Re: [PATCH] Correct -fdump-go-spec's handling of incomplete types

[Nikhil Benesch <nikhil.benesch@gmail.com>]

Sorry about this, Rainer. I think I see the issue, though it's hard to
be certain without access to a Solaris machine. Assuming the icmp6.h
header hasn't changed since the last time Solaris code was open source
[0], I think the issue is likely to be typedefs that define a named
struct and an alias for that struct in one shot. I'll start pulling on
that thread.

[0]: https://github.com/kofemann/opensolaris/blob/80192cd83/usr/src/uts/common/netinet/icmp6.h#L71-L74

On Thu, Dec 10, 2020 at 2:18 PM Rainer Orth <ro@cebitec.uni-bielefeld.de> wrote:
>
> Hi Ian,
>
> > On Tue, Dec 8, 2020 at 2:57 PM Nikhil Benesch <nikhil.benesch@gmail.com> wrote:
> >>
> >> This patch corrects -fdump-go-spec's handling of incomplete types.
> >> To my knowledge the issue fixed here has not been previously
> >> reported. It was exposed by an in-progress port of gccgo to FreeBSD.
> >>
> >> Given the following C code
> >>
> >>         struct s_fwd v_fwd;
> >>         struct s_fwd { };
> >>
> >> -fdump-go-spec currently produces the following Go code
> >>
> >>         var v_fwd struct {};
> >>         type s_fwd s_fwd;
> >>
> >> whereas the correct Go code is:
> >>
> >>         var v_fwd s_fwd;
> >>         type s_fwd struct {};
> >>
> >> (Go is considerably more permissive than C with out-of-order
> >> declarations, so anywhere an out-of-order declaration is valid in
> >> C it is valid in Go.)
> >>
> >> gcc/:
> >>         * godump.c (go_format_type): Don't consider whether a type has
> >>         been seen when determining whether to output a type by name.
> >>         Consider only the use_type_name parameter.
> >>         (go_output_typedef): When outputting a typedef, format the
> >>         declaration's original type, which contains the name of the
> >>         underlying type rather than the name of the typedef.
> >> gcc/testsuite:
> >>         * gcc.misc-tests/godump-1.c: Add test case.
> >
> > Thanks.  I changed function types to use type names, and committed like so.
>
> This patch badly broke Solaris bootstrap:
>
> runtime_sysinfo.go:623:6: error: invalid recursive type
>   623 | type ___FILE ___FILE
>       |      ^
> runtime_sysinfo.go:7045:6: error: redefinition of ‘_mld_hdr_t’
>  7045 | type _mld_hdr_t _mld_hdr
>       |      ^
> runtime_sysinfo.go:1510:6: note: previous definition of ‘_mld_hdr_t’ was here
>  1510 | type _mld_hdr_t _mld_hdr
>       |      ^
> runtime_sysinfo.go:7070:6: error: redefinition of ‘_upad128_t’
>  7070 | type _upad128_t struct { _l [4]uint32; }
>       |      ^
> runtime_sysinfo.go:7029:6: note: previous definition of ‘_upad128_t’ was here
>  7029 | type _upad128_t struct {}
>       |      ^
> runtime_sysinfo.go:7071:6: error: redefinition of ‘_zone_net_addr_t’
>  7071 | type _zone_net_addr_t _zone_net_addr
>       |      ^
> runtime_sysinfo.go:1079:6: note: previous definition of ‘_zone_net_addr_t’ was here
>  1079 | type _zone_net_addr_t _zone_net_addr
>       |      ^
> runtime_sysinfo.go:7072:6: error: redefinition of ‘_flow_arp_desc_t’
>  7072 | type _flow_arp_desc_t _flow_arp_desc_s
>       |      ^
> runtime_sysinfo.go:1127:6: note: previous definition of ‘_flow_arp_desc_t’ was here
>  1127 | type _flow_arp_desc_t _flow_arp_desc_s
>       |      ^
> runtime_sysinfo.go:7073:6: error: redefinition of ‘_flow_l3_desc_t’
>  7073 | type _flow_l3_desc_t _flow_l3_desc_s
>       |      ^
