[Sema] Prevent InstantiateClass from checking unrelated exception specs.

Sema::InstantiateClass should check only exception specs added during
class instantiation and ignore already present delayed specs. This fixes
a case where we instantiate a class before parsing member initializers,
check exceptions for a different class and fail to find a member
initializer. Which is required for comparing exception specs for
explicitly-defaulted and implicit default constructor. With the fix we
are still checking exception specs but only after member initializers
are present.

Removing errors in crash-unparsed-exception.cpp is acceptable according
to discussion in PR24000 because other compilers accept code in
crash-unparsed-exception.cpp as valid.

rdar://problem/34167492

Reviewers: davide, rsmith

Reviewed By: rsmith

Subscribers: dim, cfe-commits

Differential Revision: https://reviews.llvm.org/D37881

llvm-svn: 313906

1 files changed, 5 insertions, 9 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 1a06f9a2f85..16f73813308 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2026,12 +2026,11 @@ Sema::InstantiateClass(SourceLocation PointOfInstantiation,
   bool MergeWithParentScope = !Instantiation->isDefinedOutsideFunctionOrMethod();
   LocalInstantiationScope Scope(*this, MergeWithParentScope);
 
-  // All dllexported classes created during instantiation should be fully
-  // emitted after instantiation completes. We may not be ready to emit any
-  // delayed classes already on the stack, so save them away and put them back
-  // later.
-  decltype(DelayedDllExportClasses) ExportedClasses;
-  std::swap(ExportedClasses, DelayedDllExportClasses);
+  // Some class state isn't processed immediately but delayed till class
+  // instantiation completes. We may not be ready to handle any delayed state
+  // already on the stack as it might correspond to a different class, so save
+  // it now and put it back later.
+  SavePendingParsedClassStateRAII SavedPendingParsedClassState(*this);
 
   // Pull attributes from the pattern onto the instantiation.
   InstantiateAttrs(TemplateArgs, Pattern, Instantiation);
@@ -2118,9 +2117,6 @@ Sema::InstantiateClass(SourceLocation PointOfInstantiation,
   // default arg exprs for default constructors if necessary now.
   ActOnFinishCXXNonNestedClass(Instantiation);
 
-  // Put back the delayed exported classes that we moved out of the way.
-  std::swap(ExportedClasses, DelayedDllExportClasses);
-
   // Instantiate late parsed attributes, and attach them to their decls.
   // See Sema::InstantiateAttrs
   for (LateInstantiatedAttrVec::iterator I = LateAttrs.begin(),