https://github.com/AaronBallman created
https://github.com/llvm/llvm-project/pull/138877
We were previously recovering a bit too hard; consumeClose() would skip to a
recovery point, then we would call skipToEnd() to skip to another recovery
point. Needless to say, the follow-on diagnostics were not great. But also,
follow-on diagnostics were crashing due to unexpected null constraint
expressions.
Now we only recover once.
Fixes #138820
>From 2f2f9ba95a1a633a0262ce15a64d6b0d7e14b600 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aa...@aaronballman.com>
Date: Wed, 7 May 2025 09:55:43 -0400
Subject: [PATCH] [C++20] Fix crash with invalid concept requirement
We were previously recovering a bit too hard; consumeClose() would skip
to a recovery point, then we would call skipToEnd() to skip to another
recovery point. Needless to say, the follow-on diagnostics were not
great. But also, follow-on diagnostics were crashing due to unexpected
null constraint expressions.
Now we only recover once.
Fixes #138820
---
clang/docs/ReleaseNotes.rst | 2 ++
clang/lib/Parse/ParseExprCXX.cpp | 4 +++-
clang/test/SemaCXX/concept-crash-on-diagnostic.cpp | 12 ++++++++++++
3 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 55f774f5a672e..350244e3054cf 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -660,6 +660,8 @@ Bug Fixes to C++ Support
- Fixed a crash when forming an invalid function type in a dependent context.
(#GH138657) (#GH115725) (#GH68852)
- No longer crashes when instantiating invalid variable template specialization
whose type depends on itself. (#GH51347), (#GH55872)
+- Improved parser recovery of invalid requirement expressions. In turn, this
+ fixes crashes from follow-on processing of the invalid requirement.
(#GH138820)
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index 32b08a12a3bb6..546c228a30513 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -3706,8 +3706,10 @@ ExprResult Parser::ParseRequiresExpression() {
SkipUntil(tok::semi, tok::r_brace, SkipUntilFlags::StopBeforeMatch);
break;
}
+ // If there's an error consuming the closing bracket, consumeClose()
+ // will handle skipping to the nearest recovery point for us.
if (ExprBraces.consumeClose())
- ExprBraces.skipToEnd();
+ break;
concepts::Requirement *Req = nullptr;
SourceLocation NoexceptLoc;
diff --git a/clang/test/SemaCXX/concept-crash-on-diagnostic.cpp
b/clang/test/SemaCXX/concept-crash-on-diagnostic.cpp
index c38f8888075de..1efed72522fef 100644
--- a/clang/test/SemaCXX/concept-crash-on-diagnostic.cpp
+++ b/clang/test/SemaCXX/concept-crash-on-diagnostic.cpp
@@ -48,3 +48,15 @@ concept is_foo_concept = __is_same(foo::bar, T);
// expected-error@-1 {{'bar' is a private member of 'GH131530::foo'}}
}
+
+namespace GH138820 {
+int a;
+template<typename T>
+concept atomicish = requires() {
+ { // expected-note {{to match this '{'}}
+ a
+ ... // expected-error {{expected '}'}}
+ };
+};
+atomicish<int> f(); // expected-error {{expected 'auto' or 'decltype(auto)'
after concept name}}
+} // namespace GH138820
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