[Bug 245006] toolchain: clang issues bogus "warning: multi-line // comment [-Wcomment]"

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=245006

Dimitry Andric <dim at FreeBSD.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dim at FreeBSD.org
             Status|New                         |Open

--- Comment #3 from Dimitry Andric <dim at FreeBSD.org> ---
Apparently gcc thinks the same, you just have to add -Wcomment:

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc9/gcc/x86_64-portbld-freebsd13.0/9.2.0/lto-wrapper
Target: x86_64-portbld-freebsd13.0
Configured with: /wrkdirs/share/dim/ports/lang/gcc9/work/gcc-9.2.0/configure
--enable-multilib --enable-plugin --disable-bootstrap --disable-nls
--enable-gnu-indirect-function --libdir=/usr/local/lib/gcc9
--libexecdir=/usr/local/libexec/gcc9 --program-suffix=9
--with-as=/usr/local/bin/as --with-gmp=/usr/local
--with-gxx-include-dir=/usr/local/lib/gcc9/include/c++/
--with-ld=/usr/local/bin/ld --with-pkgversion='FreeBSD Ports Collection'
--with-system-zlib --with-isl=/usr/local --enable-languages=c,c++,objc,fortran
--prefix=/usr/local --localstatedir=/var --mandir=/usr/local/man
--infodir=/usr/local/share/info/gcc9 --build=x86_64-portbld-freebsd13.0
Thread model: posix
gcc version 9.2.0 (FreeBSD Ports Collection)

$ gcc -Wcomment -c multiline.c
multiline.c:1:1: warning: multi-line comment [-Wcomment]
    1 | // \
      | ^

And similar for gcc 4.8, 7.5 and 8.3.

I am unsure about the interpretation of the various standards though, as they
do not say much, if anything, about warnings.  The construct is completely
legal, so it causes no errors unless you insist on making all warnings errors.

Maybe you can report this upstream with gcc and clang, to see what their
opinion is?  I am hesitant to make changes to our versions unless there is a
pressing need to do so.

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