Re: [FFmpeg-devel] [PATCH] ffbuild: use response files only if ar accepts them

From: Gyan Doshi <ffmpeg@gyani.pro>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH] ffbuild: use response files only if ar accepts them
Date: Tue, 18 Mar 2025 15:36:55 +0530
Message-ID: <415171ac-e8ca-47f0-a400-4ec7fda4028e@gyani.pro> (raw)
In-Reply-To: <4fdf75a2-dc8a-4dd4-a70a-20937c1f4dec@gyani.pro>

On 2025-03-18 03:34 pm, Gyan Doshi wrote:
>
>
> On 2025-03-18 03:27 pm, Martin Storsjö wrote:
>> On Mon, 17 Mar 2025, Gyan Doshi wrote:
>>
>>>
>>>
>>> On 2025-03-17 09:44 pm, Zhao Zhili wrote:
>>>>
>>>>> On Mar 17, 2025, at 23:16, Gyan Doshi <ffmpeg@gyani.pro> wrote:
>>>>>
>>>>> This is to not break linking with toolchains that don't support 
>>>>> reading
>>>>> args from a 'response file'.
>>>>> ---
>>>>> I've assumed that ld on a system will have same support as ar.
>>>>>
>>>>> configure           | 7 +++++++
>>>>> ffbuild/library.mak | 8 ++++++++
>>>>> 2 files changed, 15 insertions(+)
>>>>>
>>>>> diff --git a/configure b/configure
>>>>> index f6964c4ee1..d84e32196d 100755
>>>>> --- a/configure
>>>>> +++ b/configure
>>>>> @@ -5230,6 +5230,12 @@ else
>>>>>      ar_o='$@'
>>>>> fi
>>>>>
>>>>> +if $ar 2>&1 | grep -qi  "@.*file"; then
>>>>> +    ar_objs="true"
>>>>> +else
>>>>> +    ar_objs=""
>>>>> +fi
>>>> Works for me.
>>>
>>> Good. Let's wait for another report.
>>
>> This unbreaks the build for me on macOS too.
>>
>> As this change did break a fairly major platform, I don't think we 
>> should wait too long to either revert the change, or push the fix.
>>
>> As for the fix - I generally find it more robust to actually _try_ 
>> doing the requested thing (use a response file), than to look for 
>> specific strings in help output.
>>
>> I see that the regex, "@.*file", should be matched by both GNU ar and 
>> llvm-ar, so that's good. But e.g. MS lib.exe also supports response 
>> files, and it doesn't include this pattern in the output. Also MS 
>> lib.exe would certainly be a case where we'd want to use response 
>> files to overcome the command line length limit.
>>
>> So TL;DR, please push this to unbreak platforms like macOS and BSD, 
>> or revert the original change. But I don't find the test entirely ideal.
>
> I'll push this now, and then work on a robust check.

Pushed as 740d4009656abeb006e2d43001b59d875c1a7a6a

Regards,
Gyan

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