src/lib.rs

#![feature(rustc_private)]
#![deny(rust_2018_idioms)]
#![warn(unreachable_pub)]
#![recursion_limit = "256"]
#![allow(clippy::match_like_matches_macro)]

// N.B. these crates are loaded from the sysroot, so they need extern crate.
extern crate rustc_ast;
extern crate rustc_ast_pretty;
extern crate rustc_data_structures;
extern crate rustc_errors;
extern crate rustc_expand;
extern crate rustc_feature;
extern crate rustc_parse;
extern crate rustc_session;
extern crate rustc_span;
extern crate thin_vec;

// Necessary to pull in object code as the rest of the rustc crates are shipped only as rmeta
// files.
#[allow(unused_extern_crates)]
extern crate rustc_driver;

use std::cell::RefCell;
use std::cmp::min;
use std::collections::HashMap;
use std::fmt;
use std::io::{self, Write};
use std::mem;
use std::panic;
use std::path::PathBuf;
use std::rc::Rc;

use rustc_ast::ast;
use rustc_span::symbol;
use thiserror::Error;

use crate::comment::LineClasses;
use crate::emitter::Emitter;
use crate::formatting::{FormatErrorMap, FormattingError, ReportedErrors, SourceFile};
use crate::modules::ModuleResolutionError;
use crate::parse::parser::DirectoryOwnership;
use crate::shape::Indent;
use crate::utils::indent_next_line;

pub use crate::config::{
    CliOptions, Color, Config, Edition, EmitMode, FileLines, FileName, NewlineStyle, Range,
    StyleEdition, Verbosity, Version, load_config,
};

pub use crate::format_report_formatter::{FormatReportFormatter, FormatReportFormatterBuilder};

pub use crate::rustfmt_diff::{ModifiedChunk, ModifiedLines};

#[macro_use]
mod utils;

macro_rules! static_regex {
    ($re:literal) => {{
        static RE: ::std::sync::OnceLock<::regex::Regex> = ::std::sync::OnceLock::new();
        RE.get_or_init(|| ::regex::Regex::new($re).unwrap())
    }};
}

mod attr;
mod chains;
mod closures;
mod comment;
pub(crate) mod config;
mod coverage;
mod emitter;
mod expr;
mod format_report_formatter;
pub(crate) mod formatting;
pub(crate) mod header;
mod ignore_path;
mod imports;
mod items;
mod lists;
mod macros;
mod matches;
mod missed_spans;
pub(crate) mod modules;
mod overflow;
mod pairs;
mod parse;
mod patterns;
mod range;
mod release_channel;
mod reorder;
mod rewrite;
pub(crate) mod rustfmt_diff;
mod shape;
mod skip;
mod sort;
pub(crate) mod source_file;
pub(crate) mod source_map;
mod spanned;
mod stmt;
mod string;
#[cfg(test)]
mod test;
mod types;
mod vertical;
pub(crate) mod visitor;

/// The various errors that can occur during formatting. Note that not all of
/// these can currently be propagated to clients.
#[derive(Error, Debug)]
pub enum ErrorKind {
    /// Line has exceeded character limit (found, maximum).
    #[error(
        "line formatted, but exceeded maximum width \
         (maximum: {1} (see `max_width` option), found: {0})"
    )]
    LineOverflow(usize, usize),
    /// Line ends in whitespace.
    #[error("left behind trailing whitespace")]
    TrailingWhitespace,
    /// Used deprecated skip attribute.
    #[error("`rustfmt_skip` is deprecated; use `rustfmt::skip`")]
    DeprecatedAttr,
    /// Used a rustfmt:: attribute other than skip or skip::macros.
    #[error("invalid attribute")]
    BadAttr,
    /// An io error during reading or writing.
    #[error("io error: {0}")]
    IoError(io::Error),
    /// Error during module resolution.
    #[error("{0}")]
    ModuleResolutionError(#[from] ModuleResolutionError),
    /// Parse error occurred when parsing the input.
    #[error("parse error")]
    ParseError,
    /// The user mandated a version and the current version of Rustfmt does not
    /// satisfy that requirement.
    #[error("version mismatch")]
    VersionMismatch,
    /// If we had formatted the given node, then we would have lost a comment.
    #[error("not formatted because a comment would be lost")]
    LostComment,
    /// Invalid glob pattern in `ignore` configuration option.
    #[error("Invalid glob pattern found in ignore list: {0}")]
    InvalidGlobPattern(ignore::Error),
}

impl ErrorKind {
    fn is_comment(&self) -> bool {
        matches!(self, ErrorKind::LostComment)
    }
}

impl From<io::Error> for ErrorKind {
    fn from(e: io::Error) -> ErrorKind {
        ErrorKind::IoError(e)
    }
}

