes not marked encode-cross-crate don't need to be encoded for downstream crates.
} else if let Some(name) = attr.name()
&& [sym::warn, sym::allow, sym::expect, sym::forbid, sym::deny].contains(&name)
{
// Lint attributes don't need to be encoded for downstream crates.
// FIXME remove this when #152369 is re-merged
} else if let hir::Attribute::Parsed(AttributeKind::DocComment { .. }) = attr {
// We keep all doc comments reachable to rustdoc because they might be "imported" into
// downstream crates if they use `#[doc(inline)]` to copy an item's documentation into
// their own.
if state.is_exported {
should_encode = true;
}
} else if let hir::Attribute::Parsed(AttributeKind::Doc(d)) = attr {
should_encode = true;
if d.hidden.is_some() {
state.is_doc_hidden = true;
}
} else {
should_encode = true;
}
should_encode
}
fn should_encode_span(def_kind: DefKind) -> bool {
match def_kind {
DefKind::Mod
| DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Variant
| DefKind::Trait
| DefKind::TyAlias
| DefKind::ForeignTy
| DefKind::TraitAlias
| DefKind::AssocTy
| DefKind::TyParam
| DefKind::ConstParam
| DefKind::LifetimeParam
| DefKind::Fn
| DefKind::Const
| DefKind::Static { .. }
| DefKind::Ctor(..)
| DefKind::AssocFn
| DefKind::AssocConst
| DefKind::Macro(_)
| DefKind::ExternCrate
| DefKind::Use
| DefKind::AnonConst
| DefKind::OpaqueTy
| DefKind::Field
| DefKind::Impl { .. }
| DefKind::Closure
| DefKind::SyntheticCoroutineBody => true,
DefKind::ForeignMod | DefKind::GlobalAsm | DefKind::TestBinderConstraints => false,
}
}
fn should_encode_attrs(def_kind: DefKind) -> bool {
match def_kind {
DefKind::Mod
| DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Variant
| DefKind::Trait
| DefKind::TyAlias
| DefKind::ForeignTy
| DefKind::TraitAlias
| DefKind::AssocTy
| DefKind::Fn
| DefKind::Const
| DefKind::Static { nested: false, .. }
| DefKind::AssocFn
| DefKind::AssocConst
| DefKind::Macro(_)
| DefKind::Field
| DefKind::ConstParam
| DefKind::Impl { .. } => true,
// Encoding attrs for `Use` items allows `#[doc(hidden)]` on re-exports
// to be read cross-crate, which is needed for diagnostic path selection
// in `visible_parent_map`. See #153477.
DefKind::Use => true,
// Tools may want to be able to detect their tool lints on
// closures from upstream crates, too. This is used by
// https://github.com/model-checking/kani and is not a performance
// or maintenance issue for us.
DefKind::Closure => true,
DefKind::SyntheticCoroutineBody => false,
DefKind::TyParam
| DefKind::Ctor(..)
| DefKind::ExternCrate
| DefKind::ForeignMod
| DefKind::AnonConst
| DefKind::OpaqueTy
| DefKind::LifetimeParam
| DefKind::Static { nested: true, .. }
| DefKind::GlobalAsm
| DefKind::TestBinderConstraints => false,
}
}
fn should_encode_expn_that_defined(def_kind: DefKind) -> bool {
match def_kind {
DefKind::Mod
| DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Variant
| DefKind::Trait
| DefKind::Impl { .. } => true,
DefKind::TyAlias
| DefKind::ForeignTy
| DefKind::TraitAlias
| DefKind::AssocTy
| DefKind::TyParam
| DefKind::Fn
| DefKind::Const
| DefKind::ConstParam
| DefKind::Static { .. }
| DefKind::Ctor(..)
| DefKind::AssocFn
| DefKind::AssocConst
| DefKind::Macro(_)
| DefKind::ExternCrate
| DefKind::Use
| DefKind::ForeignMod
| DefKind::AnonConst
| DefKind::OpaqueTy
| DefKind::Field
| DefKind::LifetimeParam
| DefKind::GlobalAsm
| DefKind::Closure
| DefKind::SyntheticCoroutineBody
| DefKind::TestBinderConstraints => false,
}
}
fn should_encode_visibility(def_kind: DefKind) -> bool {
match def_kind {
DefKind::Mod
| DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Variant
| DefKind::Trait
| DefKind::TyAlias
| DefKind::ForeignTy
| DefKind::TraitAlias
| DefKind::AssocTy
| DefKind::Fn
| DefKind::Const
| DefKind::Static { nested: false, .. }
| DefKind::Ctor(..)
| DefKind::AssocFn
| DefKind::AssocConst
| DefKind::Macro(..)
| DefKind::Field => true,
DefKind::Use
| DefKind::ForeignMod
| DefKind::TyParam
| DefKind::ConstParam
| DefKind::LifetimeParam
| DefKind::AnonConst
| DefKind::Static { nested: true, .. }
| DefKind::OpaqueTy
| DefKind::GlobalAsm
| DefKind::Impl { .. }
| DefKind::Closure
| DefKind::ExternCrate
| DefKind::SyntheticCoroutineBody
| DefKind::TestBinderConstraints => false,
}
}
fn should_encode_stability(def_kind: DefKind) -> bool {
match def_kind {
DefKind::Mod
| DefKind::Ctor(..)
| DefKind::Variant
| DefKind::Field
| DefKind::Struct
| DefKind::AssocTy
| DefKind::AssocFn
| DefKind::AssocConst
| DefKind::TyParam
| DefKind::ConstParam
| DefKind::Static { .. }
| DefKind::Const
| DefKind::Fn
| DefKind::ForeignMod
| DefKind::TyAlias
| DefKind::OpaqueTy
| DefKind::Enum
| DefKind::Union
| DefKind::Impl { .. }
| DefKind::Trait
| DefKind::TraitAlias
| DefKind::Macro(..)
| DefKind::ForeignTy => true,
DefKind::Use
| DefKind::LifetimeParam
| DefKind::AnonConst
| DefKind::GlobalAsm
| DefKind::Closure
| DefKind::ExternCrate
| DefKind::SyntheticCoroutineBody
| DefKind::TestBinderConstraints => false,
}
}
/// Whether we should encode MIR. Return a pair, resp. for CTFE and for LLVM.
///
/// Computing, optimizing and encoding the MIR is a relatively expensive operation.
/// We want to avoid this work when not required. Therefore:
/// - we only compute `mir_for_ctfe` on items with const-eval semantics;
/// - we skip `optimized_mir` for check runs.
/// - we only encode `optimized_mir` that could be generated in other crates, that is, a code that
/// is either generic or has inline hint, and is reachable from the other crates (contained
/// in reachable set).
///
/// Note: Reachable set describes definitions that might be generated or referenced from other
/// crates and it can be used to limit optimized MIR that needs to be encoded. On the other hand,
/// the reachable set doesn't have much to say about which definitions might be evaluated at compile
/// time in other crates, so it cannot be used to omit CTFE MIR. For example, `f` below is
/// unreachable and yet it can be evaluated in other crates:
///
/// ```
/// const fn f() -> usize { 0 }
/// pub struct S { pub a: [usize; f()] }
/// ```
fn should_encode_mir(
tcx: TyCtxt<'_>,
reachable_set: &LocalDefIdSet,
def_id: LocalDefId,
) -> (bool, bool) {
match tcx.def_kind(def_id) {
// instance_mir uses mir_for_ctfe rather than optimized_mir for constructors
DefKind::Ctor(_, _) => (true, false),
// Constants
DefKind::AnonConst | DefKind::AssocConst | DefKind::Const => (true, false),
// Coroutines require optimized MIR to compute layout.
DefKind::Closure if tcx.is_coroutine(def_id.to_def_id()) => (false, true),
DefKind::SyntheticCoroutineBody => (false, true),
// Full-fledged functions + closures
DefKind::AssocFn | DefKind::Fn | DefKind::Closure => {
let opt = tcx.sess.opts.unstable_opts.always_encode_mir
|| (tcx.sess.opts.output_types.should_codegen()
&& reachable_set.contains(&def_id)
&& (tcx.generics_of(def_id).requires_monomorphization(tcx)
|| tcx.cross_crate_inlinable(def_id)));
// Comptime fns do not have optimized MIR at all.
let opt =
opt && !matches!(tcx.constness(def_id), hir::Constness::Const { always: true });
// The function has a `const` modifier or is in a `const trait`.
let is_const_fn = tcx.is_const_fn(def_id.to_def_id());
(is_const_fn, opt)
}
// The others don't have MIR.
