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//! Diagnostics creation and emission for `rustc`.
//!
//! This module contains the code for creating and emitting diagnostics.
// tidy-alphabetical-start
#![allow(internal_features)]
#![allow(rustc::diagnostic_outside_of_impl)]
#![allow(rustc::direct_use_of_rustc_type_ir)]
#![allow(rustc::untranslatable_diagnostic)]
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
#![doc(rust_logo)]
#![feature(array_windows)]
#![feature(assert_matches)]
#![feature(associated_type_defaults)]
#![feature(box_patterns)]
#![feature(default_field_values)]
#![feature(error_reporter)]
#![feature(negative_impls)]
#![feature(never_type)]
#![feature(rustc_attrs)]
#![feature(rustdoc_internals)]
#![feature(try_blocks)]
#![feature(yeet_expr)]
// tidy-alphabetical-end
extern crate self as rustc_errors;
use std::assert_matches::assert_matches;
use std::backtrace::{Backtrace, BacktraceStatus};
use std::borrow::Cow;
use std::cell::Cell;
use std::error::Report;
use std::ffi::OsStr;
use std::hash::Hash;
use std::io::Write;
use std::num::NonZero;
use std::ops::DerefMut;
use std::path::{Path, PathBuf};
use std::{fmt, panic};
use Level::*;
// Used by external projects such as `rust-gpu`.
// See https://github.com/rust-lang/rust/pull/115393.
pub use anstream::{AutoStream, ColorChoice};
pub use anstyle::{
Ansi256Color, AnsiColor, Color, EffectIter, Effects, Reset, RgbColor, Style as Anstyle,
};
pub use codes::*;
pub use decorate_diag::{BufferedEarlyLint, DecorateDiagCompat, LintBuffer};
pub use diagnostic::{
BugAbort, Diag, DiagArgMap, DiagInner, DiagStyledString, Diagnostic, EmissionGuarantee,
FatalAbort, LintDiagnostic, LintDiagnosticBox, StringPart, Subdiag, Subdiagnostic,
};
pub use diagnostic_impls::{
DiagSymbolList, ElidedLifetimeInPathSubdiag, ExpectedLifetimeParameter,
IndicateAnonymousLifetime, SingleLabelManySpans,
};
pub use emitter::ColorConfig;
use emitter::{ConfusionType, DynEmitter, Emitter, detect_confusion_type, is_different};
use rustc_data_structures::AtomicRef;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
use rustc_data_structures::stable_hasher::StableHasher;
use rustc_data_structures::sync::{DynSend, Lock};
pub use rustc_error_messages::{
DiagArg, DiagArgFromDisplay, DiagArgName, DiagArgValue, DiagMessage, FluentBundle, IntoDiagArg,
LanguageIdentifier, LazyFallbackBundle, MultiSpan, SpanLabel, SubdiagMessage,
fallback_fluent_bundle, fluent_bundle, into_diag_arg_using_display,
};
use rustc_hashes::Hash128;
pub use rustc_lint_defs::{Applicability, listify, pluralize};
use rustc_lint_defs::{Lint, LintExpectationId};
use rustc_macros::{Decodable, Encodable};
pub use rustc_span::ErrorGuaranteed;
pub use rustc_span::fatal_error::{FatalError, FatalErrorMarker};
use rustc_span::source_map::SourceMap;
use rustc_span::{BytePos, DUMMY_SP, Loc, Span};
pub use snippet::Style;
use tracing::debug;
use crate::emitter::TimingEvent;
use crate::registry::Registry;
use crate::timings::TimingRecord;
pub mod annotate_snippet_emitter_writer;
pub mod codes;
mod decorate_diag;
mod diagnostic;
mod diagnostic_impls;
pub mod emitter;
pub mod error;
pub mod json;
mod lock;
pub mod markdown;
pub mod registry;
mod snippet;
mod styled_buffer;
#[cfg(test)]
mod tests;
pub mod timings;
pub mod translation;
pub type PResult<'a, T> = Result<T, Diag<'a>>;
rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
// `PResult` is used a lot. Make sure it doesn't unintentionally get bigger.
#[cfg(target_pointer_width = "64")]
rustc_data_structures::static_assert_size!(PResult<'_, ()>, 24);
#[cfg(target_pointer_width = "64")]
rustc_data_structures::static_assert_size!(PResult<'_, bool>, 24);
/// Used to avoid depending on `rustc_middle` in `rustc_attr_parsing`.
/// Always the `TyCtxt`.
pub trait LintEmitter: Copy {
type Id: Copy;
#[track_caller]
fn emit_node_span_lint(
self,
lint: &'static Lint,
hir_id: Self::Id,
span: impl Into<MultiSpan>,
decorator: impl for<'a> LintDiagnostic<'a, ()> + DynSend + 'static,
);
}
#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, Encodable, Decodable)]
pub enum SuggestionStyle {
/// Hide the suggested code when displaying this suggestion inline.
HideCodeInline,
/// Always hide the suggested code but display the message.
HideCodeAlways,
/// Do not display this suggestion in the cli output, it is only meant for tools.
CompletelyHidden,
/// Always show the suggested code.
/// This will *not* show the code if the suggestion is inline *and* the suggested code is
/// empty.
ShowCode,
/// Always show the suggested code independently.
ShowAlways,
}
impl SuggestionStyle {
fn hide_inline(&self) -> bool {
!matches!(*self, SuggestionStyle::ShowCode)
}
}
/// Represents the help messages seen on a diagnostic.
#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
pub enum Suggestions {
/// Indicates that new suggestions can be added or removed from this diagnostic.
///
/// `DiagInner`'s new_* methods initialize the `suggestions` field with
/// this variant. Also, this is the default variant for `Suggestions`.
Enabled(Vec<CodeSuggestion>),
/// Indicates that suggestions cannot be added or removed from this diagnostic.
///
/// Gets toggled when `.seal_suggestions()` is called on the `DiagInner`.
Sealed(Box<[CodeSuggestion]>),
/// Indicates that no suggestion is available for this diagnostic.
///
/// Gets toggled when `.disable_suggestions()` is called on the `DiagInner`.
Disabled,
}
impl Suggestions {
/// Returns the underlying list of suggestions.
pub fn unwrap_tag(self) -> Vec<CodeSuggestion> {
match self {
Suggestions::Enabled(suggestions) => suggestions,
Suggestions::Sealed(suggestions) => suggestions.into_vec(),
Suggestions::Disabled => Vec::new(),
}
}
}
impl Default for Suggestions {
fn default() -> Self {
Self::Enabled(vec![])
}
}
#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
pub struct CodeSuggestion {
/// Each substitute can have multiple variants due to multiple
/// applicable suggestions
///
/// `foo.bar` might be replaced with `a.b` or `x.y` by replacing
/// `foo` and `bar` on their own:
///
/// ```ignore (illustrative)
/// vec![
/// Substitution { parts: vec![(0..3, "a"), (4..7, "b")] },
/// Substitution { parts: vec![(0..3, "x"), (4..7, "y")] },
/// ]
/// ```
///
/// or by replacing the entire span:
///
/// ```ignore (illustrative)
/// vec![
/// Substitution { parts: vec![(0..7, "a.b")] },
/// Substitution { parts: vec![(0..7, "x.y")] },
/// ]
/// ```
pub substitutions: Vec<Substitution>,
pub msg: DiagMessage,
/// Visual representation of this suggestion.
pub style: SuggestionStyle,
/// Whether or not the suggestion is approximate
///
/// Sometimes we may show suggestions with placeholders,
/// which are useful for users but not useful for
/// tools like rustfix
pub applicability: Applicability,
}
#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
/// See the docs on `CodeSuggestion::substitutions`
pub struct Substitution {
pub parts: Vec<SubstitutionPart>,
}
#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
pub struct SubstitutionPart {
pub span: Span,
pub snippet: String,
}
#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
pub struct TrimmedSubstitutionPart {
pub original_span: Span,
pub span: Span,
pub snippet: String,
}
/// Used to translate between `Span`s and byte positions within a single output line in highlighted
/// code of structured suggestions.
