[Bug c++/65075] [5 Regression] constexpr regression

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65075

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Hi Jakub. Something like the below passes testing and works for the testcase:

Index: constexpr.c
===================================================================
--- constexpr.c    (revision 220731)
+++ constexpr.c    (working copy)
@@ -415,8 +415,8 @@ check_constexpr_bind_expr_vars (tree t)
   gcc_assert (TREE_CODE (t) == BIND_EXPR);

   for (tree var = BIND_EXPR_VARS (t); var; var = DECL_CHAIN (var))
-    if (TREE_CODE (var) == TYPE_DECL
-    && DECL_IMPLICIT_TYPEDEF_P (var))
+    if (DECL_IMPLICIT_TYPEDEF_P (var)
+    && !LAMBDA_TYPE_P (TREE_TYPE (var)))
       return false;
   return true;
 }

Note that I will be traveling for a week or so, thus I'm not be able to fully
handle the issue. If we rather resolve the regression immediately, please feel
free to pick up the above / double check if it makes sense to Jason.