Package: g++-8
Version: 8.3.0-6
Severity: normal
Dear Maintainer,
I noticed a bug in handling -Wc++-compat when (not) using the -x option.
Suppose you have two files containing valid C saved in files a.c and b.c,
for example, "int main(void) {}" in a.c and just a newline in b.c.
According to the documentation AFAICT you should be able to compile this
without errors in a single step by executing
g++ -Wc++-compat a.c b.c
since the correct language of the file should be determined automatically by
the suffix.
However, this leads to two times
cc1plus: warning: command line option ‘-Wc++-compat’ is valid for
C/ObjC but not for C++
One should be able to remove the warnings by forcing the language used to C
by prepending "-x c" as in
g++ -Wc++-compat -x c a.c b.c
since the manual states that -x <lang> "applies to all following input files
until the next -x option".
However, this is not the case because only the first spurious warning is fixed
by this and ony adding another -x c just before the second file, i.e.,
g++ -Wc++-compat -x c a.c -x c b.c
works as expected without any warnings.
This problem is not depending on any arch specifics (tested with native g++
8.3.0
on amd64, and cross compilers for riscv64-linux-gnu, and arm-linux-gnueabihf).
A quick test with g++ 6.3.0-18+deb9u1 on amd64 revealed the same behavior.
I did not (and do not intend to but could if need be) report this upstream.
KR, Stefan
-- System Information:
Debian Release: 10.1
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable'), (91, 'testing'), (10,
'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 4.19.0-6-amd64 (SMP w/4 CPU cores)
Kernel taint flags: TAINT_WARN, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8),
LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
Versions of packages g++-8 depends on:
ii gcc-8 8.3.0-6
ii gcc-8-base 8.3.0-6
ii libc6 2.28-10
ii libgmp10 2:6.1.2+dfsg-4
ii libisl19 0.20-2
ii libmpc3 1.1.0-1
ii libmpfr6 4.0.2-1
ii libstdc++-8-dev 8.3.0-6
ii zlib1g 1:1.2.11.dfsg-1
g++-8 recommends no packages.
Versions of packages g++-8 suggests:
pn g++-8-multilib <none>
ii gcc-8-doc 8.3.0-1~bpo10+1
pn libstdc++6-8-dbg <none>
-- no debconf information