#[derive(Debug, Clone, Copy)]
pub(crate) struct SubstitutionHighlight {
start: usize,
end: usize,
}
impl SubstitutionPart {
/// Try to turn a replacement into an addition when the span that is being
/// overwritten matches either the prefix or suffix of the replacement.
fn trim_trivial_replacements(self, sm: &SourceMap) -> TrimmedSubstitutionPart {
let mut trimmed_part = TrimmedSubstitutionPart {
original_span: self.span,
span: self.span,
snippet: self.snippet,
};
if trimmed_part.snippet.is_empty() {
return trimmed_part;
}
let Ok(snippet) = sm.span_to_snippet(trimmed_part.span) else {
return trimmed_part;
};
if let Some((prefix, substr, suffix)) = as_substr(&snippet, &trimmed_part.snippet) {
trimmed_part.span = Span::new(
trimmed_part.span.lo() + BytePos(prefix as u32),
trimmed_part.span.hi() - BytePos(suffix as u32),
trimmed_part.span.ctxt(),
trimmed_part.span.parent(),
);
trimmed_part.snippet = substr.to_string();
}
trimmed_part
}
}
impl TrimmedSubstitutionPart {
pub fn is_addition(&self, sm: &SourceMap) -> bool {
!self.snippet.is_empty() && !self.replaces_meaningful_content(sm)
}
pub fn is_deletion(&self, sm: &SourceMap) -> bool {
self.snippet.trim().is_empty() && self.replaces_meaningful_content(sm)
}
pub fn is_replacement(&self, sm: &SourceMap) -> bool {
!self.snippet.is_empty() && self.replaces_meaningful_content(sm)
}
/// Whether this is a replacement that overwrites source with a snippet
/// in a way that isn't a superset of the original string. For example,
/// replacing "abc" with "abcde" is not destructive, but replacing it
/// it with "abx" is, since the "c" character is lost.
pub fn is_destructive_replacement(&self, sm: &SourceMap) -> bool {
self.is_replacement(sm)
&& !sm
.span_to_snippet(self.span)
.is_ok_and(|snippet| as_substr(snippet.trim(), self.snippet.trim()).is_some())
}
fn replaces_meaningful_content(&self, sm: &SourceMap) -> bool {
sm.span_to_snippet(self.span)
.map_or(!self.span.is_empty(), |snippet| !snippet.trim().is_empty())
}
}
/// Given an original string like `AACC`, and a suggestion like `AABBCC`, try to detect
/// the case where a substring of the suggestion is "sandwiched" in the original, like
/// `BB` is. Return the length of the prefix, the "trimmed" suggestion, and the length
/// of the suffix.
fn as_substr<'a>(original: &'a str, suggestion: &'a str) -> Option<(usize, &'a str, usize)> {
let common_prefix = original
.chars()
.zip(suggestion.chars())
.take_while(|(c1, c2)| c1 == c2)
.map(|(c, _)| c.len_utf8())
.sum();
let original = &original[common_prefix..];
let suggestion = &suggestion[common_prefix..];
if suggestion.ends_with(original) {
let common_suffix = original.len();
Some((common_prefix, &suggestion[..suggestion.len() - original.len()], common_suffix))
} else {
None
}
}
impl CodeSuggestion {
/// Returns the assembled code suggestions, whether they should be shown with an underline
/// and whether the substitution only differs in capitalization.
pub(crate) fn splice_lines(
&self,
sm: &SourceMap,
) -> Vec<(String, Vec<TrimmedSubstitutionPart>, Vec<Vec<SubstitutionHighlight>>, ConfusionType)>
{
// For the `Vec<Vec<SubstitutionHighlight>>` value, the first level of the vector
// corresponds to the output snippet's lines, while the second level corresponds to the
// substrings within that line that should be highlighted.
use rustc_span::{CharPos, Pos};
/// Extracts a substring from the provided `line_opt` based on the specified low and high
/// indices, appends it to the given buffer `buf`, and returns the count of newline
/// characters in the substring for accurate highlighting. If `line_opt` is `None`, a
/// newline character is appended to the buffer, and 0 is returned.
///
/// ## Returns
///
/// The count of newline characters in the extracted substring.
fn push_trailing(
buf: &mut String,
line_opt: Option<&Cow<'_, str>>,
lo: &Loc,
hi_opt: Option<&Loc>,
) -> usize {
let mut line_count = 0;
// Convert CharPos to Usize, as CharPose is character offset
// Extract low index and high index
let (lo, hi_opt) = (lo.col.to_usize(), hi_opt.map(|hi| hi.col.to_usize()));
if let Some(line) = line_opt {
if let Some(lo) = line.char_indices().map(|(i, _)| i).nth(lo) {
// Get high index while account for rare unicode and emoji with char_indices
let hi_opt = hi_opt.and_then(|hi| line.char_indices().map(|(i, _)| i).nth(hi));
match hi_opt {
// If high index exist, take string from low to high index
Some(hi) if hi > lo => {
// count how many '\n' exist
line_count = line[lo..hi].matches('\n').count();
buf.push_str(&line[lo..hi])
}
Some(_) => (),
// If high index absence, take string from low index till end string.len
None => {
// count how many '\n' exist
line_count = line[lo..].matches('\n').count();
buf.push_str(&line[lo..])
}
}
}
// If high index is None
if hi_opt.is_none() {
buf.push('\n');
}
}
line_count
}
assert!(!self.substitutions.is_empty());
self.substitutions
.iter()
.filter(|subst| {
// Suggestions coming from macros can have malformed spans. This is a heavy
// handed approach to avoid ICEs by ignoring the suggestion outright.
let invalid = subst.parts.iter().any(|item| sm.is_valid_span(item.span).is_err());
if invalid {
debug!("splice_lines: suggestion contains an invalid span: {:?}", subst);
}
!invalid
})
.cloned()
.filter_map(|mut substitution| {
// Assumption: all spans are in the same file, and all spans
// are disjoint. Sort in ascending order.
substitution.parts.sort_by_key(|part| part.span.lo());
// Find the bounding span.
let lo = substitution.parts.iter().map(|part| part.span.lo()).min()?;
let hi = substitution.parts.iter().map(|part| part.span.hi()).max()?;
let bounding_span = Span::with_root_ctxt(lo, hi);
// The different spans might belong to different contexts, if so ignore suggestion.
let lines = sm.span_to_lines(bounding_span).ok()?;
assert!(!lines.lines.is_empty() || bounding_span.is_dummy());
// We can't splice anything if the source is unavailable.
if !sm.ensure_source_file_source_present(&lines.file) {
return None;
}
let mut highlights = vec![];
// To build up the result, we do this for each span:
// - push the line segment trailing the previous span
// (at the beginning a "phantom" span pointing at the start of the line)
// - push lines between the previous and current span (if any)
// - if the previous and current span are not on the same line
// push the line segment leading up to the current span
// - splice in the span substitution
//
// Finally push the trailing line segment of the last span
let sf = &lines.file;
let mut prev_hi = sm.lookup_char_pos(bounding_span.lo());
prev_hi.col = CharPos::from_usize(0);
let mut prev_line =
lines.lines.get(0).and_then(|line0| sf.get_line(line0.line_index));
let mut buf = String::new();
let mut line_highlight = vec![];
// We need to keep track of the difference between the existing code and the added
// or deleted code in order to point at the correct column *after* substitution.
let mut acc = 0;
let mut confusion_type = ConfusionType::None;
let trimmed_parts = substitution
.parts
.into_iter()
// If this is a replacement of, e.g. `"a"` into `"ab"`, adjust the
// suggestion and snippet to look as if we just suggested to add
// `"b"`, which is typically much easier for the user to understand.
.map(|part| part.trim_trivial_replacements(sm))
.collect::<Vec<_>>();
for part in &trimmed_parts {
let part_confusion = detect_confusion_type(sm, &part.snippet, part.span);
confusion_type = confusion_type.combine(part_confusion);
let cur_lo = sm.lookup_char_pos(part.span.lo());
if prev_hi.line == cur_lo.line {
let mut count =
push_trailing(&mut buf, prev_line.as_ref(), &prev_hi, Some(&cur_lo));
while count > 0 {
highlights.push(std::mem::take(&mut line_highlight));
acc = 0;
count -= 1;
}
} else {
acc = 0;
highlights.push(std::mem::take(&mut line_highlight));
let mut count = push_trailing(&mut buf, prev_line.as_ref(), &prev_hi, None);
while count > 0 {
highlights.push(std::mem::take(&mut line_highlight));
count -= 1;
}
// push lines between the previous and current span (if any)
for idx in prev_hi.line..(cur_lo.line - 1) {
if let Some(line) = sf.get_line(idx) {
buf.push_str(line.as_ref());
buf.push('\n');
highlights.push(std::mem::take(&mut line_highlight));
}
}
if let Some(cur_line) = sf.get_line(cur_lo.line - 1) {
let end = match cur_line.char_indices().nth(cur_lo.col.to_usize()) {
Some((i, _)) => i,
None => cur_line.len(),
};
buf.push_str(&cur_line[..end]);
}
}
// Add a whole line highlight per line in the snippet.
let len: isize = part
.snippet
.split('\n')
.next()
.unwrap_or(&part.snippet)
.chars()
.map(|c| match c {
'\t' => 4,
_ => 1,
})
.sum();
if !is_different(sm, &part.snippet, part.span) {
// Account for cases where we are suggesting the same code that's already
// there. This shouldn't happen often, but in some cases for multipart
// suggestions it's much easier to handle it here than in the origin.
