| Message ID | 4F68E9F2.7070406@oracle.com |
|---|---|
| State | New |
| Headers | show |
It's ill-formed to have a field with incomplete type. The best thing would be to complain about that before we get to literal_type_p so that errorcount is set, if that's not too complicated. Jason
On 03/22/2012 03:49 PM, Jason Merrill wrote: > It's ill-formed to have a field with incomplete type. The best thing > would be to complain about that before we get to literal_type_p so > that errorcount is set, if that's not too complicated. Agreed. The problem is that if we just change check_field_decls to produce an error about the incomplete field, we produce also another later: that is, considering cp_parser_lambda_expression, we get to check_field_decls from finish_struct, but we eventually also produce an error with cxx_incomplete_type_diagnostic from build_lambda_object (-> force_rvalue -> build_special_member_call -> complete_type_or_maybe_complain) Anyway, I also think not calling literal_type_p from check_field_decls if the type is incomplete is pretty ugly, but I'm not sure which is the best way to make progress: I could try returning a boolean from check_field_decls if something goes wrong in order to bail out early from cp_parser_lambda_expression (at the moment, finish_struct_1, check_bases_and_members, all return void). Or I could try to catch the incomplete field even *before* check_field_decls. What do you suggest? Thanks, Paolo.
On Thu, Mar 22, 2012 at 11:58 AM, Paolo Carlini <paolo.carlini@oracle.com> wrote: > On 03/22/2012 03:49 PM, Jason Merrill wrote: >> >> It's ill-formed to have a field with incomplete type. The best thing >> would be to complain about that before we get to literal_type_p so that >> errorcount is set, if that's not too complicated. > > Agreed. The problem is that if we just change check_field_decls to produce > an error about the incomplete field, we produce also another later: that is, Can't we set a bit saying that the field has already gone through diagnostics, just like we do when trying to avoid duplicate warnings? > considering cp_parser_lambda_expression, we get to check_field_decls from > finish_struct, but we eventually also produce an error with > cxx_incomplete_type_diagnostic from build_lambda_object (-> force_rvalue -> > build_special_member_call -> complete_type_or_maybe_complain) > > Anyway, I also think not calling literal_type_p from check_field_decls if > the type is incomplete is pretty ugly, but I'm not sure which is the best > way to make progress: I could try returning a boolean from check_field_decls > if something goes wrong in order to bail out early from > cp_parser_lambda_expression (at the moment, finish_struct_1, > check_bases_and_members, all return void). Or I could try to catch the > incomplete field even *before* check_field_decls. > > What do you suggest? > > Thanks, > Paolo. >
On 03/22/2012 12:58 PM, Paolo Carlini wrote: > Anyway, I also think not calling literal_type_p from check_field_decls > if the type is incomplete is pretty ugly, but I'm not sure which is the > best way to make progress I guess that's OK. Just add a comment explaining that we'll get an error later. Jason
Index: testsuite/g++.dg/cpp0x/lambda/lambda-ice7.C =================================================================== --- testsuite/g++.dg/cpp0x/lambda/lambda-ice7.C (revision 0) +++ testsuite/g++.dg/cpp0x/lambda/lambda-ice7.C (revision 0) @@ -0,0 +1,9 @@ +// PR c++/52487 +// { dg-options "-std=c++0x" } + +struct A; // { dg-error "forward declaration" } + +void foo(A& a) +{ + [=](){a;}; // { dg-error "invalid use of incomplete type" } +} Index: cp/class.c =================================================================== --- cp/class.c (revision 185588) +++ cp/class.c (working copy) @@ -3150,7 +3150,7 @@ check_field_decls (tree t, tree *access_decls, /* If at least one non-static data member is non-literal, the whole class becomes non-literal. */ - if (!literal_type_p (type)) + if (COMPLETE_TYPE_P (type) && !literal_type_p (type)) CLASSTYPE_LITERAL_P (t) = false; /* A standard-layout class is a class that: