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//! Types for tracking pieces of source code within a crate.
//!
//! The [`SourceMap`] tracks all the source code used within a single crate, mapping
//! from integer byte positions to the original source code location. Each bit
//! of source parsed during crate parsing (typically files, in-memory strings,
//! or various bits of macro expansion) cover a continuous range of bytes in the
//! `SourceMap` and are represented by [`SourceFile`]s. Byte positions are stored in
//! [`Span`] and used pervasively in the compiler. They are absolute positions
//! within the `SourceMap`, which upon request can be converted to line and column
//! information, source code snippets, etc.
pub use crate::hygiene::{ExpnData, ExpnKind};
pub use crate::*;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::stable_hasher::{Hash128, Hash64, StableHasher};
use rustc_data_structures::sync::{IntoDynSyncSend, Lrc, MappedReadGuard, ReadGuard, RwLock};
use std::cmp;
use std::hash::Hash;
use std::path::{self, Path, PathBuf};
use std::fs;
use std::io;
use std::io::BorrowedBuf;
use std::io::Read;
#[cfg(test)]
mod tests;
/// Returns the span itself if it doesn't come from a macro expansion,
/// otherwise return the call site span up to the `enclosing_sp` by
/// following the `expn_data` chain.
pub fn original_sp(sp: Span, enclosing_sp: Span) -> Span {
let expn_data1 = sp.ctxt().outer_expn_data();
let expn_data2 = enclosing_sp.ctxt().outer_expn_data();
if expn_data1.is_root() || !expn_data2.is_root() && expn_data1.call_site == expn_data2.call_site
{
sp
} else {
original_sp(expn_data1.call_site, enclosing_sp)
}
}
pub mod monotonic {
use std::ops::{Deref, DerefMut};
/// A `MonotonicVec` is a `Vec` which can only be grown.
/// Once inserted, an element can never be removed or swapped,
/// guaranteeing that any indices into a `MonotonicVec` are stable
// This is declared in its own module to ensure that the private
// field is inaccessible
pub struct MonotonicVec<T>(Vec<T>);
impl<T> MonotonicVec<T> {
pub fn new(val: Vec<T>) -> MonotonicVec<T> {
MonotonicVec(val)
}
pub fn push(&mut self, val: T) {
self.0.push(val);
}
}
impl<T> Default for MonotonicVec<T> {
fn default() -> Self {
MonotonicVec::new(vec![])
}
}
impl<T> Deref for MonotonicVec<T> {
type Target = Vec<T>;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl<T> !DerefMut for MonotonicVec<T> {}
}
#[derive(Clone, Encodable, Decodable, Debug, Copy, HashStable_Generic)]
pub struct Spanned<T> {
pub node: T,
pub span: Span,
}
pub fn respan<T>(sp: Span, t: T) -> Spanned<T> {
Spanned { node: t, span: sp }
}
pub fn dummy_spanned<T>(t: T) -> Spanned<T> {
respan(DUMMY_SP, t)
}
// _____________________________________________________________________________
// SourceFile, MultiByteChar, FileName, FileLines
//
/// An abstraction over the fs operations used by the Parser.
pub trait FileLoader {
/// Query the existence of a file.
fn file_exists(&self, path: &Path) -> bool;
/// Read the contents of a UTF-8 file into memory.
/// This function must return a String because we normalize
/// source files, which may require resizing.
fn read_file(&self, path: &Path) -> io::Result<String>;
/// Read the contents of a potentially non-UTF-8 file into memory.
/// We don't normalize binary files, so we can start in an Lrc.
fn read_binary_file(&self, path: &Path) -> io::Result<Lrc<[u8]>>;
}
/// A FileLoader that uses std::fs to load real files.
pub struct RealFileLoader;
impl FileLoader for RealFileLoader {
fn file_exists(&self, path: &Path) -> bool {
path.exists()
}
fn read_file(&self, path: &Path) -> io::Result<String> {
fs::read_to_string(path)
}
fn read_binary_file(&self, path: &Path) -> io::Result<Lrc<[u8]>> {
let mut file = fs::File::open(path)?;
let len = file.metadata()?.len();
let mut bytes = Lrc::new_uninit_slice(len as usize);
let mut buf = BorrowedBuf::from(Lrc::get_mut(&mut bytes).unwrap());
match file.read_buf_exact(buf.unfilled()) {
Ok(()) => {}
Err(e) if e.kind() == io::ErrorKind::UnexpectedEof => {
drop(bytes);
return fs::read(path).map(Vec::into);
}
Err(e) => return Err(e),
}
// SAFETY: If the read_buf_exact call returns Ok(()), then we have
// read len bytes and initialized the buffer.
let bytes = unsafe { bytes.assume_init() };
// At this point, we've read all the bytes that filesystem metadata reported exist.
// But we are not guaranteed to be at the end of the file, because we did not attempt to do
// a read with a non-zero-sized buffer and get Ok(0).
// So we do small read to a fixed-size buffer. If the read returns no bytes then we're
// already done, and we just return the Lrc we built above.
// If the read returns bytes however, we just fall back to reading into a Vec then turning
// that into an Lrc, losing our nice peak memory behavior. This fallback code path should
// be rarely exercised.
let mut probe = [0u8; 32];
let n = loop {
match file.read(&mut probe) {
Ok(0) => return Ok(bytes),
Err(e) if e.kind() == io::ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
Ok(n) => break n,
}
};
let mut bytes: Vec<u8> = bytes.iter().copied().chain(probe[..n].iter().copied()).collect();
file.read_to_end(&mut bytes)?;
Ok(bytes.into())
}
}
/// This is a [SourceFile] identifier that is used to correlate source files between
/// subsequent compilation sessions (which is something we need to do during
/// incremental compilation).
