bjoernager/rust
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Avoid an unnecessary allocation

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This commit is contained in:
Oli Scherer 2023-01-16 14:27:33 +00:00
parent 44ef075aeb
commit 1355559367
5 changed files with 28 additions and 27 deletions
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27
compiler/rustc_span/src/source_map.rs
View file

@ -1138,7 +1138,8 @@ impl FilePathMapping {
/// 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(&self, path: PathBuf) -> (PathBuf, bool) {
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]`.
@ -1148,7 +1149,10 @@ impl FilePathMapping {
return remap_path_prefix(&self.mapping, path);
#[instrument(level = "debug", skip(mapping), ret)]
fn remap_path_prefix(mapping: &[(PathBuf, PathBuf)], path: PathBuf) -> (PathBuf, bool) {
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.
@ -1163,9 +1167,9 @@ impl FilePathMapping {
// in remapped paths down the line.
// So, if we have an exact match, we just return that without a call
// to `Path::join()`.
to.clone()
to.into()
} else {
to.join(rest)
to.join(rest).into()
};
debug!("Match - remapped");
@ -1183,11 +1187,11 @@ impl FilePathMapping {
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.to_path_buf());
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,
virtual_name: mapped_path.into_owned(),
}
} else {
realfile.clone()
@ -1228,14 +1232,17 @@ impl FilePathMapping {
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 };
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);
return RealFileName::LocalPath(new_path.into_owned());
}
debug_assert!(new_path.is_relative());
@ -1253,12 +1260,12 @@ impl FilePathMapping {
RealFileName::Remapped {
// Erase the actual path
local_path: None,
virtual_name: file_path_abs,
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)
RealFileName::LocalPath(file_path_abs.into_owned())
}
}
RealFileName::Remapped {

2
compiler/rustc_span/src/source_map/tests.rs
View file

@ -387,7 +387,7 @@ fn path_prefix_remapping_expand_to_absolute() {
let working_directory = path("/foo");
let working_directory = RealFileName::Remapped {
local_path: Some(working_directory.clone()),
virtual_name: mapping.map_prefix(working_directory).0,
virtual_name: mapping.map_prefix(working_directory).0.into_owned(),
};
assert_eq!(working_directory.remapped_path_if_available(), path("FOO"));