} else {
line_highlight.push(SubstitutionHighlight {
start: (cur_lo.col.0 as isize + acc) as usize,
end: (cur_lo.col.0 as isize + acc + len) as usize,
});
}
buf.push_str(&part.snippet);
let cur_hi = sm.lookup_char_pos(part.span.hi());
// Account for the difference between the width of the current code and the
// snippet being suggested, so that the *later* suggestions are correctly
// aligned on the screen. Note that cur_hi and cur_lo can be on different
// lines, so cur_hi.col can be smaller than cur_lo.col
acc += len - (cur_hi.col.0 as isize - cur_lo.col.0 as isize);
prev_hi = cur_hi;
prev_line = sf.get_line(prev_hi.line - 1);
for line in part.snippet.split('\n').skip(1) {
acc = 0;
highlights.push(std::mem::take(&mut line_highlight));
let end: usize = line
.chars()
.map(|c| match c {
'\t' => 4,
_ => 1,
})
.sum();
line_highlight.push(SubstitutionHighlight { start: 0, end });
}
}
highlights.push(std::mem::take(&mut line_highlight));
// if the replacement already ends with a newline, don't print the next line
if !buf.ends_with('\n') {
push_trailing(&mut buf, prev_line.as_ref(), &prev_hi, None);
}
// remove trailing newlines
while buf.ends_with('\n') {
buf.pop();
}
if highlights.iter().all(|parts| parts.is_empty()) {
None
} else {
Some((buf, trimmed_parts, highlights, confusion_type))
}
})
.collect()
}
}
/// Signifies that the compiler died with an explicit call to `.bug`
/// or `.span_bug` rather than a failed assertion, etc.
pub struct ExplicitBug;
/// Signifies that the compiler died due to a delayed bug rather than a failed
/// assertion, etc.
pub struct DelayedBugPanic;
/// A `DiagCtxt` deals with errors and other compiler output.
/// Certain errors (fatal, bug, unimpl) may cause immediate exit,
/// others log errors for later reporting.
pub struct DiagCtxt {
inner: Lock<DiagCtxtInner>,
}
#[derive(Copy, Clone)]
pub struct DiagCtxtHandle<'a> {
dcx: &'a DiagCtxt,
/// Some contexts create `DiagCtxtHandle` with this field set, and thus all
/// errors emitted with it will automatically taint when emitting errors.
tainted_with_errors: Option<&'a Cell<Option<ErrorGuaranteed>>>,
}
impl<'a> std::ops::Deref for DiagCtxtHandle<'a> {
type Target = &'a DiagCtxt;
fn deref(&self) -> &Self::Target {
&self.dcx
}
}
/// This inner struct exists to keep it all behind a single lock;
/// this is done to prevent possible deadlocks in a multi-threaded compiler,
/// as well as inconsistent state observation.
struct DiagCtxtInner {
flags: DiagCtxtFlags,
registry: Registry,
/// The error guarantees from all emitted errors. The length gives the error count.
err_guars: Vec<ErrorGuaranteed>,
/// The error guarantee from all emitted lint errors. The length gives the
/// lint error count.
lint_err_guars: Vec<ErrorGuaranteed>,
/// The delayed bugs and their error guarantees.
delayed_bugs: Vec<(DelayedDiagInner, ErrorGuaranteed)>,
/// The error count shown to the user at the end.
deduplicated_err_count: usize,
/// The warning count shown to the user at the end.
deduplicated_warn_count: usize,
emitter: Box<DynEmitter>,
/// Must we produce a diagnostic to justify the use of the expensive
/// `trimmed_def_paths` function? Backtrace is the location of the call.
must_produce_diag: Option<Backtrace>,
/// Has this diagnostic context printed any diagnostics? (I.e. has
/// `self.emitter.emit_diagnostic()` been called?
has_printed: bool,
/// This flag indicates that an expected diagnostic was emitted and suppressed.
/// This is used for the `must_produce_diag` check.
suppressed_expected_diag: bool,
/// This set contains the code of all emitted diagnostics to avoid
/// emitting the same diagnostic with extended help (`--teach`) twice, which
/// would be unnecessary repetition.
taught_diagnostics: FxHashSet<ErrCode>,
/// Used to suggest rustc --explain `<error code>`
emitted_diagnostic_codes: FxIndexSet<ErrCode>,
/// This set contains a hash of every diagnostic that has been emitted by
/// this `DiagCtxt`. These hashes is used to avoid emitting the same error
/// twice.
emitted_diagnostics: FxHashSet<Hash128>,
/// Stashed diagnostics emitted in one stage of the compiler that may be
/// stolen and emitted/cancelled by other stages (e.g. to improve them and
/// add more information). All stashed diagnostics must be emitted with
/// `emit_stashed_diagnostics` by the time the `DiagCtxtInner` is dropped,
/// otherwise an assertion failure will occur.
stashed_diagnostics:
FxIndexMap<StashKey, FxIndexMap<Span, (DiagInner, Option<ErrorGuaranteed>)>>,
future_breakage_diagnostics: Vec<DiagInner>,
/// expected diagnostic will have the level `Expect` which additionally
/// carries the [`LintExpectationId`] of the expectation that can be
/// marked as fulfilled. This is a collection of all [`LintExpectationId`]s
/// that have been marked as fulfilled this way.
///
/// Emitting expectations after having stolen this field can happen. In particular, an
/// `#[expect(warnings)]` can easily make the `UNFULFILLED_LINT_EXPECTATIONS` lint expect
/// itself. To avoid needless complexity in this corner case, we tolerate failing to track
/// those expectations.
///
/// [RFC-2383]: https://rust-lang.github.io/rfcs/2383-lint-reasons.html
fulfilled_expectations: FxIndexSet<LintExpectationId>,
/// The file where the ICE information is stored. This allows delayed_span_bug backtraces to be
/// stored along side the main panic backtrace.
ice_file: Option<PathBuf>,
}
/// A key denoting where from a diagnostic was stashed.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
pub enum StashKey {
ItemNoType,
UnderscoreForArrayLengths,
EarlySyntaxWarning,
CallIntoMethod,
/// When an invalid lifetime e.g. `'2` should be reinterpreted
/// as a char literal in the parser
LifetimeIsChar,
/// Maybe there was a typo where a comma was forgotten before
/// FRU syntax
MaybeFruTypo,
CallAssocMethod,
AssociatedTypeSuggestion,
/// Query cycle detected, stashing in favor of a better error.
Cycle,
UndeterminedMacroResolution,
/// Used by `Parser::maybe_recover_trailing_expr`
ExprInPat,
/// If in the parser we detect a field expr with turbofish generic params it's possible that
/// it's a method call without parens. If later on in `hir_typeck` we find out that this is
/// the case we suppress this message and we give a better suggestion.
GenericInFieldExpr,
}
fn default_track_diagnostic<R>(diag: DiagInner, f: &mut dyn FnMut(DiagInner) -> R) -> R {
(*f)(diag)
}
/// Diagnostics emitted by `DiagCtxtInner::emit_diagnostic` are passed through this function. Used
/// for tracking by incremental, to replay diagnostics as necessary.
pub static TRACK_DIAGNOSTIC: AtomicRef<
fn(DiagInner, &mut dyn FnMut(DiagInner) -> Option<ErrorGuaranteed>) -> Option<ErrorGuaranteed>,
> = AtomicRef::new(&(default_track_diagnostic as _));
#[derive(Copy, Clone, Default)]
pub struct DiagCtxtFlags {
/// If false, warning-level lints are suppressed.
/// (rustc: see `--allow warnings` and `--cap-lints`)
pub can_emit_warnings: bool,
/// If Some, the Nth error-level diagnostic is upgraded to bug-level.
/// (rustc: see `-Z treat-err-as-bug`)
pub treat_err_as_bug: Option<NonZero<usize>>,
/// Eagerly emit delayed bugs as errors, so that the compiler debugger may
/// see all of the errors being emitted at once.
pub eagerly_emit_delayed_bugs: bool,
/// Show macro backtraces.
/// (rustc: see `-Z macro-backtrace`)
pub macro_backtrace: bool,
/// If true, identical diagnostics are reported only once.
pub deduplicate_diagnostics: bool,
/// Track where errors are created. Enabled with `-Ztrack-diagnostics`.
pub track_diagnostics: bool,
}
impl Drop for DiagCtxtInner {
fn drop(&mut self) {
// For tools using `interface::run_compiler` (e.g. rustc, rustdoc)
// stashed diagnostics will have already been emitted. But for others
// that don't use `interface::run_compiler` (e.g. rustfmt, some clippy
// lints) this fallback is necessary.
