src/tools/rustfmt/src/lib.rs - toolchain/rustc - Git at Google

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

 #[macro_use]
 extern crate derive_new;
 #[cfg(test)]
 #[macro_use]
 extern crate lazy_static;
 #[macro_use]
 extern crate log;

 // 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_builtin_macros;
 extern crate rustc_data_structures;
 extern crate rustc_errors;
 extern crate rustc_expand;
 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::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::{
     load_config, CliOptions, Color, Config, Edition, EmitMode, FileLines, FileName, NewlineStyle,
     Range, Verbosity,
 };

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

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

 #[macro_use]
 mod utils;

 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;
 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 release_channel;
 mod reorder;
 mod rewrite;
 pub(crate) mod rustfmt_diff;
 mod shape;
 mod skip;
 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
             .iter()
             .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().hide_parse_errors(true);
         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());
     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[FN_MAIN_PREFIX.len()..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
     /// given config. `out` is only necessary if required by the configuration.
     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));
     }
 }
	#![feature(rustc_private)]
	#![deny(rust_2018_idioms)]
	#![warn(unreachable_pub)]
	#![recursion_limit = "256"]
	#![allow(clippy::match_like_matches_macro)]
	#![allow(unreachable_pub)]

	#[macro_use]
	extern crate derive_new;
	#[cfg(test)]
	#[macro_use]
	extern crate lazy_static;
	#[macro_use]
	extern crate log;

	// 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_builtin_macros;
	extern crate rustc_data_structures;
	extern crate rustc_errors;
	extern crate rustc_expand;
	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::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::{
	load_config, CliOptions, Color, Config, Edition, EmitMode, FileLines, FileName, NewlineStyle,
	Range, Verbosity,
	};

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

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

	#[macro_use]
	mod utils;

	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;
	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 release_channel;
	mod reorder;
	mod rewrite;
	pub(crate) mod rustfmt_diff;
	mod shape;
	mod skip;
	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
	.iter()
	.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().hide_parse_errors(true);
	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());
	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[FN_MAIN_PREFIX.len()..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
	/// given config. `out` is only necessary if required by the configuration.
	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));
	}
	}