_ => (false, false),
}
}
fn should_encode_variances<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, def_kind: DefKind) -> bool {
match def_kind {
DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::OpaqueTy
| DefKind::Fn
| DefKind::Ctor(..)
| DefKind::AssocFn => true,
DefKind::AssocTy => {
// Only encode variances for RPITITs (for traits)
matches!(tcx.opt_rpitit_info(def_id), Some(ty::ImplTraitInTraitData::Trait { .. }))
}
DefKind::Mod
| DefKind::Variant
| DefKind::Field
| DefKind::AssocConst
| DefKind::TyParam
| DefKind::ConstParam
| DefKind::Static { .. }
| DefKind::Const
| DefKind::ForeignMod
| DefKind::TyAlias
| DefKind::Impl { .. }
| DefKind::Trait
| DefKind::TraitAlias
| DefKind::Macro(..)
| DefKind::ForeignTy
| DefKind::Use
| DefKind::LifetimeParam
| DefKind::AnonConst
| DefKind::GlobalAsm
| DefKind::Closure
| DefKind::ExternCrate
| DefKind::SyntheticCoroutineBody
| DefKind::TestBinderConstraints => false,
}
}
fn should_encode_generics(def_kind: DefKind) -> bool {
match def_kind {
DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Variant
| DefKind::Trait
| DefKind::TyAlias
| DefKind::ForeignTy
| DefKind::TraitAlias
| DefKind::AssocTy
| DefKind::Fn
| DefKind::Const
| DefKind::Static { .. }
| DefKind::Ctor(..)
| DefKind::AssocFn
| DefKind::AssocConst
| DefKind::AnonConst
| DefKind::OpaqueTy
| DefKind::Impl { .. }
| DefKind::Field
| DefKind::TyParam
| DefKind::Closure
| DefKind::SyntheticCoroutineBody => true,
DefKind::Mod
| DefKind::ForeignMod
| DefKind::ConstParam
| DefKind::Macro(..)
| DefKind::Use
| DefKind::LifetimeParam
| DefKind::GlobalAsm
| DefKind::ExternCrate
| DefKind::TestBinderConstraints => false,
}
}
fn should_encode_type(tcx: TyCtxt<'_>, def_id: LocalDefId, def_kind: DefKind) -> bool {
match def_kind {
DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Variant
| DefKind::Ctor(..)
| DefKind::Field
| DefKind::Fn
| DefKind::Const
| DefKind::Static { nested: false, .. }
| DefKind::TyAlias
| DefKind::ForeignTy
| DefKind::Impl { .. }
| DefKind::AssocFn
| DefKind::AssocConst
| DefKind::Closure
| DefKind::ConstParam
| DefKind::AnonConst
| DefKind::SyntheticCoroutineBody => true,
DefKind::OpaqueTy => {
let origin = tcx.local_opaque_ty_origin(def_id);
if let hir::OpaqueTyOrigin::FnReturn { parent, .. }
| hir::OpaqueTyOrigin::AsyncFn { parent, .. } = origin
&& let hir::Node::TraitItem(trait_item) = tcx.hir_node_by_def_id(parent)
&& let (_, hir::TraitFn::Required(..)) = trait_item.expect_fn()
{
false
} else {
true
}
}
DefKind::AssocTy => {
let assoc_item = tcx.associated_item(def_id);
match assoc_item.container {
ty::AssocContainer::InherentImpl | ty::AssocContainer::TraitImpl(_) => true,
ty::AssocContainer::Trait => assoc_item.defaultness(tcx).has_value(),
}
}
DefKind::TyParam => {
let hir::Node::GenericParam(param) = tcx.hir_node_by_def_id(def_id) else { bug!() };
let hir::GenericParamKind::Type { default, .. } = param.kind else { bug!() };
default.is_some()
}
DefKind::Trait
| DefKind::TraitAlias
| DefKind::Mod
| DefKind::ForeignMod
| DefKind::Macro(..)
| DefKind::Static { nested: true, .. }
| DefKind::Use
| DefKind::LifetimeParam
| DefKind::GlobalAsm
| DefKind::ExternCrate
| DefKind::TestBinderConstraints => false,
}
}
fn should_encode_fn_sig(def_kind: DefKind) -> bool {
match def_kind {
DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn) => true,
DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Variant
| DefKind::Field
| DefKind::Const
| DefKind::Static { .. }
| DefKind::Ctor(..)
| DefKind::TyAlias
| DefKind::OpaqueTy
| DefKind::ForeignTy
| DefKind::Impl { .. }
| DefKind::AssocConst
| DefKind::Closure
| DefKind::ConstParam
| DefKind::AnonConst
| DefKind::AssocTy
| DefKind::TyParam
| DefKind::Trait
| DefKind::TraitAlias
| DefKind::Mod
| DefKind::ForeignMod
| DefKind::Macro(..)
| DefKind::Use
| DefKind::LifetimeParam
| DefKind::GlobalAsm
| DefKind::ExternCrate
| DefKind::SyntheticCoroutineBody
| DefKind::TestBinderConstraints => false,
}
}
fn should_encode_constness(def_kind: DefKind) -> bool {
match def_kind {
DefKind::Fn
| DefKind::AssocFn
| DefKind::Closure
| DefKind::Ctor(_, CtorKind::Fn)
| DefKind::Impl { of_trait: false } => true,
DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Field
| DefKind::Const
| DefKind::AssocConst
| DefKind::AnonConst
| DefKind::Static { .. }
| DefKind::TyAlias
| DefKind::OpaqueTy
| DefKind::Impl { .. }
| DefKind::ForeignTy
| DefKind::ConstParam
| DefKind::AssocTy
| DefKind::TyParam
| DefKind::Trait
| DefKind::TraitAlias
| DefKind::Mod
| DefKind::ForeignMod
| DefKind::Macro(..)
| DefKind::Use
| DefKind::LifetimeParam
| DefKind::GlobalAsm
| DefKind::ExternCrate
| DefKind::Ctor(_, CtorKind::Const)
| DefKind::Variant
| DefKind::SyntheticCoroutineBody
| DefKind::TestBinderConstraints => false,
}
}
fn should_encode_const(def_kind: DefKind) -> bool {
match def_kind {
// FIXME(mgca): should we remove Const and AssocConst here?
DefKind::Const | DefKind::AssocConst | DefKind::AnonConst => true,
DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::Variant
| DefKind::Ctor(..)
| DefKind::Field
| DefKind::Fn
| DefKind::Static { .. }
| DefKind::TyAlias
| DefKind::OpaqueTy
| DefKind::ForeignTy
| DefKind::Impl { .. }
| DefKind::AssocFn
| DefKind::Closure
| DefKind::ConstParam
| DefKind::AssocTy
| DefKind::TyParam
| DefKind::Trait
| DefKind::TraitAlias
| DefKind::Mod
| DefKind::ForeignMod
| DefKind::Macro(..)
| DefKind::Use
| DefKind::LifetimeParam
| DefKind::GlobalAsm
| DefKind::ExternCrate
| DefKind::SyntheticCoroutineBody
| DefKind::TestBinderConstraints => false,
}
}
impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
fn encode_attrs(&mut self, def_id: LocalDefId) {
let tcx = self.tcx;
let mut state = AnalyzeAttrState {
is_exported: tcx.effective_visibilities(()).is_exported(def_id),
is_doc_hidden: false,
};
let attr_iter = tcx
.hir_attrs(tcx.local_def_id_to_hir_id(def_id))
.iter()
.filter(|attr| analyze_attr(*attr, &mut state));
record_array!(self.tables.attributes[def_id.to_def_id()] <- attr_iter);
let mut attr_flags = AttrFlags::empty();
if state.is_doc_hidden {
attr_flags |= AttrFlags::IS_DOC_HIDDEN;
}
self.tables.attr_flags.set(def_id.local_def_index, attr_flags);
}
fn encode_def_ids(&mut self) {
self.encode_info_for_mod(CRATE_DEF_ID);
// Proc-macro crates only export proc-macro items, which are looked
// up using `proc_macro_data`
if self.is_proc_macro {
return;
}
let tcx = self.tcx;
for local_id in tcx.iter_local_def_id() {
let def_id = local_id.to_def_id();
let def_kind = tcx.def_kind(local_id);
self.tables.def_kind.set_some(def_id.index, def_kind);
// The `DefCollector` will sometimes create unnecessary `DefId`s
// for trivial const arguments which are directly lowered to
// `ConstArgKind::Path`. We never actually access this `DefId`
// anywhere so we don't need to encode it for other crates.
