Michael Haubenwallner <michael.haubenwallner@ssi-schaefer.com> writes:

> On 08/23/2017 11:24 PM, Mathieu Lirzin wrote:
>> Michael Haubenwallner <michael.haubenwallner@ssi-schaefer.com> writes:
>>> On 08/22/2017 12:40 AM, Mathieu Lirzin wrote:
>>>> Michael Haubenwallner <michael.haubenwallner@ssi-schaefer.com> writes:
>>>>
>>>>>        # If LTLIBOBJS is used, we must also clear LIBOBJS (which might
>>>>>        # be created by libtool as a side-effect of creating LTLIBOBJS).
>>>>> -      $clean_files{"\$($var)"} = MOSTLY_CLEAN if $var =~ s/^LT//;
>>>>> +      if ($var =~ s/^LT//) {
>>>>> +	$clean_files{"\$($var)"} = MOSTLY_CLEAN;
>>>>> +	$output_rules .= "\$($var): $dirstamp\n" if ($dirstamp);
>>>>> +      }
>>>>>      }
>>>>>  
>>>>>    return $dir;
>>>
>> 
>> Regarding that part of the code even before you made it seems to me that
>> the conditional second '$clean_files{"\$($var)"} = MOSTLY_CLEAN'
>> statement is useless. Am I overlooking something?
> It took a while for me too to understand what's going on here:
>
> Consider $var = 'LTLIBOBJS';
>
>> Here is the snippet of the code before your changed.
>> 
>> --8<---------------cut here---------------start------------->8---
>> 	  define_variable ('LIBOBJDIR', "$dir", INTERNAL);
>> 	  $clean_files{"\$($var)"} = MOSTLY_CLEAN;
>
> here, unconditionally: $clean_files{'$(LTLIBOBJS)'} = MOSTLY_CLEAN;
>
>> 	  # If LTLIBOBJS is used, we must also clear LIBOBJS (which might
>> 	  # be created by libtool as a side-effect of creating LTLIBOBJS).
>> 	  $clean_files{"\$($var)"} = MOSTLY_CLEAN if $var =~ s/^LT//;
>
> Crucial here is that trailing { if $var =~ s/^LT// }:
> First, leading 'LT' eventually is dropped: $var = 'LIBOBJS';
> If the leading 'LT' was actually found: $clean_files{'LIBOBJS'} = MOSTLY_CLEAN;

I overlooked the regexp substitution.  This code is too complex for what it
achieves.  I have pushed the following patch in commit
5521219348c55af354878583b99c5f9d66d6d38a