//
// Important: it is sound to produce an `ErrorGuaranteed` when stashing
// errors because they are guaranteed to be emitted here or earlier.
self.emit_stashed_diagnostics();
// Important: it is sound to produce an `ErrorGuaranteed` when emitting
// delayed bugs because they are guaranteed to be emitted here if
// necessary.
self.flush_delayed();
// Sanity check: did we use some of the expensive `trimmed_def_paths` functions
// unexpectedly, that is, without producing diagnostics? If so, for debugging purposes, we
// suggest where this happened and how to avoid it.
if !self.has_printed && !self.suppressed_expected_diag && !std::thread::panicking() {
if let Some(backtrace) = &self.must_produce_diag {
let suggestion = match backtrace.status() {
BacktraceStatus::Disabled => String::from(
"Backtraces are currently disabled: set `RUST_BACKTRACE=1` and re-run \
to see where it happened.",
),
BacktraceStatus::Captured => format!(
"This happened in the following `must_produce_diag` call's backtrace:\n\
{backtrace}",
),
_ => String::from("(impossible to capture backtrace where this happened)"),
};
panic!(
"`trimmed_def_paths` called, diagnostics were expected but none were emitted. \
Use `with_no_trimmed_paths` for debugging. {suggestion}"
);
}
}
}
}
impl DiagCtxt {
pub fn disable_warnings(mut self) -> Self {
self.inner.get_mut().flags.can_emit_warnings = false;
self
}
pub fn with_flags(mut self, flags: DiagCtxtFlags) -> Self {
self.inner.get_mut().flags = flags;
self
}
pub fn with_ice_file(mut self, ice_file: PathBuf) -> Self {
self.inner.get_mut().ice_file = Some(ice_file);
self
}
pub fn with_registry(mut self, registry: Registry) -> Self {
self.inner.get_mut().registry = registry;
self
}
pub fn new(emitter: Box<DynEmitter>) -> Self {
Self { inner: Lock::new(DiagCtxtInner::new(emitter)) }
}
pub fn make_silent(&self) {
let mut inner = self.inner.borrow_mut();
let translator = inner.emitter.translator().clone();
inner.emitter = Box::new(emitter::SilentEmitter { translator });
}
pub fn set_emitter(&self, emitter: Box<dyn Emitter + DynSend>) {
self.inner.borrow_mut().emitter = emitter;
}
/// Translate `message` eagerly with `args` to `SubdiagMessage::Eager`.
pub fn eagerly_translate<'a>(
&self,
message: DiagMessage,
args: impl Iterator<Item = DiagArg<'a>>,
) -> SubdiagMessage {
let inner = self.inner.borrow();
inner.eagerly_translate(message, args)
}
/// Translate `message` eagerly with `args` to `String`.
pub fn eagerly_translate_to_string<'a>(
&self,
message: DiagMessage,
args: impl Iterator<Item = DiagArg<'a>>,
) -> String {
let inner = self.inner.borrow();
inner.eagerly_translate_to_string(message, args)
}
// This is here to not allow mutation of flags;
// as of this writing it's used in Session::consider_optimizing and
// in tests in rustc_interface.
pub fn can_emit_warnings(&self) -> bool {
self.inner.borrow_mut().flags.can_emit_warnings
}
/// Resets the diagnostic error count as well as the cached emitted diagnostics.
///
/// NOTE: *do not* call this function from rustc. It is only meant to be called from external
/// tools that want to reuse a `Parser` cleaning the previously emitted diagnostics as well as
/// the overall count of emitted error diagnostics.
pub fn reset_err_count(&self) {
// Use destructuring so that if a field gets added to `DiagCtxtInner`, it's impossible to
// fail to update this method as well.
let mut inner = self.inner.borrow_mut();
let DiagCtxtInner {
flags: _,
registry: _,
err_guars,
lint_err_guars,
delayed_bugs,
deduplicated_err_count,
deduplicated_warn_count,
emitter: _,
must_produce_diag,
has_printed,
suppressed_expected_diag,
taught_diagnostics,
emitted_diagnostic_codes,
emitted_diagnostics,
stashed_diagnostics,
future_breakage_diagnostics,
fulfilled_expectations,
ice_file: _,
} = inner.deref_mut();
// For the `Vec`s and `HashMap`s, we overwrite with an empty container to free the
// underlying memory (which `clear` would not do).
*err_guars = Default::default();
*lint_err_guars = Default::default();
*delayed_bugs = Default::default();
*deduplicated_err_count = 0;
*deduplicated_warn_count = 0;
*must_produce_diag = None;
*has_printed = false;
*suppressed_expected_diag = false;
*taught_diagnostics = Default::default();
*emitted_diagnostic_codes = Default::default();
*emitted_diagnostics = Default::default();
*stashed_diagnostics = Default::default();
*future_breakage_diagnostics = Default::default();
*fulfilled_expectations = Default::default();
}
pub fn handle<'a>(&'a self) -> DiagCtxtHandle<'a> {
DiagCtxtHandle { dcx: self, tainted_with_errors: None }
}
/// Link this to a taintable context so that emitting errors will automatically set
/// the `Option<ErrorGuaranteed>` instead of having to do that manually at every error
/// emission site.
pub fn taintable_handle<'a>(
&'a self,
tainted_with_errors: &'a Cell<Option<ErrorGuaranteed>>,
) -> DiagCtxtHandle<'a> {
DiagCtxtHandle { dcx: self, tainted_with_errors: Some(tainted_with_errors) }
}
}
impl<'a> DiagCtxtHandle<'a> {
/// Stashes a diagnostic for possible later improvement in a different,
/// later stage of the compiler. Possible actions depend on the diagnostic
/// level:
/// - Level::Bug, Level:Fatal: not allowed, will trigger a panic.
/// - Level::Error: immediately counted as an error that has occurred, because it
/// is guaranteed to be emitted eventually. Can be later accessed with the
/// provided `span` and `key` through
/// [`DiagCtxtHandle::try_steal_modify_and_emit_err`] or
/// [`DiagCtxtHandle::try_steal_replace_and_emit_err`]. These do not allow
/// cancellation or downgrading of the error. Returns
/// `Some(ErrorGuaranteed)`.
/// - Level::DelayedBug: this does happen occasionally with errors that are
/// downgraded to delayed bugs. It is not stashed, but immediately
/// emitted as a delayed bug. This is because stashing it would cause it
/// to be counted by `err_count` which we don't want. It doesn't matter
/// that we cannot steal and improve it later, because it's not a
/// user-facing error. Returns `Some(ErrorGuaranteed)` as is normal for
/// delayed bugs.
/// - Level::Warning and lower (i.e. !is_error()): can be accessed with the
/// provided `span` and `key` through [`DiagCtxtHandle::steal_non_err()`]. This
/// allows cancelling and downgrading of the diagnostic. Returns `None`.
pub fn stash_diagnostic(
&self,
span: Span,
key: StashKey,
diag: DiagInner,
) -> Option<ErrorGuaranteed> {
let guar = match diag.level {
Bug | Fatal => {
self.span_bug(
span,
format!("invalid level in `stash_diagnostic`: {:?}", diag.level),
);
}
// We delay a bug here so that `-Ztreat-err-as-bug -Zeagerly-emit-delayed-bugs`
// can be used to create a backtrace at the stashing site instead of whenever the
// diagnostic context is dropped and thus delayed bugs are emitted.
Error => Some(self.span_delayed_bug(span, format!("stashing {key:?}"))),
DelayedBug => {
return self.inner.borrow_mut().emit_diagnostic(diag, self.tainted_with_errors);
}
ForceWarning | Warning | Note | OnceNote | Help | OnceHelp | FailureNote | Allow
| Expect => None,
};
// FIXME(Centril, #69537): Consider reintroducing panic on overwriting a stashed diagnostic
// if/when we have a more robust macro-friendly replacement for `(span, key)` as a key.
// See the PR for a discussion.
self.inner
.borrow_mut()
.stashed_diagnostics
.entry(key)
.or_default()
.insert(span.with_parent(None), (diag, guar));
guar
}
/// Steal a previously stashed non-error diagnostic with the given `Span`
/// and [`StashKey`] as the key. Panics if the found diagnostic is an
/// error.
pub fn steal_non_err(self, span: Span, key: StashKey) -> Option<Diag<'a, ()>> {
// FIXME(#120456) - is `swap_remove` correct?
let (diag, guar) = self.inner.borrow_mut().stashed_diagnostics.get_mut(&key).and_then(
|stashed_diagnostics| stashed_diagnostics.swap_remove(&span.with_parent(None)),
)?;
assert!(!diag.is_error());
assert!(guar.is_none());
Some(Diag::new_diagnostic(self, diag))
}
/// Steals a previously stashed error with the given `Span` and
/// [`StashKey`] as the key, modifies it, and emits it. Returns `None` if
/// no matching diagnostic is found. Panics if the found diagnostic's level
/// isn't `Level::Error`.
pub fn try_steal_modify_and_emit_err<F>(
self,
span: Span,
key: StashKey,
mut modify_err: F,
) -> Option<ErrorGuaranteed>
where
F: FnMut(&mut Diag<'_>),
{
// FIXME(#120456) - is `swap_remove` correct?
let err = self.inner.borrow_mut().stashed_diagnostics.get_mut(&key).and_then(
|stashed_diagnostics| stashed_diagnostics.swap_remove(&span.with_parent(None)),
);
err.map(|(err, guar)| {
// The use of `::<ErrorGuaranteed>` is safe because level is `Level::Error`.
assert_eq!(err.level, Error);
assert!(guar.is_some());
let mut err = Diag::<ErrorGuaranteed>::new_diagnostic(self, err);
modify_err(&mut err);
assert_eq!(err.level, Error);
err.emit()
})
}
/// Steals a previously stashed error with the given `Span` and
/// [`StashKey`] as the key, cancels it if found, and emits `new_err`.
