[Bug driver/99608] New: gcc doesn't print diagnostics carets when file is passed through stdin

[Bug driver/99608] New: gcc doesn't print diagnostics carets when file is passed through stdin

[freezer at posteo dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99608

            Bug ID: 99608
           Summary: gcc doesn't print diagnostics carets when file is
                    passed through stdin
           Product: gcc
           Version: 10.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: driver
          Assignee: unassigned at gcc dot gnu.org
          Reporter: freezer at posteo dot de
  Target Milestone: ---

When a file is passed to gcc through stdin, gcc won't print any diagnostics
carets for the passed file.

Example:

// test.c
int main(int argc, char **argv)
{
    return 0;
}

When test.c is passed to gcc through stdin, the following is printed:

$ cat test.c | gcc -Wall -Wextra -xc -
<stdin>: In function ‘main’:
<stdin>:1:14: warning: unused parameter ‘argc’ [-Wunused-parameter]
<stdin>:1:27: warning: unused parameter ‘argv’ [-Wunused-parameter]

(Note that forcing the -fdiagnostics-show-caret option doesn't change anything)

I would have expected the same output as when the file is passed to gcc as an
argument:

$ gcc -Wall -Wextra test.c
test.c: In function ‘main’:
test.c:1:14: warning: unused parameter ‘argc’ [-Wunused-parameter]
    1 | int main(int argc, char **argv)
      |          ~~~~^~~~
test.c:1:27: warning: unused parameter ‘argv’ [-Wunused-parameter]
    1 | int main(int argc, char **argv)
      |                    ~~~~~~~^~~~

[Bug middle-end/99608] gcc doesn't print diagnostics carets when file is passed through stdin

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99608

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
          Component|driver                      |middle-end
         Resolution|---                         |WONTFIX

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is done on purpose.  It is based on the original file, rather than the
preprocessed source or otherwise.  With stdin, there is no original file being
referenced.

[Bug middle-end/99608] gcc doesn't print diagnostics carets when file is passed through stdin

[freezer at posteo dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99608

--- Comment #2 from freezer at posteo dot de ---
That's too bad. For my use case it would be more efficient if I passed the file
directly to gcc through stdin. There is really no way to change this, maybe
through an option?

With clang this works as expected. The same diagnostics are printed independent
of whether the file was passed through stdin or as a command-line argument.

[Bug middle-end/99608] gcc doesn't print diagnostics carets when file is passed through stdin

[freezer at posteo dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99608

--- Comment #3 from freezer at posteo dot de ---
In my opinion the current behavior is somehow inconsistent since the carets are
displayed for included files.

Example:

// test.cpp
#include <coroutine>

int main(int argc, char **argv)
{
    return 0;
}

$ cat test.cpp | g++ -Wall -Wextra -xc++ -
In file included from <stdin>:1:
/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include/g++-v10/coroutine:295:2: error:
#error "the coroutine header requires -fcoroutines"
  295 | #error "the coroutine header requires -fcoroutines"
      |  ^~~~~
<stdin>: In function ‘int main(int, char**)’:
<stdin>:3:14: warning: unused parameter ‘argc’ [-Wunused-parameter]
<stdin>:3:27: warning: unused parameter ‘argv’ [-Wunused-parameter]