Package: gcc-8
Version: 8.2.0-9
Severity: normal
Dear Maintainer,
I have a piece of code in a CMake project that fails to compile when building
in RelWithDebInfo mode.
The problem seems to come from gcc-8 when both -Wall and -O2 options are set:
char* copy_string(const char* str) {
int len = strlen(str)+1;
char* dest = malloc(sizeof(char)*len);
if(dest) {
strncpy(dest, str, len);
}
return dest;
}
gcc reports the following error:
test_strncpy.c:7:3: error: ‘strncpy’ specified bound depends on the length of
the source argument [-Werror=stringop-overflow=]
strncpy(dest, str, len);
^~~~~~~~~~~~~~~~~~~~~~~
test_strncpy.c:5:13: note: length computed here
int len = strlen(str)+1;
^~~~~~~~~~~
cc1: all warnings being treated as errors
In this case, there is no problem in the source code, but -Werror=stringop-
overflow still reports an error.
Gcc only reports an error when -O2 and -Werror=stringop-overflow (which is
enabled by -Wall) are set. Replacing strncpy with memcpy also fixes the
problem.
*** Reporter, please consider answering these questions, where appropriate ***
* What led up to the situation?
* What exactly did you do (or not do) that was effective (or
ineffective)?
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* What outcome did you expect instead?
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-- System Information:
Debian Release: buster/sid
APT prefers testing
APT policy: (500, 'testing'), (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 4.18.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8), LANGUAGE=
(charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
Versions of packages gcc-8 depends on:
ii binutils 2.31.1-10
ii cpp-8 8.2.0-9
ii gcc-8-base 8.2.0-9
ii libc6 2.27-8
ii libcc1-0 8.2.0-9
ii libgcc-8-dev 8.2.0-9
ii libgcc1 1:8.2.0-9
ii libgmp10 2:6.1.2+dfsg-3
ii libisl19 0.20-2
ii libmpc3 1.1.0-1
ii libmpfr6 4.0.1-1
ii libstdc++6 8.2.0-9
ii zlib1g 1:1.2.11.dfsg-1
Versions of packages gcc-8 recommends:
ii libc6-dev 2.27-8
Versions of packages gcc-8 suggests:
pn gcc-8-doc <none>
pn gcc-8-locales <none>
ii gcc-8-multilib 8.2.0-9
pn libasan5-dbg <none>
pn libatomic1-dbg <none>
pn libgcc1-dbg <none>
pn libgomp1-dbg <none>
pn libitm1-dbg <none>
pn liblsan0-dbg <none>
pn libmpx2-dbg <none>
pn libquadmath0-dbg <none>
pn libtsan0-dbg <none>
pn libubsan1-dbg <none>
-- no debconf information
