Sema: Improve comment introduced in r193397


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194052 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaLambda.cpp b/lib/Sema/SemaLambda.cpp
index 2e1cd10..3fff746 100644
--- a/lib/Sema/SemaLambda.cpp
+++ b/lib/Sema/SemaLambda.cpp
@@ -1241,6 +1241,11 @@
     //   A conditional-expression e is a core constant expression unless the
     //   evaluation of e, following the rules of the abstract machine, would
     //   evaluate [...] a lambda-expression.
+    //
+    // This is technically incorrect, there are some constant evaluated contexts
+    // where this should be allowed.  We should probably fix this when DR1607 is
+    // ratified, it lays out the exact set of conditions where we shouldn't
+    // allow a lambda-expression.
     case ConstantEvaluated:
       // We don't actually diagnose this case immediately, because we
       // could be within a context where we might find out later that