Re: [PATCH] configure: Fix error message when C compiler is not working

[Thomas Huth <thuth@redhat.com>]

On 08/03/2024 12.26, Peter Maydell wrote:
> On Fri, 8 Mar 2024 at 06:01, Thomas Huth <thuth@redhat.com> wrote:
>>
>> If you try to run the configure script on a system without a working
>> C compiler, you get a very misleading error message:
>>
>>   ERROR: Unrecognized host OS (uname -s reports 'Linux')
>>
>> We should rather tell the user that we were not able to use the C
>> compiler instead, otherwise they will have a hard time to figure
>> out what was going wrong.
>>
>> Fixes: 264b803721 ("configure: remove compiler sanity check")
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   configure | 12 +++++++-----
>>   1 file changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/configure b/configure
>> index 3cd736b139..a036923dee 100755
>> --- a/configure
>> +++ b/configure
>> @@ -411,7 +411,7 @@ else
>>     # Using uname is really broken, but it is just a fallback for architectures
>>     # that are going to use TCI anyway
>>     cpu=$(uname -m)
>> -  echo "WARNING: unrecognized host CPU, proceeding with 'uname -m' output '$cpu'"
>> +  echo "WARNING: could not determine host CPU, proceeding with 'uname -m' output '$cpu'"
>>   fi
>>
>>   # Normalise host CPU name to the values used by Meson cross files and in source
>> @@ -1000,10 +1000,12 @@ if test -z "$ninja"; then
>>   fi
>>
>>   if test "$host_os" = "bogus"; then
>> -    # Now that we know that we're not printing the help and that
>> -    # the compiler works (so the results of the check_defines we used
>> -    # to identify the OS are reliable), if we didn't recognize the
>> -    # host OS we should stop now.
>> +    # Now that we know that we're not printing the help, we should stop now
>> +    # if we didn't recognize the host OS (or the C compiler is not working).
>> +    write_c_skeleton;
>> +    if ! compile_object ; then
>> +        error_exit "C compiler \"$cc\" is not usable"
>> +    fi
>>       error_exit "Unrecognized host OS (uname -s reports '$(uname -s)')"
>>   fi
> 
> Why doesn't it work to check the C compiler works before we
> do the "what is the host CPU" test ? Does that make the
> --help output not work when there's no C compiler?

Right, that's the problem: --help would not work when there is no working C 
compiler.

  Thomas