/// Result of formatting a snippet of code along with ranges of lines that didn't get formatted,
/// i.e., that got returned as they were originally.
#[derive(Debug)]
struct FormattedSnippet {
    snippet: String,
    non_formatted_ranges: Vec<(usize, usize)>,
}

impl FormattedSnippet {
    /// In case the snippet needed to be wrapped in a function, this shifts down the ranges of
    /// non-formatted code.
    fn unwrap_code_block(&mut self) {
        self.non_formatted_ranges
            .iter_mut()
            .for_each(|(low, high)| {
                *low -= 1;
                *high -= 1;
            });
    }

    /// Returns `true` if the line n did not get formatted.
    fn is_line_non_formatted(&self, n: usize) -> bool {
        self.non_formatted_ranges
            .iter()
            .any(|(low, high)| *low <= n && n <= *high)
    }
}

/// Reports on any issues that occurred during a run of Rustfmt.
///
/// Can be reported to the user using the `Display` impl on [`FormatReportFormatter`].
#[derive(Clone)]
pub struct FormatReport {
    // Maps stringified file paths to their associated formatting errors.
    internal: Rc<RefCell<(FormatErrorMap, ReportedErrors)>>,
    non_formatted_ranges: Vec<(usize, usize)>,
}

impl FormatReport {
    fn new() -> FormatReport {
        FormatReport {
            internal: Rc::new(RefCell::new((HashMap::new(), ReportedErrors::default()))),
            non_formatted_ranges: Vec::new(),
        }
    }

    fn add_non_formatted_ranges(&mut self, mut ranges: Vec<(usize, usize)>) {
        self.non_formatted_ranges.append(&mut ranges);
    }

    fn append(&self, f: FileName, mut v: Vec<FormattingError>) {
        self.track_errors(&v);
        self.internal
            .borrow_mut()
            .0
            .entry(f)
            .and_modify(|fe| fe.append(&mut v))
            .or_insert(v);
    }

    fn track_errors(&self, new_errors: &[FormattingError]) {
        let errs = &mut self.internal.borrow_mut().1;
        if !new_errors.is_empty() {
            errs.has_formatting_errors = true;
        }
        if errs.has_operational_errors && errs.has_check_errors && errs.has_unformatted_code_errors
        {
            return;
        }
        for err in new_errors {
            match err.kind {
                ErrorKind::LineOverflow(..) => {
                    errs.has_operational_errors = true;
                }
                ErrorKind::TrailingWhitespace => {
                    errs.has_operational_errors = true;
                    errs.has_unformatted_code_errors = true;
                }
                ErrorKind::LostComment => {
                    errs.has_unformatted_code_errors = true;
                }
                ErrorKind::DeprecatedAttr | ErrorKind::BadAttr | ErrorKind::VersionMismatch => {
                    errs.has_check_errors = true;
                }
                _ => {}
            }
        }
    }

    fn add_diff(&mut self) {
        self.internal.borrow_mut().1.has_diff = true;
    }

    fn add_macro_format_failure(&mut self) {
        self.internal.borrow_mut().1.has_macro_format_failure = true;
    }

    fn add_parsing_error(&mut self) {
        self.internal.borrow_mut().1.has_parsing_errors = true;
    }

    fn warning_count(&self) -> usize {
        self.internal
            .borrow()
            .0
            .values()
            .map(|errors| errors.len())
            .sum()
    }

    /// Whether any warnings or errors are present in the report.
    pub fn has_warnings(&self) -> bool {
        self.internal.borrow().1.has_formatting_errors
    }

    /// Print the report to a terminal using colours and potentially other
    /// fancy output.
    #[deprecated(note = "Use FormatReportFormatter with colors enabled instead")]
    pub fn fancy_print(
        &self,
        mut t: Box<dyn term::Terminal<Output = io::Stderr>>,
    ) -> Result<(), term::Error> {
        writeln!(
            t,
            "{}",
            FormatReportFormatterBuilder::new(self)
                .enable_colors(true)
                .build()
        )?;
        Ok(())
    }
}

