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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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8
compiler/rustc_mir_build/src/thir/pattern/check_match.rs
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@ -17,6 +17,7 @@ use rustc_hir as hir;
use rustc_hir::def::*;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::HirId;
use rustc_middle::middle::limits::get_limit_size;
use rustc_middle::thir::visit::Visitor;
use rustc_middle::thir::*;
use rustc_middle::ty::print::with_no_trimmed_paths;
@ -26,7 +27,7 @@ use rustc_session::lint::builtin::{
};
use rustc_session::Session;
use rustc_span::hygiene::DesugaringKind;
use rustc_span::Span;
use rustc_span::{sym, Span};
pub(crate) fn check_match(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(), ErrorGuaranteed> {
let typeck_results = tcx.typeck(def_id);
@ -403,8 +404,11 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> {
arms: &[MatchArm<'p, 'tcx>],
scrut_ty: Ty<'tcx>,
) -> Result<UsefulnessReport<'p, 'tcx>, ErrorGuaranteed> {
let pattern_complexity_limit =
get_limit_size(cx.tcx.hir().krate_attrs(), cx.tcx.sess, sym::pattern_complexity);
let report =
rustc_pattern_analysis::analyze_match(&cx, &arms, scrut_ty).map_err(|err| {
rustc_pattern_analysis::analyze_match(&cx, &arms, scrut_ty, pattern_complexity_limit)
.map_err(|err| {
self.error = Err(err);
err
})?;