// FIXME(mgca): This probably isn't true, they probably are accessed, but, test case?
if def_kind == DefKind::AnonConst
&& matches!(
tcx.hir_node_by_def_id(local_id),
hir::Node::ConstArg(_)
| hir::Node::Infer(hir::InferArg { kind: hir::InferArgKind::Const, .. })
)
{
continue;
}
if def_kind == DefKind::Field
&& let hir::Node::Field(field) = tcx.hir_node_by_def_id(local_id)
&& let Some(anon) = field.default
{
record!(self.tables.default_fields[def_id] <- anon.def_id.to_def_id());
}
if should_encode_span(def_kind) {
let def_span = tcx.def_span(local_id);
record!(self.tables.def_span[def_id] <- def_span);
}
if should_encode_attrs(def_kind) {
self.encode_attrs(local_id);
}
if should_encode_expn_that_defined(def_kind) {
record!(self.tables.expn_that_defined[def_id] <- self.tcx.expn_that_defined(def_id));
}
if should_encode_span(def_kind)
&& let Some(ident_span) = tcx.def_ident_span(def_id)
{
record!(self.tables.def_ident_span[def_id] <- ident_span);
}
if def_kind.has_codegen_attrs() {
record!(self.tables.codegen_fn_attrs[def_id] <- self.tcx.codegen_fn_attrs(def_id));
}
if should_encode_visibility(def_kind) {
let vis = self
.tcx
.local_visibility(local_id)
.map_id(|mod_id| mod_id.to_local_def_id().local_def_index);
record!(self.tables.visibility[def_id] <- vis);
}
if should_encode_stability(def_kind) {
self.encode_stability(def_id);
self.encode_const_stability(def_id);
self.encode_default_body_stability(def_id);
self.encode_deprecation(def_id);
}
if should_encode_variances(tcx, def_id, def_kind) {
let v = self.tcx.variances_of(def_id);
record_array!(self.tables.variances_of[def_id] <- v);
}
if should_encode_fn_sig(def_kind) {
record!(self.tables.fn_sig[def_id] <- tcx.fn_sig(def_id));
}
if should_encode_generics(def_kind) {
let g = tcx.generics_of(def_id);
record!(self.tables.generics_of[def_id] <- g);
record!(self.tables.explicit_clauses_of[def_id] <- self.tcx.explicit_clauses_of(def_id));
let inferred_outlives = self.tcx.inferred_outlives_of(def_id);
record_defaulted_array!(self.tables.inferred_outlives_of[def_id] <- inferred_outlives);
for param in &g.own_params {
if let ty::GenericParamDefKind::Const { has_default: true, .. } = param.kind {
let default = self.tcx.const_param_default(param.def_id);
record!(self.tables.const_param_default[param.def_id] <- default);
}
}
}
if tcx.is_conditionally_const(def_id) {
record!(self.tables.const_conditions[def_id] <- self.tcx.const_conditions(def_id));
}
if should_encode_type(tcx, local_id, def_kind) {
record!(self.tables.type_of[def_id] <- self.tcx.type_of(def_id));
}
if should_encode_constness(def_kind) {
let constness = self.tcx.constness(def_id);
self.tables.constness.set(def_id.index, constness);
}
if let DefKind::Fn | DefKind::AssocFn = def_kind {
let asyncness = tcx.asyncness(def_id);
self.tables.asyncness.set(def_id.index, asyncness);
record_array!(self.tables.fn_arg_idents[def_id] <- tcx.fn_arg_idents(def_id));
}
if let Some(name) = tcx.intrinsic(def_id) {
record!(self.tables.intrinsic[def_id] <- name);
}
if let DefKind::TyParam | DefKind::Trait = def_kind {
let default = self.tcx.object_lifetime_default(def_id);
record!(self.tables.object_lifetime_default[def_id] <- default);
}
if let DefKind::Trait = def_kind {
record!(self.tables.trait_def[def_id] <- self.tcx.trait_def(def_id));
record_defaulted_array!(self.tables.explicit_super_clauses_of[def_id] <-
self.tcx.explicit_super_clauses_of(def_id).skip_binder());
record_defaulted_array!(self.tables.explicit_implied_clauses_of[def_id] <-
self.tcx.explicit_implied_clauses_of(def_id).skip_binder());
let module_children = self.tcx.module_children_local(local_id);
record_array!(self.tables.module_children_non_reexports[def_id] <-
module_children.iter().map(|child| child.res.def_id().index));
if self.tcx.is_const_trait(def_id) {
record_defaulted_array!(self.tables.explicit_implied_const_bounds[def_id]
<- self.tcx.explicit_implied_const_bounds(def_id).skip_binder());
}
}
if let DefKind::TraitAlias = def_kind {
record!(self.tables.trait_def[def_id] <- self.tcx.trait_def(def_id));
record_defaulted_array!(self.tables.explicit_super_clauses_of[def_id] <-
self.tcx.explicit_super_clauses_of(def_id).skip_binder());
record_defaulted_array!(self.tables.explicit_implied_clauses_of[def_id] <-
self.tcx.explicit_implied_clauses_of(def_id).skip_binder());
}
if let DefKind::Trait | DefKind::Impl { .. } = def_kind {
let associated_item_def_ids = self.tcx.associated_item_def_ids(def_id);
record_array!(self.tables.associated_item_or_field_def_ids[def_id] <-
associated_item_def_ids.iter().map(|&def_id| {
assert!(def_id.is_local());
def_id.index
})
);
for &def_id in associated_item_def_ids {
self.encode_info_for_assoc_item(def_id);
}
}
if let DefKind::Closure | DefKind::SyntheticCoroutineBody = def_kind
&& let Some(coroutine_kind) = self.tcx.coroutine_kind(def_id)
{
self.tables.coroutine_kind.set(def_id.index, Some(coroutine_kind))
}
if def_kind == DefKind::Closure
&& tcx.type_of(def_id).skip_binder().is_coroutine_closure()
{
let coroutine_for_closure = self.tcx.coroutine_for_closure(def_id);
self.tables
.coroutine_for_closure
.set_some(def_id.index, coroutine_for_closure.into());
// If this async closure has a by-move body, record it too.
if tcx.needs_coroutine_by_move_body_def_id(coroutine_for_closure) {
self.tables.coroutine_by_move_body_def_id.set_some(
coroutine_for_closure.index,
self.tcx.coroutine_by_move_body_def_id(coroutine_for_closure).into(),
);
}
}
if let DefKind::Static { .. } = def_kind {
if !self.tcx.is_foreign_item(def_id) {
match self.tcx.eval_static_initializer(def_id) {
Ok(data) => record!(self.tables.eval_static_initializer[def_id] <- data),
Err(err) => match err {
interpret::ErrorHandled::Reported(_, _) => {
self.tcx.dcx().delayed_bug(format!(
"eval_static_initializer returned an error in metadata emission"
));
}
interpret::ErrorHandled::TooGeneric(span) => {
span_bug!(span, "generic static???");
}
},
};
}
}
if let DefKind::Enum | DefKind::Struct | DefKind::Union = def_kind {
self.encode_info_for_adt(local_id);
}
if let DefKind::Mod = def_kind {
self.encode_info_for_mod(local_id);
}
if let DefKind::Macro(_) = def_kind {
self.encode_info_for_macro(local_id);
}
if let DefKind::TyAlias = def_kind {
self.tables
.type_alias_is_checked
.set(def_id.index, self.tcx.type_alias_is_checked(def_id));
if self.tcx.type_alias_is_checked(def_id) {
record!(self.tables.args_known_to_outlive_alias_params[def_id] <- tcx.args_known_to_outlive_alias_params(def_id));
}
}
if let DefKind::OpaqueTy = def_kind {
self.encode_explicit_item_bounds(def_id);
self.encode_explicit_item_self_bounds(def_id);
record!(self.tables.opaque_ty_origin[def_id] <- self.tcx.opaque_ty_origin(def_id));
self.encode_precise_capturing_args(def_id);
if tcx.is_conditionally_const(def_id) {
record_defaulted_array!(self.tables.explicit_implied_const_bounds[def_id]
<- tcx.explicit_implied_const_bounds(def_id).skip_binder());
}
record!(self.tables.args_known_to_outlive_alias_params[def_id] <- tcx.args_known_to_outlive_alias_params(def_id));
}
if let DefKind::AssocTy = def_kind {
let assoc_item = tcx.associated_item(def_id);
match assoc_item.container {
ty::AssocContainer::Trait => {
record!(self.tables.args_known_to_outlive_alias_params[def_id] <- tcx.args_known_to_outlive_alias_params(def_id));
}
ty::AssocContainer::InherentImpl => {
record!(self.tables.args_known_to_outlive_alias_params[def_id] <- tcx.args_known_to_outlive_alias_params(def_id));
}
ty::AssocContainer::TraitImpl(_) => {}
}
}
if let DefKind::AnonConst = def_kind {
record!(self.tables.anon_const_kind[def_id] <- self.tcx.anon_const_kind(def_id));
}
if let DefKind::Const | DefKind::AssocConst = def_kind {
record!(self.tables.const_of_item[def_id] <- self.tcx.const_of_item(def_id));
}
if tcx.impl_method_has_trait_impl_trait_tys(def_id)
&& let Ok(table) = self.tcx.collect_return_position_impl_trait_in_trait_tys(def_id)
{
record!(self.tables.collect_return_position_impl_trait_in_trait_tys[def_id] <- table);
}
if let DefKind::Impl { .. } | DefKind::Trait = def_kind {
let table = tcx.associated_types_for_impl_traits_in_trait_or_impl(def_id);
record!(self.tables.associated_types_for_impl_traits_in_trait_or_impl[def_id] <- table);
}
}
for (def_id, impls) in &tcx.crate_inherent_impls(()).0.inherent_impls {
record_defaulted_array!(self.tables.inherent_impls[def_id.to_def_id()] <- impls.iter().map(|def_id| {
assert!(def_id.is_local());