///
/// The [StableSourceFileId] also contains the CrateNum of the crate the source
/// file was originally parsed for. This way we get two separate entries in
/// the [SourceMap] if the same file is part of both the local and an upstream
/// crate. Trying to only have one entry for both cases is problematic because
/// at the point where we discover that there's a local use of the file in
/// addition to the upstream one, we might already have made decisions based on
/// the assumption that it's an upstream file. Treating the two files as
/// different has no real downsides.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Encodable, Decodable, Debug)]
pub struct StableSourceFileId {
/// A hash of the source file's [`FileName`]. This is hash so that it's size
/// is more predictable than if we included the actual [`FileName`] value.
pub file_name_hash: Hash64,
/// The [`CrateNum`] of the crate this source file was originally parsed for.
/// We cannot include this information in the hash because at the time
/// of hashing we don't have the context to map from the [`CrateNum`]'s numeric
/// value to a `StableCrateId`.
pub cnum: CrateNum,
}
// FIXME: we need a more globally consistent approach to the problem solved by
// StableSourceFileId, perhaps built atop source_file.name_hash.
impl StableSourceFileId {
pub fn new(source_file: &SourceFile) -> StableSourceFileId {
StableSourceFileId::new_from_name(&source_file.name, source_file.cnum)
}
fn new_from_name(name: &FileName, cnum: CrateNum) -> StableSourceFileId {
let mut hasher = StableHasher::new();
name.hash(&mut hasher);
StableSourceFileId { file_name_hash: hasher.finish(), cnum }
}
}
// _____________________________________________________________________________
// SourceMap
//
#[derive(Default)]
pub(super) struct SourceMapFiles {
source_files: monotonic::MonotonicVec<Lrc<SourceFile>>,
stable_id_to_source_file: FxHashMap<StableSourceFileId, Lrc<SourceFile>>,
}
pub struct SourceMap {
files: RwLock<SourceMapFiles>,
file_loader: IntoDynSyncSend<Box<dyn FileLoader + Sync + Send>>,
// This is used to apply the file path remapping as specified via
// `--remap-path-prefix` to all `SourceFile`s allocated within this `SourceMap`.
path_mapping: FilePathMapping,
/// The algorithm used for hashing the contents of each source file.
hash_kind: SourceFileHashAlgorithm,
}
impl SourceMap {
pub fn new(path_mapping: FilePathMapping) -> SourceMap {
Self::with_file_loader_and_hash_kind(
Box::new(RealFileLoader),
path_mapping,
SourceFileHashAlgorithm::Md5,
)
}
pub fn with_file_loader_and_hash_kind(
file_loader: Box<dyn FileLoader + Sync + Send>,
path_mapping: FilePathMapping,
hash_kind: SourceFileHashAlgorithm,
) -> SourceMap {
SourceMap {
files: Default::default(),
file_loader: IntoDynSyncSend(file_loader),
path_mapping,
hash_kind,
}
}
pub fn path_mapping(&self) -> &FilePathMapping {
&self.path_mapping
}
pub fn file_exists(&self, path: &Path) -> bool {
self.file_loader.file_exists(path)
}
pub fn load_file(&self, path: &Path) -> io::Result<Lrc<SourceFile>> {
let src = self.file_loader.read_file(path)?;
let filename = path.to_owned().into();
Ok(self.new_source_file(filename, src))
}
/// Loads source file as a binary blob.
///
/// Unlike `load_file`, guarantees that no normalization like BOM-removal
/// takes place.
pub fn load_binary_file(&self, path: &Path) -> io::Result<Lrc<[u8]>> {
let bytes = self.file_loader.read_binary_file(path)?;
// We need to add file to the `SourceMap`, so that it is present
// in dep-info. There's also an edge case that file might be both
// loaded as a binary via `include_bytes!` and as proper `SourceFile`
// via `mod`, so we try to use real file contents and not just an
// empty string.
let text = std::str::from_utf8(&bytes).unwrap_or("").to_string();
self.new_source_file(path.to_owned().into(), text);
Ok(bytes)
}
// By returning a `MonotonicVec`, we ensure that consumers cannot invalidate
// any existing indices pointing into `files`.
pub fn files(&self) -> MappedReadGuard<'_, monotonic::MonotonicVec<Lrc<SourceFile>>> {
ReadGuard::map(self.files.borrow(), |files| &files.source_files)
}
pub fn source_file_by_stable_id(
&self,
stable_id: StableSourceFileId,
) -> Option<Lrc<SourceFile>> {
self.files.borrow().stable_id_to_source_file.get(&stable_id).cloned()
}
fn register_source_file(
&self,
file_id: StableSourceFileId,
mut file: SourceFile,
) -> Result<Lrc<SourceFile>, OffsetOverflowError> {
let mut files = self.files.borrow_mut();
file.start_pos = BytePos(if let Some(last_file) = files.source_files.last() {
// Add one so there is some space between files. This lets us distinguish
// positions in the `SourceMap`, even in the presence of zero-length files.
last_file.end_position().0.checked_add(1).ok_or(OffsetOverflowError)?
} else {
0
});
let file = Lrc::new(file);
files.source_files.push(file.clone());
files.stable_id_to_source_file.insert(file_id, file.clone());
Ok(file)
}
/// Creates a new `SourceFile`.
