Currently a `{D,Subd}iagnosticMessage` can be created from any type that
impls `Into<String>`. That includes `&str`, `String`, and `Cow<'static,
str>`, which are reasonable. It also includes `&String`, which is pretty
weird, and results in many places making unnecessary allocations for
patterns like this:
```
self.fatal(&format!(...))
```
This creates a string with `format!`, takes a reference, passes the
reference to `fatal`, which does an `into()`, which clones the
reference, doing a second allocation. Two allocations for a single
string, bleh.
This commit changes the `From` impls so that you can only create a
`{D,Subd}iagnosticMessage` from `&str`, `String`, or `Cow<'static,
str>`. This requires changing all the places that currently create one
from a `&String`. Most of these are of the `&format!(...)` form
described above; each one removes an unnecessary static `&`, plus an
allocation when executed. There are also a few places where the existing
use of `&String` was more reasonable; these now just use `clone()` at
the call site.
As well as making the code nicer and more efficient, this is a step
towards possibly using `Cow<'static, str>` in
`{D,Subd}iagnosticMessage::{Str,Eager}`. That would require changing
the `From<&'a str>` impls to `From<&'static str>`, which is doable, but
I'm not yet sure if it's worthwhile.
Remove the `NodeId` of `ast::ExprKind::Async`
This is a followup to https://github.com/rust-lang/rust/pull/104833#pullrequestreview-1314537416.
In my original attempt, I was using `LoweringContext::expr`, which was not correct as it creates a fresh `DefId`.
It now uses the correct `DefId` for the wrapping `Expr`, and also makes forwarding `#[track_caller]` attributes more explicit.
It partially expands crate attributes before the main expansion pass (without modifying the crate), and the produced preliminary crate attribute list is used for querying a few attributes that are required very early.
Crate-level cfg attributes are then expanded normally during the main expansion pass, like attributes on any other nodes.
Migrate `rustc_lint` lint diagnostics
Part 2 of [Migrate `rustc_lint` errors to `SessionDiagnostic`](https://github.com/rust-lang/rust/pull/100776)
r? `@davidtwco`
# TODO
- [x] Refactor some lints manually implementing `DecorateLint` to use `Option<Subdiagnostic>`.
- [x] Add `#[rustc_lint_diagnostics]` to lint functions in `context.rs`.
- [x] Migrate `hidden_unicode_codepoints.rs`.
- [x] Migrate `UnsafeCode` in `builtin.rs`.
- [x] Migrate the rest of `builtin.rs`.
Fix stack overflow in recursive AST walk in early lint
The src/test/ui/issues/issue-74564-if-expr-stack-overflow.rs test case added to verify https://github.com/rust-lang/rust/issues/74564 still crashes with a stack overflow on s390x-ibm-linux.
Symptom is a very deep recursion in compiler/rustc_lint/src/early.rs:
fn visit_expr(&mut self, e: &'a ast::Expr) {
self.with_lint_attrs(e.id, &e.attrs, |cx| {
lint_callback!(cx, check_expr, e);
ast_visit::walk_expr(cx, e);
})
}
(where walk_expr recursively calls back into visit_expr). The crash happens at a nesting depth of over 17000 stack frames when using the default 8 MB stack size on s390x.
This patch fixes the problem by adding a ensure_sufficient_stack call to the with_lint_attrs routine (which also should take care of all the other mutually recursive visitors here).
Fixes part of https://github.com/rust-lang/rust/issues/105383.
The src/test/ui/issues/issue-74564-if-expr-stack-overflow.rs test case
added to verify https://github.com/rust-lang/rust/issues/74564 still
crashes with a stack overflow on s390x-ibm-linux.
Symptom is a very deep recursion in compiler/rustc_lint/src/early.rs:
fn visit_expr(&mut self, e: &'a ast::Expr) {
self.with_lint_attrs(e.id, &e.attrs, |cx| {
lint_callback!(cx, check_expr, e);
ast_visit::walk_expr(cx, e);
})
}
(where walk_expr recursively calls back into visit_expr). The crash
happens at a nesting depth of over 17000 stack frames when using the
default 8 MB stack size on s390x.