/// Deprecated - Use FormatReportFormatter instead
// https://github.com/rust-lang/rust/issues/78625
// https://github.com/rust-lang/rust/issues/39935
impl fmt::Display for FormatReport {
    // Prints all the formatting errors.
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
        write!(fmt, "{}", FormatReportFormatterBuilder::new(self).build())?;
        Ok(())
    }
}

/// Format the given snippet. The snippet is expected to be *complete* code.
/// When we cannot parse the given snippet, this function returns `None`.
fn format_snippet(snippet: &str, config: &Config, is_macro_def: bool) -> Option<FormattedSnippet> {
    let mut config = config.clone();
    panic::catch_unwind(|| {
        let mut out: Vec<u8> = Vec::with_capacity(snippet.len() * 2);
        config.set().emit_mode(config::EmitMode::Stdout);
        config.set().verbose(Verbosity::Quiet);
        config.set().show_parse_errors(false);
        if is_macro_def {
            config.set().error_on_unformatted(true);
        }

        let (formatting_error, result) = {
            let input = Input::Text(snippet.into());
            let mut session = Session::new(config, Some(&mut out));
            let result = session.format_input_inner(input, is_macro_def);
            (
                session.errors.has_macro_format_failure
                    || session.out.as_ref().unwrap().is_empty() && !snippet.is_empty()
                    || result.is_err()
                    || (is_macro_def && session.has_unformatted_code_errors()),
                result,
            )
        };
        if formatting_error {
            None
        } else {
            String::from_utf8(out).ok().map(|snippet| FormattedSnippet {
                snippet,
                non_formatted_ranges: result.unwrap().non_formatted_ranges,
            })
        }
    })
    // Discard panics encountered while formatting the snippet
    // The ? operator is needed to remove the extra Option
    .ok()?
}

/// Format the given code block. Mainly targeted for code block in comment.
/// The code block may be incomplete (i.e., parser may be unable to parse it).
/// To avoid panic in parser, we wrap the code block with a dummy function.
/// The returned code block does **not** end with newline.
fn format_code_block(
    code_snippet: &str,
    config: &Config,
    is_macro_def: bool,
) -> Option<FormattedSnippet> {
    const FN_MAIN_PREFIX: &str = "fn main() {\n";

    fn enclose_in_main_block(s: &str, config: &Config) -> String {
        let indent = Indent::from_width(config, config.tab_spaces());
        let mut result = String::with_capacity(s.len() * 2);
        result.push_str(FN_MAIN_PREFIX);
        let mut need_indent = true;
        for (kind, line) in LineClasses::new(s) {
            if need_indent {
                result.push_str(&indent.to_string(config));
            }
            result.push_str(&line);
            result.push('\n');
            need_indent = indent_next_line(kind, &line, config);
        }
        result.push('}');
        result
    }

    // Wrap the given code block with `fn main()` if it does not have one.
    let snippet = enclose_in_main_block(code_snippet, config);
    let mut result = String::with_capacity(snippet.len());
    let mut is_first = true;

    // While formatting the code, ignore the config's newline style setting and always use "\n"
    // instead of "\r\n" for the newline characters. This is ok because the output here is
    // not directly outputted by rustfmt command, but used by the comment formatter's input.
    // We have output-file-wide "\n" ==> "\r\n" conversion process after here if it's necessary.
    let mut config_with_unix_newline = config.clone();
    config_with_unix_newline
        .set()
        .newline_style(NewlineStyle::Unix);
    let mut formatted = format_snippet(&snippet, &config_with_unix_newline, is_macro_def)?;
    // Remove wrapping main block
    formatted.unwrap_code_block();

    // Trim "fn main() {" on the first line and "}" on the last line,
    // then unindent the whole code block.
    let block_len = formatted
        .snippet
        .rfind('}')
        .unwrap_or_else(|| formatted.snippet.len());