/// If a file already exists in the `SourceMap` with the same ID, that file is returned
/// unmodified.
pub fn new_source_file(&self, filename: FileName, src: String) -> Lrc<SourceFile> {
self.try_new_source_file(filename, src).unwrap_or_else(|OffsetOverflowError| {
eprintln!("fatal error: rustc does not support files larger than 4GB");
crate::fatal_error::FatalError.raise()
})
}
fn try_new_source_file(
&self,
filename: FileName,
src: String,
) -> Result<Lrc<SourceFile>, OffsetOverflowError> {
// Note that filename may not be a valid path, eg it may be `<anon>` etc,
// but this is okay because the directory determined by `path.pop()` will
// be empty, so the working directory will be used.
let (filename, _) = self.path_mapping.map_filename_prefix(&filename);
let file_id = StableSourceFileId::new_from_name(&filename, LOCAL_CRATE);
match self.source_file_by_stable_id(file_id) {
Some(lrc_sf) => Ok(lrc_sf),
None => {
let source_file = SourceFile::new(filename, src, self.hash_kind)?;
// Let's make sure the file_id we generated above actually matches
// the ID we generate for the SourceFile we just created.
debug_assert_eq!(StableSourceFileId::new(&source_file), file_id);
self.register_source_file(file_id, source_file)
}
}
}
/// Allocates a new `SourceFile` representing a source file from an external
/// crate. The source code of such an "imported `SourceFile`" is not available,
/// but we still know enough to generate accurate debuginfo location
/// information for things inlined from other crates.
pub fn new_imported_source_file(
&self,
filename: FileName,
src_hash: SourceFileHash,
name_hash: Hash128,
source_len: u32,
cnum: CrateNum,
file_local_lines: FreezeLock<SourceFileLines>,
multibyte_chars: Vec<MultiByteChar>,
non_narrow_chars: Vec<NonNarrowChar>,
normalized_pos: Vec<NormalizedPos>,
metadata_index: u32,
) -> Lrc<SourceFile> {
let source_len = RelativeBytePos::from_u32(source_len);
let source_file = SourceFile {
name: filename,
src: None,
src_hash,
external_src: FreezeLock::new(ExternalSource::Foreign {
kind: ExternalSourceKind::AbsentOk,
metadata_index,
}),
start_pos: BytePos(0),
source_len,
lines: file_local_lines,
multibyte_chars,
non_narrow_chars,
normalized_pos,
name_hash,
cnum,
};
let file_id = StableSourceFileId::new(&source_file);
self.register_source_file(file_id, source_file)
.expect("not enough address space for imported source file")
}
/// If there is a doctest offset, applies it to the line.
pub fn doctest_offset_line(&self, file: &FileName, orig: usize) -> usize {
match file {
FileName::DocTest(_, offset) => {
if *offset < 0 {
orig - (-(*offset)) as usize
} else {
orig + *offset as usize
}
}
_ => orig,
}
}
/// Return the SourceFile that contains the given `BytePos`
pub fn lookup_source_file(&self, pos: BytePos) -> Lrc<SourceFile> {
let idx = self.lookup_source_file_idx(pos);
(*self.files.borrow().source_files)[idx].clone()
}
/// Looks up source information about a `BytePos`.
pub fn lookup_char_pos(&self, pos: BytePos) -> Loc {
let sf = self.lookup_source_file(pos);
let (line, col, col_display) = sf.lookup_file_pos_with_col_display(pos);
Loc { file: sf, line, col, col_display }
}
/// If the corresponding `SourceFile` is empty, does not return a line number.
pub fn lookup_line(&self, pos: BytePos) -> Result<SourceFileAndLine, Lrc<SourceFile>> {
let f = self.lookup_source_file(pos);
let pos = f.relative_position(pos);
match f.lookup_line(pos) {
Some(line) => Ok(SourceFileAndLine { sf: f, line }),
None => Err(f),
}
}
pub fn span_to_string(
&self,
sp: Span,
filename_display_pref: FileNameDisplayPreference,
) -> String {
let (source_file, lo_line, lo_col, hi_line, hi_col) = self.span_to_location_info(sp);
let file_name = match source_file {
Some(sf) => sf.name.display(filename_display_pref).to_string(),
None => return "no-location".to_string(),
};
format!(
"{file_name}:{lo_line}:{lo_col}{}",
if let FileNameDisplayPreference::Short = filename_display_pref {
String::new()
} else {
format!(": {hi_line}:{hi_col}")
}
)
}
pub fn span_to_location_info(
&self,
sp: Span,
) -> (Option<Lrc<SourceFile>>, usize, usize, usize, usize) {
if self.files.borrow().source_files.is_empty() || sp.is_dummy() {
return (None, 0, 0, 0, 0);
}
let lo = self.lookup_char_pos(sp.lo());
let hi = self.lookup_char_pos(sp.hi());
(Some(lo.file), lo.line, lo.col.to_usize() + 1, hi.line, hi.col.to_usize() + 1)
}
/// Format the span location suitable for embedding in build artifacts
pub fn span_to_embeddable_string(&self, sp: Span) -> String {
self.span_to_string(sp, FileNameDisplayPreference::Remapped)
}
/// Format the span location suitable for pretty printing annotations with relative line numbers
pub fn span_to_relative_line_string(&self, sp: Span, relative_to: Span) -> String {
if self.files.borrow().source_files.is_empty() || sp.is_dummy() || relative_to.is_dummy() {
return "no-location".to_string();
}
let lo = self.lookup_char_pos(sp.lo());
let hi = self.lookup_char_pos(sp.hi());
let offset = self.lookup_char_pos(relative_to.lo());
if lo.file.name != offset.file.name || !relative_to.contains(sp) {
return self.span_to_embeddable_string(sp);
}
let lo_line = lo.line.saturating_sub(offset.line);
let hi_line = hi.line.saturating_sub(offset.line);
format!(
"{}:+{}:{}: +{}:{}",
lo.file.name.display(FileNameDisplayPreference::Remapped),
lo_line,
lo.col.to_usize() + 1,
hi_line,
hi.col.to_usize() + 1,
)
}
/// Format the span location to be printed in diagnostics. Must not be emitted
/// to build artifacts as this may leak local file paths. Use span_to_embeddable_string
/// for string suitable for embedding.
