Part three of PR15721: if we have an invalid CXXDefaultInitExpr, don't crash if

we try to constant-evaluate it. Patch by Karthik Bhat, test by me.

llvm-svn: 190722

2 files changed, 24 insertions, 2 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 218ce8101b5..0a2cc7b3d6d 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -3742,8 +3742,12 @@ public:
     { return StmtVisitorTy::Visit(E->getReplacement()); }
   RetTy VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E)
     { return StmtVisitorTy::Visit(E->getExpr()); }
-  RetTy VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E)
-    { return StmtVisitorTy::Visit(E->getExpr()); }
+  RetTy VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
+    // The initializer may not have been parsed yet, or might be erroneous.
+    if (!E->getExpr())
+      return Error(E);
+    return StmtVisitorTy::Visit(E->getExpr());
+  }
   // We cannot create any objects for which cleanups are required, so there is
   // nothing to do here; all cleanups must come from unevaluated subexpressions.
   RetTy VisitExprWithCleanups(const ExprWithCleanups *E)
diff --git a/clang/test/SemaCXX/constant-expression-cxx11.cpp b/clang/test/SemaCXX/constant-expression-cxx11.cpp
index 363ca8c7d9d..c7766878583 100644
--- a/clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -1776,3 +1776,21 @@ namespace ZeroSizeTypes {
     return &arr[3] - &arr[0]; // expected-note {{subtraction of pointers to type 'int [0]' of zero size}}
   }
 }
+
+namespace BadDefaultInit {
+  template<int N> struct X { static const int n = N; };
+
+  struct A { // expected-note {{subexpression}}
+    int k = X<A().k>::n; // expected-error {{defaulted default constructor of 'A' cannot be used}} expected-error {{not a constant expression}} expected-note {{in call to 'A()'}}
+  };
+
+  // FIXME: The "constexpr constructor must initialize all members" diagnostic
+  // here is bogus (we discard the k(k) initializer because the parameter 'k'
+  // has been marked invalid).
+  struct B { // expected-note 2{{candidate}}
+    constexpr B( // expected-error {{must initialize all members}} expected-note {{candidate}}
+        int k = X<B().k>::n) : // expected-error {{no matching constructor}}
+      k(k) {}
+    int k; // expected-note {{not initialized}}
+  };
+}