Date: Thu, 20 Feb 2020 17:20:45 +0000
To: ~alpine/devel@lists.alpinelinux.org
From: Rasmus Thomsen <oss@cogitri.dev>
Reply-To: Rasmus Thomsen <oss@cogitri.dev>
Subject: Using buildtypes that respect our C{,PP,XX}FLAGS in CMake and Meson
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Hello list,

due to we've noticed that most aports use the RelWithDebInfo or Release
buildtype for CMake or the meson equivalents debugoptimized or release,
which overwrite the C{,PP,XX}FLAGS set by abuild. E.g. meson can add
-O2 or even -O3 to release builds and many upstreams add additional
flags to their release builds they deem increase performance. As such
we should switch to the None buildtype for CMake and for Meson to the
plain buildtype, so that no additional flags are added to our aports.

To make the impact of this clear, here's a comparison between
CMAKE_BUILD_TYPE=3DRelWithDebInfo and CMAKE_BUILD_TYPE=3DNone for attica:

attica-5.67.0-r0 installed size:
823296

attica-5.67.0-r1 installed size:
823296

attica-5.67.0-r2 installed size:
589824

-r0 is compiled with RelWithDebInfo and the flags the builders use, -r1
is compiled with None and CFLAGS set to -O2 in abuild.conf and -r2 is
compile with None and the default flags of abuild (-Os -fomit-frame-
pointer).

Similiar (although not as drastic, but maybe that's just on libtracker
vs attica) differences can be seen with meson (using the same flags as
above):

libtracker-2.3.2-r0 installed size:
5718016

libtracker-2.3.2-r1 installed size:
5713920

libtracker-2.3.2-r2 installed size:
4911104

As such I'd suggest multiple steps to be taken:

1) Change existing aports over to the None/plain buildtype to make sure
this doesn't break anything (we'll probably use some performance but
get smaller packages due to our CFLAGS, but that's the goal here, I
suppose)

2) Change Alpine policy to only use the None/plain buildtype.
Additionally, the buildtype _must be_ mentioned, since at least Meson
defaults to 'debug' if no buildtype is specified.

3) Change newapkbuild so that new aports use the correct buildtype (
https://gitlab.alpinelinux.org/alpine/abuild/merge_requests/29)

Thanks,

Rasmus Thomsen