pub fn span_to_diagnostic_string(&self, sp: Span) -> String {
self.span_to_string(sp, self.path_mapping.filename_display_for_diagnostics)
}
pub fn span_to_filename(&self, sp: Span) -> FileName {
self.lookup_char_pos(sp.lo()).file.name.clone()
}
pub fn filename_for_diagnostics<'a>(&self, filename: &'a FileName) -> FileNameDisplay<'a> {
filename.display(self.path_mapping.filename_display_for_diagnostics)
}
pub fn is_multiline(&self, sp: Span) -> bool {
let lo = self.lookup_source_file_idx(sp.lo());
let hi = self.lookup_source_file_idx(sp.hi());
if lo != hi {
return true;
}
let f = (*self.files.borrow().source_files)[lo].clone();
let lo = f.relative_position(sp.lo());
let hi = f.relative_position(sp.hi());
f.lookup_line(lo) != f.lookup_line(hi)
}
#[instrument(skip(self), level = "trace")]
pub fn is_valid_span(&self, sp: Span) -> Result<(Loc, Loc), SpanLinesError> {
let lo = self.lookup_char_pos(sp.lo());
trace!(?lo);
let hi = self.lookup_char_pos(sp.hi());
trace!(?hi);
if lo.file.start_pos != hi.file.start_pos {
return Err(SpanLinesError::DistinctSources(Box::new(DistinctSources {
begin: (lo.file.name.clone(), lo.file.start_pos),
end: (hi.file.name.clone(), hi.file.start_pos),
})));
}
Ok((lo, hi))
}
pub fn is_line_before_span_empty(&self, sp: Span) -> bool {
match self.span_to_prev_source(sp) {
Ok(s) => s.rsplit_once('\n').unwrap_or(("", &s)).1.trim_start().is_empty(),
Err(_) => false,
}
}
pub fn span_to_lines(&self, sp: Span) -> FileLinesResult {
debug!("span_to_lines(sp={:?})", sp);
let (lo, hi) = self.is_valid_span(sp)?;
assert!(hi.line >= lo.line);
if sp.is_dummy() {
return Ok(FileLines { file: lo.file, lines: Vec::new() });
}
let mut lines = Vec::with_capacity(hi.line - lo.line + 1);
// The span starts partway through the first line,
// but after that it starts from offset 0.
let mut start_col = lo.col;
// For every line but the last, it extends from `start_col`
// and to the end of the line. Be careful because the line
// numbers in Loc are 1-based, so we subtract 1 to get 0-based
// lines.
//
// FIXME: now that we handle DUMMY_SP up above, we should consider
// asserting that the line numbers here are all indeed 1-based.
let hi_line = hi.line.saturating_sub(1);
for line_index in lo.line.saturating_sub(1)..hi_line {
let line_len = lo.file.get_line(line_index).map_or(0, |s| s.chars().count());
lines.push(LineInfo { line_index, start_col, end_col: CharPos::from_usize(line_len) });
start_col = CharPos::from_usize(0);
}
// For the last line, it extends from `start_col` to `hi.col`:
lines.push(LineInfo { line_index: hi_line, start_col, end_col: hi.col });
Ok(FileLines { file: lo.file, lines })
}
/// Extracts the source surrounding the given `Span` using the `extract_source` function. The
/// extract function takes three arguments: a string slice containing the source, an index in
/// the slice for the beginning of the span and an index in the slice for the end of the span.
fn span_to_source<F, T>(&self, sp: Span, extract_source: F) -> Result<T, SpanSnippetError>
where
F: Fn(&str, usize, usize) -> Result<T, SpanSnippetError>,
{
let local_begin = self.lookup_byte_offset(sp.lo());
let local_end = self.lookup_byte_offset(sp.hi());
if local_begin.sf.start_pos != local_end.sf.start_pos {
Err(SpanSnippetError::DistinctSources(Box::new(DistinctSources {
begin: (local_begin.sf.name.clone(), local_begin.sf.start_pos),
end: (local_end.sf.name.clone(), local_end.sf.start_pos),
})))
} else {
self.ensure_source_file_source_present(&local_begin.sf);
let start_index = local_begin.pos.to_usize();
let end_index = local_end.pos.to_usize();
let source_len = local_begin.sf.source_len.to_usize();
if start_index > end_index || end_index > source_len {
return Err(SpanSnippetError::MalformedForSourcemap(MalformedSourceMapPositions {
name: local_begin.sf.name.clone(),
source_len,
begin_pos: local_begin.pos,
end_pos: local_end.pos,
}));
}
if let Some(ref src) = local_begin.sf.src {
extract_source(src, start_index, end_index)
} else if let Some(src) = local_begin.sf.external_src.read().get_source() {
extract_source(src, start_index, end_index)
} else {
Err(SpanSnippetError::SourceNotAvailable { filename: local_begin.sf.name.clone() })
}
}
}
pub fn is_span_accessible(&self, sp: Span) -> bool {
self.span_to_source(sp, |src, start_index, end_index| {
Ok(src.get(start_index..end_index).is_some())
})
.is_ok_and(|is_accessible| is_accessible)
}
/// Returns the source snippet as `String` corresponding to the given `Span`.
pub fn span_to_snippet(&self, sp: Span) -> Result<String, SpanSnippetError> {
self.span_to_source(sp, |src, start_index, end_index| {
src.get(start_index..end_index)
.map(|s| s.to_string())
.ok_or(SpanSnippetError::IllFormedSpan(sp))
})
}
pub fn span_to_margin(&self, sp: Span) -> Option<usize> {
Some(self.indentation_before(sp)?.len())
}
pub fn indentation_before(&self, sp: Span) -> Option<String> {
self.span_to_source(sp, |src, start_index, _| {
let before = &src[..start_index];
let last_line = before.rsplit_once('\n').map_or(before, |(_, last)| last);
Ok(last_line
.split_once(|c: char| !c.is_whitespace())
.map_or(last_line, |(indent, _)| indent)
.to_string())
})
.ok()
}
/// Returns the source snippet as `String` before the given `Span`.
