From: Chandler Carruth <chandlerc@gmail.com>
Date: Sat, 13 Feb 2010 10:17:50 +0000 (+0000)
Subject: Skip implicit instantiation of templated variables where a more recent
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=291b441a095b289c30d9f311fe37a2cf5ed6fd45;p=clang

Skip implicit instantiation of templated variables where a more recent
redeclaration provides an explicit instantiation or is invalid.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@96097 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index caeea58470..a55193aa74 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2323,6 +2323,24 @@ void Sema::PerformPendingImplicitInstantiations(bool LocalOnly) {
     VarDecl *Var = cast<VarDecl>(Inst.first);
     assert(Var->isStaticDataMember() && "Not a static data member?");
 
+    // Don't try to instantiate declarations if the most recent redeclaration
+    // is invalid.
+    if (Var->getMostRecentDeclaration()->isInvalidDecl())
+      continue;
+
+    // Check if the most recent declaration has changed the specialization kind
+    // and removed the need for implicit instantiation.
+    switch (Var->getMostRecentDeclaration()->getTemplateSpecializationKind()) {
+    case TSK_Undeclared:
+      assert(false && "Cannot instantitiate an undeclared specialization.");
+    case TSK_ExplicitInstantiationDeclaration:
+    case TSK_ExplicitInstantiationDefinition:
+    case TSK_ExplicitSpecialization:
+      continue;  // No longer need implicit instantiation.
+    case TSK_ImplicitInstantiation:
+      break;
+    }
+
     PrettyStackTraceActionsDecl CrashInfo(DeclPtrTy::make(Var),
                                           Var->getLocation(), *this,
                                           Context.getSourceManager(),
diff --git a/test/SemaTemplate/explicit-instantiation.cpp b/test/SemaTemplate/explicit-instantiation.cpp
index 227856f1a8..de51f0992b 100644
--- a/test/SemaTemplate/explicit-instantiation.cpp
+++ b/test/SemaTemplate/explicit-instantiation.cpp
@@ -76,3 +76,10 @@ template void print_type<double>(double*);
 // PR5069
 template<int I> void foo0 (int (&)[I + 1]) { }
 template void foo0<2> (int (&)[3]);
+
+namespace explicit_instantiation_after_implicit_instantiation {
+  template <int I> struct X0 { static int x; };
+  template <int I> int X0<I>::x;
+  void test1() { (void)&X0<1>::x; }
+  template struct X0<1>;
+}