    // It's possible that `block_len < FN_MAIN_PREFIX.len()`. This can happen if the code block was
    // formatted into the empty string, leading to the enclosing `fn main() {\n}` being formatted
    // into `fn main() {}`. In this case no unindentation is done.
    let block_start = min(FN_MAIN_PREFIX.len(), block_len);

    let mut is_indented = true;
    let indent_str = Indent::from_width(config, config.tab_spaces()).to_string(config);
    for (kind, ref line) in LineClasses::new(&formatted.snippet[block_start..block_len]) {
        if !is_first {
            result.push('\n');
        } else {
            is_first = false;
        }
        let trimmed_line = if !is_indented {
            line
        } else if line.len() > config.max_width() {
            // If there are lines that are larger than max width, we cannot tell
            // whether we have succeeded but have some comments or strings that
            // are too long, or we have failed to format code block. We will be
            // conservative and just return `None` in this case.
            return None;
        } else if line.len() > indent_str.len() {
            // Make sure that the line has leading whitespaces.
            if line.starts_with(indent_str.as_ref()) {
                let offset = if config.hard_tabs() {
                    1
                } else {
                    config.tab_spaces()
                };
                &line[offset..]
            } else {
                line
            }
        } else {
            line
        };
        result.push_str(trimmed_line);
        is_indented = indent_next_line(kind, line, config);
    }
    Some(FormattedSnippet {
        snippet: result,
        non_formatted_ranges: formatted.non_formatted_ranges,
    })
}

/// A session is a run of rustfmt across a single or multiple inputs.
pub struct Session<'b, T: Write> {
    pub config: Config,
    pub out: Option<&'b mut T>,
    pub(crate) errors: ReportedErrors,
    source_file: SourceFile,
    emitter: Box<dyn Emitter + 'b>,
}

impl<'b, T: Write + 'b> Session<'b, T> {
    pub fn new(config: Config, mut out: Option<&'b mut T>) -> Session<'b, T> {
        let emitter = create_emitter(&config);

        if let Some(ref mut out) = out {
            let _ = emitter.emit_header(out);
        }

        Session {
            config,
            out,
            emitter,
            errors: ReportedErrors::default(),
            source_file: SourceFile::new(),
        }
    }

    /// The main entry point for Rustfmt. Formats the given input according to the
    /// session's config.
    pub fn format(&mut self, input: Input) -> Result<FormatReport, ErrorKind> {
        self.format_input_inner(input, false)
    }

    pub fn override_config<F, U>(&mut self, mut config: Config, f: F) -> U
    where
        F: FnOnce(&mut Session<'b, T>) -> U,
    {
        mem::swap(&mut config, &mut self.config);
        let result = f(self);
        mem::swap(&mut config, &mut self.config);
        result
    }

    pub fn add_operational_error(&mut self) {
        self.errors.has_operational_errors = true;
    }

    pub fn has_operational_errors(&self) -> bool {
        self.errors.has_operational_errors
    }

    pub fn has_parsing_errors(&self) -> bool {
        self.errors.has_parsing_errors
    }

    pub fn has_formatting_errors(&self) -> bool {
        self.errors.has_formatting_errors
    }

    pub fn has_check_errors(&self) -> bool {
        self.errors.has_check_errors
    }

    pub fn has_diff(&self) -> bool {
        self.errors.has_diff
    }

    pub fn has_unformatted_code_errors(&self) -> bool {
        self.errors.has_unformatted_code_errors
    }

    pub fn has_no_errors(&self) -> bool {
        !(self.has_operational_errors()
            || self.has_parsing_errors()
            || self.has_formatting_errors()
            || self.has_check_errors()
            || self.has_diff()
            || self.has_unformatted_code_errors()
            || self.errors.has_macro_format_failure)
    }
}

pub(crate) fn create_emitter<'a>(config: &Config) -> Box<dyn Emitter + 'a> {
    match config.emit_mode() {
        EmitMode::Files if config.make_backup() => {
            Box::new(emitter::FilesWithBackupEmitter::default())
        }
        EmitMode::Files => Box::new(emitter::FilesEmitter::new(
            config.print_misformatted_file_names(),
        )),
        EmitMode::Stdout | EmitMode::Coverage => {
            Box::new(emitter::StdoutEmitter::new(config.verbose()))
        }
        EmitMode::Json => Box::new(emitter::JsonEmitter::default()),
        EmitMode::ModifiedLines => Box::new(emitter::ModifiedLinesEmitter::default()),
        EmitMode::Checkstyle => Box::new(emitter::CheckstyleEmitter::default()),
        EmitMode::Diff => Box::new(emitter::DiffEmitter::new(config.clone())),
    }
}

impl<'b, T: Write + 'b> Drop for Session<'b, T> {
    fn drop(&mut self) {
        if let Some(ref mut out) = self.out {
            let _ = self.emitter.emit_footer(out);
        }
    }
}

