bjoernager/rust
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Use Cow in {D,Subd}iagnosticMessage.

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Each of `{D,Subd}iagnosticMessage::{Str,Eager}` has a comment:
```
// FIXME(davidtwco): can a `Cow<'static, str>` be used here?
```
This commit answers that question in the affirmative. It's not the most
compelling change ever, but it might be worth merging.

This requires changing the `impl<'a> From<&'a str>` impls to `impl
From<&'static str>`, which involves a bunch of knock-on changes that
require/result in call sites being a little more precise about exactly
what kind of string they use to create errors, and not just `&str`. This
will result in fewer unnecessary allocations, though this will not have
any notable perf effects given that these are error paths.

Note that I was lazy within Clippy, using `to_string` in a few places to
preserve the existing string imprecision. I could have used `impl
Into<{D,Subd}iagnosticMessage>` in various places as is done in the
compiler, but that would have required changes to *many* call sites
(mostly changing `&format("...")` to `format!("...")`) which didn't seem
worthwhile.
This commit is contained in:
Nicholas Nethercote 2023-05-04 10:55:21 +10:00
parent 1c53407e8c
commit 781111ef35
45 changed files with 308 additions and 287 deletions
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4
compiler/rustc_resolve/src/macros.rs
View file

@ -827,7 +827,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
if !is_allowed(feature) && !allowed_by_implication {
let lint_buffer = &mut self.lint_buffer;
let soft_handler =
|lint, span, msg: &_| lint_buffer.buffer_lint(lint, node_id, span, msg);
|lint, span, msg: String| lint_buffer.buffer_lint(lint, node_id, span, msg);
stability::report_unstable(
self.tcx.sess,
feature,
@ -846,7 +846,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
let (message, lint) = stability::deprecation_message_and_lint(depr, "macro", &path);
stability::early_report_deprecation(
&mut self.lint_buffer,
&message,
message,
depr.suggestion,
lint,
span,