r284802 - Don't try to use !Previous.empty() as a proxy for "Is this a redeclaration?" --

[Richard Smith via cfe-commits]

Author: rsmith
Date: Thu Oct 20 22:15:03 2016
New Revision: 284802

URL: http://llvm.org/viewvc/llvm-project?rev=284802&view=rev
Log:
Don't try to use !Previous.empty() as a proxy for "Is this a redeclaration?" --
we don't collapse that down to a single entry if it's not a redeclaration.
Instead, set the Redeclaration bit on the Declarator to indicate whether a
function is a redeclaration (which may not have been linked into the
redeclaration chain if it's a dependent context friend).

Fixes a rejects-valid; see testcase.

Modified:
    cfe/trunk/lib/Sema/SemaDecl.cpp
    cfe/trunk/lib/Sema/SemaDeclCXX.cpp
    cfe/trunk/test/SemaCXX/friend.cpp

Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=284802&r1=284801&r2=284802&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDecl.cpp Thu Oct 20 22:15:03 2016
@@ -8445,7 +8445,7 @@ Sema::ActOnFunctionDeclarator(Scope *S,
                                 ? cast<NamedDecl>(FunctionTemplate)
                                 : NewFD);
 
-    if (isFriend && D.isRedeclaration()) {
+    if (isFriend && NewFD->getPreviousDecl()) {
       AccessSpecifier Access = AS_public;
       if (!NewFD->isInvalidDecl())
         Access = NewFD->getPreviousDecl()->getAccess();
@@ -8901,8 +8901,6 @@ bool Sema::CheckFunctionDeclaration(Scop
         NewFD->setPreviousDeclaration(cast<FunctionDecl>(OldDecl));
         if (isa<CXXMethodDecl>(NewFD))
           NewFD->setAccess(OldDecl->getAccess());
-      } else {
-        Redeclaration = false;
       }
     }
   }

Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=284802&r1=284801&r2=284802&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Thu Oct 20 22:15:03 2016
@@ -13785,10 +13785,9 @@ NamedDecl *Sema::ActOnFriendFunctionDecl
     // template in the translation unit.
     if (functionDeclHasDefaultArgument(FD)) {
       // 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()) {
+      // if we're in a dependent context. If the function is known to be a
+      // redeclaration, we will have narrowed Previous down to the right decl.
+      if (D.isRedeclaration()) {
         Diag(FD->getLocation(), diag::err_friend_decl_with_def_arg_redeclared);
         Diag(Previous.getRepresentativeDecl()->getLocation(),
              diag::note_previous_declaration);

Modified: cfe/trunk/test/SemaCXX/friend.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/friend.cpp?rev=284802&r1=284801&r2=284802&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/friend.cpp (original)
+++ cfe/trunk/test/SemaCXX/friend.cpp Thu Oct 20 22:15:03 2016
@@ -379,3 +379,12 @@ namespace tag_redecl {
     X *q = p;
   }
 }
+
+namespace default_arg {
+  void f();
+  void f(void*); // expected-note {{previous}}
+  struct X {
+    friend void f(int a, int b = 0) {}
+    friend void f(void *p = 0) {} // expected-error {{must be the only}}
+  };
+}