#[derive(Debug)]
pub enum Input {
    File(PathBuf),
    Text(String),
}

impl Input {
    fn file_name(&self) -> FileName {
        match *self {
            Input::File(ref file) => FileName::Real(file.clone()),
            Input::Text(..) => FileName::Stdin,
        }
    }

    fn to_directory_ownership(&self) -> Option<DirectoryOwnership> {
        match self {
            Input::File(ref file) => {
                // If there exists a directory with the same name as an input,
                // then the input should be parsed as a sub module.
                let file_stem = file.file_stem()?;
                if file.parent()?.to_path_buf().join(file_stem).is_dir() {
                    Some(DirectoryOwnership::Owned {
                        relative: file_stem.to_str().map(symbol::Ident::from_str),
                    })
                } else {
                    None
                }
            }
            _ => None,
        }
    }
}

#[cfg(test)]
mod unit_tests {
    use super::*;

    #[test]
    fn test_no_panic_on_format_snippet_and_format_code_block() {
        // `format_snippet()` and `format_code_block()` should not panic
        // even when we cannot parse the given snippet.
        let snippet = "let";
        assert!(format_snippet(snippet, &Config::default(), false).is_none());
        assert!(format_code_block(snippet, &Config::default(), false).is_none());
    }

    fn test_format_inner<F>(formatter: F, input: &str, expected: &str) -> bool
    where
        F: Fn(&str, &Config, bool) -> Option<FormattedSnippet>,
    {
        let output = formatter(input, &Config::default(), false);
        output.is_some() && output.unwrap().snippet == expected
    }

    #[test]
    fn test_format_snippet() {
        let snippet = "fn main() { println!(\"hello, world\"); }";
        #[cfg(not(windows))]
        let expected = "fn main() {\n    \
                        println!(\"hello, world\");\n\
                        }\n";
        #[cfg(windows)]
        let expected = "fn main() {\r\n    \
                        println!(\"hello, world\");\r\n\
                        }\r\n";
        assert!(test_format_inner(format_snippet, snippet, expected));
    }

    #[test]
    fn test_format_code_block_fail() {
        #[rustfmt::skip]
        let code_block = "this_line_is_100_characters_long_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(x, y, z);";
        assert!(format_code_block(code_block, &Config::default(), false).is_none());
    }

    #[test]
    fn test_format_code_block() {
        // simple code block
        let code_block = "let x=3;";
        let expected = "let x = 3;";
        assert!(test_format_inner(format_code_block, code_block, expected));

        // more complex code block, taken from chains.rs.
        let code_block =
"let (nested_shape, extend) = if !parent_rewrite_contains_newline && is_continuable(&parent) {
(
chain_indent(context, shape.add_offset(parent_rewrite.len())),
context.config.indent_style() == IndentStyle::Visual || is_small_parent,
)
} else if is_block_expr(context, &parent, &parent_rewrite) {
match context.config.indent_style() {
// Try to put the first child on the same line with parent's last line
IndentStyle::Block => (parent_shape.block_indent(context.config.tab_spaces()), true),
// The parent is a block, so align the rest of the chain with the closing
// brace.
IndentStyle::Visual => (parent_shape, false),
}
} else {
(
chain_indent(context, shape.add_offset(parent_rewrite.len())),
false,
)
};
";
        let expected =
"let (nested_shape, extend) = if !parent_rewrite_contains_newline && is_continuable(&parent) {
    (
        chain_indent(context, shape.add_offset(parent_rewrite.len())),
        context.config.indent_style() == IndentStyle::Visual || is_small_parent,
    )
} else if is_block_expr(context, &parent, &parent_rewrite) {
    match context.config.indent_style() {
        // Try to put the first child on the same line with parent's last line
        IndentStyle::Block => (parent_shape.block_indent(context.config.tab_spaces()), true),
        // The parent is a block, so align the rest of the chain with the closing
        // brace.
        IndentStyle::Visual => (parent_shape, false),
    }
} else {
    (
        chain_indent(context, shape.add_offset(parent_rewrite.len())),
        false,
    )
};";
        assert!(test_format_inner(format_code_block, code_block, expected));
    }
}