pub fn span_to_prev_source(&self, sp: Span) -> Result<String, SpanSnippetError> {
self.span_to_source(sp, |src, start_index, _| {
src.get(..start_index).map(|s| s.to_string()).ok_or(SpanSnippetError::IllFormedSpan(sp))
})
}
/// Extends the given `Span` to just after the previous occurrence of `c`. Return the same span
/// if no character could be found or if an error occurred while retrieving the code snippet.
pub fn span_extend_to_prev_char(&self, sp: Span, c: char, accept_newlines: bool) -> Span {
if let Ok(prev_source) = self.span_to_prev_source(sp) {
let prev_source = prev_source.rsplit(c).next().unwrap_or("");
if !prev_source.is_empty() && (accept_newlines || !prev_source.contains('\n')) {
return sp.with_lo(BytePos(sp.lo().0 - prev_source.len() as u32));
}
}
sp
}
/// Extends the given `Span` to just after the previous occurrence of `pat` when surrounded by
/// whitespace. Returns None if the pattern could not be found or if an error occurred while
/// retrieving the code snippet.
pub fn span_extend_to_prev_str(
&self,
sp: Span,
pat: &str,
accept_newlines: bool,
include_whitespace: bool,
) -> Option<Span> {
// assure that the pattern is delimited, to avoid the following
// fn my_fn()
// ^^^^ returned span without the check
// ---------- correct span
let prev_source = self.span_to_prev_source(sp).ok()?;
for ws in &[" ", "\t", "\n"] {
let pat = pat.to_owned() + ws;
if let Some(pat_pos) = prev_source.rfind(&pat) {
let just_after_pat_pos = pat_pos + pat.len() - 1;
let just_after_pat_plus_ws = if include_whitespace {
just_after_pat_pos
+ prev_source[just_after_pat_pos..]
.find(|c: char| !c.is_whitespace())
.unwrap_or(0)
} else {
just_after_pat_pos
};
let len = prev_source.len() - just_after_pat_plus_ws;
let prev_source = &prev_source[just_after_pat_plus_ws..];
if accept_newlines || !prev_source.trim_start().contains('\n') {
return Some(sp.with_lo(BytePos(sp.lo().0 - len as u32)));
}
}
}
None
}
/// Returns the source snippet as `String` after the given `Span`.
pub fn span_to_next_source(&self, sp: Span) -> Result<String, SpanSnippetError> {
self.span_to_source(sp, |src, _, end_index| {
src.get(end_index..).map(|s| s.to_string()).ok_or(SpanSnippetError::IllFormedSpan(sp))
})
}
/// Extends the given `Span` while the next character matches the predicate
pub fn span_extend_while(
&self,
span: Span,
f: impl Fn(char) -> bool,
) -> Result<Span, SpanSnippetError> {
self.span_to_source(span, |s, _start, end| {
let n = s[end..].char_indices().find(|&(_, c)| !f(c)).map_or(s.len() - end, |(i, _)| i);
Ok(span.with_hi(span.hi() + BytePos(n as u32)))
})
}
/// Extends the given `Span` to previous character while the previous character matches the predicate
pub fn span_extend_prev_while(
&self,
span: Span,
f: impl Fn(char) -> bool,
) -> Result<Span, SpanSnippetError> {
self.span_to_source(span, |s, start, _end| {
let n = s[..start]
.char_indices()
.rfind(|&(_, c)| !f(c))
.map_or(start, |(i, _)| start - i - 1);
Ok(span.with_lo(span.lo() - BytePos(n as u32)))
})
}
/// Extends the given `Span` to just before the next occurrence of `c`.
pub fn span_extend_to_next_char(&self, sp: Span, c: char, accept_newlines: bool) -> Span {
if let Ok(next_source) = self.span_to_next_source(sp) {
let next_source = next_source.split(c).next().unwrap_or("");
if !next_source.is_empty() && (accept_newlines || !next_source.contains('\n')) {
return sp.with_hi(BytePos(sp.hi().0 + next_source.len() as u32));
}
}
sp
}
/// Extends the given `Span` to contain the entire line it is on.
pub fn span_extend_to_line(&self, sp: Span) -> Span {
self.span_extend_to_prev_char(self.span_extend_to_next_char(sp, '\n', true), '\n', true)
}
/// Given a `Span`, tries to get a shorter span ending before the first occurrence of `char`
/// `c`.
pub fn span_until_char(&self, sp: Span, c: char) -> Span {
match self.span_to_snippet(sp) {
Ok(snippet) => {
let snippet = snippet.split(c).next().unwrap_or("").trim_end();
if !snippet.is_empty() && !snippet.contains('\n') {
sp.with_hi(BytePos(sp.lo().0 + snippet.len() as u32))
} else {
sp
}
}
_ => sp,
}
}
/// Given a 'Span', tries to tell if it's wrapped by "<>" or "()"
/// the algorithm searches if the next character is '>' or ')' after skipping white space
/// then searches the previous character to match '<' or '(' after skipping white space
/// return true if wrapped by '<>' or '()'
pub fn span_wrapped_by_angle_or_parentheses(&self, span: Span) -> bool {
self.span_to_source(span, |src, start_index, end_index| {
if src.get(start_index..end_index).is_none() {
return Ok(false);
}
// test the right side to match '>' after skipping white space
let end_src = &src[end_index..];
let mut i = 0;
let mut found_right_parentheses = false;
let mut found_right_angle = false;
while let Some(cc) = end_src.chars().nth(i) {
if cc == ' ' {
i = i + 1;
} else if cc == '>' {
// found > in the right;
found_right_angle = true;
break;
} else if cc == ')' {
found_right_parentheses = true;
break;
} else {
// failed to find '>' return false immediately
return Ok(false);
}
}
// test the left side to match '<' after skipping white space
i = start_index;
let start_src = &src[0..start_index];
while let Some(cc) = start_src.chars().nth(i) {
if cc == ' ' {
if i == 0 {
return Ok(false);
}
i = i - 1;
} else if cc == '<' {
// found < in the left
if !found_right_angle {
// skip something like "(< )>"
return Ok(false);
}
break;
} else if cc == '(' {
if !found_right_parentheses {
// skip something like "<(>)"
return Ok(false);
}
break;
} else {
// failed to find '<' return false immediately
return Ok(false);
}
}
return Ok(true);
})
.is_ok_and(|is_accessible| is_accessible)
}
/// Given a `Span`, tries to get a shorter span ending just after the first occurrence of `char`
/// `c`.
