PR12710 - broken default argument handling for templates.

I broke this in r155838 by not actually instantiating non-dependent default arg
expressions. The motivation for that change was to avoid producing duplicate
conversion warnings for such default args (we produce them once when we parse
the template - there's no need to produce them at each instantiation) but
without actually instantiating the default arg, things break in weird ways.

Technically, I think we could still get the right diagnostic experience without
the bugs if we instantiated the non-dependent args (for non-dependent params
only) immediately, rather than lazily. But I'm not sure if such a refactoring/
change would be desirable so here's the conservative fix for now.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@155893 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 7 deletions

diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 3635e64f3d..344af6097d 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1594,13 +1594,11 @@ ParmVarDecl *Sema::SubstParmVarDecl(ParmVarDecl *OldParm,
   } else if (OldParm->hasUnparsedDefaultArg()) {
     NewParm->setUnparsedDefaultArg();
     UnparsedDefaultArgInstantiations[OldParm].push_back(NewParm);
-  } else if (Expr *Arg = OldParm->getDefaultArg()) {
-    if (Arg->isInstantiationDependent() ||
-        OldDI->getType()->isInstantiationDependentType())
-      NewParm->setUninstantiatedDefaultArg(Arg);
-    else
-      NewParm->setDefaultArg(Arg);
-  }
+  } else if (Expr *Arg = OldParm->getDefaultArg())
+    // FIXME: if we non-lazily instantiated non-dependent default args for
+    // non-dependent parameter types we could remove a bunch of duplicate
+    // conversion warnings for such arguments.
+    NewParm->setUninstantiatedDefaultArg(Arg);
 
   NewParm->setHasInheritedDefaultArg(OldParm->hasInheritedDefaultArg());