[Bug c/99131] New: gcc doesn't detect missing comma in array initialisation

[Bug c/99131] New: gcc doesn't detect missing comma in array initialisation

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99131

            Bug ID: 99131
           Summary: gcc doesn't detect missing comma in array
                    initialisation
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

For this C code:

const char * a[ 4] = {
        " fred ",
        " bert "
        " harry ",
        " eric "
};

Note missing "," on the bert line. gcc doesn't say very much:

$ /home/dcb/gcc/results/bin/gcc -c -g -O2 -Wall -Wextra feb17f.cc
$

Here is a recent clang doing something more useful:

$ /home/dcb/llvm/clang1200rc1/bin/clang++ -c -g -O2 -Wall -Wextra feb17f.cc
feb17f.cc:7:2: warning: suspicious concatenation of string literals in an array
initialization; did you mean to separate the elements with a comma?
[-Wstring-concatenation]
        " harry ",
        ^
feb17f.cc:6:2: note: place parentheses around the string literal to silence
warning
        " bert "
        ^
1 warning generated.

[Bug c/99131] gcc doesn't detect missing comma in array initialisation

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99131

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
           Severity|normal                      |enhancement
             Blocks|                            |87403


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87403
[Bug 87403] [Meta-bug] Issues that suggest a new warning

[Bug c/99131] gcc doesn't detect missing comma in array initialisation

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99131

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |egallager at gcc dot gnu.org
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-02-17
     Ever confirmed|0                           |1

--- Comment #1 from Eric Gallager <egallager at gcc dot gnu.org> ---
Having this warning would have saved me a lot of grief trying to hunt down a
particular bug I remember having to deal with in the past; confirmed.

[Bug c/99131] gcc doesn't detect missing comma in array initialisation

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99131

--- Comment #2 from David Binderman <dcb314 at hotmail dot com> ---
I usually write code that compiles warning free on both gcc and clang.

I only noticed this difference between gcc and clang as a result
of compiling the latest release of the tor browser. I thought it
would be good to generalise it.

I guess there must be some way to get both gcc and clang to emit
all possible warning messages they can, then diff the two lists,
to find out where one compiler could be enhanced. The strings 
command might be the way forward on this.

I'd be happy to help with testing any prototype implementation.

Interesting, my usual static analyser, cppcheck, has nothing to say
also, so that's probably worth a bug report too.

[Bug c/99131] gcc doesn't detect missing comma in array initialisation [-Wstring-concatenation]

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99131

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|gcc doesn't detect missing  |gcc doesn't detect missing
                   |comma in array              |comma in array
                   |initialisation              |initialisation
                   |                            |[-Wstring-concatenation]
                 CC|                            |dmalcolm at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org

--- Comment #3 from Eric Gallager <egallager at gcc dot gnu.org> ---
Adding clang's name for this warning to the title for easier findability. Also
this warning has found a few issues in GCC's own code; see here:
https://gcc.gnu.org/pipermail/gcc-patches/2021-March/566749.html
...and here:
https://gcc.gnu.org/pipermail/gcc-patches/2021-March/566750.html

[Bug c/99131] gcc doesn't detect missing comma in array initialisation [-Wstring-concatenation]

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99131

--- Comment #4 from David Binderman <dcb314 at hotmail dot com> ---
Interestingly, I compiled fedora rawhide with clang and found
a whopping 247 cases of this warning across 11 packages.