C++ modules: Don't call DeclContext::lookup when half-way through deserializing

decls. That can reenter deserialization and explode horribly by trying to merge
a declaration that we've not got very far through deserializing yet.

llvm-svn: 186236

2 files changed, 25 insertions, 0 deletions

diff --git a/clang/test/PCH/cxx-templates.cpp b/clang/test/PCH/cxx-templates.cpp
index 433f73f12a2..f57245e7c1c 100644
--- a/clang/test/PCH/cxx-templates.cpp
+++ b/clang/test/PCH/cxx-templates.cpp
@@ -94,3 +94,8 @@ namespace rdar13135282 {
 void CallDependentSpecializedFunc(DependentSpecializedFuncClass<int> &x) {
   DependentSpecializedFunc(x);
 }
+
+namespace cyclic_module_load {
+  extern std::valarray<int> x;
+  std::valarray<int> y(x);
+}
diff --git a/clang/test/PCH/cxx-templates.h b/clang/test/PCH/cxx-templates.h
index 00064aeefa5..ce6b7051ecc 100644
--- a/clang/test/PCH/cxx-templates.h
+++ b/clang/test/PCH/cxx-templates.h
@@ -276,3 +276,23 @@ template<typename T> class DependentSpecializedFuncClass {
   void foo() {}
   friend void DependentSpecializedFunc<>(DependentSpecializedFuncClass);
 };
+
+namespace cyclic_module_load {
+  // Reduced from a libc++ modules crasher.
+  namespace std {
+    template<class> class mask_array;
+    template<class> class valarray {
+    public:
+      valarray(const valarray &v);
+    };
+
+    class gslice {
+      valarray<int> x;
+      valarray<int> stride() const { return x; }
+    };
+
+    template<class> class mask_array {
+      template<class> friend class valarray;
+    };
+  }
+}