Retain previous language linkage of friend function declarations
With this extension, friend function declarations will retain the language
linkage specified for previous declarations instead of emitting an error
diagnostic.
The feature is known to be compatible with GCC and MSVC and permits a
language to be specified indirectly where it cannot otherwise be written
directly in class scope.
Work is ongoing to improve linkage spec diagnostics.
Fixes PR17337.
Reviewed by Richard Smith.
llvm-svn: 193206
diff --git a/clang/test/SemaCXX/linkage-spec.cpp b/clang/test/SemaCXX/linkage-spec.cpp
index bdc217d..1598d0e 100644
--- a/clang/test/SemaCXX/linkage-spec.cpp
+++ b/clang/test/SemaCXX/linkage-spec.cpp
@@ -1,4 +1,5 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wretained-language-linkage -DW_RETAINED_LANGUAGE_LINKAGE %s
extern "C" {
extern "C" void f(int);
}
@@ -154,3 +155,21 @@
::f_pr7927(E_7927);
::f_pr7927(0);
}
+
+namespace PR17337 {
+ extern "C++" {
+ class Foo;
+ extern "C" int bar3(Foo *y);
+ class Foo {
+ int x;
+ friend int bar3(Foo *y);
+#ifdef W_RETAINED_LANGUAGE_LINKAGE
+// expected-note@-5 {{previous declaration is here}}
+// expected-warning@-3 {{retaining previous language linkage}}
+#endif
+ };
+ extern "C" int bar3(Foo *y) {
+ return y->x;
+ }
+ }
+}