-Wmaybe-uninitialized came about in gcc-4.7. ~Brian
________________________________ Brian Robert Callahan, Ph.D. Lecturer, ITWS@RPI Office: Amos Eaton 132 ________________________________ From: Bug-apl [bug-apl-bounces+callab5=rpi....@gnu.org] on behalf of Louis Chrétien via Bugs and suggestions for GNU APL [bug-apl@gnu.org] Sent: Wednesday, July 08, 2020 1:04 PM To: bug-apl Subject: Re: Probably minor bug As well you should… 😉 The latest SVN (1304) does not compile anymore on Mac OS 10.4: g++ -DHAVE_CONFIG_H -I. -I.. -Wall -I sql -Werror -g -O2 -MT apl-main.o -MD -MP -MF .deps/apl-main.Tpo -c -o apl-main.o `test -f 'main.cc<http://main.cc>' || echo './'`main.cc<http://main.cc> In file included from main.cc:34<http://main.cc:34>: In file included from ./Command.hh:28: In file included from ./Value.hh:24: In file included from ./CharCell.hh:24: In file included from ./Cell.hh:30: In file included from ./PrintBuffer.hh:30: ./Shape.hh:75:32: error: unknown warning group '-Wmaybe-uninitialized', ignored [-Werror,-Wunknown-warning-option] #pragma GCC diagnostic ignored "-Wmaybe-uninitialized" ^ 1 error generated. make[3]: *** [apl-main.o] Error 1 make[2]: *** [all-recursive] Error 1 make[1]: *** [all-recursive] Error 1 make: *** [all] Error 2 On Jul 1, 2020, at 22:25, Chris Moller <mol...@mollerware.com<mailto:mol...@mollerware.com>> wrote: Hi Chris, thanks for looking into this. I have added your #pragma in SVN 1303. I am not particular fond of #pragmas for a number of reasons, but since other contributors to GNU APL have used them already earlier I suppose this one should do no harm. Best Regards, Jürgen On 7/2/20 4:25 AM, Chris Moller wrote: Hi, Jürgen, CXXFLAGS=-Werror=maybe-uninitialized Way down deep in the gcc code, in tree-ssa-uninit.c, there's a statement: warn_uninitialized_vars (/*warn_possibly_uninitialized=*/1); elsewhere in the same file is: warn_uninitialized_vars (/*warn_possibly_uninitialized=*/!optimize); The former is what's causing the killer warnings. I don't have any idea why that one unconditionally looks for uninitialisations while the latter conditions on the optimisation level, but I expect it would be pointless trying to get the gcc people to do anything about it. Fortunately, a more specific version of your README-11-bogus-compiler-warnings suggestion of CXXFLAGS=-Werror=maybe-uninitialized might be what you need: make your Shape.hh pragma #pragma GCC diagnostic ignored "-Wmaybe-uninitialized" instead of #pragma GCC diagnostic ignored "-Wuninitialized" Maybe not ideal, but maybe better than nothing. On 27/06/2020 12:16, Dr. Jürgen Sauermann wrote: Hi Chris, this warning is haunting us for quite a while now. I have written a README-11-bogus-compiler-warnings with work-arounds. Unfortunately the loop below is not entirely bogus (what happens is that for some r the uninitialized value other.rho[r] is being copied to the never-used value rho[r]). Unfortunately the obvious fix for the warning has shown to cause significant perfomance impacts because it prevents loop unrolling (and there was a separate trouble report concerning that performance drop on bug-apl). At that time I filed a gcc trouble report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94905 asking to fix this, but I am afraid that this may take some time. My bug report was merged into a meta-bug which is open since 2005: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24639 Best Regards, Jürgen On 6/27/20 5:01 PM, Chris Moller wrote: Shape.hh: In member function 'Shape Shape::insert_axis(Axis, ShapeItem) const': Shape.hh:69:46: error: ''target_mem_ref' not supported by dump_expr<expression error>' may be used uninitialized in this function [-Werror=maybe-uninitialized] 69 | loop(r, MAX_RANK) rho[r] = other.rho[r]; | ~~~~~~~~~~~^ Just to finish the build, I patched around the bug by editing out the Wall and the Werror in the Makefile, so: [moller@hpbox]~tinkering/gnuapl/trunk% apl -v 10:47:53 BUILDTAG: --------- Project: GNU APL Version / SVN: 1.8 / 1210 Build Date: 2019-12-19 17:09:01 UTC Build OS: Linux 4.19.3-200.fc28.x86_64 x86_64 config.status: 'PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig:/usr/local/lib/pkgconfig:/usr/lib64/pkgconfig:/usr/lib/pkgconfig' Archive SVN: 1161 [moller@hpbox]~tinkering/gnuapl/trunk% gcc --version 10:49:35 gcc (GCC) 10.1.1 20200507 (Red Hat 10.1.1-1) [moller@hpbox]~tinkering/gnuapl/trunk% cat /etc/redhat-release 10:51:45 Fedora release 32 (Thirty Two) [moller@hpbox]~tinkering/gnuapl/trunk% uname -a 10:52:29 Linux hpbox 5.6.19-300.fc32.x86_64 #1 SMP Wed Jun 17 16:10:48 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux --- Louis Chrétien lchret...@mac.com<mailto:lchret...@mac.com>
