Index: include/clang/Basic/DiagnosticSemaKinds.td =================================================================== --- include/clang/Basic/DiagnosticSemaKinds.td +++ include/clang/Basic/DiagnosticSemaKinds.td @@ -2778,6 +2778,9 @@ def warn_attribute_ignored_on_inline : Warning<"%0 attribute ignored on inline function">, InGroup; +def warn_attribute_ignored_on_non_external : + Warning<"%0 attribute is ignored on a non-external symbol">, + InGroup; def warn_nocf_check_attribute_ignored : Warning<"'nocf_check' attribute ignored; use -fcf-protection to enable the attribute">, InGroup; Index: lib/Sema/SemaDeclAttr.cpp =================================================================== --- lib/Sema/SemaDeclAttr.cpp +++ lib/Sema/SemaDeclAttr.cpp @@ -2615,6 +2615,14 @@ return; } + // Visibility attributes have no effect on symbols with internal linkage. + if (const auto *ND = dyn_cast(D)) { + if (!ND->isExternallyVisible()) + S.Diag(AL.getRange().getBegin(), + diag::warn_attribute_ignored_on_non_external) + << AL; + } + // Check that the argument is a string literal. StringRef TypeStr; SourceLocation LiteralLoc; Index: test/Sema/attr-visibility.c =================================================================== --- test/Sema/attr-visibility.c +++ test/Sema/attr-visibility.c @@ -26,3 +26,9 @@ int x __attribute__((type_visibility("default"))); // expected-error {{'type_visibility' attribute only applies to types and namespaces}} int PR17105 __attribute__((visibility(hidden))); // expected-error {{'visibility' attribute requires a string}} + +static int test8 __attribute__((visibility("default"))); // expected-warning {{'visibility' attribute is ignored on a non-external symbol}} +static int test9 __attribute__((visibility("hidden"))); // expected-warning {{'visibility' attribute is ignored on a non-external symbol}} +static int test10 __attribute__((visibility("internal"))); // expected-warning {{'visibility' attribute is ignored on a non-external symbol}} + +static int test11() __attribute__((visibility("default"))); // expected-warning {{'visibility' attribute is ignored on a non-external symbol}} Index: test/SemaCXX/ast-print.cpp =================================================================== --- test/SemaCXX/ast-print.cpp +++ test/SemaCXX/ast-print.cpp @@ -209,10 +209,8 @@ } } -namespace { // CHECK: struct {{\[\[gnu::visibility\(\"hidden\"\)\]\]}} S; struct [[gnu::visibility("hidden")]] S; -} // CHECK: struct CXXFunctionalCastExprPrint { // CHECK-NEXT: } fce = CXXFunctionalCastExprPrint{}; Index: test/SemaCXX/attr-visibility.cpp =================================================================== --- test/SemaCXX/attr-visibility.cpp +++ test/SemaCXX/attr-visibility.cpp @@ -18,3 +18,9 @@ struct x3 { static int y; } __attribute((visibility("default"))); // expected-warning {{attribute 'visibility' after definition is ignored}} + +const int test4 __attribute__((visibility("default"))) = 0; // expected-warning {{'visibility' attribute is ignored on a non-external symbol}} + +namespace { + int test5 __attribute__((visibility("default"))); // expected-warning {{'visibility' attribute is ignored on a non-external symbol}} +};