Fix a small difference in sema and codegen views of what needs to be output.

In the included testcase, soma thinks that we already have a definition after we
see the out of line decl. Codegen puts it in a deferred list, to be output if
a use is seen. This would break when we saw an explicit template instantiation
definition, since codegen would not be notified.

This patch adds a method to the consumer interface so that soma can notify
codegen that this decl is now required.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@152024 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenAction.cpp b/lib/CodeGen/CodeGenAction.cpp
index 02e0860..b669d99 100644
--- a/lib/CodeGen/CodeGenAction.cpp
+++ b/lib/CodeGen/CodeGenAction.cpp
@@ -73,6 +73,10 @@
     llvm::Module *takeModule() { return TheModule.take(); }
     llvm::Module *takeLinkModule() { return LinkModule.take(); }
 
+    virtual void MarkVarRequired(VarDecl *VD) {
+      Gen->MarkVarRequired(VD);
+    }
+
     virtual void Initialize(ASTContext &Ctx) {
       Context = &Ctx;
 
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 922a5df..b2bfab0 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -1722,6 +1722,9 @@
   }
 }
 
+void CodeGenModule::MarkVarRequired(VarDecl *VD) {
+  GetAddrOfGlobalVar(VD);
+}
 
 void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD) {
   const FunctionDecl *D = cast<FunctionDecl>(GD.getDecl());
diff --git a/lib/CodeGen/CodeGenModule.h b/lib/CodeGen/CodeGenModule.h
index ba4887d..93eee44 100644
--- a/lib/CodeGen/CodeGenModule.h
+++ b/lib/CodeGen/CodeGenModule.h
@@ -658,6 +658,11 @@
   /// EmitTopLevelDecl - Emit code for a single top level declaration.
   void EmitTopLevelDecl(Decl *D);
 
+  /// MarkVarRequired - Tell the consumer that this variable must be output.
+  /// This is needed when the definition is initially one that can be deferred,
+  /// but we then see an explicit template instantiation definition.
+  void MarkVarRequired(VarDecl *VD);
+
   /// AddUsedGlobal - Add a global which should be forced to be
   /// present in the object file; these are emitted to the llvm.used
   /// metadata global.
diff --git a/lib/CodeGen/ModuleBuilder.cpp b/lib/CodeGen/ModuleBuilder.cpp
index ddbe27b..f81f623 100644
--- a/lib/CodeGen/ModuleBuilder.cpp
+++ b/lib/CodeGen/ModuleBuilder.cpp
@@ -59,6 +59,10 @@
                                                *M, *TD, Diags));
     }
 
+    virtual void MarkVarRequired(VarDecl *VD) {
+      Builder->MarkVarRequired(VD);
+    }
+
     virtual bool HandleTopLevelDecl(DeclGroupRef DG) {
       // Make sure to emit all elements of a Decl.
       for (DeclGroupRef::iterator I = DG.begin(), E = DG.end(); I != E; ++I)
diff --git a/lib/Frontend/MultiplexConsumer.cpp b/lib/Frontend/MultiplexConsumer.cpp
index cef4590..a1d1156 100644
--- a/lib/Frontend/MultiplexConsumer.cpp
+++ b/lib/Frontend/MultiplexConsumer.cpp
@@ -209,6 +209,11 @@
   return Continue;
 }
 
+void  MultiplexConsumer::MarkVarRequired(VarDecl *VD) {
+  for (size_t i = 0, e = Consumers.size(); i != e; ++i)
+    Consumers[i]->MarkVarRequired(VD);
+}
+
 void MultiplexConsumer::HandleInterestingDecl(DeclGroupRef D) {
   for (size_t i = 0, e = Consumers.size(); i != e; ++i)
     Consumers[i]->HandleInterestingDecl(D);
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index d491dfc..4633db7 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2596,21 +2596,25 @@
     return;
   }
 
+  TemplateSpecializationKind TSK = Var->getTemplateSpecializationKind();
+
   // Never instantiate an explicit specialization.
-  if (Var->getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
+  if (TSK == TSK_ExplicitSpecialization)
     return;
 
   // C++0x [temp.explicit]p9:
   //   Except for inline functions, other explicit instantiation declarations
   //   have the effect of suppressing the implicit instantiation of the entity
   //   to which they refer.
-  if (Var->getTemplateSpecializationKind()
-        == TSK_ExplicitInstantiationDeclaration)
+  if (TSK == TSK_ExplicitInstantiationDeclaration)
     return;
 
   // If we already have a definition, we're done.
-  if (Var->getDefinition())
+  if (Var->getDefinition()) {
+    if (TSK == TSK_ExplicitInstantiationDefinition)
+      Consumer.MarkVarRequired(Var);
     return;
+  }
 
   InstantiatingTemplate Inst(*this, PointOfInstantiation, Var);
   if (Inst)