def_id.index
}));
}
for (def_id, res_map) in &tcx.resolutions(()).doc_link_resolutions {
record!(self.tables.doc_link_resolutions[def_id.to_def_id()] <- res_map);
}
for (def_id, traits) in &tcx.resolutions(()).doc_link_traits_in_scope {
record_array!(self.tables.doc_link_traits_in_scope[def_id.to_def_id()] <- traits);
}
}
fn encode_externally_implementable_items(&mut self) -> LazyArray<EiiMapEncodedKeyValue> {
empty_proc_macro!(self);
let externally_implementable_items = self.tcx.externally_implementable_items(LOCAL_CRATE);
self.lazy_array(externally_implementable_items.iter().map(
|(foreign_item, (decl, impls))| {
(
*foreign_item,
(decl.clone(), impls.iter().map(|(impl_did, i)| (*impl_did, *i)).collect()),
)
},
))
}
#[instrument(level = "trace", skip(self))]
fn encode_info_for_adt(&mut self, local_def_id: LocalDefId) {
let def_id = local_def_id.to_def_id();
let tcx = self.tcx;
let adt_def = tcx.adt_def(def_id);
record!(self.tables.repr_options[def_id] <- adt_def.repr());
let params_in_repr = self.tcx.params_in_repr(def_id);
record!(self.tables.params_in_repr[def_id] <- params_in_repr);
if adt_def.is_enum() {
let module_children = tcx.module_children_local(local_def_id);
record_array!(self.tables.module_children_non_reexports[def_id] <-
module_children.iter().map(|child| child.res.def_id().index));
} else {
// For non-enum, there is only one variant, and its def_id is the adt's.
debug_assert_eq!(adt_def.variants().len(), 1);
debug_assert_eq!(adt_def.non_enum_variant().def_id, def_id);
// Therefore, the loop over variants will encode its fields as the adt's children.
}
for (idx, variant) in adt_def.variants().iter_enumerated() {
let data = VariantData {
discr: variant.discr,
idx,
ctor: variant.ctor.map(|(kind, def_id)| (kind, def_id.index)),
is_non_exhaustive: variant.is_field_list_non_exhaustive(),
};
record!(self.tables.variant_data[variant.def_id] <- data);
record_array!(self.tables.associated_item_or_field_def_ids[variant.def_id] <- variant.fields.iter().map(|f| {
assert!(f.did.is_local());
f.did.index
}));
for field in &variant.fields {
self.tables.safety.set(field.did.index, field.safety);
record!(
self.tables.mut_restriction[field.did] <- field.mut_restriction
);
}
if let Some((CtorKind::Fn, ctor_def_id)) = variant.ctor {
let fn_sig = tcx.fn_sig(ctor_def_id);
// FIXME only encode signature for ctor_def_id
record!(self.tables.fn_sig[variant.def_id] <- fn_sig);
}
}
if let Some(destructor) = tcx.adt_destructor(local_def_id) {
record!(self.tables.adt_destructor[def_id] <- destructor);
}
if let Some(destructor) = tcx.adt_async_destructor(local_def_id) {
record!(self.tables.adt_async_destructor[def_id] <- destructor);
}
}
#[instrument(level = "debug", skip(self))]
fn encode_info_for_mod(&mut self, local_def_id: LocalDefId) {
let tcx = self.tcx;
let def_id = local_def_id.to_def_id();
// If we are encoding a proc-macro crates, `encode_info_for_mod` will
// only ever get called for the crate root. We still want to encode
// the crate root for consistency with other crates (some of the resolver
// code uses it). However, we skip encoding anything relating to child
// items - we encode information about proc-macros later on.
if self.is_proc_macro {
// Encode this here because we don't do it in encode_def_ids.
record!(self.tables.expn_that_defined[def_id] <- tcx.expn_that_defined(local_def_id));
} else {
let module_children = tcx.module_children_local(local_def_id);
record_array!(self.tables.module_children_non_reexports[def_id] <-
module_children.iter().filter(|child| child.reexport_chain.is_empty())
.map(|child| child.res.def_id().index));
record_defaulted_array!(self.tables.module_children_reexports[def_id] <-
module_children.iter().filter(|child| !child.reexport_chain.is_empty()));
let ambig_module_children = tcx
.resolutions(())
.ambig_module_children
.get(&local_def_id)
.map_or_default(|v| &v[..]);
record_defaulted_array!(self.tables.ambig_module_children[def_id] <-
ambig_module_children);
}
}
fn encode_explicit_item_bounds(&mut self, def_id: DefId) {
debug!("EncodeContext::encode_explicit_item_bounds({:?})", def_id);
let bounds = self.tcx.explicit_item_bounds(def_id).skip_binder();
record_defaulted_array!(self.tables.explicit_item_bounds[def_id] <- bounds);
}
fn encode_explicit_item_self_bounds(&mut self, def_id: DefId) {
debug!("EncodeContext::encode_explicit_item_self_bounds({:?})", def_id);
let bounds = self.tcx.explicit_item_self_bounds(def_id).skip_binder();
record_defaulted_array!(self.tables.explicit_item_self_bounds[def_id] <- bounds);
}
#[instrument(level = "debug", skip(self))]
fn encode_info_for_assoc_item(&mut self, def_id: DefId) {
let tcx = self.tcx;
let item = tcx.associated_item(def_id);
if matches!(item.container, AssocContainer::Trait | AssocContainer::TraitImpl(_)) {
self.tables.defaultness.set(def_id.index, item.defaultness(tcx));
}
record!(self.tables.assoc_container[def_id] <- item.container);
if let AssocContainer::Trait = item.container
&& item.is_type()
{
self.encode_explicit_item_bounds(def_id);
self.encode_explicit_item_self_bounds(def_id);
if tcx.is_conditionally_const(def_id) {
record_defaulted_array!(self.tables.explicit_implied_const_bounds[def_id]
<- self.tcx.explicit_implied_const_bounds(def_id).skip_binder());
}
}
if let ty::AssocKind::Type { data: ty::AssocTypeData::Rpitit(rpitit_info) } = item.kind {
record!(self.tables.opt_rpitit_info[def_id] <- rpitit_info);
if matches!(rpitit_info, ty::ImplTraitInTraitData::Trait { .. }) {
record_array!(
self.tables.assumed_wf_types_for_rpitit[def_id]
<- self.tcx.assumed_wf_types_for_rpitit(def_id)
);
self.encode_precise_capturing_args(def_id);
}
}
}
fn encode_precise_capturing_args(&mut self, def_id: DefId) {
let Some(precise_capturing_args) = self.tcx.rendered_precise_capturing_args(def_id) else {
return;
};
record_array!(self.tables.rendered_precise_capturing_args[def_id] <- precise_capturing_args);
}
fn encode_mir(&mut self) {
if self.is_proc_macro {
return;
}
let tcx = self.tcx;
let reachable_set = tcx.reachable_set(());
let keys_and_jobs = tcx.mir_keys(()).iter().filter_map(|&def_id| {
let (encode_const, encode_opt) = should_encode_mir(tcx, reachable_set, def_id);
if encode_const || encode_opt { Some((def_id, encode_const, encode_opt)) } else { None }
});
for (def_id, encode_const, encode_opt) in keys_and_jobs {
debug_assert!(encode_const || encode_opt);
debug!("EntryBuilder::encode_mir({:?})", def_id);
if encode_opt {
record!(self.tables.optimized_mir[def_id.to_def_id()] <- tcx.optimized_mir(def_id));
self.tables
.cross_crate_inlinable
.set(def_id.to_def_id().index, self.tcx.cross_crate_inlinable(def_id));
record!(self.tables.closure_saved_names_of_captured_variables[def_id.to_def_id()]
<- tcx.closure_saved_names_of_captured_variables(def_id));
if self.tcx.is_coroutine(def_id.to_def_id())
&& let Some(witnesses) = tcx.mir_coroutine_witnesses(def_id)
{
record!(self.tables.mir_coroutine_witnesses[def_id.to_def_id()] <- witnesses);
}
}
let mut is_trivial = false;
if encode_const {
if let Some((val, ty)) = tcx.trivial_const(def_id) {
is_trivial = true;
record!(self.tables.trivial_const[def_id.to_def_id()] <- (val, ty));
} else {
is_trivial = false;
record!(self.tables.mir_for_ctfe[def_id.to_def_id()] <- tcx.mir_for_ctfe(def_id));
}
// FIXME(generic_const_exprs): this feels wrong to have in `encode_mir`
let abstract_const = tcx.thir_abstract_const(def_id);
if let Ok(Some(abstract_const)) = abstract_const {
record!(self.tables.thir_abstract_const[def_id.to_def_id()] <- abstract_const);
}
if should_encode_const(tcx.def_kind(def_id)) {
let qualifs = tcx.mir_const_qualif(def_id);
record!(self.tables.mir_const_qualif[def_id.to_def_id()] <- qualifs);
let body = tcx.hir_maybe_body_owned_by(def_id);
if let Some(body) = body {
let const_data = rendered_const(self.tcx, &body, def_id);
record!(self.tables.rendered_const[def_id.to_def_id()] <- const_data);
}
}
}
if !is_trivial {
record!(self.tables.promoted_mir[def_id.to_def_id()] <- tcx.promoted_mir(def_id));
}
if self.tcx.is_coroutine(def_id.to_def_id())
&& let Some(witnesses) = tcx.mir_coroutine_witnesses(def_id)
{
record!(self.tables.mir_coroutine_witnesses[def_id.to_def_id()] <- witnesses);
}
}
// Encode all the deduced parameter attributes for everything that has MIR, even for items
// that can't be inlined. But don't if we aren't optimizing in non-incremental mode, to
// save the query traffic.