> runtime_sysinfo.go:1130:6: note: previous definition of ‘_flow_l3_desc_t’ was here
>  1130 | type _flow_l3_desc_t _flow_l3_desc_s
>       |      ^
> runtime_sysinfo.go:7074:6: error: redefinition of ‘_mac_ipaddr_t’
>  7074 | type _mac_ipaddr_t _mac_ipaddr_s
>       |      ^
> runtime_sysinfo.go:1150:6: note: previous definition of ‘_mac_ipaddr_t’ was here
>  1150 | type _mac_ipaddr_t _mac_ipaddr_s
>       |      ^
> runtime_sysinfo.go:7075:6: error: redefinition of ‘_mactun_info_t’
>  7075 | type _mactun_info_t _mactun_info_s
>       |      ^
> runtime_sysinfo.go:1213:6: note: previous definition of ‘_mactun_info_t’ was here
>  1213 | type _mactun_info_t _mactun_info_s
>       |      ^
> runtime_sysinfo.go:187:19: error: use of undefined type ‘_timespec’
>   187 | type _timestruc_t _timespec
>       |                   ^
> runtime_sysinfo.go:1213:21: error: use of undefined type ‘_mactun_info_s’
>  1213 | type _mactun_info_t _mactun_info_s
>       |                     ^
> runtime_sysinfo.go:741:13: error: use of undefined type ‘_ip6_hdr’
>   741 | type _ip6_t _ip6_hdr
>       |             ^
> runtime_sysinfo.go:1079:23: error: use of undefined type ‘_zone_net_addr’
>  1079 | type _zone_net_addr_t _zone_net_addr
>       |                       ^
> runtime_sysinfo.go:1127:23: error: use of undefined type ‘_flow_arp_desc_s’
>  1127 | type _flow_arp_desc_t _flow_arp_desc_s
>       |                       ^
> runtime_sysinfo.go:1130:22: error: use of undefined type ‘_flow_l3_desc_s’
>  1130 | type _flow_l3_desc_t _flow_l3_desc_s
>       |                      ^
> runtime_sysinfo.go:1150:20: error: use of undefined type ‘_mac_ipaddr_s’
>  1150 | type _mac_ipaddr_t _mac_ipaddr_s
>       |                    ^
> runtime_sysinfo.go:1210:28: error: use of undefined type ‘_mac_resource_props_s’
>  1210 | type _mac_resource_props_t _mac_resource_props_s
>       |                            ^
> runtime_sysinfo.go:1510:17: error: use of undefined type ‘_mld_hdr’
>  1510 | type _mld_hdr_t _mld_hdr
>       |                 ^
> runtime_sysinfo.go:1519:17: error: use of undefined type ‘_mld2mar’
>  1519 | type _mld2mar_t _mld2mar
>       |                 ^
> runtime_sysinfo.go:1535:29: error: use of undefined type ‘_nd_neighbor_solicit’
>  1535 | type _nd_neighbor_solicit_t _nd_neighbor_solicit
>       |                             ^
> runtime_sysinfo.go:1538:28: error: use of undefined type ‘_nd_neighbor_advert’
>  1538 | type _nd_neighbor_advert_t _nd_neighbor_advert
>       |                            ^
> runtime_sysinfo.go:1541:21: error: use of undefined type ‘_nd_redirect’
>  1541 | type _nd_redirect_t _nd_redirect
>       |                     ^
> runtime_sysinfo.go:1548:28: error: use of undefined type ‘_nd_opt_prefix_info’
>  1548 | type _nd_opt_prefix_info_t _nd_opt_prefix_info
>       |                            ^
> make: *** [Makefile:2959: runtime.lo] Error 1
>
> Comparing runtime_sysinfo.go with a slightly older version in two
> instances:
>
> -type ___gnuc_va_list *int8
> -type ___va_list *int8
> -type ___FILE struct { _cnt int32; _ptr *uint8; _base *uint8; _flag uint8; _magic uint8; Godump_0_pad [2]byte; }
> +type ___FILE ___FILE
>
> +type _mld_hdr_t _mld_hdr
>
> -type _mld_hdr_t struct { mld_icmp6_hdr _icmp6_hdr; mld_addr [16]byte; }
> +type _mld_hdr_t _mld_hdr
>
>         Rainer
>
> --
> -----------------------------------------------------------------------------
> Rainer Orth, Center for Biotechnology, Bielefeld University