On 1/1/21 1:49 PM, Bruno Haible wrote:
Hi,
Paul Murphy wrote in
<https://lists.gnu.org/archive/html/bug-gnulib/2020-12/msg00106.html>:
While trying to build gdb with ldbl == ieee128 on ppc64le, we found out
gnulib's copy of cdefs.h needs to be synchronized with upstream glibc.
The only notable divergence is to ensure
__LDOUBLE_REDIRECTS_TO_FLOAT128_ABI is always defined as this macro is
fairly recent.
Why would this be needed? Nothing in Gnulib uses this macro.
The cdefs.h of Gnulib is meant to be a minimal replacement (you can also
call it a "mock") of the one in Glibc.
Can you show the error message you got when compiling gdb, and how
you traced it back to a Gnulib issue?
This was encountered when building IBM's advance toolchain (or
sufficiently new GCC) with the -mabi=ieeelongdouble option, and glibc
2.32 or newer.
This can be reproduced by building Tulio's branch of AT with IEEE128
enabled. https://github.com/tuliom/advance-toolchain/tree/ldbl-ieee128
We ran into the following:
In file included from
/home/tuliom/opt/at-next-15.0-0-alpha/include/stdio.h:871,
from ./stdio.h:43,
from
/home/tuliom/tmp/at-build-tray/at15.0-0-alpha.redhat-8_ppc64le_ppc64le/sources
/gdb/gnulib/import/tempname.h:23,
from
/home/tuliom/tmp/at-build-tray/at15.0-0-alpha.redhat-8_ppc64le_ppc64le/sources
/gdb/gnulib/import/tempname.c:20:
/home/tuliom/opt/at-next-15.0-0-alpha/include/bits/stdio-ldbl.h: In
function ‘__LDBL_REDIR1_DECL’:
/home/tuliom/opt/at-next-15.0-0-alpha/include/bits/stdio-ldbl.h:36:1:
error: expected declaration specifiers before ‘__LDBL_REDIR1_DECL’
36 | __LDBL_REDIR1_DECL (scanf, __isoc99_scanfieee128)
| ^~~~~~~~~~~~~~~~~~
The missing macro is provided by glibc's cdefs.h. Thus, the wrong
cdefs.h was picked up. I found gnulib provides its own copy which does
not provide these. Likewise, I verified applying this patch to AT's
gdb. This fixed compilation, and the redirects worked as expected.
