Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

importlib.metadata is just as good as distlib.database and a bit more
battle-proven for "egg" based distributions, and in fact that is exactly
why mkvenv.py is not using distlib.database to find entry points: it
simply does not work for eggs.

The only disadvantage of importlib.metadata is that it is not available
by default before Python 3.8, so we need a fallback to pkg_resources
(again, just like for the case of finding entry points).  Do so to
fix issues where incorrect egg metadata results in a JSONDecodeError.

While at it, reuse the new _get_version function to diagnose an incorrect
version of the package even if importlib.metadata is not available.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Do not use the rule in build.ninja, because the path to meson is hardcoded
in build.ninja and this breaks if meson moves (for example if the distro
meson suddenly becomes too old after an update).

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reintroduce the cmd_line.txt mangling to remove the sphinx_build option
when rerunning meson.  The mechanism was removed in commit 75cc286
("configure: remove backwards-compatibility code", 2023-01-11) because
the fixups were obsolete at the time; however, the Meson deprecation
mechanism doesn't quite work when options are finally removed, so we
need to bring it back.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

If sphinx is present but the theme is not, mkvenv will print an
inaccurate diagnostic:

ERROR: Could not find a version that satisfies the requirement sphinx-rtd-theme>=0.5.0 (from versions: none)
ERROR: No matching distribution found for sphinx-rtd-theme>=0.5.0

'sphinx>=1.6.0' not found:
 • Python package 'sphinx' version '5.3.0' was found, but isn't suitable.
 • mkvenv was configured to operate offline and did not check PyPI.

Instead, ignore the packages that were found to be present, and report
an error based on the first absent package.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Since custom runners are not generally available, make it possible to
debug the differences between a successful and a failing build by
comparing the logs and the build.ninja rules.

Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Some scripts are invoked via the first "python3" binary in the PATH,
because they are executable and their shebang line is "#! /usr/bin/env
python3".  To enforce usage of $(PYTHON), make them nonexecutable.
Scripts invoked via meson need nothing else, and meson-buildoptions.py
is already using $(PYTHON).  For probe-gdb-support.py however the
invocation in the configure script has to be adjusted.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

…to staging

Fixes for Python venv changes

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* tag 'for-upstream-urgent' of https://gitlab.com/bonzini/qemu:
  scripts: make sure scripts are invoked via $(PYTHON)
  gitlab: custom-runners: preserve more artifacts for debugging
  mkvenv: pass first missing package to diagnose()
  configure: fix backwards-compatibility for meson sphinx_build option
  build: rebuild build.ninja using "meson setup --reconfigure"
  mkvenv: replace distlib.database with importlib.metadata/pkg_resources
  remove remaining traces of meson submodule

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>