On 3/17/21 6:00 PM, Sandra Loosemore wrote:
On 3/17/21 4:40 PM, Martin Sebor wrote:
[*] Does -Wformat-diag really trigger when using older GCC to build?
I thought it only triggered in stage 2 and 3 when using the same GCC
to rebuild itself.
I always end up hopelessly confused by anything involving configure
scripts and makefiles, but....
Our scripts normally configure cross-compilers with
--disable-build-format-warnings and there's a comment on that bit that
these diagnostics are normally enabled when building non-stage-1
compilers. A cross compiler doesn't bootstrap so is never stage 1, I
guess. For the purposes of testing this patch I did an explicit
--enable-build-format-warnings instead, anyway.
Jan-Benedict, who reported the problem to me off-list, said he just did
configure --target=nios2-linux-gnu
and
make all-gcc
using the host gcc including with his distro, identified as "Debian
10.2.1-6".
I see. I routinely notice -Wformat warnings when building
cross-compilers (my system compiler is GCC 8.3) so I've been
assuming they're to be expected. For instance this one:
/src/gcc/master/gcc/gimple-fold.c: In function ‘bool
gimple_fold_builtin_strncpy(gimple_stmt_iterator*, tree, tree, tree)’:
/src/gcc/master/gcc/gimple-fold.c:1921:4: warning: format ‘%G’ expects
argument of type ‘gcall*’, but argument 4 has type ‘gimple*’ [-Wformat=]
"%G%qD destination unchanged after copying no bytes "
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"from a string of length %E",
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
stmt, fndecl, slen);
~~~~
Since, as you say, cross-compilers don't build stages 2 and later,
disabling these warnings for their builds would seem like the only
solution. Either that, or building them with the current GCC.
Either way, I'll try to remember to relax the warning for GCC 12
as I mentioned.
Martin