/// Panics if the found diagnostic's level isn't `Level::Error`.
pub fn try_steal_replace_and_emit_err(
self,
span: Span,
key: StashKey,
new_err: Diag<'_>,
) -> ErrorGuaranteed {
// FIXME(#120456) - is `swap_remove` correct?
let old_err = self.inner.borrow_mut().stashed_diagnostics.get_mut(&key).and_then(
|stashed_diagnostics| stashed_diagnostics.swap_remove(&span.with_parent(None)),
);
match old_err {
Some((old_err, guar)) => {
assert_eq!(old_err.level, Error);
assert!(guar.is_some());
// Because `old_err` has already been counted, it can only be
// safely cancelled because the `new_err` supplants it.
Diag::<ErrorGuaranteed>::new_diagnostic(self, old_err).cancel();
}
None => {}
};
new_err.emit()
}
pub fn has_stashed_diagnostic(&self, span: Span, key: StashKey) -> bool {
let inner = self.inner.borrow();
if let Some(stashed_diagnostics) = inner.stashed_diagnostics.get(&key)
&& !stashed_diagnostics.is_empty()
{
stashed_diagnostics.contains_key(&span.with_parent(None))
} else {
false
}
}
/// Emit all stashed diagnostics.
pub fn emit_stashed_diagnostics(&self) -> Option<ErrorGuaranteed> {
self.inner.borrow_mut().emit_stashed_diagnostics()
}
/// This excludes delayed bugs.
#[inline]
pub fn err_count(&self) -> usize {
let inner = self.inner.borrow();
inner.err_guars.len()
+ inner.lint_err_guars.len()
+ inner
.stashed_diagnostics
.values()
.map(|a| a.values().filter(|(_, guar)| guar.is_some()).count())
.sum::<usize>()
}
/// This excludes lint errors and delayed bugs. Unless absolutely
/// necessary, prefer `has_errors` to this method.
pub fn has_errors_excluding_lint_errors(&self) -> Option<ErrorGuaranteed> {
self.inner.borrow().has_errors_excluding_lint_errors()
}
/// This excludes delayed bugs.
pub fn has_errors(&self) -> Option<ErrorGuaranteed> {
self.inner.borrow().has_errors()
}
/// This excludes nothing. Unless absolutely necessary, prefer `has_errors`
/// to this method.
pub fn has_errors_or_delayed_bugs(&self) -> Option<ErrorGuaranteed> {
self.inner.borrow().has_errors_or_delayed_bugs()
}
pub fn print_error_count(&self) {
let mut inner = self.inner.borrow_mut();
// Any stashed diagnostics should have been handled by
// `emit_stashed_diagnostics` by now.
assert!(inner.stashed_diagnostics.is_empty());
if inner.treat_err_as_bug() {
return;
}
let warnings = match inner.deduplicated_warn_count {
0 => Cow::from(""),
1 => Cow::from("1 warning emitted"),
count => Cow::from(format!("{count} warnings emitted")),
};
let errors = match inner.deduplicated_err_count {
0 => Cow::from(""),
1 => Cow::from("aborting due to 1 previous error"),
count => Cow::from(format!("aborting due to {count} previous errors")),
};
match (errors.len(), warnings.len()) {
(0, 0) => return,
(0, _) => {
// Use `ForceWarning` rather than `Warning` to guarantee emission, e.g. with a
// configuration like `--cap-lints allow --force-warn bare_trait_objects`.
inner.emit_diagnostic(
DiagInner::new(ForceWarning, DiagMessage::Str(warnings)),
None,
);
}
(_, 0) => {
inner.emit_diagnostic(DiagInner::new(Error, errors), self.tainted_with_errors);
}
(_, _) => {
inner.emit_diagnostic(
DiagInner::new(Error, format!("{errors}; {warnings}")),
self.tainted_with_errors,
);
}
}
let can_show_explain = inner.emitter.should_show_explain();
let are_there_diagnostics = !inner.emitted_diagnostic_codes.is_empty();
if can_show_explain && are_there_diagnostics {
let mut error_codes = inner
.emitted_diagnostic_codes
.iter()
.filter_map(|&code| {
if inner.registry.try_find_description(code).is_ok() {
Some(code.to_string())
} else {
None
}
})
.collect::<Vec<_>>();
if !error_codes.is_empty() {
error_codes.sort();
if error_codes.len() > 1 {
let limit = if error_codes.len() > 9 { 9 } else { error_codes.len() };
let msg1 = format!(
"Some errors have detailed explanations: {}{}",
error_codes[..limit].join(", "),
if error_codes.len() > 9 { "..." } else { "." }
);
let msg2 = format!(
"For more information about an error, try `rustc --explain {}`.",
&error_codes[0]
);
inner.emit_diagnostic(DiagInner::new(FailureNote, msg1), None);
inner.emit_diagnostic(DiagInner::new(FailureNote, msg2), None);
} else {
let msg = format!(
"For more information about this error, try `rustc --explain {}`.",
&error_codes[0]
);
inner.emit_diagnostic(DiagInner::new(FailureNote, msg), None);
}
}
}
}
/// This excludes delayed bugs. Used for early aborts after errors occurred
/// -- e.g. because continuing in the face of errors is likely to lead to
/// bad results, such as spurious/uninteresting additional errors -- when
/// returning an error `Result` is difficult.
pub fn abort_if_errors(&self) {
if let Some(guar) = self.has_errors() {
guar.raise_fatal();
}
}
/// `true` if we haven't taught a diagnostic with this code already.
/// The caller must then teach the user about such a diagnostic.
///
/// Used to suppress emitting the same error multiple times with extended explanation when
/// calling `-Zteach`.
pub fn must_teach(&self, code: ErrCode) -> bool {
self.inner.borrow_mut().taught_diagnostics.insert(code)
}
pub fn emit_diagnostic(&self, diagnostic: DiagInner) -> Option<ErrorGuaranteed> {
self.inner.borrow_mut().emit_diagnostic(diagnostic, self.tainted_with_errors)
}
pub fn emit_artifact_notification(&self, path: &Path, artifact_type: &str) {
self.inner.borrow_mut().emitter.emit_artifact_notification(path, artifact_type);
}
pub fn emit_timing_section_start(&self, record: TimingRecord) {
self.inner.borrow_mut().emitter.emit_timing_section(record, TimingEvent::Start);
}
pub fn emit_timing_section_end(&self, record: TimingRecord) {
self.inner.borrow_mut().emitter.emit_timing_section(record, TimingEvent::End);
}
pub fn emit_future_breakage_report(&self) {
let inner = &mut *self.inner.borrow_mut();
let diags = std::mem::take(&mut inner.future_breakage_diagnostics);
if !diags.is_empty() {
inner.emitter.emit_future_breakage_report(diags, &inner.registry);
}
}
pub fn emit_unused_externs(
&self,
lint_level: rustc_lint_defs::Level,
loud: bool,
unused_externs: &[&str],
) {
let mut inner = self.inner.borrow_mut();
// This "error" is an odd duck.
// - It's only produce with JSON output.
// - It's not emitted the usual way, via `emit_diagnostic`.
// - The `$message_type` field is "unused_externs" rather than the usual
// "diagnostic".
//
// We count it as a lint error because it has a lint level. The value
// of `loud` (which comes from "unused-externs" or
// "unused-externs-silent"), also affects whether it's treated like a
// hard error or not.
if loud && lint_level.is_error() {
// This `unchecked_error_guaranteed` is valid. It is where the
// `ErrorGuaranteed` for unused_extern errors originates.
#[allow(deprecated)]
inner.lint_err_guars.push(ErrorGuaranteed::unchecked_error_guaranteed());
inner.panic_if_treat_err_as_bug();
}
inner.emitter.emit_unused_externs(lint_level, unused_externs)
}
/// This methods steals all [`LintExpectationId`]s that are stored inside
/// [`DiagCtxtInner`] and indicate that the linked expectation has been fulfilled.
#[must_use]
pub fn steal_fulfilled_expectation_ids(&self) -> FxIndexSet<LintExpectationId> {
std::mem::take(&mut self.inner.borrow_mut().fulfilled_expectations)
}
pub fn flush_delayed(&self) {
self.inner.borrow_mut().flush_delayed();
}
/// Used when trimmed_def_paths is called and we must produce a diagnostic
/// to justify its cost.
#[track_caller]
pub fn set_must_produce_diag(&self) {
assert!(
self.inner.borrow().must_produce_diag.is_none(),
"should only need to collect a backtrace once"
);
self.inner.borrow_mut().must_produce_diag = Some(Backtrace::capture());
}
}
// This `impl` block contains only the public diagnostic creation/emission API.
//
// Functions beginning with `struct_`/`create_` create a diagnostic. Other
// functions create and emit a diagnostic all in one go.
impl<'a> DiagCtxtHandle<'a> {
// No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
// user-facing.
#[track_caller]
pub fn struct_bug(self, msg: impl Into<Cow<'static, str>>) -> Diag<'a, BugAbort> {
Diag::new(self, Bug, msg.into())
}
// No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
// user-facing.
#[track_caller]
pub fn bug(self, msg: impl Into<Cow<'static, str>>) -> ! {
self.struct_bug(msg).emit()
}
// No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
// user-facing.
