Re: [PATCH] gdb/testsuite: dont test dprintf to stderr in gdb.mi/mi-dprintf.exp

[Andrew Burgess <aburgess@redhat.com>]

Bruno Larsen via Gdb-patches <gdb-patches@sourceware.org> writes:

> As mentioned in commit 3f5bbc3e2075ef5061a815c73fdc277218489f22, some
> compilers such as clang don't add debug information about stderr by
> default, leaving it to external debug packages. However, different to
> that commit, there seems to be no simple way to test if stderr is present
> without introducing a failure,

I don't understand what you mean here.  In the previous commit, you just
print stderr and check GDB's reply.  Why no adopt the same approach for
this test?

I revised this test to use this proc:

  # Check for stderr.
  proc mi_gdb_is_stderr_available {} {
      set has_stderr_symbol false
      gdb_test_multiple "-data-evaluate-expression stderr" "stderr symbol check" {
  	-re "\\^error,msg=\"'stderr' has unknown type; cast it to its declared type\"\r\n$::mi_gdb_prompt$" {
  	    # Default value of false is fine.
  	}
  	-re "$::mi_gdb_prompt$" {
  	    set has_stderr_symbol true
  	}
      }
      return $has_stderr_symbol
  }
  
  set has_stderr_symbol [mi_gdb_is_stderr_available]

And then replaced your:

 if ![test_compiler_info clang*]

with:

 if {$::has_stderr_symbol}

And (when testing with Clang) I don't see any failures.

I think, in general, we should avoid as much as possible placing
specific compiler checks into test scripts unless we can make a _really_
strong argument that a special behaviour will _only_ happen for this one
compiler.

In this case, if a compiler check really was the _only_ way to solve
this problem we would still be better off placing the check into a new
proc in lib/*.exp somewhere -- but in this case I don't think that's
necessary, we should be able to check for stderr.

Also, I think the new stderr checking proc should be placed into
lib/mi-support.exp.

Thanks,
Andrew


>                                 so instead this commit just disables
> tests that rely on stderr when clang is detected


> ---
>  gdb/testsuite/gdb.mi/mi-dprintf.exp | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/gdb/testsuite/gdb.mi/mi-dprintf.exp b/gdb/testsuite/gdb.mi/mi-dprintf.exp
> index e40fa6121fa..735f7fc234e 100644
> --- a/gdb/testsuite/gdb.mi/mi-dprintf.exp
> +++ b/gdb/testsuite/gdb.mi/mi-dprintf.exp
> @@ -127,7 +127,6 @@ proc mi_continue_dprintf {args} {
>  mi_continue_dprintf "gdb"
>  
>  # The "call" style depends on having I/O functions available, so test.
> -
>  if ![target_info exists gdb,noinferiorio] {
>  
>      # Now switch styles and rerun; in the absence of redirection the
> @@ -136,9 +135,12 @@ if ![target_info exists gdb,noinferiorio] {
>      mi_gdb_test "set dprintf-style call" ".*" "mi set dprintf style to call"
>      mi_continue_dprintf "call"
>  
> -    mi_gdb_test "set dprintf-function fprintf" ".*" "mi set dprintf-channel stderr"
> -    mi_gdb_test "set dprintf-channel stderr" ".*" "mi set dprintf channel"
> -    mi_continue_dprintf "fprintf"
> +    # Clang does not add information about stderr, so skip these tests if needed.
> +    if ![test_compiler_info clang*] {
> +	mi_gdb_test "set dprintf-function fprintf" ".*" "mi set dprintf-channel stderr"
> +	mi_gdb_test "set dprintf-channel stderr" ".*" "mi set dprintf channel"
> +	mi_continue_dprintf "fprintf"
> +    }
>  }
>  
>  set target_can_dprintf 0
> -- 
> 2.41.0