From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3662 invoked by alias); 24 Jan 2009 17:36:39 -0000 Received: (qmail 3614 invoked by uid 48); 24 Jan 2009 17:36:28 -0000 Date: Sat, 24 Jan 2009 17:36:00 -0000 Subject: [Bug c/38961] New: if () block not true but a command in it is still in effect X-Bugzilla-Reason: CC Message-ID: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "jellegeerts at gmail dot com" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2009-01/txt/msg02668.txt.bz2 Complete command line that triggered the bug: gcc -v -save-temps -ansi -Wall -Wextra -Werror -pedantic -pedantic-errors -g -O2 -o gcc_bug gcc_bug.c Output of the command line: ********************** Reading specs from /usr/lib/gcc/i486-slackware-linux/4.2.4/specs Target: i486-slackware-linux Configured with: ../gcc-4.2.4/configure --prefix=/usr --enable-shared --enable-languages=ada,c,c++,fortran,java,objc --enable-threads=posix --enable-__cxa_atexit --disable-checking --with-gnu-ld --verbose --with-arch=i486 --target=i486-slackware-linux --host=i486-slackware-linux Thread model: posix gcc version 4.2.4 /usr/libexec/gcc/i486-slackware-linux/4.2.4/cc1 -E -quiet -v gcc_bug.c -mtune=i486 -march=i486 -ansi -Wall -Wextra -Werror -pedantic -pedantic-errors -fworking-directory -O2 -fpch-preprocess -o gcc_bug.i ignoring nonexistent directory "/usr/lib/gcc/i486-slackware-linux/4.2.4/../../../../i486-slackware-linux/include" #include "..." search starts here: #include <...> search starts here: /usr/local/include /usr/lib/gcc/i486-slackware-linux/4.2.4/include /usr/include End of search list. /usr/libexec/gcc/i486-slackware-linux/4.2.4/cc1 -fpreprocessed gcc_bug.i -quiet -dumpbase gcc_bug.c -mtune=i486 -march=i486 -ansi -auxbase gcc_bug -g -O2 -Wall -Wextra -Werror -pedantic -pedantic-errors -ansi -version -o gcc_bug.s GNU C version 4.2.4 (i486-slackware-linux) compiled by GNU C version 4.2.4. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: d3491cea3997204b3b932c449c79b80e /usr/lib/gcc/i486-slackware-linux/4.2.4/../../../../i486-slackware-linux/bin/as -V -Qy -o gcc_bug.o gcc_bug.s GNU assembler version 2.18.50.0.9 (i486-slackware-linux) using BFD version (Linux/GNU Binutils) 2.18.50.0.9.20080822 /usr/libexec/gcc/i486-slackware-linux/4.2.4/collect2 --eh-frame-hdr -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 -o gcc_bug /usr/lib/gcc/i486-slackware-linux/4.2.4/../../../crt1.o /usr/lib/gcc/i486-slackware-linux/4.2.4/../../../crti.o /usr/lib/gcc/i486-slackware-linux/4.2.4/crtbegin.o -L/usr/lib/gcc/i486-slackware-linux/4.2.4 -L/usr/lib/gcc/i486-slackware-linux/4.2.4 -L/usr/lib/gcc/i486-slackware-linux/4.2.4/../../../../i486-slackware-linux/lib -L/usr/lib/gcc/i486-slackware-linux/4.2.4/../../.. gcc_bug.o -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /usr/lib/gcc/i486-slackware-linux/4.2.4/crtend.o /usr/lib/gcc/i486-slackware-linux/4.2.4/../../../crtn.o ********************** The source code that triggered the bug: ********************** #include #include const char *logout_cmd = NULL; static void foo() { const char *logout_cmd = logout_cmd; if ( ! logout_cmd ) { /* This line is not executed. */ printf("line %d, logout_cmd = %s\n", __LINE__, logout_cmd); /* This line is not executed when stepping through the code * with gdb, but logout_cmd still is assigned the value * "lxsession-logout", possible optimization bug? */ logout_cmd = "lxsession-logout"; } printf("line %d, logout_cmd = %s\n", __LINE__, logout_cmd); if (strcmp(logout_cmd, "openbox --exit")) printf("gcc bug triggered\n"); } int main(void) { printf("line %d, logout_cmd = %s\n", __LINE__, logout_cmd); logout_cmd = "openbox --exit"; printf("line %d, logout_cmd = %s\n", __LINE__, logout_cmd); foo(); printf("line %d, logout_cmd = %s\n", __LINE__, logout_cmd); return 0; } ********************** -- Summary: if () block not true but a command in it is still in effect Product: gcc Version: 4.2.4 Status: UNCONFIRMED Severity: major Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: jellegeerts at gmail dot com GCC host triplet: i486-slackware-linux http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38961