Fix C++ PCH issues.

PCH got a severe beating by the boost-using test case reported here: http://llvm.org/PR8099
Fix issues like:

-When PCH reading, make sure Decl's getASTContext() doesn't get called since a Decl in the parent hierarchy may be initializing.
-In ASTDeclReader::VisitFunctionDecl VisitRedeclarable should be called before using FunctionDecl's isCanonicalDecl()
-In ASTDeclReader::VisitRedeclarableTemplateDecl CommonOrPrev must be initialized before anything else.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@113391 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 2 deletions

diff --git a/lib/AST/TemplateName.cpp b/lib/AST/TemplateName.cpp
index ef7b315314..439f4e81ad 100644
--- a/lib/AST/TemplateName.cpp
+++ b/lib/AST/TemplateName.cpp
@@ -44,8 +44,14 @@ TemplateDecl *TemplateName::getAsTemplateDecl() const {
 
 bool TemplateName::isDependent() const {
   if (TemplateDecl *Template = getAsTemplateDecl()) {
-    return isa<TemplateTemplateParmDecl>(Template) ||
-      Template->getDeclContext()->isDependentContext();
+    if (isa<TemplateTemplateParmDecl>(Template))
+      return true;
+    // FIXME: Hack, getDeclContext() can be null if Template is still
+    // initializing due to PCH reading, so we check it before using it.
+    // Should probably modify TemplateSpecializationType to allow constructing
+    // it without the isDependent() checking.
+    return Template->getDeclContext() &&
+           Template->getDeclContext()->isDependentContext();
   }
 
   assert(!getAsOverloadedTemplate() &&