#[track_caller]
pub fn struct_span_bug(
self,
span: impl Into<MultiSpan>,
msg: impl Into<Cow<'static, str>>,
) -> Diag<'a, BugAbort> {
self.struct_bug(msg).with_span(span)
}
// No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
// user-facing.
#[track_caller]
pub fn span_bug(self, span: impl Into<MultiSpan>, msg: impl Into<Cow<'static, str>>) -> ! {
self.struct_span_bug(span, msg.into()).emit()
}
#[track_caller]
pub fn create_bug(self, bug: impl Diagnostic<'a, BugAbort>) -> Diag<'a, BugAbort> {
bug.into_diag(self, Bug)
}
#[track_caller]
pub fn emit_bug(self, bug: impl Diagnostic<'a, BugAbort>) -> ! {
self.create_bug(bug).emit()
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_fatal(self, msg: impl Into<DiagMessage>) -> Diag<'a, FatalAbort> {
Diag::new(self, Fatal, msg)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn fatal(self, msg: impl Into<DiagMessage>) -> ! {
self.struct_fatal(msg).emit()
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_span_fatal(
self,
span: impl Into<MultiSpan>,
msg: impl Into<DiagMessage>,
) -> Diag<'a, FatalAbort> {
self.struct_fatal(msg).with_span(span)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn span_fatal(self, span: impl Into<MultiSpan>, msg: impl Into<DiagMessage>) -> ! {
self.struct_span_fatal(span, msg).emit()
}
#[track_caller]
pub fn create_fatal(self, fatal: impl Diagnostic<'a, FatalAbort>) -> Diag<'a, FatalAbort> {
fatal.into_diag(self, Fatal)
}
#[track_caller]
pub fn emit_fatal(self, fatal: impl Diagnostic<'a, FatalAbort>) -> ! {
self.create_fatal(fatal).emit()
}
#[track_caller]
pub fn create_almost_fatal(
self,
fatal: impl Diagnostic<'a, FatalError>,
) -> Diag<'a, FatalError> {
fatal.into_diag(self, Fatal)
}
#[track_caller]
pub fn emit_almost_fatal(self, fatal: impl Diagnostic<'a, FatalError>) -> FatalError {
self.create_almost_fatal(fatal).emit()
}
// FIXME: This method should be removed (every error should have an associated error code).
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_err(self, msg: impl Into<DiagMessage>) -> Diag<'a> {
Diag::new(self, Error, msg)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn err(self, msg: impl Into<DiagMessage>) -> ErrorGuaranteed {
self.struct_err(msg).emit()
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_span_err(
self,
span: impl Into<MultiSpan>,
msg: impl Into<DiagMessage>,
) -> Diag<'a> {
self.struct_err(msg).with_span(span)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn span_err(
self,
span: impl Into<MultiSpan>,
msg: impl Into<DiagMessage>,
) -> ErrorGuaranteed {
self.struct_span_err(span, msg).emit()
}
#[track_caller]
pub fn create_err(self, err: impl Diagnostic<'a>) -> Diag<'a> {
err.into_diag(self, Error)
}
#[track_caller]
pub fn emit_err(self, err: impl Diagnostic<'a>) -> ErrorGuaranteed {
self.create_err(err).emit()
}
/// Ensures that an error is printed. See `Level::DelayedBug`.
//
// No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
// user-facing.
#[track_caller]
pub fn delayed_bug(self, msg: impl Into<Cow<'static, str>>) -> ErrorGuaranteed {
Diag::<ErrorGuaranteed>::new(self, DelayedBug, msg.into()).emit()
}
/// Ensures that an error is printed. See [`Level::DelayedBug`].
///
/// Note: this function used to be called `delay_span_bug`. It was renamed
/// to match similar functions like `span_err`, `span_warn`, etc.
//
// No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
// user-facing.
#[track_caller]
pub fn span_delayed_bug(
self,
sp: impl Into<MultiSpan>,
msg: impl Into<Cow<'static, str>>,
) -> ErrorGuaranteed {
Diag::<ErrorGuaranteed>::new(self, DelayedBug, msg.into()).with_span(sp).emit()
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_warn(self, msg: impl Into<DiagMessage>) -> Diag<'a, ()> {
Diag::new(self, Warning, msg)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn warn(self, msg: impl Into<DiagMessage>) {
self.struct_warn(msg).emit()
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_span_warn(
self,
span: impl Into<MultiSpan>,
msg: impl Into<DiagMessage>,
) -> Diag<'a, ()> {
self.struct_warn(msg).with_span(span)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn span_warn(self, span: impl Into<MultiSpan>, msg: impl Into<DiagMessage>) {
self.struct_span_warn(span, msg).emit()
}
#[track_caller]
pub fn create_warn(self, warning: impl Diagnostic<'a, ()>) -> Diag<'a, ()> {
warning.into_diag(self, Warning)
}
#[track_caller]
pub fn emit_warn(self, warning: impl Diagnostic<'a, ()>) {
self.create_warn(warning).emit()
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_note(self, msg: impl Into<DiagMessage>) -> Diag<'a, ()> {
Diag::new(self, Note, msg)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn note(&self, msg: impl Into<DiagMessage>) {
self.struct_note(msg).emit()
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_span_note(
self,
span: impl Into<MultiSpan>,
msg: impl Into<DiagMessage>,
) -> Diag<'a, ()> {
self.struct_note(msg).with_span(span)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn span_note(self, span: impl Into<MultiSpan>, msg: impl Into<DiagMessage>) {
self.struct_span_note(span, msg).emit()
}
#[track_caller]
pub fn create_note(self, note: impl Diagnostic<'a, ()>) -> Diag<'a, ()> {
note.into_diag(self, Note)
}
#[track_caller]
pub fn emit_note(self, note: impl Diagnostic<'a, ()>) {
self.create_note(note).emit()
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_help(self, msg: impl Into<DiagMessage>) -> Diag<'a, ()> {
Diag::new(self, Help, msg)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_failure_note(self, msg: impl Into<DiagMessage>) -> Diag<'a, ()> {
Diag::new(self, FailureNote, msg)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_allow(self, msg: impl Into<DiagMessage>) -> Diag<'a, ()> {
Diag::new(self, Allow, msg)
}
#[rustc_lint_diagnostics]
#[track_caller]
pub fn struct_expect(self, msg: impl Into<DiagMessage>, id: LintExpectationId) -> Diag<'a, ()> {
Diag::new(self, Expect, msg).with_lint_id(id)
}
}
// Note: we prefer implementing operations on `DiagCtxt`, rather than
// `DiagCtxtInner`, whenever possible. This minimizes functions where
// `DiagCtxt::foo()` just borrows `inner` and forwards a call to
// `DiagCtxtInner::foo`.
impl DiagCtxtInner {
fn new(emitter: Box<DynEmitter>) -> Self {
Self {
flags: DiagCtxtFlags { can_emit_warnings: true, ..Default::default() },
registry: Registry::new(&[]),
err_guars: Vec::new(),
lint_err_guars: Vec::new(),
delayed_bugs: Vec::new(),
deduplicated_err_count: 0,
deduplicated_warn_count: 0,
emitter,
must_produce_diag: None,
has_printed: false,
suppressed_expected_diag: false,
taught_diagnostics: Default::default(),
emitted_diagnostic_codes: Default::default(),
emitted_diagnostics: Default::default(),
stashed_diagnostics: Default::default(),
future_breakage_diagnostics: Vec::new(),
fulfilled_expectations: Default::default(),
ice_file: None,
}
}
/// Emit all stashed diagnostics.
fn emit_stashed_diagnostics(&mut self) -> Option<ErrorGuaranteed> {
let mut guar = None;
let has_errors = !self.err_guars.is_empty();
for (_, stashed_diagnostics) in std::mem::take(&mut self.stashed_diagnostics).into_iter() {
for (_, (diag, _guar)) in stashed_diagnostics {
if !diag.is_error() {
// Unless they're forced, don't flush stashed warnings when
// there are errors, to avoid causing warning overload. The
// stash would've been stolen already if it were important.
if !diag.is_force_warn() && has_errors {
continue;
}
}
guar = guar.or(self.emit_diagnostic(diag, None));
}
}
guar
}
// Return value is only `Some` if the level is `Error` or `DelayedBug`.
fn emit_diagnostic(
&mut self,
mut diagnostic: DiagInner,
taint: Option<&Cell<Option<ErrorGuaranteed>>>,
) -> Option<ErrorGuaranteed> {
if diagnostic.has_future_breakage() {
// Future breakages aren't emitted if they're `Level::Allow` or
// `Level::Expect`, but they still need to be constructed and
// stashed below, so they'll trigger the must_produce_diag check.
assert_matches!(diagnostic.level, Error | ForceWarning | Warning | Allow | Expect);
self.future_breakage_diagnostics.push(diagnostic.clone());
}
// We call TRACK_DIAGNOSTIC with an empty closure for the cases that
// return early *and* have some kind of side-effect, except where
// noted.
match diagnostic.level {
Bug => {}
Fatal | Error => {
if self.treat_next_err_as_bug() {
// `Fatal` and `Error` can be promoted to `Bug`.
diagnostic.level = Bug;
}
}
DelayedBug => {
// Note that because we check these conditions first,
// `-Zeagerly-emit-delayed-bugs` and `-Ztreat-err-as-bug`
// continue to work even after we've issued an error and
// stopped recording new delayed bugs.
if self.flags.eagerly_emit_delayed_bugs {
// `DelayedBug` can be promoted to `Error` or `Bug`.
if self.treat_next_err_as_bug() {
diagnostic.level = Bug;
} else {
diagnostic.level = Error;
}
} else {
// If we have already emitted at least one error, we don't need
// to record the delayed bug, because it'll never be used.
return if let Some(guar) = self.has_errors() {
Some(guar)
} else {
// No `TRACK_DIAGNOSTIC` call is needed, because the
// incremental session is deleted if there is a delayed
// bug. This also saves us from cloning the diagnostic.
let backtrace = std::backtrace::Backtrace::capture();
// This `unchecked_error_guaranteed` is valid. It is where the
// `ErrorGuaranteed` for delayed bugs originates. See
// `DiagCtxtInner::drop`.
