https://github.com/zyn0217 created
https://github.com/llvm/llvm-project/pull/118050
This aligns with the logic in `TreeTransform::RebuildQualifiedType()` where we
refrain from adding const qualifiers to function types. Previously, we seemed
to overlook this edge case when copy-capturing a variable that is of function
type within a const-qualified lambda.
This issue also reveals other related problems as in incorrect type printout
and a suspicious implementation in DeduceTemplateArguments. I decide to leave
them in follow-up work.
Fixes #84961
>From 92b8a28eb7664b3cac6a8039834b099b010af3ed Mon Sep 17 00:00:00 2001
From: Younan Zhang <zyn7...@gmail.com>
Date: Fri, 29 Nov 2024 13:19:30 +0800
Subject: [PATCH] [Clang] Don't add top-level const qualifiers to captured
function types
---
clang/docs/ReleaseNotes.rst | 1 +
clang/lib/Sema/SemaExpr.cpp | 11 +++++++++--
.../test/SemaCXX/lambda-capture-type-deduction.cpp | 14 ++++++++++++++
3 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 8bd06fadfdc984..553856f3060bc1 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -712,6 +712,7 @@ Bug Fixes to C++ Support
- Name independent data members were not correctly initialized from default
member initializers. (#GH114069)
- Fixed expression transformation for ``[[assume(...)]]``, allowing using pack
indexing expressions within the
assumption if they also occur inside of a dependent lambda. (#GH114787)
+- Lambdas now capture function types without considering top-level const
qualifiers. (#GH84961)
- Clang now uses valid deduced type locations when diagnosing functions with
trailing return type
missing placeholder return type. (#GH78694)
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 6c7472ce92703b..04b713a91dedfa 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -18479,7 +18479,10 @@ static bool
isVariableAlreadyCapturedInScopeInfo(CapturingScopeInfo *CSI,
// are mutable in the sense that user can change their value - they are
// private instances of the captured declarations.
const Capture &Cap = CSI->getCapture(Var);
- if (Cap.isCopyCapture() &&
+ // C++ [dcl.fct]p7:
+ // [When] adding cv-qualifications on top of the function type [...] the
+ // cv-qualifiers are ignored.
+ if (Cap.isCopyCapture() && !DeclRefType->isFunctionType() &&
!(isa<LambdaScopeInfo>(CSI) &&
!cast<LambdaScopeInfo>(CSI)->lambdaCaptureShouldBeConst()) &&
!(isa<CapturedRegionScopeInfo>(CSI) &&
@@ -18789,7 +18792,11 @@ static bool captureInLambda(LambdaScopeInfo *LSI,
ValueDecl *Var,
// parameter-declaration-clause is not followed by mutable.
DeclRefType = CaptureType.getNonReferenceType();
bool Const = LSI->lambdaCaptureShouldBeConst();
- if (Const && !CaptureType->isReferenceType())
+ // C++ [dcl.fct]p7:
+ // [When] adding cv-qualifications on top of the function type [...] the
+ // cv-qualifiers are ignored.
+ if (Const && !CaptureType->isReferenceType() &&
+ !DeclRefType->isFunctionType())
DeclRefType.addConst();
}
diff --git a/clang/test/SemaCXX/lambda-capture-type-deduction.cpp
b/clang/test/SemaCXX/lambda-capture-type-deduction.cpp
index a86f3018989927..ba7ab34f943be1 100644
--- a/clang/test/SemaCXX/lambda-capture-type-deduction.cpp
+++ b/clang/test/SemaCXX/lambda-capture-type-deduction.cpp
@@ -319,3 +319,17 @@ constexpr void foo() {
}
} // namespace GH47400
+
+namespace GH84961 {
+
+template <typename T> void g(const T &t) {}
+
+template <typename T> void f(const T &t) {
+ [t] { g(t); }();
+}
+
+void h() {
+ f(h);
+}
+
+} // namespace GH84961
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