[PATCH] D17576: Fix assertion failure on MaybeODRUseExprs.

[Manman Ren via cfe-commits]

manmanren created this revision.
manmanren added reviewers: rsmith, EricWF, faisalv.
manmanren added a subscriber: cfe-commits.

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

http://reviews.llvm.org/D17576

Files:
  lib/Sema/SemaTemplateInstantiateDecl.cpp
  test/SemaTemplate/default-arguments-cxx0x.cpp

Index: test/SemaTemplate/default-arguments-cxx0x.cpp
===================================================================
--- test/SemaTemplate/default-arguments-cxx0x.cpp
+++ test/SemaTemplate/default-arguments-cxx0x.cpp
@@ -75,3 +75,13 @@
     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;
+  };
+}
Index: lib/Sema/SemaTemplateInstantiateDecl.cpp
===================================================================
--- lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2110,6 +2110,8 @@
     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());


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