#[allow(deprecated)]
let guar = ErrorGuaranteed::unchecked_error_guaranteed();
self.delayed_bugs
.push((DelayedDiagInner::with_backtrace(diagnostic, backtrace), guar));
Some(guar)
};
}
}
ForceWarning if diagnostic.lint_id.is_none() => {} // `ForceWarning(Some(...))` is below, with `Expect`
Warning => {
if !self.flags.can_emit_warnings {
// We are not emitting warnings.
if diagnostic.has_future_breakage() {
// The side-effect is at the top of this method.
TRACK_DIAGNOSTIC(diagnostic, &mut |_| None);
}
return None;
}
}
Note | Help | FailureNote => {}
OnceNote | OnceHelp => panic!("bad level: {:?}", diagnostic.level),
Allow => {
// Nothing emitted for allowed lints.
if diagnostic.has_future_breakage() {
// The side-effect is at the top of this method.
TRACK_DIAGNOSTIC(diagnostic, &mut |_| None);
self.suppressed_expected_diag = true;
}
return None;
}
Expect | ForceWarning => {
self.fulfilled_expectations.insert(diagnostic.lint_id.unwrap());
if let Expect = diagnostic.level {
// Nothing emitted here for expected lints.
TRACK_DIAGNOSTIC(diagnostic, &mut |_| None);
self.suppressed_expected_diag = true;
return None;
}
}
}
TRACK_DIAGNOSTIC(diagnostic, &mut |mut diagnostic| {
if let Some(code) = diagnostic.code {
self.emitted_diagnostic_codes.insert(code);
}
let already_emitted = {
let mut hasher = StableHasher::new();
diagnostic.hash(&mut hasher);
let diagnostic_hash = hasher.finish();
!self.emitted_diagnostics.insert(diagnostic_hash)
};
let is_error = diagnostic.is_error();
let is_lint = diagnostic.is_lint.is_some();
// Only emit the diagnostic if we've been asked to deduplicate or
// haven't already emitted an equivalent diagnostic.
if !(self.flags.deduplicate_diagnostics && already_emitted) {
debug!(?diagnostic);
debug!(?self.emitted_diagnostics);
let not_yet_emitted = |sub: &mut Subdiag| {
debug!(?sub);
if sub.level != OnceNote && sub.level != OnceHelp {
return true;
}
let mut hasher = StableHasher::new();
sub.hash(&mut hasher);
let diagnostic_hash = hasher.finish();
debug!(?diagnostic_hash);
self.emitted_diagnostics.insert(diagnostic_hash)
};
diagnostic.children.retain_mut(not_yet_emitted);
if already_emitted {
let msg = "duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`";
diagnostic.sub(Note, msg, MultiSpan::new());
}
if is_error {
self.deduplicated_err_count += 1;
} else if matches!(diagnostic.level, ForceWarning | Warning) {
self.deduplicated_warn_count += 1;
}
self.has_printed = true;
self.emitter.emit_diagnostic(diagnostic, &self.registry);
}
if is_error {
// If we have any delayed bugs recorded, we can discard them
// because they won't be used. (This should only occur if there
// have been no errors previously emitted, because we don't add
// new delayed bugs once the first error is emitted.)
if !self.delayed_bugs.is_empty() {
assert_eq!(self.lint_err_guars.len() + self.err_guars.len(), 0);
self.delayed_bugs.clear();
self.delayed_bugs.shrink_to_fit();
}
// This `unchecked_error_guaranteed` is valid. It is where the
// `ErrorGuaranteed` for errors and lint errors originates.
#[allow(deprecated)]
let guar = ErrorGuaranteed::unchecked_error_guaranteed();
if is_lint {
self.lint_err_guars.push(guar);
} else {
if let Some(taint) = taint {
taint.set(Some(guar));
}
self.err_guars.push(guar);
}
self.panic_if_treat_err_as_bug();
Some(guar)
} else {
None
}
})
}
fn treat_err_as_bug(&self) -> bool {
self.flags
.treat_err_as_bug
.is_some_and(|c| self.err_guars.len() + self.lint_err_guars.len() >= c.get())
}
// Use this one before incrementing `err_count`.
fn treat_next_err_as_bug(&self) -> bool {
self.flags
.treat_err_as_bug
.is_some_and(|c| self.err_guars.len() + self.lint_err_guars.len() + 1 >= c.get())
}
fn has_errors_excluding_lint_errors(&self) -> Option<ErrorGuaranteed> {
self.err_guars.get(0).copied().or_else(|| {
if let Some((_diag, guar)) = self
.stashed_diagnostics
.values()
.flat_map(|stashed_diagnostics| stashed_diagnostics.values())
.find(|(diag, guar)| guar.is_some() && diag.is_lint.is_none())
{
*guar
} else {
None
}
})
}
fn has_errors(&self) -> Option<ErrorGuaranteed> {
self.err_guars.get(0).copied().or_else(|| self.lint_err_guars.get(0).copied()).or_else(
|| {
self.stashed_diagnostics.values().find_map(|stashed_diagnostics| {
stashed_diagnostics.values().find_map(|(_, guar)| *guar)
})
},
)
}
fn has_errors_or_delayed_bugs(&self) -> Option<ErrorGuaranteed> {
self.has_errors().or_else(|| self.delayed_bugs.get(0).map(|(_, guar)| guar).copied())
}
/// Translate `message` eagerly with `args` to `SubdiagMessage::Eager`.
fn eagerly_translate<'a>(
&self,
message: DiagMessage,
args: impl Iterator<Item = DiagArg<'a>>,
) -> SubdiagMessage {
SubdiagMessage::Translated(Cow::from(self.eagerly_translate_to_string(message, args)))
}
/// Translate `message` eagerly with `args` to `String`.
fn eagerly_translate_to_string<'a>(
&self,
message: DiagMessage,
args: impl Iterator<Item = DiagArg<'a>>,
) -> String {
let args = crate::translation::to_fluent_args(args);
self.emitter
.translator()
.translate_message(&message, &args)
.map_err(Report::new)
.unwrap()
.to_string()
}
fn eagerly_translate_for_subdiag(
&self,
diag: &DiagInner,
msg: impl Into<SubdiagMessage>,
) -> SubdiagMessage {
let msg = diag.subdiagnostic_message_to_diagnostic_message(msg);
self.eagerly_translate(msg, diag.args.iter())
}
fn flush_delayed(&mut self) {
// Stashed diagnostics must be emitted before delayed bugs are flushed.
// Otherwise, we might ICE prematurely when errors would have
// eventually happened.
assert!(self.stashed_diagnostics.is_empty());
if !self.err_guars.is_empty() {
// If an error happened already. We shouldn't expose delayed bugs.
return;
}
if self.delayed_bugs.is_empty() {
// Nothing to do.
return;
}
let bugs: Vec<_> =
std::mem::take(&mut self.delayed_bugs).into_iter().map(|(b, _)| b).collect();
let backtrace = std::env::var_os("RUST_BACKTRACE").as_deref() != Some(OsStr::new("0"));
let decorate = backtrace || self.ice_file.is_none();
let mut out = self
.ice_file
.as_ref()
.and_then(|file| std::fs::File::options().create(true).append(true).open(file).ok());
// Put the overall explanation before the `DelayedBug`s, to frame them
// better (e.g. separate warnings from them). Also, use notes, which
// don't count as errors, to avoid possibly triggering
// `-Ztreat-err-as-bug`, which we don't want.
let note1 = "no errors encountered even though delayed bugs were created";
let note2 = "those delayed bugs will now be shown as internal compiler errors";
self.emit_diagnostic(DiagInner::new(Note, note1), None);
self.emit_diagnostic(DiagInner::new(Note, note2), None);
for bug in bugs {
if let Some(out) = &mut out {
_ = write!(
out,
"delayed bug: {}\n{}\n",
bug.inner
.messages
.iter()
.filter_map(|(msg, _)| msg.as_str())
.collect::<String>(),
&bug.note
);
}
let mut bug = if decorate { bug.decorate(self) } else { bug.inner };
// "Undelay" the delayed bugs into plain bugs.
if bug.level != DelayedBug {
// NOTE(eddyb) not panicking here because we're already producing
// an ICE, and the more information the merrier.
