Do not find friend function definitions inside non-instantiated class.
Previously if a file-level function was defined inside befriending
template class, it always was treated as defined. For instance, the code like:
```
int func(int x);
template<typename T> class C1 {
friend int func(int x) { return x; }
};
template<typename T> class C2 {
friend int func(int x) { return x; }
};
```
could not be compiled due to function redefinition, although not of the templates
is instantiated. Moreover, the body of friend function can contain use of template
parameters, attempt to get definition of such function outside any instantiation
causes compiler abnormal termination.
Other compilers (gcc, icc) follow viewpoint that the body of the function defined
in friend declaration becomes available when corresponding class is instantiated.
This patch implements this viewpoint in clang.
Definitions introduced by friend declarations in template classes are not added
to the redeclaration chain of corresponding function. Only when the template is
instantiated, instantiation of the function definition is placed to the chain.
The fix was made in collaboration with Richard Smith.
This change fixes PR8035, PR17923, PR22307 and PR25848.
Differential Revision: http://reviews.llvm.org/D16989
llvm-svn: 283207
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 2fe520b..0f7f0ff 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -13786,9 +13786,14 @@
// and shall be the only declaration of the function or function
// template in the translation unit.
if (functionDeclHasDefaultArgument(FD)) {
- if (FunctionDecl *OldFD = FD->getPreviousDecl()) {
+ // We can't look at FD->getPreviousDecl() because it may not have been set
+ // if we're in a dependent context. If we get this far with a non-empty
+ // Previous set, we must have a valid previous declaration of this
+ // function.
+ if (!Previous.empty()) {
Diag(FD->getLocation(), diag::err_friend_decl_with_def_arg_redeclared);
- Diag(OldFD->getLocation(), diag::note_previous_declaration);
+ Diag(Previous.getRepresentativeDecl()->getLocation(),
+ diag::note_previous_declaration);
} else if (!D.isFunctionDefinition())
Diag(FD->getLocation(), diag::err_friend_decl_with_def_arg_must_be_def);
}