c++: for contracts, cdtors never return this

When targetm.cxx.cdtor_return_this() holds, cdtors have a
non-VOID_TYPE_P result, but IMHO this ABI implementation detail
shouldn't leak to the abstract language conceptual framework, in which
cdtors don't have return values.  For contracts, specifically those
that establish postconditions on results, such a leakage is present,
and the present patch puts an end to it: with it, cdtors get an error
for result postconditions regardless of the ABI.  This fixes
g++.dg/contracts/contracts-ctor-dtor2.C on arm-eabi.

for  gcc/cp/ChangeLog

	* contracts.cc (check_postcondition_result): Cope with
	cdtor_return_this.

diff --git a/gcc/cp/contracts.cc b/gcc/cp/contracts.cc
index 66d2298a9bfac706f329de3ad0621251617a978d..035ca4827e75866ddf4666535e61ad92326d9cf1 100644 (file)
--- a/gcc/cp/contracts.cc
+++ b/gcc/cp/contracts.cc
@@ -636,7 +636,11 @@ make_postcondition_variable (cp_expr id)
 bool
 check_postcondition_result (tree decl, tree type, location_t loc)
 {
-  if (VOID_TYPE_P (type))
+  /* Do not be confused by targetm.cxx.cdtor_return_this ();
+     conceptually, cdtors have no return value.  */
+  if (VOID_TYPE_P (type)
+      || DECL_CONSTRUCTOR_P (decl)
+      || DECL_DESTRUCTOR_P (decl))
     {
       error_at (loc,
                DECL_CONSTRUCTOR_P (decl)