pub fn span_through_char(&self, sp: Span, c: char) -> Span {
if let Ok(snippet) = self.span_to_snippet(sp) {
if let Some(offset) = snippet.find(c) {
return sp.with_hi(BytePos(sp.lo().0 + (offset + c.len_utf8()) as u32));
}
}
sp
}
/// Given a `Span`, gets a new `Span` covering the first token and all its trailing whitespace
/// or the original `Span`.
///
/// If `sp` points to `"let mut x"`, then a span pointing at `"let "` will be returned.
pub fn span_until_non_whitespace(&self, sp: Span) -> Span {
let mut whitespace_found = false;
self.span_take_while(sp, |c| {
if !whitespace_found && c.is_whitespace() {
whitespace_found = true;
}
!whitespace_found || c.is_whitespace()
})
}
/// Given a `Span`, gets a new `Span` covering the first token without its trailing whitespace
/// or the original `Span` in case of error.
///
/// If `sp` points to `"let mut x"`, then a span pointing at `"let"` will be returned.
pub fn span_until_whitespace(&self, sp: Span) -> Span {
self.span_take_while(sp, |c| !c.is_whitespace())
}
/// Given a `Span`, gets a shorter one until `predicate` yields `false`.
pub fn span_take_while<P>(&self, sp: Span, predicate: P) -> Span
where
P: for<'r> FnMut(&'r char) -> bool,
{
if let Ok(snippet) = self.span_to_snippet(sp) {
let offset = snippet.chars().take_while(predicate).map(|c| c.len_utf8()).sum::<usize>();
sp.with_hi(BytePos(sp.lo().0 + (offset as u32)))
} else {
sp
}
}
/// Given a `Span`, return a span ending in the closest `{`. This is useful when you have a
/// `Span` enclosing a whole item but we need to point at only the head (usually the first
/// line) of that item.
///
/// *Only suitable for diagnostics.*
pub fn guess_head_span(&self, sp: Span) -> Span {
// FIXME: extend the AST items to have a head span, or replace callers with pointing at
// the item's ident when appropriate.
self.span_until_char(sp, '{')
}
/// Returns a new span representing just the first character of the given span.
pub fn start_point(&self, sp: Span) -> Span {
let width = {
let sp = sp.data();
let local_begin = self.lookup_byte_offset(sp.lo);
let start_index = local_begin.pos.to_usize();
let src = local_begin.sf.external_src.read();
let snippet = if let Some(ref src) = local_begin.sf.src {
Some(&src[start_index..])
} else {
src.get_source().map(|src| &src[start_index..])
};
match snippet {
None => 1,
Some(snippet) => match snippet.chars().next() {
None => 1,
Some(c) => c.len_utf8(),
},
}
};
sp.with_hi(BytePos(sp.lo().0 + width as u32))
}
/// Returns a new span representing just the last character of this span.
pub fn end_point(&self, sp: Span) -> Span {
let pos = sp.hi().0;
let width = self.find_width_of_character_at_span(sp, false);
let corrected_end_position = pos.checked_sub(width).unwrap_or(pos);
let end_point = BytePos(cmp::max(corrected_end_position, sp.lo().0));
sp.with_lo(end_point)
}
/// Returns a new span representing the next character after the end-point of this span.
/// Special cases:
/// - if span is a dummy one, returns the same span
/// - if next_point reached the end of source, return a span exceeding the end of source,
/// which means sm.span_to_snippet(next_point) will get `Err`
/// - respect multi-byte characters
pub fn next_point(&self, sp: Span) -> Span {
if sp.is_dummy() {
return sp;
}
let start_of_next_point = sp.hi().0;
let width = self.find_width_of_character_at_span(sp, true);
// If the width is 1, then the next span should only contain the next char besides current ending.
// However, in the case of a multibyte character, where the width != 1, the next span should
// span multiple bytes to include the whole character.
let end_of_next_point =
start_of_next_point.checked_add(width).unwrap_or(start_of_next_point);
let end_of_next_point = BytePos(cmp::max(start_of_next_point + 1, end_of_next_point));
Span::new(BytePos(start_of_next_point), end_of_next_point, sp.ctxt(), None)
}
/// Check whether span is followed by some specified expected string in limit scope
pub fn span_look_ahead(&self, span: Span, expect: &str, limit: Option<usize>) -> Option<Span> {
let mut sp = span;
for _ in 0..limit.unwrap_or(100_usize) {
sp = self.next_point(sp);
if let Ok(ref snippet) = self.span_to_snippet(sp) {
if snippet == expect {
return Some(sp);
}
if snippet.chars().any(|c| !c.is_whitespace()) {
break;
}
}
}
None
}
/// Finds the width of the character, either before or after the end of provided span,
/// depending on the `forwards` parameter.
