Commit d17519a7 authored Aug 11, 2017 by Hans Wennborg

Merging r309569:

------------------------------------------------------------------------
r309569 | alexfh | 2017-07-31 08:21:26 -0700 (Mon, 31 Jul 2017) | 39 lines

Fix -Wshadow false positives with function-local classes.

Summary:
Fixes http://llvm.org/PR33947.

https://godbolt.org/g/54XRMT

void f(int a) {
  struct A {
    void g(int a) {}
    A() { int a; }
  };
}

3 : <source>:3:16: warning: declaration shadows a local variable [-Wshadow]
    void g(int a) {}
               ^
1 : <source>:1:12: note: previous declaration is here
void f(int a) {
           ^
4 : <source>:4:15: warning: declaration shadows a local variable [-Wshadow]
    A() { int a; }
              ^
1 : <source>:1:12: note: previous declaration is here
void f(int a) {
           ^
2 warnings generated.

The local variable `a` of the function `f` can't be accessed from a method of
the function-local class A, thus no shadowing occurs and no diagnostic is
needed.

Reviewers: rnk, rsmith, arphaman, Quuxplusone

Reviewed By: rnk, Quuxplusone

Subscribers: Quuxplusone, cfe-commits

Differential Revision: https://reviews.llvm.org/D35941
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llvm-svn: 310674

parent 2ab63b13

clang/lib/Sema/SemaDecl.cpp

+15 −0

Original line number	Diff line number	Diff line
		@@ -6999,6 +6999,21 @@ void Sema::CheckShadow(NamedDecl D, NamedDecl ShadowedDecl,
		return;
		}
		}

		if (cast<VarDecl>(ShadowedDecl)->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;
		ParentDC && !ParentDC->Equals(OldDC);
		ParentDC = getLambdaAwareParentOfDeclContext(ParentDC)) {
		// Only block literals, captured statements, and lambda expressions
		// can capture; other scopes don't.
		if (!isa<BlockDecl>(ParentDC) && !isa<CapturedDecl>(ParentDC) &&
		!isLambdaCallOperator(ParentDC)) {
		return;
		}
		}
		}
		}
		}

clang/test/SemaCXX/warn-shadow.cpp

+9 −0

Original line number	Diff line number	Diff line
		@@ -213,3 +213,12 @@ typedef int externC; // expected-note {{previous declaration is here}}
		void handleLinkageSpec() {
		typedef void externC; // expected-warning {{declaration shadows a typedef in the global namespace}}
		}

		namespace PR33947 {
		void f(int a) {
		struct A {
		void g(int a) {}
		A() { int a; }
		};
		}
		}