if tcx.sess.opts.output_types.should_codegen()
&& tcx.sess.opts.optimize != OptLevel::No
&& tcx.sess.opts.incremental.is_none()
{
for &local_def_id in tcx.mir_keys(()) {
if let DefKind::AssocFn | DefKind::Fn = tcx.def_kind(local_def_id) {
record_array!(self.tables.deduced_param_attrs[local_def_id.to_def_id()] <-
self.tcx.deduced_param_attrs(local_def_id.to_def_id()));
}
}
}
}
#[instrument(level = "debug", skip(self))]
fn encode_stability(&mut self, def_id: DefId) {
// The query lookup can take a measurable amount of time in crates with many items. Check if
// the stability attributes are even enabled before using their queries.
if self.feat.staged_api() || self.tcx.sess.opts.unstable_opts.force_unstable_if_unmarked {
if let Some(stab) = self.tcx.lookup_stability(def_id) {
record!(self.tables.lookup_stability[def_id] <- stab)
}
}
}
#[instrument(level = "debug", skip(self))]
fn encode_const_stability(&mut self, def_id: DefId) {
// The query lookup can take a measurable amount of time in crates with many items. Check if
// the stability attributes are even enabled before using their queries.
if self.feat.staged_api() || self.tcx.sess.opts.unstable_opts.force_unstable_if_unmarked {
if let Some(stab) = self.tcx.lookup_const_stability(def_id) {
record!(self.tables.lookup_const_stability[def_id] <- stab)
}
}
}
#[instrument(level = "debug", skip(self))]
fn encode_default_body_stability(&mut self, def_id: DefId) {
// The query lookup can take a measurable amount of time in crates with many items. Check if
// the stability attributes are even enabled before using their queries.
if self.feat.staged_api() || self.tcx.sess.opts.unstable_opts.force_unstable_if_unmarked {
if let Some(stab) = self.tcx.lookup_default_body_stability(def_id) {
record!(self.tables.lookup_default_body_stability[def_id] <- stab)
}
}
}
#[instrument(level = "debug", skip(self))]
fn encode_deprecation(&mut self, def_id: DefId) {
if let Some(depr) = self.tcx.lookup_deprecation(def_id) {
record!(self.tables.lookup_deprecation_entry[def_id] <- depr);
}
}
#[instrument(level = "debug", skip(self))]
fn encode_info_for_macro(&mut self, def_id: LocalDefId) {
let tcx = self.tcx;
let (_, macro_def, _) = tcx.hir_expect_item(def_id).expect_macro();
self.tables.is_macro_rules.set(def_id.local_def_index, macro_def.macro_rules);
record!(self.tables.macro_definition[def_id.to_def_id()] <- &*macro_def.body);
}
fn encode_native_libraries(&mut self) -> LazyArray<NativeLib> {
empty_proc_macro!(self);
let used_libraries = self.tcx.native_libraries(LOCAL_CRATE);
self.lazy_array(used_libraries.iter())
}
fn encode_foreign_modules(&mut self) -> LazyArray<ForeignModule> {
empty_proc_macro!(self);
let foreign_modules = self.tcx.foreign_modules(LOCAL_CRATE);
self.lazy_array(foreign_modules.iter().map(|(_, m)| m).cloned())
}
fn encode_hygiene(&mut self) -> (SyntaxContextTable, ExpnDataTable, ExpnHashTable) {
let mut syntax_contexts: TableBuilder<_, _> = Default::default();
let mut expn_data_table: TableBuilder<_, _> = Default::default();
let mut expn_hash_table: TableBuilder<_, _> = Default::default();
HygieneEncodeContext::encode(
&Rc::clone(&self.hygiene_ctxt),
&mut (&mut *self, &mut syntax_contexts, &mut expn_data_table, &mut expn_hash_table),
|(this, syntax_contexts, _, _), index, ctxt_data| {
syntax_contexts.set_some(index, this.lazy(ctxt_data));
},
|(this, _, expn_data_table, expn_hash_table), index, expn_data, hash| {
if let Some(index) = index.as_local() {
expn_data_table
.set_some(index.as_raw(), this.lazy(expn_data.expect("local expn")));
expn_hash_table.set_some(index.as_raw(), this.lazy(hash));
}
},
);
(
syntax_contexts.encode(&mut self.opaque),
expn_data_table.encode(&mut self.opaque),
expn_hash_table.encode(&mut self.opaque),
)
}
fn encode_proc_macros(&mut self) -> Option<ProcMacroData> {
let is_proc_macro = self.tcx.crate_types().contains(&CrateType::ProcMacro);
if is_proc_macro {
let tcx = self.tcx;
let proc_macro_decls_static = tcx.proc_macro_decls_static(()).unwrap().local_def_index;
let stability = tcx.lookup_stability(CRATE_DEF_ID);
for (i, span) in self.tcx.sess.proc_macro_quoted_spans() {
let span = self.lazy(span);
self.tables.proc_macro_quoted_spans.set_some(i, span);
}
self.tables.def_kind.set_some(LOCAL_CRATE.as_def_id().index, DefKind::Mod);
record!(self.tables.def_span[LOCAL_CRATE.as_def_id()] <- tcx.def_span(LOCAL_CRATE.as_def_id()));
self.encode_attrs(LOCAL_CRATE.as_def_id().expect_local());
let vis = tcx
.local_visibility(CRATE_DEF_ID)
.map_id(|mod_id| mod_id.to_local_def_id().local_def_index);
record!(self.tables.visibility[LOCAL_CRATE.as_def_id()] <- vis);
if let Some(stability) = stability {
record!(self.tables.lookup_stability[LOCAL_CRATE.as_def_id()] <- stability);
}
self.encode_deprecation(LOCAL_CRATE.as_def_id());
if let Some(res_map) = tcx.resolutions(()).doc_link_resolutions.get(&CRATE_MOD_ID) {
record!(self.tables.doc_link_resolutions[LOCAL_CRATE.as_def_id()] <- res_map);
}
if let Some(traits) = tcx.resolutions(()).doc_link_traits_in_scope.get(&CRATE_MOD_ID) {
record_array!(self.tables.doc_link_traits_in_scope[LOCAL_CRATE.as_def_id()] <- traits);
}
let mut macros = vec![];
// Normally, this information is encoded when we walk the items
// defined in this crate. However, we skip doing that for proc-macro crates,
// so we manually encode just the information that we need
for &proc_macro in &tcx.resolutions(()).proc_macros {
let id = proc_macro;
let proc_macro = tcx.local_def_id_to_hir_id(proc_macro);
let mut name = tcx.hir_name(proc_macro);
let span = tcx.hir_span(proc_macro);
// Proc-macros may have attributes like `#[allow_internal_unstable]`,
// so downstream crates need access to them.
