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My collegue just today noticed that gcc version 3.4.0 behaves a bid odd on Linux when --pedantic-errors is used as compilation option to C-compiler (gcc): <helix:/tmp> cat main.c #include <stdio.h> #include <stdlib.h> int main(void){printf("Hello world\n"); exit(EXIT_SUCCESS);} <helix:/tmp> gcc --version gcc (GCC) 3.4.0 Copyright (C) 2004 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. <helix:/tmp> gcc --pedantic main.c <helix:/tmp> gcc --pedantic-errors main.c In file included from /usr/include/libio.h:32, from /usr/include/stdio.h:65, from main.c:1: /usr/include/_G_config.h:50: error: invalid use of structure with flexible array member <helix:/tmp> If g++ is used instead of gcc: <helix:/tmp> g++ --version g++ (GCC) 3.4.0 Copyright (C) 2004 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. <helix:/tmp> g++ --pedantic main.c <helix:/tmp> g++ --pedantic-errors main.c <helix:/tmp> This problem does not happen on Solaris/HPUX version nor does it happen when older version (tested with 3.3.3 and 2.95.3) of gcc is used.
Can you provide the preprocessed source? Also it looks like -pedantic-errors is enabling -Wsystem-headers which could be right or could be wrong but then this should be fixed in glibc anyways, they should be using __extension__.
Subject: Re: --pedantic-errors behaves differently from --pedantic with C-compiler on Linux On Mon, 31 May 2004, pinskia at gcc dot gnu dot org wrote: > Can you provide the preprocessed source? > Also it looks like -pedantic-errors is enabling -Wsystem-headers which could be right or could be > wrong but then this should be fixed in glibc anyways, they should be using __extension__. I'm testing a patch. From the introductory text for this patch: The reason this didn't happen before 3.4 (although the detection of these misuses went into 3.3) is that pedwarn_with_decl didn't give any diagnostics in system headers at all, whereas with -pedantic-errors pedwarns in system headers cause errors unless there's a separate in_system_header check. We may wish to revisit this and cause pedwarn() not to give diagnostics in system headers at all unless -Wsystem-headers (and also to revisit the various local in_system_header checks on warnings or, after such a change, pedwarns, that may predate -Wsystem-headers and the general disabling of warnings in system headers by default), but the safe fix for 3.4 branch is clearly that below which adds local tests of in_system_header to the pedwarns-if-pedantic for flexible array member misuse. The disabling of warnings in system headers is intended to reduce the extent to which existing headers need fixing with fixincludes. It also means __extension__ is mainly needed by such headers only in macros.
*** Bug 15752 has been marked as a duplicate of this bug. ***
Created an attachment (id=6438) [edit] gcc -E -pedantic-errors main.c > main.E Although there already seems to be quite clear understanding (and even patch?) to this I still provide this bziped -E output if needed for reference.
Subject: Bug 15749 CVSROOT: /cvs/gcc Module name: gcc Changes by: jsm28@gcc.gnu.org 2004-05-31 22:06:34 Modified files: gcc : ChangeLog c-decl.c gcc/testsuite : ChangeLog Added files: gcc/testsuite/gcc.dg: pr15749-1.c pr15749-1.h Log message: PR c/15749 * c-decl.c (grokdeclarator, finish_struct): Don't pedwarn for misuses of structures with flexible array members if in_system_header. testsuite: * gcc.dg/pr15749-1.c, gcc.dg/pr15749-1.h: New test. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.3808&r2=2.3809 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/c-decl.c.diff?cvsroot=gcc&r1=1.503&r2=1.504 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.3798&r2=1.3799 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/pr15749-1.c.diff?cvsroot=gcc&r1=NONE&r2=1.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/pr15749-1.h.diff?cvsroot=gcc&r1=NONE&r2=1.1
Subject: Bug 15749 CVSROOT: /cvs/gcc Module name: gcc Branch: gcc-3_4-branch Changes by: jsm28@gcc.gnu.org 2004-05-31 22:12:01 Modified files: gcc : ChangeLog c-decl.c gcc/testsuite : ChangeLog Added files: gcc/testsuite/gcc.dg: pr15749-1.c pr15749-1.h Log message: PR c/15749 * c-decl.c (grokdeclarator, finish_struct): Don't pedwarn for misuses of structures with flexible array members if in_system_header. testsuite: * gcc.dg/pr15749-1.c, gcc.dg/pr15749-1.h: New test. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=2.2326.2.458&r2=2.2326.2.459 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/c-decl.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.470.4.13&r2=1.470.4.14 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.3389.2.189&r2=1.3389.2.190 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/pr15749-1.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/pr15749-1.h.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1
Fixed.