//
// We are at the `DiagInner`/`DiagCtxtInner` level rather than
// the usual `Diag`/`DiagCtxt` level, so we must augment `bug`
// in a lower-level fashion.
bug.arg("level", bug.level);
let msg = crate::fluent_generated::errors_invalid_flushed_delayed_diagnostic_level;
let msg = self.eagerly_translate_for_subdiag(&bug, msg); // after the `arg` call
bug.sub(Note, msg, bug.span.primary_span().unwrap().into());
}
bug.level = Bug;
self.emit_diagnostic(bug, None);
}
// Panic with `DelayedBugPanic` to avoid "unexpected panic" messages.
panic::panic_any(DelayedBugPanic);
}
fn panic_if_treat_err_as_bug(&self) {
if self.treat_err_as_bug() {
let n = self.flags.treat_err_as_bug.map(|c| c.get()).unwrap();
assert_eq!(n, self.err_guars.len() + self.lint_err_guars.len());
if n == 1 {
panic!("aborting due to `-Z treat-err-as-bug=1`");
} else {
panic!("aborting after {n} errors due to `-Z treat-err-as-bug={n}`");
}
}
}
}
struct DelayedDiagInner {
inner: DiagInner,
note: Backtrace,
}
impl DelayedDiagInner {
fn with_backtrace(diagnostic: DiagInner, backtrace: Backtrace) -> Self {
DelayedDiagInner { inner: diagnostic, note: backtrace }
}
fn decorate(self, dcx: &DiagCtxtInner) -> DiagInner {
// We are at the `DiagInner`/`DiagCtxtInner` level rather than the
// usual `Diag`/`DiagCtxt` level, so we must construct `diag` in a
// lower-level fashion.
let mut diag = self.inner;
let msg = match self.note.status() {
BacktraceStatus::Captured => crate::fluent_generated::errors_delayed_at_with_newline,
// Avoid the needless newline when no backtrace has been captured,
// the display impl should just be a single line.
_ => crate::fluent_generated::errors_delayed_at_without_newline,
};
diag.arg("emitted_at", diag.emitted_at.clone());
diag.arg("note", self.note);
let msg = dcx.eagerly_translate_for_subdiag(&diag, msg); // after the `arg` calls
diag.sub(Note, msg, diag.span.primary_span().unwrap_or(DUMMY_SP).into());
diag
}
}
/// | Level | is_error | EmissionGuarantee | Top-level | Sub | Used in lints?
/// | ----- | -------- | ----------------- | --------- | --- | --------------
/// | Bug | yes | BugAbort | yes | - | -
/// | Fatal | yes | FatalAbort/FatalError[^star] | yes | - | -
/// | Error | yes | ErrorGuaranteed | yes | - | yes
/// | DelayedBug | yes | ErrorGuaranteed | yes | - | -
/// | ForceWarning | - | () | yes | - | lint-only
/// | Warning | - | () | yes | yes | yes
/// | Note | - | () | rare | yes | -
/// | OnceNote | - | () | - | yes | lint-only
/// | Help | - | () | rare | yes | -
/// | OnceHelp | - | () | - | yes | lint-only
/// | FailureNote | - | () | rare | - | -
/// | Allow | - | () | yes | - | lint-only
/// | Expect | - | () | yes | - | lint-only
///
/// [^star]: `FatalAbort` normally, `FatalError` in the non-aborting "almost fatal" case that is
/// occasionally used.
///
#[derive(Copy, PartialEq, Eq, Clone, Hash, Debug, Encodable, Decodable)]
pub enum Level {
/// For bugs in the compiler. Manifests as an ICE (internal compiler error) panic.
Bug,
/// An error that causes an immediate abort. Used for things like configuration errors,
/// internal overflows, some file operation errors.
Fatal,
/// An error in the code being compiled, which prevents compilation from finishing. This is the
/// most common case.
Error,
/// This is a strange one: lets you register an error without emitting it. If compilation ends
/// without any other errors occurring, this will be emitted as a bug. Otherwise, it will be
/// silently dropped. I.e. "expect other errors are emitted" semantics. Useful on code paths
/// that should only be reached when compiling erroneous code.
DelayedBug,
/// A `force-warn` lint warning about the code being compiled. Does not prevent compilation
/// from finishing.
///
/// Requires a [`LintExpectationId`] for expected lint diagnostics. In all other cases this
/// should be `None`.
ForceWarning,
/// A warning about the code being compiled. Does not prevent compilation from finishing.
/// Will be skipped if `can_emit_warnings` is false.
Warning,
/// A message giving additional context.
Note,
/// A note that is only emitted once.
OnceNote,
/// A message suggesting how to fix something.
Help,
/// A help that is only emitted once.
OnceHelp,
/// Similar to `Note`, but used in cases where compilation has failed. When printed for human
/// consumption, it doesn't have any kind of `note:` label.
FailureNote,
/// Only used for lints.
Allow,
/// Only used for lints. Requires a [`LintExpectationId`] for silencing the lints.
Expect,
}
impl fmt::Display for Level {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.to_str().fmt(f)
}
}
impl Level {
fn color(self) -> anstyle::Style {
match self {
Bug | Fatal | Error | DelayedBug => AnsiColor::BrightRed.on_default(),
ForceWarning | Warning => {
if cfg!(windows) {
AnsiColor::BrightYellow.on_default()
} else {
AnsiColor::Yellow.on_default()
}
}
Note | OnceNote => AnsiColor::BrightGreen.on_default(),
Help | OnceHelp => AnsiColor::BrightCyan.on_default(),
FailureNote => anstyle::Style::new(),
Allow | Expect => unreachable!(),
}
}
pub fn to_str(self) -> &'static str {
match self {
Bug | DelayedBug => "error: internal compiler error",
Fatal | Error => "error",
ForceWarning | Warning => "warning",
Note | OnceNote => "note",
Help | OnceHelp => "help",
FailureNote => "failure-note",
Allow | Expect => unreachable!(),
}
}
pub fn is_failure_note(&self) -> bool {
matches!(*self, FailureNote)
}
// Can this level be used in a subdiagnostic message?
fn can_be_subdiag(&self) -> bool {
match self {
Bug | DelayedBug | Fatal | Error | ForceWarning | FailureNote | Allow | Expect => false,
Warning | Note | Help | OnceNote | OnceHelp => true,
}
}
}
impl IntoDiagArg for Level {
fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
DiagArgValue::Str(Cow::from(self.to_string()))
}
}
// FIXME(eddyb) this doesn't belong here AFAICT, should be moved to callsite.
pub fn elided_lifetime_in_path_suggestion(
source_map: &SourceMap,
n: usize,
path_span: Span,
incl_angl_brckt: bool,
insertion_span: Span,
) -> ElidedLifetimeInPathSubdiag {
let expected = ExpectedLifetimeParameter { span: path_span, count: n };
// Do not try to suggest anything if generated by a proc-macro.
let indicate = source_map.is_span_accessible(insertion_span).then(|| {
let anon_lts = vec!["'_"; n].join(", ");
let suggestion =
if incl_angl_brckt { format!("<{anon_lts}>") } else { format!("{anon_lts}, ") };
IndicateAnonymousLifetime { span: insertion_span.shrink_to_hi(), count: n, suggestion }
});
ElidedLifetimeInPathSubdiag { expected, indicate }
}
pub fn report_ambiguity_error<'a, G: EmissionGuarantee>(
diag: &mut Diag<'a, G>,
ambiguity: rustc_lint_defs::AmbiguityErrorDiag,
) {
diag.span_label(ambiguity.label_span, ambiguity.label_msg);
diag.note(ambiguity.note_msg);
diag.span_note(ambiguity.b1_span, ambiguity.b1_note_msg);
for help_msg in ambiguity.b1_help_msgs {
diag.help(help_msg);
}
diag.span_note(ambiguity.b2_span, ambiguity.b2_note_msg);
for help_msg in ambiguity.b2_help_msgs {
diag.help(help_msg);
}
}
/// Grammatical tool for displaying messages to end users in a nice form.
///
/// Returns "an" if the given string starts with a vowel, and "a" otherwise.
pub fn a_or_an(s: &str) -> &'static str {
let mut chars = s.chars();
let Some(mut first_alpha_char) = chars.next() else {
return "a";
};
if first_alpha_char == '`' {
let Some(next) = chars.next() else {
return "a";
};
first_alpha_char = next;
}
if ["a", "e", "i", "o", "u", "&"].contains(&&first_alpha_char.to_lowercase().to_string()[..]) {
"an"
} else {
"a"
}
}
#[derive(Clone, Copy, PartialEq, Hash, Debug)]
pub enum TerminalUrl {
No,
Yes,
Auto,
}