This patch fixes the problem by adding a ensure_sufficient_stack
call to the with_lint_attrs routine (which also should take care
of all the other mutually recursive visitors here).
Fixes part of https://github.com/rust-lang/rust/issues/105383.
This commit partly undoes #104863, which combined the builtin lints pass
with other lints. This caused a slowdown, because often there are no
other lints, and it's faster to do a pass with a single lint directly
than it is to do a combined pass with a `passes` vector containing a
single lint.
I removed these in #105291, and subsequently learned they are necessary
for performance.
This commit reinstates them with the new and more descriptive names
`RuntimeCombined{Early,Late}LintPass`, similar to the existing passes
like `BuiltinCombinedEarlyLintPass`. It also adds some comments,
particularly emphasising how we have ways to combine passes at both
compile-time and runtime. And it moves some comments around.
`EarlyContextAndPass` wraps a single early lint pass. We aggregate
multiple passes into that single pass by using `EarlyLintPassObjects`.
This commit removes `EarlyLintPassObjects` by changing
`EarlyContextAndPass` into `EarlyContextAndPasses`. I.e. it just removes
a level of indirection. This makes the code simpler and slightly faster.
The commit does likewise for late lints.
This avoids calling `early_lint_node` twice.
Note: one `early_lint_node` call had `!pre_expansion` for the second
argument and the other had `false`. The new single call just has
`!pre_expansion`. This results in a reduction of duplicate error
messages in some `ui-fulldeps` tests. The order of some `ui-fulldeps`
output also changes, but that doesn't matter.
The lint definitions use macros heavily. This commit merges some of them
that are split unnecessarily. I find the reduced indirection makes it
easier to imagine what the generated code will look like.
The compiler currently has `-Ztime` and `-Ztime-passes`. I've used
`-Ztime-passes` for years but only recently learned about `-Ztime`.
What's the difference? Let's look at the `-Zhelp` output:
```
-Z time=val -- measure time of rustc processes (default: no)
-Z time-passes=val -- measure time of each rustc pass (default: no)
```
The `-Ztime-passes` description is clear, but the `-Ztime` one is less so.
Sounds like it measures the time for the entire process?
No. The real difference is that `-Ztime-passes` prints out info about passes,
and `-Ztime` does the same, but only for a subset of those passes. More
specifically, there is a distinction in the profiling code between a "verbose
generic activity" and an "extra verbose generic activity". `-Ztime-passes`
prints both kinds, while `-Ztime` only prints the first one. (It took me
a close reading of the source code to determine this difference.)
In practice this distinction has low value. Perhaps in the past the "extra
verbose" output was more voluminous, but now that we only print stats for a
pass if it exceeds 5ms or alters the RSS, `-Ztime-passes` is less spammy. Also,
a lot of the "extra verbose" cases are for individual lint passes, and you need
to also use `-Zno-interleave-lints` to see those anyway.
Therefore, this commit removes `-Ztime` and the associated machinery. One thing
to note is that the existing "extra verbose" activities all have an extra
string argument, so the commit adds the ability to accept an extra argument to
the "verbose" activities.
The `visit_path_segment` method of both the AST and HIR visitors has a
`path_span` argument that isn't necessary. This commit removes it.
There are two very small and inconsequential functional changes.
- One call to `NodeCollector::insert` now is passed a path segment
identifier span instead of a full path span. This span is only used in
a panic message printed in the case of an internal compiler bug.
- Likewise, one call to `LifetimeCollectVisitor::record_elided_anchor`
now uses a path segment identifier span instead of a full path span.
This span is used to make some `'_` lifetimes.
This extends the LintLevelBuilder to handle lint level attributes on
struct expression fields and pattern fields.
This also updates the early lints to honor lint levels on generic
parameters.
Previously, we were emitting weird name lints (for renamed or unknown lints)
before expansion, most importantly before cfg expansion.
This meant that the weird name lints would not fire
for lint attributes hidden inside cfg_attr. The same applied
for lint level specifications of those lints.
By moving the lints for the lint names to the post-expansion
phase, these issues are resolved.