let attrs = tcx.hir_attrs(proc_macro);
let (macro_kind, kind) = if find_attr!(attrs, ProcMacro) {
(MacroKind::Bang, ProcMacroKind::Bang { name: name.as_str().to_owned() })
} else if find_attr!(attrs, ProcMacroAttribute) {
(MacroKind::Attr, ProcMacroKind::Attr { name: name.as_str().to_owned() })
} else if let Some((trait_name, helper_attrs)) = find_attr!(attrs,
ProcMacroDerive { trait_name, helper_attrs } => (trait_name, helper_attrs))
{
name = *trait_name;
(
MacroKind::Derive,
ProcMacroKind::CustomDerive {
trait_name: name.as_str().to_owned(),
attributes: helper_attrs
.iter()
.map(|attr| attr.as_str().to_owned())
.collect(),
},
)
} else {
bug!("Unknown proc-macro type for item {:?}", id);
};
macros.push((id.local_def_index, self.lazy(kind)));
let mut def_key = self.tcx.hir_def_key(id);
def_key.disambiguated_data.data = DefPathData::MacroNs(name);
let def_id = id.to_def_id();
self.tables.def_kind.set_some(def_id.index, DefKind::Macro(macro_kind.into()));
self.encode_attrs(id);
record!(self.tables.def_keys[def_id] <- def_key);
record!(self.tables.def_ident_span[def_id] <- span);
record!(self.tables.def_span[def_id] <- span);
record!(self.tables.visibility[def_id] <- ty::Visibility::Public);
if let Some(stability) = stability {
record!(self.tables.lookup_stability[def_id] <- stability);
}
}
let macros = self.lazy_array(macros);
Some(ProcMacroData { proc_macro_decls_static, stability, macros })
} else {
None
}
}
fn encode_debugger_visualizers(&mut self) -> LazyArray<DebuggerVisualizerFile> {
empty_proc_macro!(self);
self.lazy_array(
self.tcx
.debugger_visualizers(LOCAL_CRATE)
.iter()
// Erase the path since it may contain privacy sensitive data
// that we don't want to end up in crate metadata.
// The path is only needed for the local crate because of
// `--emit dep-info`.
.map(DebuggerVisualizerFile::path_erased),
)
}
fn encode_crate_deps(&mut self) -> LazyArray<CrateDep> {
empty_proc_macro!(self);
let deps = self
.tcx
.crates(())
.iter()
.map(|&cnum| {
let dep = CrateDep {
name: self.tcx.crate_name(cnum),
hash: self.tcx.crate_hash(cnum),
host_hash: self.tcx.crate_host_hash(cnum),
kind: self.tcx.crate_dep_kind(cnum),
extra_filename: self.tcx.extra_filename(cnum).to_owned(),
is_private: self.tcx.is_private_dep(cnum),
};
(cnum, dep)
})
.collect::<Vec<_>>();
{
// Sanity-check the crate numbers
let mut expected_cnum = 1;
for &(n, _) in &deps {
assert_eq!(n, CrateNum::new(expected_cnum));
expected_cnum += 1;
}
}
// We're just going to write a list of crate 'name-hash-version's, with
// the assumption that they are numbered 1 to n.
// FIXME (#2166): This is not nearly enough to support correct versioning
// but is enough to get transitive crate dependencies working.
self.lazy_array(deps.iter().map(|(_, dep)| dep))
}
fn encode_target_modifiers(&mut self) -> LazyArray<TargetModifier> {
empty_proc_macro!(self);
let tcx = self.tcx;
self.lazy_array(tcx.sess.opts.gather_target_modifiers())
}
fn encode_enabled_denied_partial_mitigations(&mut self) -> LazyArray<DeniedPartialMitigation> {
empty_proc_macro!(self);
let tcx = self.tcx;
self.lazy_array(tcx.sess.gather_enabled_denied_partial_mitigations())
}
fn encode_lib_features(&mut self) -> LazyArray<(Symbol, FeatureStability)> {
empty_proc_macro!(self);
let tcx = self.tcx;
let lib_features = tcx.lib_features(LOCAL_CRATE);
self.lazy_array(lib_features.to_sorted_vec())
}
fn encode_stability_implications(&mut self) -> LazyArray<(Symbol, Symbol)> {
empty_proc_macro!(self);
let tcx = self.tcx;
let implications = tcx.stability_implications(LOCAL_CRATE);
let sorted = implications.to_sorted_stable_ord();
self.lazy_array(sorted.into_iter().map(|(k, v)| (*k, *v)))
}
fn encode_canonical_symbols(&mut self) -> LazyArray<(Symbol, DefIndex)> {
empty_proc_macro!(self);
let tcx = self.tcx;
let canonical_symbols = &tcx.canonical_symbols(LOCAL_CRATE);
self.lazy_array(canonical_symbols.iter().map(|cs| (cs.symbol, cs.def_id.index)))
}
fn encode_diagnostic_items(&mut self) -> LazyArray<(Symbol, DefIndex)> {
empty_proc_macro!(self);
let tcx = self.tcx;
let diagnostic_items = &tcx.diagnostic_items(LOCAL_CRATE).name_to_id;
self.lazy_array(diagnostic_items.iter().map(|(&name, def_id)| (name, def_id.index)))
}
fn encode_fake_doc_items(&mut self) -> LazyArray<DefIndex> {
empty_proc_macro!(self);
let tcx = self.tcx;
let fake_doc_items = &tcx.fake_doc_items(LOCAL_CRATE);
self.lazy_array(fake_doc_items.iter().map(|cs| cs.index))
}
fn encode_lang_items(&mut self) -> LazyArray<(DefIndex, LangItem)> {
empty_proc_macro!(self);
let lang_items = self.tcx.lang_items().iter();
self.lazy_array(lang_items.filter_map(|(lang_item, def_id)| {
def_id.as_local().map(|id| (id.local_def_index, lang_item))
}))
}
fn encode_lang_items_missing(&mut self) -> LazyArray<LangItem> {
empty_proc_macro!(self);
let tcx = self.tcx;
self.lazy_array(&tcx.lang_items().missing)
}
fn encode_stripped_cfg_items(&mut self) -> LazyArray<StrippedCfgItem<DefIndex>> {
self.lazy_array(
self.tcx
.stripped_cfg_items(LOCAL_CRATE)
.into_iter()
.map(|item| item.clone().map_scope_id(|def_id| def_id.index)),
)
}
fn encode_traits(&mut self) -> LazyArray<DefIndex> {
empty_proc_macro!(self);
self.lazy_array(self.tcx.traits(LOCAL_CRATE).iter().map(|def_id| def_id.index))
}
/// Encodes an index, mapping each trait to its (local) implementations.
