[Bug c++/94590] Incorrectly accepts invalid C++11 braced initialisation of double from long double if sizeof(long double)==sizeof(double)

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94590

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot 
gnu.org

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Untested fix:

--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -1008,10 +1008,17 @@ check_narrowing (tree type, tree init, tsubst_flags_t
complain,
              || !int_fits_type_p (init, type)))
        ok = false;
     }
+  /* [dcl.init.list]#7.2: "from long double to double or float, or from
+      double to float".  */
   else if (TREE_CODE (ftype) == REAL_TYPE
           && TREE_CODE (type) == REAL_TYPE)
     {
-      if (TYPE_PRECISION (type) < TYPE_PRECISION (ftype))
+      if ((same_type_p (ftype, long_double_type_node)
+          && (same_type_p (type, double_type_node)
+              || same_type_p (type, float_type_node)))
+         || (same_type_p (ftype, double_type_node)
+             && same_type_p (type, float_type_node))
+         || (TYPE_PRECISION (type) < TYPE_PRECISION (ftype)))
        {
          if (TREE_CODE (init) == REAL_CST)
            {