Bug 891621 – www-client/firefox-109.0: build fails with ffast-math enabled (error Cannot build libopus with -ffast-math unless FLOAT_APPROX is defined)

• Status: UNCONFIRMED
• Product: Gentoo Linux

[Description Alex Pushkin 2023-01-21 17:06:47 UTC]

Created attachment 848937 [details]
firefox ffast-math error txt

Firefox will not compile with 'ffast-math' enabled on a fresh stage3 snapshot.

Error: error Cannot build libopus with -ffast-math unless FLOAT_APPROX is defined.

I split the build.log file into parts and also added emerge --info at the top. 

File content (line number):
- emerge --info: 1;
- error ffast-math: 78;
- head -1000 build.log: 285;
- tail -1000 build.log: 1292.

[Comment 1 Sam James 2023-01-21 17:08:13 UTC]

So, our options are:
1. Filter it out
2. Add FLOAT_APPROX to CPPFLAGS or similar
3. Add a build system patch and upstream it to Mozilla to pass 2. onto opus automatically when building with Ofast (as Mozilla's build system handles optimisation)

[Comment 2 Joonas Niilola 2023-01-24 12:23:13 UTC]

Can you build media-libs/opus with these settings? I wonder if this is best reported at https://gitlab.xiph.org/xiph/opus/-/issues and then Firefox could ship the upstream-fixed release. Looks like the current version shipped with Firefox is pretty up-to-date, 
https://gitlab.xiph.org/xiph/opus/-/commit/997fdf54e781ae1c04dee42018f35388a04fe483 (version based on this commit).

Well of course it doesn't guarantee -ffast-math will work throughout the build, but at least one down...