#[instrument(level = "debug", skip(self))]
fn encode_impls(&mut self) -> LazyArray<TraitImpls> {
empty_proc_macro!(self);
let tcx = self.tcx;
let mut trait_impls: FxIndexMap<DefId, Vec<(DefIndex, Option<SimplifiedType>)>> =
FxIndexMap::default();
for id in tcx.hir_free_items() {
let DefKind::Impl { of_trait } = tcx.def_kind(id.owner_id) else {
continue;
};
let def_id = id.owner_id.to_def_id();
if of_trait {
let header = tcx.impl_trait_header(def_id);
record!(self.tables.impl_trait_header[def_id] <- header);
let impl_is_fully_generic_for_reflection =
tcx.impl_is_fully_generic_for_reflection(def_id);
self.tables
.impl_is_fully_generic_for_reflection
.set(def_id.index, impl_is_fully_generic_for_reflection);
self.tables.defaultness.set(def_id.index, tcx.defaultness(def_id));
let trait_ref = header.trait_ref.instantiate_identity().skip_norm_wip();
let simplified_self_ty = fast_reject::simplify_type(
self.tcx,
trait_ref.self_ty(),
TreatParams::InstantiateWithInfer,
);
trait_impls
.entry(trait_ref.def_id)
.or_default()
.push((id.owner_id.def_id.local_def_index, simplified_self_ty));
let trait_def = tcx.trait_def(trait_ref.def_id);
if let Ok(mut an) = trait_def.ancestors(tcx, def_id)
&& let Some(specialization_graph::Node::Impl(parent)) = an.nth(1)
{
self.tables.impl_parent.set_some(def_id.index, parent.into());
}
// if this is an impl of `CoerceUnsized`, create its
// "unsized info", else just store None
if tcx.is_lang_item(trait_ref.def_id, LangItem::CoerceUnsized) {
let coerce_unsized_info = tcx.coerce_unsized_info(def_id).unwrap();
record!(self.tables.coerce_unsized_info[def_id] <- coerce_unsized_info);
}
}
}
let trait_impls: Vec<_> = trait_impls
.into_iter()
.map(|(trait_def_id, impls)| TraitImpls {
trait_id: (trait_def_id.krate.as_u32(), trait_def_id.index),
impls: self.lazy_array(&impls),
})
.collect();
self.lazy_array(&trait_impls)
}
#[instrument(level = "debug", skip(self))]
fn encode_incoherent_impls(&mut self) -> LazyArray<IncoherentImpls> {
empty_proc_macro!(self);
let tcx = self.tcx;
let all_impls: Vec<_> = tcx
.crate_inherent_impls(())
.0
.incoherent_impls
.iter()
.map(|(&simp, impls)| IncoherentImpls {
self_ty: self.lazy(simp),
impls: self.lazy_array(impls.iter().map(|def_id| def_id.local_def_index)),
})
.collect();
self.lazy_array(&all_impls)
}
fn encode_exportable_items(&mut self) -> LazyArray<DefIndex> {
empty_proc_macro!(self);
self.lazy_array(self.tcx.exportable_items(LOCAL_CRATE).iter().map(|def_id| def_id.index))
}
fn encode_stable_order_of_exportable_impls(&mut self) -> LazyArray<(DefIndex, usize)> {
empty_proc_macro!(self);
let stable_order_of_exportable_impls =
self.tcx.stable_order_of_exportable_impls(LOCAL_CRATE);
self.lazy_array(
stable_order_of_exportable_impls.iter().map(|(def_id, idx)| (def_id.index, *idx)),
)
}
// Encodes all symbols exported from this crate into the metadata.
//
// This pass is seeded off the reachability list calculated in the
// middle::reachable module but filters out items that either don't have a
// symbol associated with them (they weren't translated) or if they're an FFI
// definition (as that's not defined in this crate).
fn encode_exported_symbols(
&mut self,
exported_symbols: &[(ExportedSymbol<'tcx>, SymbolExportInfo)],
) -> LazyArray<(ExportedSymbol<'static>, SymbolExportInfo)> {
empty_proc_macro!(self);
self.lazy_array(exported_symbols.iter().cloned())
}
fn encode_dylib_dependency_formats(&mut self) -> LazyArray<Option<LinkagePreference>> {
empty_proc_macro!(self);
let formats = self.tcx.dependency_formats(());
if let Some(arr) = formats.get(&CrateType::Dylib) {
return self.lazy_array(arr.iter().skip(1 /* skip LOCAL_CRATE */).map(
|slot| match *slot {
Linkage::NotLinked | Linkage::IncludedFromDylib => None,
Linkage::Dynamic => Some(LinkagePreference::RequireDynamic),
Linkage::Static => Some(LinkagePreference::RequireStatic),
},
));
}
LazyArray::default()
}
}
/// Used to prefetch queries which will be needed later by metadata encoding.
/// Only a subset of the queries are actually prefetched to keep this code smaller.
fn prefetch_mir(tcx: TyCtxt<'_>) {
if !tcx.sess.opts.output_types.should_codegen() {
// We won't emit MIR, so don't prefetch it.
return;
}
let reachable_set = tcx.reachable_set(());
par_for_each_in(tcx.mir_keys(()), |&&def_id| {
if tcx.is_trivial_const(def_id) {
return;
}
let (encode_const, encode_opt) = should_encode_mir(tcx, reachable_set, def_id);
if encode_const {
tcx.ensure_done().mir_for_ctfe(def_id);
}
if encode_opt {
tcx.ensure_done().optimized_mir(def_id);
}
if encode_opt || encode_const {
tcx.ensure_done().promoted_mir(def_id);
}
})
}
// NOTE(eddyb) The following comment was preserved for posterity, even
// though it's no longer relevant as EBML (which uses nested & tagged
// "documents") was replaced with a scheme that can't go out of bounds.
//
// And here we run into yet another obscure archive bug: in which metadata
// loaded from archives may have trailing garbage bytes. Awhile back one of
// our tests was failing sporadically on the macOS 64-bit builders (both nopt
// and opt) by having ebml generate an out-of-bounds panic when looking at
// metadata.
//
// Upon investigation it turned out that the metadata file inside of an rlib
// (and ar archive) was being corrupted. Some compilations would generate a
// metadata file which would end in a few extra bytes, while other
// compilations would not have these extra bytes appended to the end. These
// extra bytes were interpreted by ebml as an extra tag, so they ended up
// being interpreted causing the out-of-bounds.
//
// The root cause of why these extra bytes were appearing was never
// discovered, and in the meantime the solution we're employing is to insert
// the length of the metadata to the start of the metadata. Later on this
// will allow us to slice the metadata to the precise length that we just
// generated regardless of trailing bytes that end up in it.
pub struct EncodedMetadata {
// The declaration order matters because `full_metadata` should be dropped
// before `_temp_dir`.
full_metadata: Option<Mmap>,
// This is an optional stub metadata containing only the crate header.
// The header should be very small, so we load it directly into memory.
stub_metadata: Option<Vec<u8>>,
// The path containing the metadata, to record as work product.
path: Option<Box<Path>>,
// We need to carry MaybeTempDir to avoid deleting the temporary
// directory while accessing the Mmap.
_temp_dir: Option<MaybeTempDir>,
}
impl EncodedMetadata {
#[inline]
pub fn from_path(
path: PathBuf,
stub_path: Option<PathBuf>,
temp_dir: Option<MaybeTempDir>,
) -> std::io::Result<Self> {
let file = std::fs::File::open(&path)?;
let file_metadata = file.metadata()?;
if file_metadata.len() == 0 {
return Ok(Self {
full_metadata: None,
stub_metadata: None,
path: None,
_temp_dir: None,
});
}
let full_mmap = unsafe { Some(Mmap::map(file)?) };
let stub =
if let Some(stub_path) = stub_path { Some(std::fs::read(stub_path)?) } else { None };
Ok(Self {
full_metadata: full_mmap,
stub_metadata: stub,
path: Some(path.into()),
_temp_dir: temp_dir,
})
}
#[inline]
pub fn full(&self) -> &[u8] {
&self.full_metadata.as_deref().unwrap_or_default()
}
#[inline]
pub fn stub_or_full(&self) -> &[u8] {
self.stub_metadata.as_deref().unwrap_or(self.full())
}
#[inline]
pub fn path(&self) -> Option<&Path> {
self.path.as_deref()
}
}
impl<S: Encoder> Encodable<S> for EncodedMetadata {
fn encode(&self, s: &mut S) {
self.stub_metadata.encode(s);
let slice = self.full();
slice.encode(s)
}
}
impl<D: Decoder> Decodable<D> for EncodedMetadata {
fn decode(d: &mut D) -> Self {
let stub = <Option<Vec<u8>>>::decode(d);
let len = d.read_usize();
let full_metadata = if len > 0 {
let mut mmap = MmapMut::map_anon(len).unwrap();
mmap.copy_from_slice(d.read_raw_bytes(len));
Some(mmap.make_read_only().unwrap())
} else {
None
};
Self { full_metadata, stub_metadata: stub, path: None, _temp_dir: None }
}
}
#[instrument(level = "trace", skip(tcx))]
pub fn encode_metadata(tcx: TyCtxt<'_>, path: &Path, ref_path: Option<&Path>) {
// Since encoding metadata is not in a query, and nothing is cached,
// there's no need to do dep-graph tracking for any of it.
tcx.dep_graph.assert_ignored();
// Generate the metadata stub manually, as that is a small file compared to full metadata.
if let Some(ref_path) = ref_path {
let _prof_timer = tcx.prof.verbose_generic_activity("generate_crate_metadata_stub");
with_encode_metadata_header(tcx, ref_path, |ecx| {
let header: LazyValue<CrateHeader> = ecx.lazy(CrateHeader {
name: tcx.crate_name(LOCAL_CRATE),
triple: tcx.sess.opts.target_triple.clone(),
hash: tcx.crate_hash(LOCAL_CRATE),
is_proc_macro_crate: false,
is_stub: true,
});
header.position.get()
})
}
let _prof_timer = tcx.prof.verbose_generic_activity("generate_crate_metadata");
let dep_node = tcx.metadata_dep_node();
// If the metadata dep-node is green, try to reuse the saved work product.
if tcx.dep_graph.is_fully_enabled()
&& let work_product_id =
WorkProductId::from_cgu_name(WorkProduct::METADATA_WORKPRODUCT_CGU_NAME)
&& let Some(work_product) = tcx.dep_graph.previous_work_product(&work_product_id)
&& tcx.dep_graph.try_mark_green(tcx, &dep_node).is_some()
{
let saved_path = &work_product.saved_files[OutputType::Metadata.extension()];
let incr_comp_session_dir = &tcx.incr_comp_session.unwrap().session_directory;
let source_file_in_incr_dir = &incr_comp_session_dir.join(saved_path);
debug!("copying preexisting metadata from {source_file_in_incr_dir:?} to {path:?}");
match rustc_fs_util::link_or_copy(&source_file_in_incr_dir, path) {
Ok(_) => {}
Err(err) => tcx.dcx().emit_fatal(FailCreateFileEncoder { err }),
};
return;
};
if tcx.sess.opts.jobs.frontend.is_some() {
// Prefetch some queries used by metadata encoding.
