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.

llvm-svn: 152024

9 files changed, 49 insertions, 4 deletions

diff --git a/clang/include/clang/AST/ASTConsumer.h b/clang/include/clang/AST/ASTConsumer.h
index 3c0e0fc9dc3..6e35aefbe97 100644
--- a/clang/include/clang/AST/ASTConsumer.h
+++ b/clang/include/clang/AST/ASTConsumer.h
@@ -90,6 +90,11 @@ public:
   /// modified by the introduction of an implicit zero initializer.
   virtual void CompleteTentativeDefinition(VarDecl *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.
+  virtual void MarkVarRequired(VarDecl *D) {}
+
   /// \brief Callback involved at the end of a translation unit to
   /// notify the consumer that a vtable for the given C++ class is
   /// required.
diff --git a/clang/include/clang/Frontend/MultiplexConsumer.h b/clang/include/clang/Frontend/MultiplexConsumer.h
index 8814aa31bba..c2eb1ccbda6 100644
--- a/clang/include/clang/Frontend/MultiplexConsumer.h
+++ b/clang/include/clang/Frontend/MultiplexConsumer.h
@@ -35,6 +35,7 @@ public:
 
   // ASTConsumer
   virtual void Initialize(ASTContext &Context);
+  virtual void MarkVarRequired(VarDecl *VD);
   virtual bool HandleTopLevelDecl(DeclGroupRef D);
   virtual void HandleInterestingDecl(DeclGroupRef D);
   virtual void HandleTranslationUnit(ASTContext &Ctx);
diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index 02e08602922..b669d994ad8 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -73,6 +73,10 @@ namespace clang {
     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/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 922a5df344f..b2bfab055b6 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1722,6 +1722,9 @@ static void ReplaceUsesOfNonProtoTypeWithRealFunction(llvm::GlobalValue *Old,
   }
 }
 
+void CodeGenModule::MarkVarRequired(VarDecl *VD) {
+  GetAddrOfGlobalVar(VD);
+}
 
 void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD) {
   const FunctionDecl *D = cast<FunctionDecl>(GD.getDecl());
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index ba4887d057e..93eee444310 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -658,6 +658,11 @@ public:
   /// 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/clang/lib/CodeGen/ModuleBuilder.cpp b/clang/lib/CodeGen/ModuleBuilder.cpp
index ddbe27bc176..f81f6236d62 100644
--- a/clang/lib/CodeGen/ModuleBuilder.cpp
+++ b/clang/lib/CodeGen/ModuleBuilder.cpp
@@ -59,6 +59,10 @@ namespace {
                                                *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/clang/lib/Frontend/MultiplexConsumer.cpp b/clang/lib/Frontend/MultiplexConsumer.cpp
index cef4590955a..a1d1156529f 100644
--- a/clang/lib/Frontend/MultiplexConsumer.cpp
+++ b/clang/lib/Frontend/MultiplexConsumer.cpp
@@ -209,6 +209,11 @@ bool MultiplexConsumer::HandleTopLevelDecl(DeclGroupRef D) {
   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/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index d491dfc51ed..4633db737ac 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2596,21 +2596,25 @@ void Sema::InstantiateStaticDataMemberDefinition(
     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)
diff --git a/clang/test/CodeGenCXX/pr12104.cpp b/clang/test/CodeGenCXX/pr12104.cpp
new file mode 100644
index 00000000000..d126108073f
--- /dev/null
+++ b/clang/test/CodeGenCXX/pr12104.cpp
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s
+
+template <int dimm> struct Patch {
+  static const unsigned int no_neighbor = 1;
+};
+template <int dim>
+const unsigned int Patch<dim>::no_neighbor;
+void f(const unsigned int);
+void g() {
+  f(Patch<1>::no_neighbor);
+}
+template struct Patch<1>;
+
+// CHECK: _ZN5PatchILi1EE11no_neighborE