Hack in a loud error for PR12086. Better than a silent miscompile.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151586 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index ddd04a4..a3a71b7 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -1376,8 +1376,19 @@
     return 0;
 
   ASTContext &ctx = getContext();
-  // Synthesize a fake VarDecl for the array and initialize that.
   unsigned numInits = init->getNumInits();
+  // FIXME: This check is here because we would otherwise silently miscompile
+  // nested global std::initializer_lists. Better would be to have a real
+  // implementation.
+  for (unsigned i = 0; i < numInits; ++i) {
+    const InitListExpr *inner = dyn_cast<InitListExpr>(init->getInit(i));
+    if (inner && inner->initializesStdInitializerList()) {
+      ErrorUnsupported(inner, "nested global std::initializer_list");
+      return 0;
+    }
+  }
+
+  // Synthesize a fake VarDecl for the array and initialize that.
   QualType elementType = init->getInit(0)->getType();
   llvm::APInt numElements(ctx.getTypeSize(ctx.getSizeType()), numInits);
   QualType arrayType = ctx.getConstantArrayType(elementType, numElements,
diff --git a/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist-pr12086.cpp b/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist-pr12086.cpp
new file mode 100644
index 0000000..14d2f77
--- /dev/null
+++ b/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist-pr12086.cpp
@@ -0,0 +1,37 @@
+// RUN: %clang_cc1 -std=c++11 -emit-llvm -o - -verify %s
+
+namespace std {
+  typedef decltype(sizeof(int)) size_t;
+
+  // libc++'s implementation
+  template <class _E>
+  class initializer_list
+  {
+    const _E* __begin_;
+    size_t    __size_;
+
+    initializer_list(const _E* __b, size_t __s)
+      : __begin_(__b),
+        __size_(__s)
+    {}
+
+  public:
+    typedef _E        value_type;
+    typedef const _E& reference;
+    typedef const _E& const_reference;
+    typedef size_t    size_type;
+
+    typedef const _E* iterator;
+    typedef const _E* const_iterator;
+
+    initializer_list() : __begin_(nullptr), __size_(0) {}
+
+    size_t    size()  const {return __size_;}
+    const _E* begin() const {return __begin_;}
+    const _E* end()   const {return __begin_ + __size_;}
+  };
+}
+
+std::initializer_list<std::initializer_list<int>> pleasefail = {
+  {1, 2}, {3, 4}, {5, 6} // expected-error {{cannot compile}}
+};