Re: [FFmpeg-devel] [PATCH 1/2] ffbuild: compose linker response files in a loop

[Gyan Doshi <ffmpeg@gyani.pro>]

On 2025-03-22 03:29 am, Martin Storsjö wrote:
> On Fri, 21 Mar 2025, Gyan Doshi wrote:
>
>> Avoids echo failing due to the same ARG_MAX limit that prompted
>> response files to be used with the linker.
>
> I presume this is only a fix for a hypothetical issue, _if_ echo would 
> be a native windows executable and not the msys2/cygwin one which 
> bypasses the limit?

Yes, trying to address edge cases.

>
>> ---
>> ffbuild/library.mak | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/ffbuild/library.mak b/ffbuild/library.mak
>> index 7e1871b74c..15302852ec 100644
>> --- a/ffbuild/library.mak
>> +++ b/ffbuild/library.mak
>> @@ -36,7 +36,8 @@ endif
>> $(SUBDIR)$(LIBNAME): $(OBJS) $(STLIBOBJS)
>>     $(RM) $@
>> ifeq ($(AR_OBJS),true)
>> -    $(Q)echo $^ > $@.objs
>> +    -$(RM) $@.objs
>> +    $(Q)$(foreach ARG,$^,echo -n "$(ARG) " >> $@.objs;)
>
> Does this instance even work, it looks broken, like it is missing 
> something?

Tested both static and shared building. All working with no noticeable 
speed difference although I didn't formally bench.

Regards,
Gyan


>
>>     $(AR) $(ARFLAGS) $(AR_O) @$@.objs
>> else
>>     $(AR) $(ARFLAGS) $(AR_O) $^
>> @@ -73,7 +74,9 @@ $(SUBDIR)$(SLIBNAME): $(SUBDIR)$(SLIBNAME_WITH_MAJOR)
>> $(SUBDIR)$(SLIBNAME_WITH_MAJOR): $(OBJS) $(SHLIBOBJS) $(SLIBOBJS) 
>> $(SUBDIR)lib$(NAME).ver
>>     $(SLIB_CREATE_DEF_CMD)
>> ifeq ($(AR_OBJS),true)
>> -    $(Q)echo $$(filter %.o,$$^) > $$@.objs
>> +    -$(RM) $$@.objs
>> +    $(Q)$(eval LDARGS=$$(filter %.o,$$^))
>> +    $(Q)$(foreach ARG,$$(LDARGS),echo -n "$(ARG) " >> $$@.objs;)
>
> Wouldn't this be quite significantly slow on msys2, where process 
> creation is much slower than on unix? I think it's not worth to make 
> things that much slower (which I only guess here) to fix a 
> hypothetical issue.
>
> // Martin
>
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