[PATCH for-8.0 00/30] Meson changes for QEMU 8.0

[Paolo Bonzini <pbonzini@redhat.com>]

The final bout of conversions removes the remaining compiler tests
for emulators, applies a few cleanups that are enabled by version 0.63
of Meson, and updates the documentation.

Committing this however requires first a libvirt-ci update, in order to
enable using Python 3.8/3.9 on CentOS 8 and SLES 15.  I am still working
on it but the review can start early for these patches.

A final comparison for the effort has a net negative of around 4000
lines of code, despite the growth of QEMU itself in the meanwhile:

      before                             after
--------------------------------------------------------------------------
 8647 configure                     4240 meson.build
 1296 Makefile                      1970 configure                            
  985 tests/Makefile.include         337 Makefile
  440 rules.mak                      224 scripts/meson-buildoptions.py
  379 scripts/tap-driver.pl          171 tests/Makefile.include
  287 Makefile.target                129 scripts/nsis.py
  263 tests/tcg/configure.sh         113 scripts/mtest2make.py
  129 scripts/create_config           48 scripts/undefsym.py
~5500 various Makefile fragments   ~6500 various meson.build files
--------------------------------------------------------------------------
17926 total                        13732 total

Completing the conversion took roughly two years and a lot of the complexity
in how QEMU is built is indeed essential, but I think it's agreed that:

- the disruption to the developers was minimal, and even Windows only took
  a month or so to solidify;

- there is overall feature parity for both configure/Makefile<->meson and for
  tap-driver.pl<->"meson test", but with fewer bugs and fewer (though not zero)
  workarounds required.  For Meson, the main recurring issue is probably the
  gnutls headers issue on Homebrew; see for example commit 76f67bac79f6,
  "meson: Propagate gnutls dependency to migration", 2021-04-01)

- the original target of the conversion ("make it trivial to do trivial
  things; easy to extend existing things; possible to do everything else")
  has been achieved.  New dependencies such as ninja, were introduced in
  such a way as to make them familiar to shell/Make users, and did
  provide subtle quality of life improvements (e.g. rebuild targets
  on command line changes)

New build system features since the introduction of Meson include switching
to config/targets files, custom device configuration (--with-devices-ARCH=),
the modinfo mechanism for module loading, entitlement support for
Hypervisor.framework, the preinstall tree, autogenerated parsing of the
configure command line, and cross-compilation of pc-bios/ (admittedly
not done by Meson, but not hindered either).

Big thanks to Akihiko, Alex, Daniel, Marc-André, Richard, Thomas and
everybody else that shared the work and the reviews!

Thanks,

Paolo

Paolo Bonzini (30):
  configure: remove useless write_c_skeleton
  configure: remove dead function
  configure: remove useless test
  configure: preserve qemu-ga variables
  configure: remove backwards-compatibility and obsolete options
  meson: tweak hardening options for Windows
  meson: support meson 0.64 -Doptimization=plain
  meson: require 0.63.0
  meson: use prefer_static option
  meson: remove static_kwargs
  meson: cleanup dummy-cpus.c rules
  modinfo: lookup compile_commands.json by object
  configure: remove backwards-compatibility code
  configure: test all warnings
  meson: cleanup compiler detection
  build: move glib detection and workarounds to meson
  configure: remove pkg-config functions
  configure, meson: move --enable-modules to Meson
  configure, meson: move --enable-debug-info to Meson
  meson: prepare move of QEMU_CFLAGS to meson
  build: move sanitizer tests to meson
  build: move SafeStack tests to meson
  build: move coroutine backend selection to meson
  build: move stack protector flag selection to meson
  build: move warning flag selection to meson
  build: move remaining compiler flag tests to meson
  build: move compiler version check to meson
  docs: update build system docs
  configure: do not rerun the tests with -Werror
  meson: always log qemu-iotests verbosely

 accel/meson.build                             |   9 +-
 block/meson.build                             |   1 +
 configure                                     | 760 +-----------------
 contrib/plugins/Makefile                      |   7 +-
 docs/devel/build-system.rst                   | 286 ++++---
 meson                                         |   2 +-
 meson.build                                   | 684 +++++++++++-----
 meson_options.txt                             |  13 +
 plugins/meson.build                           |   2 +-
 qga/meson.build                               |   2 +-
 scripts/meson-buildoptions.py                 |   3 +
 scripts/meson-buildoptions.sh                 |  22 +
 scripts/modinfo-collect.py                    |  23 +-
 tcg/meson.build                               |   2 +-
 tests/qemu-iotests/meson.build                |   3 +-
 tests/unit/meson.build                        |   2 +-
 ...{coroutine-win32.c => coroutine-windows.c} |   0
 util/meson.build                              |   2 +-
 18 files changed, 716 insertions(+), 1107 deletions(-)
 rename util/{coroutine-win32.c => coroutine-windows.c} (100%)

-- 
2.38.1