https://github.com/cor3ntin created
https://github.com/llvm/llvm-project/pull/107214
We were incorrectly not deduplicating results when looking up `_` which, for a
lambda init capture, would result in an ambiguous lookup.
The same bug caused some diagnostic notes to be emitted twice.
Fixes #107024
>From 75af619d96d874d67dc142e9c09ffc2a61737d96 Mon Sep 17 00:00:00 2001
From: cor3ntin <corentinja...@gmail.com>
Date: Tue, 3 Sep 2024 20:36:15 +0200
Subject: [PATCH] [Clang] Fix handling of placeholder variables name in init
captures (#107055)
We were incorrectly not deduplicating results when looking up `_` which,
for a lambda init capture, would result in an ambiguous lookup.
The same bug caused some diagnostic notes to be emitted twice.
Fixes #107024
---
clang/docs/ReleaseNotes.rst | 2 ++
clang/lib/Sema/SemaLambda.cpp | 1 -
clang/lib/Sema/SemaLookup.cpp | 2 +-
clang/test/SemaCXX/cxx2c-placeholder-vars.cpp | 6 ++++--
4 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 5eed9827343dd5..5acc44ed177a7d 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -1121,6 +1121,8 @@ Bug Fixes to C++ Support
Fixes (#GH85992).
- Fixed a crash-on-invalid bug involving extraneous template parameter with
concept substitution. (#GH73885)
- Fixed assertion failure by skipping the analysis of an invalid field
declaration. (#GH99868)
+- Fix handling of ``_`` as the name of a lambda's init capture variable.
(#GH107024)
+
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
index 601077e9f3334d..809b94bb7412b9 100644
--- a/clang/lib/Sema/SemaLambda.cpp
+++ b/clang/lib/Sema/SemaLambda.cpp
@@ -1318,7 +1318,6 @@ void
Sema::ActOnLambdaExpressionAfterIntroducer(LambdaIntroducer &Intro,
if (C->Init.isUsable()) {
addInitCapture(LSI, cast<VarDecl>(Var), C->Kind == LCK_ByRef);
- PushOnScopeChains(Var, CurScope, false);
} else {
TryCaptureKind Kind = C->Kind == LCK_ByRef ? TryCapture_ExplicitByRef
: TryCapture_ExplicitByVal;
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 7a6a64529f52ec..d3d4bf27ae7283 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -570,7 +570,7 @@ void LookupResult::resolveKind() {
// For non-type declarations, check for a prior lookup result naming this
// canonical declaration.
- if (!D->isPlaceholderVar(getSema().getLangOpts()) && !ExistingI) {
+ if (!ExistingI) {
auto UniqueResult = Unique.insert(std::make_pair(D, I));
if (!UniqueResult.second) {
// We've seen this entity before.
diff --git a/clang/test/SemaCXX/cxx2c-placeholder-vars.cpp
b/clang/test/SemaCXX/cxx2c-placeholder-vars.cpp
index 5cf66b48784e91..29ca3b5ef3df72 100644
--- a/clang/test/SemaCXX/cxx2c-placeholder-vars.cpp
+++ b/clang/test/SemaCXX/cxx2c-placeholder-vars.cpp
@@ -50,14 +50,16 @@ void f() {
void lambda() {
(void)[_ = 0, _ = 1] { // expected-warning {{placeholder variables are
incompatible with C++ standards before C++2c}} \
- // expected-note 4{{placeholder declared here}}
+ // expected-note 2{{placeholder declared here}}
(void)_++; // expected-error {{ambiguous reference to placeholder '_',
which is defined multiple times}}
};
{
int _ = 12;
- (void)[_ = 0]{}; // no warning (different scope)
+ (void)[_ = 0]{ return _;}; // no warning (different scope)
}
+
+ auto GH107024 = [_ = 42]() { return _; }();
}
namespace global_var {
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