gdb/ser-unix: work around conflicting types for tcflag_t

When trying to cross-compile GDB to sparc-buildroot-linux-uclibc, I get:

      CXX    ser-unix.o
    In file included from /data1/smarchi/many-buildroots/toolchains/sparc/sparc-buildroot-linux-uclibc/sysroot/usr/include/termios.h:39,
                     from /home/smarchi/src/binutils-gdb/gdb/ser-unix.c:51:
    /data1/smarchi/many-buildroots/toolchains/sparc/sparc-buildroot-linux-uclibc/sysroot/usr/include/bits/termios.h:26:22: error: conflicting declaration ‘typedef unsigned int tcflag_t’
       26 | typedef unsigned int tcflag_t;
          |                      ^~~~~~~~
    In file included from /home/smarchi/src/binutils-gdb/gdb/ser-unix.c:46:
    /data1/smarchi/many-buildroots/toolchains/sparc/sparc-buildroot-linux-uclibc/sysroot/usr/include/asm/termbits.h:13:25: note: previous declaration as ‘typedef long unsigned int tcflag_t’
       13 | typedef unsigned long   tcflag_t;
          |                         ^~~~~~~~

uClibc and the kernel don't agree on the definition of tcflag_t for this
architecture.  Here' uClibc [1]:

    typedef unsigned int tcflag_t;

And here's the kernel [2]:

    #if defined(__sparc__) && defined(__arch64__)
    typedef unsigned int	tcflag_t;
    #else
    typedef unsigned long	tcflag_t; <--- that branch is take
    #endif

glibc [3] has the same definition as uClibc, so we would get the same
problem.

I propose to work around this the same way as we handle differences in
the termios structure, by renaming the version from the kernel.

I opened a bug on the glibc bugzilla [4] to ask if this is something
that would need to be fixed on the libc side, but in the mean time we
need to work around it.

[1] https://github.com/kraj/uClibc/blob/ca1c74d67dd115d059a875150e10b8560a9c35a8/libc/sysdeps/linux/sparc/bits/termios.h#L26
[2] https://github.com/torvalds/linux/blob/e7c375b181600caf135cfd03eadbc45eb530f2cb/arch/sparc/include/uapi/asm/termbits.h#L7-L11
[3] https://gitlab.com/gnutools/glibc/-/blob/efc8642051e6c4fe5165e8986c1338ba2c180de6/bits/termios.h#L104
[4] https://sourceware.org/bugzilla/show_bug.cgi?id=33643

Change-Id: I71c6e0df5ac8e2ff3db3233a2220faaf70c3df6d
Approved-By: Tom Tromey <tom@tromey.com>

diff --git a/gdb/ser-unix.c b/gdb/ser-unix.c
index 553220e5b0858a6244c8b3e95f9e3ddfcb1fb988..f9ef84416299864cf185923734a659d98ac4798e 100644 (file)
--- a/gdb/ser-unix.c
+++ b/gdb/ser-unix.c
@@ -43,8 +43,10 @@
 /* Workaround to resolve conflicting declarations of termios
    in <asm/termbits.h> and <termios.h>.  */
 #  define termios asmtermios
+#  define tcflag_t asmtcflag_t
 #  include <asm/termbits.h>
 #  undef termios
+#  undef tcflag_t
 #endif
 
 #ifdef HAVE_TERMIOS_H