[libc-commits] [libc] [compiler-rt] [clang-tools-extra] [clang] [llvm] [flang] [libcxx] [clang] Avoid -Wshadow warning when init-capture named same as class field (PR #74512)

[Mariya Podchishchaeva via libc-commits]

https://github.com/Fznamznon updated https://github.com/llvm/llvm-project/pull/74512

>From 169d962b64b8ae242c3a6d332677296cf7503839 Mon Sep 17 00:00:00 2001
From: "Podchishchaeva, Mariya" <mariya.podchishchaeva at intel.com>
Date: Tue, 5 Dec 2023 10:28:44 -0800
Subject: [PATCH 1/2] [clang] Avoid -Wshadow warning when init-capture named
 same as class field

Shadowing warning doesn't make much sense since field is not available
in lambda's body without capturing this.

Fixes https://github.com/llvm/llvm-project/issues/71976
---
 clang/docs/ReleaseNotes.rst                   |  3 +++
 clang/lib/Sema/SemaDecl.cpp                   |  8 +++++---
 clang/test/SemaCXX/warn-shadow-in-lambdas.cpp | 18 ++++++++++++++++++
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 828dd10e3d6db..7ac81e16492d1 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -655,6 +655,9 @@ Bug Fixes in This Version
   Fixes (`#64467 <https://github.com/llvm/llvm-project/issues/64467>`_)
 - Clang's ``-Wchar-subscripts`` no longer warns on chars whose values are known non-negative constants.
   Fixes (`#18763 <https://github.com/llvm/llvm-project/issues/18763>`_)
+- Clang's ``-Wshadow`` no longer warns when init-capture named same as class
+  field.
+  Fixes (`#71976 <https://github.com/llvm/llvm-project/issues/71976>`_)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index f12424d33b7da..65d095b2431dd 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -8395,10 +8395,11 @@ void Sema::CheckShadow(NamedDecl *D, NamedDecl *ShadowedDecl,
 
   unsigned WarningDiag = diag::warn_decl_shadow;
   SourceLocation CaptureLoc;
-  if (isa<VarDecl>(D) && isa<VarDecl>(ShadowedDecl) && NewDC &&
-      isa<CXXMethodDecl>(NewDC)) {
+  if (isa<VarDecl>(D) && NewDC && isa<CXXMethodDecl>(NewDC)) {
     if (const auto *RD = dyn_cast<CXXRecordDecl>(NewDC->getParent())) {
       if (RD->isLambda() && OldDC->Encloses(NewDC->getLexicalParent())) {
+        if (!isa<VarDecl>(ShadowedDecl))
+          return;
         if (RD->getLambdaCaptureDefault() == LCD_None) {
           // Try to avoid warnings for lambdas with an explicit capture list.
           const auto *LSI = cast<LambdaScopeInfo>(getCurFunction());
@@ -8416,7 +8417,8 @@ void Sema::CheckShadow(NamedDecl *D, NamedDecl *ShadowedDecl,
         }
       }
 
-      if (cast<VarDecl>(ShadowedDecl)->hasLocalStorage()) {
+      if (const auto *VD = dyn_cast<VarDecl>(ShadowedDecl);
+          VD && VD->hasLocalStorage()) {
         // A variable can't shadow a local variable in an enclosing scope, if
         // they are separated by a non-capturing declaration context.
         for (DeclContext *ParentDC = NewDC;
diff --git a/clang/test/SemaCXX/warn-shadow-in-lambdas.cpp b/clang/test/SemaCXX/warn-shadow-in-lambdas.cpp
index bda6a65c02168..58af7a2e65c55 100644
--- a/clang/test/SemaCXX/warn-shadow-in-lambdas.cpp
+++ b/clang/test/SemaCXX/warn-shadow-in-lambdas.cpp
@@ -179,3 +179,21 @@ void f() {
 #endif
 }
 }
+
+namespace GH71976 {
+struct A {
+  int b = 5;
+  int foo() {
+    return [b = b]() { return b; }();
+  }
+};
+
+struct B {
+  int a;
+  void foo() {
+    auto b = [a = this->a] {
+
+    };
+  }
+};
+}

>From 3798e1f25a8d812c082ac5815c490eb9c7f67e62 Mon Sep 17 00:00:00 2001
From: "Podchishchaeva, Mariya" <mariya.podchishchaeva at intel.com>
Date: Wed, 6 Dec 2023 02:24:59 -0800
Subject: [PATCH 2/2] Apply comments

---
 clang/docs/ReleaseNotes.rst                   | 4 ++--
 clang/lib/Sema/SemaDecl.cpp                   | 1 +
 clang/test/SemaCXX/warn-shadow-in-lambdas.cpp | 4 ++--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 2d1f3ed22cf2e..f5e0d4fa39737 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -661,8 +661,8 @@ Bug Fixes in This Version
 - Fixed false positive error emitted when templated alias inside a class
   used private members of the same class.
   Fixes (`#41693 <https://github.com/llvm/llvm-project/issues/41693>`_)
-- Clang's ``-Wshadow`` no longer warns when init-capture named same as class
-  field.
+- Clang's ``-Wshadow`` no longer warns when an init-capture is named the same as
+  a class field.
   Fixes (`#71976 <https://github.com/llvm/llvm-project/issues/71976>`_)
 
 Bug Fixes to Compiler Builtins
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 65d095b2431dd..f590d1b3ade81 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -8398,6 +8398,7 @@ void Sema::CheckShadow(NamedDecl *D, NamedDecl *ShadowedDecl,
   if (isa<VarDecl>(D) && NewDC && isa<CXXMethodDecl>(NewDC)) {
     if (const auto *RD = dyn_cast<CXXRecordDecl>(NewDC->getParent())) {
       if (RD->isLambda() && OldDC->Encloses(NewDC->getLexicalParent())) {
+        // If it is not VarDecl then it can not shadow.
         if (!isa<VarDecl>(ShadowedDecl))
           return;
         if (RD->getLambdaCaptureDefault() == LCD_None) {
diff --git a/clang/test/SemaCXX/warn-shadow-in-lambdas.cpp b/clang/test/SemaCXX/warn-shadow-in-lambdas.cpp
index 58af7a2e65c55..3008e9018f30b 100644
--- a/clang/test/SemaCXX/warn-shadow-in-lambdas.cpp
+++ b/clang/test/SemaCXX/warn-shadow-in-lambdas.cpp
@@ -184,14 +184,14 @@ namespace GH71976 {
 struct A {
   int b = 5;
   int foo() {
-    return [b = b]() { return b; }();
+    return [b = b]() { return b; }(); // no diagnostic, init-capture does not shadow b
   }
 };
 
 struct B {
   int a;
   void foo() {
-    auto b = [a = this->a] {
+    auto b = [a = this->a] { // no diagnostic, init-capture does not shadow a
 
     };
   }