https://github.com/vinayakdsci updated
https://github.com/llvm/llvm-project/pull/81127
>From be1f3528d9fa90bf0fe930744f9df054d0b45425 Mon Sep 17 00:00:00 2001
From: Vinayak Dev <vinayakdev....@gmail.com>
Date: Thu, 8 Feb 2024 17:29:44 +0530
Subject: [PATCH] [Clang][Sema]: Allow copy constructor side effects
---
clang/lib/Sema/SemaDecl.cpp | 3 ++-
clang/test/SemaCXX/warn-unused-variables.cpp | 28 ++++++++++++++++++--
2 files changed, 28 insertions(+), 3 deletions(-)
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 18a5d93ab8e8c6..175533b0bd99a9 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2044,7 +2044,8 @@ static bool ShouldDiagnoseUnusedDecl(const LangOptions
&LangOpts,
return false;
if (Init) {
- const auto *Construct = dyn_cast<CXXConstructExpr>(Init);
+ const auto *Construct =
+ dyn_cast<CXXConstructExpr>(Init->IgnoreImpCasts());
if (Construct && !Construct->isElidable()) {
const CXXConstructorDecl *CD = Construct->getConstructor();
if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>() &&
diff --git a/clang/test/SemaCXX/warn-unused-variables.cpp
b/clang/test/SemaCXX/warn-unused-variables.cpp
index b649c7d8089355..92032a9c2b8125 100644
--- a/clang/test/SemaCXX/warn-unused-variables.cpp
+++ b/clang/test/SemaCXX/warn-unused-variables.cpp
@@ -1,5 +1,5 @@
// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label
-Wno-c++1y-extensions -verify %s
-// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label
-Wno-c++1y-extensions -verify -std=gnu++11 %s
+// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label
-Wno-c++1y-extensions -verify -std=gnu++17 %s
template<typename T> void f() {
T t;
t = 17;
@@ -183,7 +183,7 @@ void foo(int size) {
NonTriviallyDestructible array[2]; // no warning
NonTriviallyDestructible nestedArray[2][2]; // no warning
- Foo fooScalar = 1; // expected-warning {{unused variable 'fooScalar'}}
+ Foo fooScalar = 1; // no warning
Foo fooArray[] = {1,2}; // expected-warning {{unused variable 'fooArray'}}
Foo fooNested[2][2] = { {1,2}, {3,4} }; // expected-warning {{unused
variable 'fooNested'}}
}
@@ -297,3 +297,27 @@ void RAIIWrapperTest() {
}
} // namespace gh54489
+
+// Ensure that -Wunused-variable does not emit warning
+// on copy constructors with side effects
+namespace gh79518 {
+
+struct S {
+ S(int);
+};
+
+// With an initializer list
+struct A {
+ int x;
+ A(int x) : x(x) {}
+};
+
+void foo() {
+ S s(0); // no warning
+ S s2 = 0; // no warning
+ S s3{0}; // no warning
+
+ A a = 1; // no warning
+}
+
+} // namespace gh79518
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