#[instrument(skip(self, sp))]
fn find_width_of_character_at_span(&self, sp: Span, forwards: bool) -> u32 {
let sp = sp.data();
if sp.lo == sp.hi && !forwards {
debug!("early return empty span");
return 1;
}
let local_begin = self.lookup_byte_offset(sp.lo);
let local_end = self.lookup_byte_offset(sp.hi);
debug!("local_begin=`{:?}`, local_end=`{:?}`", local_begin, local_end);
if local_begin.sf.start_pos != local_end.sf.start_pos {
debug!("begin and end are in different files");
return 1;
}
let start_index = local_begin.pos.to_usize();
let end_index = local_end.pos.to_usize();
debug!("start_index=`{:?}`, end_index=`{:?}`", start_index, end_index);
// Disregard indexes that are at the start or end of their spans, they can't fit bigger
// characters.
if (!forwards && end_index == usize::MIN) || (forwards && start_index == usize::MAX) {
debug!("start or end of span, cannot be multibyte");
return 1;
}
let source_len = local_begin.sf.source_len.to_usize();
debug!("source_len=`{:?}`", source_len);
// Ensure indexes are also not malformed.
if start_index > end_index || end_index > source_len - 1 {
debug!("source indexes are malformed");
return 1;
}
let src = local_begin.sf.external_src.read();
let snippet = if let Some(src) = &local_begin.sf.src {
src
} else if let Some(src) = src.get_source() {
src
} else {
return 1;
};
if forwards {
(snippet.ceil_char_boundary(end_index + 1) - end_index) as u32
} else {
(end_index - snippet.floor_char_boundary(end_index - 1)) as u32
}
}
pub fn get_source_file(&self, filename: &FileName) -> Option<Lrc<SourceFile>> {
// Remap filename before lookup
let filename = self.path_mapping().map_filename_prefix(filename).0;
for sf in self.files.borrow().source_files.iter() {
if filename == sf.name {
return Some(sf.clone());
}
}
None
}
/// For a global `BytePos`, computes the local offset within the containing `SourceFile`.
pub fn lookup_byte_offset(&self, bpos: BytePos) -> SourceFileAndBytePos {
let idx = self.lookup_source_file_idx(bpos);
let sf = (*self.files.borrow().source_files)[idx].clone();
let offset = bpos - sf.start_pos;
SourceFileAndBytePos { sf, pos: offset }
}
/// Returns the index of the [`SourceFile`] (in `self.files`) that contains `pos`.
/// This index is guaranteed to be valid for the lifetime of this `SourceMap`,
/// since `source_files` is a `MonotonicVec`
pub fn lookup_source_file_idx(&self, pos: BytePos) -> usize {
self.files.borrow().source_files.partition_point(|x| x.start_pos <= pos) - 1
}
pub fn count_lines(&self) -> usize {
self.files().iter().fold(0, |a, f| a + f.count_lines())
}
pub fn ensure_source_file_source_present(&self, source_file: &SourceFile) -> bool {
source_file.add_external_src(|| {
let FileName::Real(ref name) = source_file.name else {
return None;
};
let local_path: Cow<'_, Path> = match name {
RealFileName::LocalPath(local_path) => local_path.into(),
RealFileName::Remapped { local_path: Some(local_path), .. } => local_path.into(),
RealFileName::Remapped { local_path: None, virtual_name } => {
// The compiler produces better error messages if the sources of dependencies
// are available. Attempt to undo any path mapping so we can find remapped
// dependencies.
// We can only use the heuristic because `add_external_src` checks the file
// content hash.
self.path_mapping.reverse_map_prefix_heuristically(virtual_name)?.into()
}
};
self.file_loader.read_file(&local_path).ok()
})
}
pub fn is_imported(&self, sp: Span) -> bool {
let source_file_index = self.lookup_source_file_idx(sp.lo());
let source_file = &self.files()[source_file_index];
source_file.is_imported()
}
/// Gets the span of a statement. If the statement is a macro expansion, the
/// span in the context of the block span is found. The trailing semicolon is included
/// on a best-effort basis.
pub fn stmt_span(&self, stmt_span: Span, block_span: Span) -> Span {
if !stmt_span.from_expansion() {
return stmt_span;
}
let mac_call = original_sp(stmt_span, block_span);
self.mac_call_stmt_semi_span(mac_call).map_or(mac_call, |s| mac_call.with_hi(s.hi()))
}
/// Tries to find the span of the semicolon of a macro call statement.
/// The input must be the *call site* span of a statement from macro expansion.
/// ```ignore (illustrative)
/// // v output
/// mac!();
/// // ^^^^^^ input
/// ```
pub fn mac_call_stmt_semi_span(&self, mac_call: Span) -> Option<Span> {
let span = self.span_extend_while(mac_call, char::is_whitespace).ok()?;
let span = span.shrink_to_hi().with_hi(BytePos(span.hi().0.checked_add(1)?));
if self.span_to_snippet(span).as_deref() != Ok(";") {
return None;
}
Some(span)
}
}
#[derive(Clone)]
pub struct FilePathMapping {
mapping: Vec<(PathBuf, PathBuf)>,
filename_display_for_diagnostics: FileNameDisplayPreference,
}
impl FilePathMapping {
pub fn empty() -> FilePathMapping {
FilePathMapping::new(Vec::new())
}
pub fn new(mapping: Vec<(PathBuf, PathBuf)>) -> FilePathMapping {
let filename_display_for_diagnostics = if mapping.is_empty() {
FileNameDisplayPreference::Local
} else {
FileNameDisplayPreference::Remapped
};
FilePathMapping { mapping, filename_display_for_diagnostics }
}
/// Applies any path prefix substitution as defined by the mapping.
