There are lots of warnings that become fatal, that are simply unfixable
by the end user. Things like using old versions of software (because
they're using some kind of LTS release), warnings about compilers not
supporting certain kinds of checks, or standards being upgraded due to
skipped implementations (MSVC has c++98 and c++14, but not c++11). None
of these should be fatal, they're informative, and too important to
reduce to notices, but not important enough to stop meson if they're
printed.
Profiling showed that we were spending 25s inside os.path.realpath()
on Windows while generating compile lines for build.ninja, inside
NinjaBackend.generate()
The real path for these will not (should not) change during a single
meson invocation, so cache all these.
Brings build.ninja generation from 73s to 47s on my machine.
Which adds the `use-set-for-membership` check. It's generally faster in
python to use a set with the `in` keyword, because it's a hash check
instead of a linear walk, this is especially true with strings, where
it's actually O(n^2), one loop over the container, and an inner loop of
the strings (as string comparison works by checking that `a[n] == b[n]`,
in a loop).
Also, I'm tired of complaining about this in reviews, let the tools do
it for me :)
Adds a new maximum warning level that is roughly equivalent to "all warnings".
This adds a way to use `/Wall` with MSVC (without the previous broken warning),
`-Weverything` with clang, and almost all general warnings in GCC with
strictness roughly equivalent to clang's `-Weverything`.
The GCC case must be implemented by meson since GCC doesn't provide a similar
option. To avoid maintenance headaches for meson, this warning level is
defined objectively: all warnings are included except those that require
specific values or are specific to particular language revisions. This warning
level is mainly intended for new code, and it is expected (nearly guaranteed)
that projects will need to add some suppressions to build cleanly with it.
More commonly, it's just a handy way to occasionally take a look at what
warnings are present with some compiler, in case anything interesting shows up
you might want to enable in general.
Since the warnings enabled at this level are inherently unstable with respect
to compiler versions, it is intended for use by developers and not to be set as
the default.
-Wnon-virtual-dtor is not what people think of as a standard warning
flag. It was previously removed from -Wall in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=16190 on the grounds that
people didn't like it and were refusing to use -Wall at all because it
forced this warning. Instead, it is enabled by -Weffc++ which is
typically not enabled and even comes with GCC documentation warnings
stating that the standard library doesn't obey it, and you might need to
`grep -v` and filter out warnings. (!!!)
It doesn't fit into the typical semantics of Meson's warning_level
option, which usually aligns with compiler standard warning levels
rather than a niche ideological warning level.
It was originally added in commit 22af56e05a,
but without any specific rationale included, and has gone unquestioned
since then -- except by the Meson users who see it, assume there is a
finely crafted design behind it, and quietly opt out by rolling their own
warning options with `add_project_arguments('-Wall', ...)`.
Furthermore a GCC component maintainer for the C++ standard library
opened a Meson bug report specially to tell us that this warning flag is
a "dumb option" and "broken by design" and "doesn't warn about the right
thing anyway", thus it should not be used. This is a reasonably
authoritative source that maybe, just maybe, this flag... is too
opinionated to force upon Meson users without recourse. It's gone beyond
opinionated and into the realm of compiler vendors seem to think that
the state of the language would be better if the flag did not exist at
all, whether default or not.
Fixes#11096
ccache was used in all command lines but disabled using CCACHE_DISABLE
in Compiler.compile() method. Wrapping invokations still has a cost,
especially on Windows.
With sccache things are even worse because CCACHE_DISABLE was not
respected at all, making configure *extremely* slow on Windows when
sccache is installed.
https://github.com/mesonbuild/meson/pull/9287 changed the `optimization=0`
to pass `-O0` to the compiler. This change is reasonable by itself
but unfortunately, it breaks `buildtype=plain`, which promises
that “no extra build flags are used”.
`buildtype=plain` is important for distros like NixOS,
which manage compiler flags for optimization and hardening
themselves.
Let’s introduce a new optimization level that does nothing
and set it as the default for `buildtype=plain`.
We need to support cases where the library might be called "foo.so" and
therefore we check for exact matches too. But this also allows
`cc.find_library('libfoo')` to find libfoo.so, which is strange and
won't work in many cases. Emit a warning when this happens.
Fixes#10838
We *mostly* just need to do the same thing. Plug in one utility method
to make sanity_check_impl find the right compile args, and plug in
DEVNULL to the test run. It's that simple.
This solves a few inconsistencies. The main one is that fortran never
logged the sanity checks to the Meson debug log, making it hard to
debug.
There's also some interesting quirks we built up in the dedicated
fortran handling. For example:
- in commit 5b109c9ad2 we added cwd to
building the fortran executable, with a wordy comment about how the
compiler has defects. But the clike base has always done that on
general principle anyway, so we would never have had that bug in the
first place.
- in commit d6be7822a0 we added special
deletion of an old "bad existing exe file" just for fortran. Looking
at the PR discussion for this odd requirement, it turns out that the
real problem is mixing WSL and native Windows without deleting the
build directory. This is apparently fortran specific simply because
"contemporary Windows 10 Fortran users" switch between the two?
The actual problem is that this never used .exe as the output name, so
Windows thinks you want to run something other than the thing you
asked to run, because it's not even a Window executable. But... the
common clike handling could have fixed that without needing special
cases.
This used to be fine, until imports were removed from this file. Now a
function annotated as T.NoReturn doesn't actually tell mypy that it
cannot return, though, so we manually do it.
We no longer need these upfront at all, since we now import the ones we
need for the language we are detecting, at the time of actual detection.
This avoids importing 28 files, consisting of just under 9,000 lines of
code, at interpreter startup. Now, it is only imported depending on
which languages are invoked by add_languages, which may not even be
anything. And even if we do end up importing a fair chunk of it for
C/C++ projects, spreading the import cost around the interpreter runtime
helps responsiveness.
Only import the ones we need for the language we are detecting, once we
actually detect that language.
This will allow finally dropping the main imports of these files in a
followup commit.
Instead of comparing against specific compiler classes, check the
logical compiler id or language etc.
In a couple cases, we seem to be missing a couple things by being a bit
too strict about the exact class type.
This is wasteful and generally unneeded, since code can just use the
compiler they detected instead of manually poking at the internals of
this subpackage.
It also avoids importing an absolute ton of code the instant one runs
`from . import compilers`
Gijs Peskens