[clang] [clang] Avoid -Wshadow warning when init-capture named same as class field (PR #74512)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Mariya Podchishchaeva (Fznamznon)

<details>
<summary>Changes</summary>


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

---
Full diff: https://github.com/llvm/llvm-project/pull/74512.diff


3 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+3) 
- (modified) clang/lib/Sema/SemaDecl.cpp (+5-3) 
- (modified) clang/test/SemaCXX/warn-shadow-in-lambdas.cpp (+18) 


``````````diff
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] {
+
+    };
+  }
+};
+}

``````````

</details>


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