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

[Martin Storsjö]

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?

> ---
> 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?

> 	$(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