r271251 - [MSVC] Fix stack overflow in unqualified type lookup logic, by Will

[Alexey Bataev via cfe-commits]

Author: abataev
Date: Tue May 31 01:21:27 2016
New Revision: 271251

URL: http://llvm.org/viewvc/llvm-project?rev=271251&view=rev
Log:
[MSVC] Fix stack overflow in unqualified type lookup logic, by Will
Wilson.

An unqualified lookup for in base classes may cause stack overflow if
the base class is a specialization of current class.
Patch by Will Wilson.

Modified:
    cfe/trunk/lib/Sema/SemaDecl.cpp
    cfe/trunk/test/SemaTemplate/ms-lookup-template-base-classes.cpp

Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=271251&r1=271250&r2=271251&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDecl.cpp Tue May 31 01:21:27 2016
@@ -163,11 +163,17 @@ lookupUnqualifiedTypeNameInBase(Sema &S,
       auto *TD = TST->getTemplateName().getAsTemplateDecl();
       if (!TD)
         continue;
-      auto *BasePrimaryTemplate =
-          dyn_cast_or_null<CXXRecordDecl>(TD->getTemplatedDecl());
-      if (!BasePrimaryTemplate)
-        continue;
-      BaseRD = BasePrimaryTemplate;
+      if (auto *BasePrimaryTemplate =
+          dyn_cast_or_null<CXXRecordDecl>(TD->getTemplatedDecl())) {
+        if (BasePrimaryTemplate->getCanonicalDecl() != RD->getCanonicalDecl())
+          BaseRD = BasePrimaryTemplate;
+        else if (auto *CTD = dyn_cast<ClassTemplateDecl>(TD)) {
+          if (const ClassTemplatePartialSpecializationDecl *PS =
+                  CTD->findPartialSpecialization(Base.getType()))
+            if (PS->getCanonicalDecl() != RD->getCanonicalDecl())
+              BaseRD = PS;
+        }
+      }
     }
     if (BaseRD) {
       for (NamedDecl *ND : BaseRD->lookup(&II)) {

Modified: cfe/trunk/test/SemaTemplate/ms-lookup-template-base-classes.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/ms-lookup-template-base-classes.cpp?rev=271251&r1=271250&r2=271251&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/ms-lookup-template-base-classes.cpp (original)
+++ cfe/trunk/test/SemaTemplate/ms-lookup-template-base-classes.cpp Tue May 31 01:21:27 2016
@@ -603,3 +603,32 @@ struct Base {
 template struct UseUnqualifiedTypeNames<Base>;
 struct BadBase { };
 template struct UseUnqualifiedTypeNames<BadBase>; // expected-note-re 2 {{in instantiation {{.*}} requested here}}
+
+namespace partial_template_lookup {
+
+class Bar;
+class Spare;
+
+template <class T, class X = Bar>
+class FooTemplated;
+
+class FooBase {
+public:
+  typedef int BaseTypedef;
+};
+
+// Partial template spec (unused)
+template <class T>
+class FooTemplated<T, Spare> {};
+
+// Partial template spec (used)
+template <class T>
+class FooTemplated<T, Bar> : public FooBase {};
+
+// Full template spec
+template <class T, class X>
+class FooTemplated : public FooTemplated<T, Bar> {
+public:
+  BaseTypedef Member; // expected-warning {{unqualified lookup}}
+};
+}