r261803 - Fix assertion failure on MaybeODRUseExprs.

[Manman Ren via cfe-commits]

Author: mren
Date: Wed Feb 24 17:05:43 2016
New Revision: 261803

URL: http://llvm.org/viewvc/llvm-project?rev=261803&view=rev
Log:
Fix assertion failure on MaybeODRUseExprs.

In VisitNonTypeTemplateParamDecl, before SubstExpr with the default argument,
we should create a ConstantEvaluated ExpressionEvaluationContext. Without this,
it is possible to use a PotentiallyEvaluated ExpressionEvaluationContext; and
MaybeODRUseExprs will not be cleared when popping the context, causing
assertion failure.

This is similar to how we handle the context before SubstExpr with the
default argument, in SubstDefaultTemplateArgument.

Part of PR13986.
rdar://24480205

Differential Revision: http://reviews.llvm.org/D17576

Modified:
    cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
    cfe/trunk/test/SemaTemplate/default-arguments-cxx0x.cpp

Modified: cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp?rev=261803&r1=261802&r2=261803&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp Wed Feb 24 17:05:43 2016
@@ -2110,6 +2110,8 @@ Decl *TemplateDeclInstantiator::VisitNon
     Param->setInvalidDecl();
 
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
+    EnterExpressionEvaluationContext ConstantEvaluated(SemaRef,
+                                                       Sema::ConstantEvaluated);
     ExprResult Value = SemaRef.SubstExpr(D->getDefaultArgument(), TemplateArgs);
     if (!Value.isInvalid())
       Param->setDefaultArgument(Value.get());

Modified: cfe/trunk/test/SemaTemplate/default-arguments-cxx0x.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/default-arguments-cxx0x.cpp?rev=261803&r1=261802&r2=261803&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/default-arguments-cxx0x.cpp (original)
+++ cfe/trunk/test/SemaTemplate/default-arguments-cxx0x.cpp Wed Feb 24 17:05:43 2016
@@ -75,3 +75,13 @@ namespace rdar23810407 {
     g<int>();
   }
 }
+
+// rdar://problem/24480205
+namespace PR13986 {
+  constexpr unsigned Dynamic = 0;
+  template <unsigned> class A { template <unsigned = Dynamic> void m_fn1(); };
+  class Test {
+    ~Test() {}
+    A<1> m_target;
+  };
+}