// This is not necessary for correctness, but is only done for performance reasons.
// It can be removed if it turns out to cause trouble or be detrimental to performance.
par_join(
|| prefetch_mir(tcx),
|| {
let _ = tcx.exported_non_generic_symbols(LOCAL_CRATE);
let _ = tcx.exported_generic_symbols(LOCAL_CRATE);
},
);
}
// Perform metadata encoding inside a task, so the dep-graph can check if any encoded
// information changes, and maybe reuse the work product.
tcx.dep_graph.with_task(
dep_node,
tcx,
|| {
with_encode_metadata_header(tcx, path, |ecx| {
// Encode all the entries and extra information in the crate,
// culminating in the `CrateRoot` which points to all of it.
let root = ecx.encode_crate_root();
// Flush buffer to ensure backing file has the correct size.
ecx.opaque.flush();
// Record metadata size for self-profiling
tcx.prof.artifact_size(
"crate_metadata",
"crate_metadata",
ecx.opaque.file().metadata().unwrap().len(),
);
root.position.get()
})
},
None,
);
}
fn with_encode_metadata_header(
tcx: TyCtxt<'_>,
path: &Path,
f: impl FnOnce(&mut EncodeContext<'_, '_>) -> usize,
) {
let mut encoder = opaque::FileEncoder::new(path)
.unwrap_or_else(|err| tcx.dcx().emit_fatal(FailCreateFileEncoder { err }));
encoder.emit_raw_bytes(METADATA_HEADER);
// Will be filled with the root position after encoding everything.
encoder.emit_raw_bytes(&0u64.to_le_bytes());
let source_map_files = tcx.sess.source_map().files();
let source_file_cache = (Arc::clone(&source_map_files[0]), 0);
let required_source_files = Some(FxIndexSet::default());
drop(source_map_files);
let mut ecx = EncodeContext {
opaque: encoder,
tcx,
feat: tcx.features(),
tables: Default::default(),
lazy_state: LazyState::NoNode,
span_shorthands: Default::default(),
type_shorthands: Default::default(),
predicate_shorthands: Default::default(),
source_file_cache,
interpret_allocs: Default::default(),
required_source_files,
is_proc_macro: tcx.crate_types().contains(&CrateType::ProcMacro),
hygiene_ctxt: Default::default(),
symbol_index_table: Default::default(),
};
// Encode the rustc version string in a predictable location.
rustc_version(tcx.sess.cfg_version).encode(&mut ecx);
let root_position = f(&mut ecx);
// Make sure we report any errors from writing to the file.
// If we forget this, compilation can succeed with an incomplete rmeta file,
// causing an ICE when the rmeta file is read by another compilation.
if let Err((path, err)) = ecx.opaque.finish() {
tcx.dcx().emit_fatal(FailWriteFile { path: &path, err });
}
let file = ecx.opaque.file();
if let Err(err) = encode_root_position(file, root_position) {
tcx.dcx().emit_fatal(FailWriteFile { path: ecx.opaque.path(), err });
}
}
fn encode_root_position(mut file: &File, pos: usize) -> Result<(), std::io::Error> {
// We will return to this position after writing the root position.
let pos_before_seek = file.stream_position().unwrap();
// Encode the root position.
let header = METADATA_HEADER.len();
file.seek(std::io::SeekFrom::Start(header as u64))?;
file.write_all(&pos.to_le_bytes())?;
// Return to the position where we are before writing the root position.
file.seek(std::io::SeekFrom::Start(pos_before_seek))?;
Ok(())
}
pub(crate) fn provide(providers: &mut Providers) {
*providers = Providers {
doc_link_resolutions: |tcx, def_id| {
tcx.resolutions(())
.doc_link_resolutions
.get(&def_id)
.unwrap_or_else(|| span_bug!(tcx.def_span(def_id), "no resolutions for a doc link"))
},
doc_link_traits_in_scope: |tcx, def_id| {
tcx.resolutions(()).doc_link_traits_in_scope.get(&def_id).unwrap_or_else(|| {
span_bug!(tcx.def_span(def_id), "no traits in scope for a doc link")
})
},
..*providers
}
}
/// Build a textual representation of an unevaluated constant expression.
///
/// If the const expression is too complex, an underscore `_` is returned.
/// For const arguments, it's `{ _ }` to be precise.
/// This means that the output is not necessarily valid Rust code.
///
/// Currently, only
///
/// * literals (optionally with a leading `-`)
/// * unit `()`
/// * blocks (`{ … }`) around simple expressions and
/// * paths without arguments
///
/// are considered simple enough. Simple blocks are included since they are
/// necessary to disambiguate unit from the unit type.
/// This list might get extended in the future.
///
/// Without this censoring, in a lot of cases the output would get too large
/// and verbose. Consider `match` expressions, blocks and deeply nested ADTs.
/// Further, private and `doc(hidden)` fields of structs would get leaked
/// since HIR datatypes like the `body` parameter do not contain enough
/// semantic information for this function to be able to hide them –
/// at least not without significant performance overhead.
///
/// Whenever possible, prefer to evaluate the constant first and try to
/// use a different method for pretty-printing. Ideally this function
/// should only ever be used as a fallback.
pub fn rendered_const<'tcx>(tcx: TyCtxt<'tcx>, body: &hir::Body<'_>, def_id: LocalDefId) -> String {
let value = body.value;
#[derive(PartialEq, Eq)]
enum Classification {
Literal,
Simple,
Complex,
}
use Classification::*;
fn classify(expr: &hir::Expr<'_>) -> Classification {
match &expr.kind {
hir::ExprKind::Unary(hir::UnOp::Neg, expr) => {
if matches!(expr.kind, hir::ExprKind::Lit(_)) { Literal } else { Complex }
}
hir::ExprKind::Lit(_) => Literal,
hir::ExprKind::Tup([]) => Simple,
hir::ExprKind::Block(hir::Block { stmts: [], expr: Some(expr), .. }, _) => {
if classify(expr) == Complex { Complex } else { Simple }
}
// Paths with a self-type or arguments are too “complex” following our measure since
// they may leak private fields of structs (with feature `adt_const_params`).
// Consider: `<Self as Trait<{ Struct { private: () } }>>::CONSTANT`.
// Paths without arguments are definitely harmless though.
hir::ExprKind::Path(hir::QPath::Resolved(_, hir::Path { segments, .. })) => {
if segments.iter().all(|segment| segment.args.is_none()) { Simple } else { Complex }
}
// FIXME: Claiming that those kinds of QPaths are simple is probably not true if the Ty
// contains const arguments. Is there a *concise* way to check for this?
hir::ExprKind::Path(hir::QPath::TypeRelative(..)) => Simple,
_ => Complex,
}
}
match classify(value) {
// For non-macro literals, we avoid invoking the pretty-printer and use the source snippet
// instead to preserve certain stylistic choices the user likely made for the sake of
// legibility, like:
//
// * hexadecimal notation
// * underscores
// * character escapes
//
// FIXME: This passes through `-/*spacer*/0` verbatim.
Literal
if !value.span.from_expansion()
&& let Ok(snippet) = tcx.sess.source_map().span_to_snippet(value.span) =>
{
snippet
}
// Otherwise we prefer pretty-printing to get rid of extraneous whitespace, comments and
// other formatting artifacts.
Literal | Simple => id_to_string(&tcx, body.id().hir_id),
// FIXME: Omit the curly braces if the enclosing expression is an array literal
// with a repeated element (an `ExprKind::Repeat`) as in such case it
// would not actually need any disambiguation.
Complex => {
if tcx.def_kind(def_id) == DefKind::AnonConst {
"{ _ }".to_owned()
} else {
"_".to_owned()
}
}
}
}