Hi,
On 17/01/2018 15:58, Jason Merrill wrote:
On Tue, Jan 16, 2018 at 4:40 PM, Paolo Carlini <paolo.carl...@oracle.com> wrote:
On 16/01/2018 22:35, Jason Merrill wrote:
On Tue, Jan 16, 2018 at 3:32 PM, Paolo Carlini <paolo.carl...@oracle.com>
wrote:
thus I figured out what was badly wrong in my first try: I misread
ensure_literal_type_for_constexpr_object and missed that it can return
NULL_TREE without emitting an hard error. Thus my first try even caused
miscompilations :( Anyway, when DECL_DECLARED_CONSTEXPR_P is true we are
safe and indeed we want to clear it as matter of error recovery. Then, in
this safe case the only change in the below is returning early, thus
avoiding any internal inconsistencies later and also the redundant /
misleading diagnostic which I already mentioned.
I can't see how this could be right. In the cases where we don't give
an error (e.g. because we're dealing with an instantiation of a
variable template) there is no error, so we need to proceed with the
rest of cp_finish_decl as normal.
The cases where we don't give an error all fall under
DECL_DECLARED_CONSTEXPR_P == false, thus aren't affected at all.
Ah, true. Though that's a bit subtle; maybe change ensure_... to
return error_mark_node in the error case?
Agreed. The below does that and I'm finishing testing it (in libstdc++
at the moment, so far so good and I checked separately for those nasty
breakages I had yesterday). Note, however, this isn't exactly equivalent
to my previous patch: it's definitely cleaner and less subtle IMO but
more aggressive because we immediately bail out of cp_finish_decl in all
cases of error, not just when DECL_DECLARED_CONSTEXPR_P == true. Ok if
it passes?
Thanks!
Paolo.
////////////////////////
/cp
2018-01-17 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/81054
* constexpr.c (ensure_literal_type_for_constexpr_object): Return
error_mark_node when we give an error.
decl.c (cp_finish_decl): Use the latter.
/testsuite
2018-01-17 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/81054
* g++.dg/cpp0x/constexpr-ice19.C: New.
Index: cp/constexpr.c
===================================================================
--- cp/constexpr.c (revision 256794)
+++ cp/constexpr.c (working copy)
@@ -75,7 +75,8 @@ literal_type_p (tree t)
}
/* If DECL is a variable declared `constexpr', require its type
- be literal. Return the DECL if OK, otherwise NULL. */
+ be literal. Return error_mark_node if we give an error, the
+ DECL otherwise. */
tree
ensure_literal_type_for_constexpr_object (tree decl)
@@ -97,6 +98,7 @@ ensure_literal_type_for_constexpr_object (tree dec
error ("the type %qT of %<constexpr%> variable %qD "
"is not literal", type, decl);
explain_non_literal_class (type);
+ decl = error_mark_node;
}
else
{
@@ -105,10 +107,10 @@ ensure_literal_type_for_constexpr_object (tree dec
error ("variable %qD of non-literal type %qT in %<constexpr%>
"
"function", decl, type);
explain_non_literal_class (type);
+ decl = error_mark_node;
}
cp_function_chain->invalid_constexpr = true;
}
- return NULL;
}
}
return decl;
Index: cp/decl.c
===================================================================
--- cp/decl.c (revision 256794)
+++ cp/decl.c (working copy)
@@ -6810,8 +6810,12 @@ cp_finish_decl (tree decl, tree init, bool init_co
cp_apply_type_quals_to_decl (cp_type_quals (type), decl);
}
- if (!ensure_literal_type_for_constexpr_object (decl))
- DECL_DECLARED_CONSTEXPR_P (decl) = 0;
+ if (ensure_literal_type_for_constexpr_object (decl)
+ == error_mark_node)
+ {
+ DECL_DECLARED_CONSTEXPR_P (decl) = 0;
+ return;
+ }
if (VAR_P (decl)
&& DECL_CLASS_SCOPE_P (decl)
Index: testsuite/g++.dg/cpp0x/constexpr-ice19.C
===================================================================
--- testsuite/g++.dg/cpp0x/constexpr-ice19.C (nonexistent)
+++ testsuite/g++.dg/cpp0x/constexpr-ice19.C (working copy)
@@ -0,0 +1,13 @@
+// PR c++/81054
+// { dg-do compile { target c++11 } }
+
+struct A
+{
+ volatile int i;
+ constexpr A() : i() {}
+};
+
+struct B
+{
+ static constexpr A a {}; // { dg-error "not literal" }
+};