/// The return value is the remapped path and a boolean indicating whether
/// the path was affected by the mapping.
pub fn map_prefix<'a>(&'a self, path: impl Into<Cow<'a, Path>>) -> (Cow<'a, Path>, bool) {
let path = path.into();
if path.as_os_str().is_empty() {
// Exit early if the path is empty and therefore there's nothing to remap.
// This is mostly to reduce spam for `RUSTC_LOG=[remap_path_prefix]`.
return (path, false);
}
return remap_path_prefix(&self.mapping, path);
#[instrument(level = "debug", skip(mapping), ret)]
fn remap_path_prefix<'a>(
mapping: &'a [(PathBuf, PathBuf)],
path: Cow<'a, Path>,
) -> (Cow<'a, Path>, bool) {
// NOTE: We are iterating over the mapping entries from last to first
// because entries specified later on the command line should
// take precedence.
for (from, to) in mapping.iter().rev() {
debug!("Trying to apply {from:?} => {to:?}");
if let Ok(rest) = path.strip_prefix(from) {
let remapped = if rest.as_os_str().is_empty() {
// This is subtle, joining an empty path onto e.g. `foo/bar` will
// result in `foo/bar/`, that is, there'll be an additional directory
// separator at the end. This can lead to duplicated directory separators
// in remapped paths down the line.
// So, if we have an exact match, we just return that without a call
// to `Path::join()`.
to.into()
} else {
to.join(rest).into()
};
debug!("Match - remapped");
return (remapped, true);
} else {
debug!("No match - prefix {from:?} does not match");
}
}
debug!("not remapped");
(path, false)
}
}
fn map_filename_prefix(&self, file: &FileName) -> (FileName, bool) {
match file {
FileName::Real(realfile) if let RealFileName::LocalPath(local_path) = realfile => {
let (mapped_path, mapped) = self.map_prefix(local_path);
let realfile = if mapped {
RealFileName::Remapped {
local_path: Some(local_path.clone()),
virtual_name: mapped_path.into_owned(),
}
} else {
realfile.clone()
};
(FileName::Real(realfile), mapped)
}
FileName::Real(_) => unreachable!("attempted to remap an already remapped filename"),
other => (other.clone(), false),
}
}
/// Expand a relative path to an absolute path with remapping taken into account.
/// Use this when absolute paths are required (e.g. debuginfo or crate metadata).
///
/// The resulting `RealFileName` will have its `local_path` portion erased if
/// possible (i.e. if there's also a remapped path).
pub fn to_embeddable_absolute_path(
&self,
file_path: RealFileName,
working_directory: &RealFileName,
) -> RealFileName {
match file_path {
// Anything that's already remapped we don't modify, except for erasing
// the `local_path` portion.
RealFileName::Remapped { local_path: _, virtual_name } => {
RealFileName::Remapped {
// We do not want any local path to be exported into metadata
local_path: None,
// We use the remapped name verbatim, even if it looks like a relative
// path. The assumption is that the user doesn't want us to further
// process paths that have gone through remapping.
virtual_name,
}
}
RealFileName::LocalPath(unmapped_file_path) => {
// If no remapping has been applied yet, try to do so
let (new_path, was_remapped) = self.map_prefix(unmapped_file_path);
if was_remapped {
// It was remapped, so don't modify further
return RealFileName::Remapped {
local_path: None,
virtual_name: new_path.into_owned(),
};
}
if new_path.is_absolute() {
// No remapping has applied to this path and it is absolute,
// so the working directory cannot influence it either, so
// we are done.
return RealFileName::LocalPath(new_path.into_owned());
}
debug_assert!(new_path.is_relative());
let unmapped_file_path_rel = new_path;
match working_directory {
RealFileName::LocalPath(unmapped_working_dir_abs) => {
let file_path_abs = unmapped_working_dir_abs.join(unmapped_file_path_rel);
// Although neither `working_directory` nor the file name were subject
// to path remapping, the concatenation between the two may be. Hence
// we need to do a remapping here.
let (file_path_abs, was_remapped) = self.map_prefix(file_path_abs);
if was_remapped {
RealFileName::Remapped {
// Erase the actual path
local_path: None,
virtual_name: file_path_abs.into_owned(),
}
} else {
// No kind of remapping applied to this path, so
// we leave it as it is.
RealFileName::LocalPath(file_path_abs.into_owned())
}
}
RealFileName::Remapped {
local_path: _,
virtual_name: remapped_working_dir_abs,
} => {
// If working_directory has been remapped, then we emit
// Remapped variant as the expanded path won't be valid
RealFileName::Remapped {
local_path: None,
virtual_name: Path::new(remapped_working_dir_abs)
.join(unmapped_file_path_rel),
}
}
}
}
}
}
/// Attempts to (heuristically) reverse a prefix mapping.
///
/// Returns [`Some`] if there is exactly one mapping where the "to" part is
/// a prefix of `path` and has at least one non-empty
/// [`Normal`](path::Component::Normal) component. The component
/// restriction exists to avoid reverse mapping overly generic paths like
/// `/` or `.`).
///
/// This is a heuristic and not guaranteed to return the actual original
/// path! Do not rely on the result unless you have other means to verify
/// that the mapping is correct (e.g. by checking the file content hash).
#[instrument(level = "debug", skip(self), ret)]
fn reverse_map_prefix_heuristically(&self, path: &Path) -> Option<PathBuf> {
let mut found = None;
for (from, to) in self.mapping.iter() {
let has_normal_component = to.components().any(|c| match c {
path::Component::Normal(s) => !s.is_empty(),
_ => false,
});
if !has_normal_component {
continue;
}
let Ok(rest) = path.strip_prefix(to) else {
continue;
};
if found.is_some() {
return None;
}
found = Some(from.join(rest));
}
found
}
}