[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.

llvm-svn: 271251

1 files changed, 11 insertions, 5 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index f845a65a000..64da16add18 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -163,11 +163,17 @@ lookupUnqualifiedTypeNameInBase(Sema &S, const IdentifierInfo &II,
       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)) {