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Rollup merge of #121917 - GuillaumeGomez:pattern-complexity_limit.rs, r=Nadrieril

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Add new `pattern_complexity` attribute to add possibility to limit and check recursion in pattern matching

Needed for https://github.com/rust-lang/rust-analyzer/issues/9528.

This PR adds a new attribute only available when running rust testsuite called `pattern_complexity` which allows to set the maximum recursion for the pattern matching. It is quite useful to ensure the complexity doesn't grow, like in `tests/ui/pattern/usefulness/issue-118437-exponential-time-on-diagonal-match.rs`.

r? `@Nadrieril`
This commit is contained in:
Guillaume Gomez 2024-03-03 14:07:43 +01:00 • committed by GitHub
commit 7d8f74f8b2
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13 changed files with 197 additions and 6 deletions
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11
compiler/rustc_middle/src/middle/limits.rs
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@ -40,6 +40,13 @@ pub fn get_recursion_limit(krate_attrs: &[Attribute], sess: &Session) -> Limit {
}
fn get_limit(krate_attrs: &[Attribute], sess: &Session, name: Symbol, default: usize) -> Limit {
match get_limit_size(krate_attrs, sess, name) {
Some(size) => Limit::new(size),
None => Limit::new(default),
}
}
pub fn get_limit_size(krate_attrs: &[Attribute], sess: &Session, name: Symbol) -> Option<usize> {
for attr in krate_attrs {
if !attr.has_name(name) {
continue;
@ -47,7 +54,7 @@ fn get_limit(krate_attrs: &[Attribute], sess: &Session, name: Symbol, default: u
if let Some(s) = attr.value_str() {
match s.as_str().parse() {
Ok(n) => return Limit::new(n),
Ok(n) => return Some(n),
Err(e) => {
let value_span = attr
.meta()
@ -69,5 +76,5 @@ fn get_limit(krate_attrs: &[Attribute], sess: &Session, name: Symbol, default: u
}
}
}
return Limit::new(default);
None
}