I believe these tests may have been flaky as a result of the bug fixed
in the previous commit. A big hint is that they were all crashing with
SIGSEGV with no stack trace. I suspect that some lingering SIGIOs from
cancelations were being delivered to a thread after its `munmap` call,
which was happening because the test runner called `Io.Threaded.deinit`
to cause all of the (detached) worker threads to exit.
If this passes, I'll re-run the x86_64-linux CI jobs on this commit a
few times before merge to try and be sure there are no lingering
failures.
Resolves: https://codeberg.org/ziglang/zig/issues/30096
Resolves: https://codeberg.org/ziglang/zig/issues/30592
Resolves: https://codeberg.org/ziglang/zig/issues/30682
As the comment explains, if a signal were to arrive between a detached
thread's `munmap` and `exit` calls, the signal handler would immediately
trigger SIGSEGV due to the stack being unmapped. To solve this, we need
to block all signals before entering this logic. The musl implementation
which this logic was ported from does this exact thing; that logic was
just lost when porting.
Notably, this would lead to a crash with no stack trace, because the
SIGSEGV handler would itself crash due to the missing stack.
It doesn't make any sense for a task to be canceled while it's
panicking.
As a happy accident, this also solves some cases where safety panics in
`Io.Threaded` would cause stack traces not to print due to invalid
thread-local state: when cancelation is blocked, `Io.Threaded` doesn't
consult said thread-local state at all. For instance, try inserting a
panic just after a call to `Syscall.start()` in `Io.Threaded`, and then
call the `Io` function in question from a `concurrent` task. Before this
PR, the stack trace fails to print, because the panic handler sees the
thread-local cancelation state in an unexpected state, leading to a
recursive panic. After this PR, the stack trace prints fine.
There are various reasons why one might want to still create libc-less
compilations on these targets. Case in point: Compiling our bundled crt0 for
OpenBSD.
We will still default to linking libc on these targets, though.
This was removed in 125a9aa82b. But now that our
x86_64-linux machines have had their resources properly allocated, resulting in
runs taking 1-3 hours rather than 4-8, we can add this back.
Remove the RemoveDir step with no replacement. This step had no valid
purpose. Mutating source files? That should be done with
UpdateSourceFiles step. Deleting temporary directories? That required
creating the tmp directories in the configure phase which is broken.
Deleting cached artifacts? That's going to cause problems.
Similarly, remove the `Build.makeTempPath` function. This was used to
create a temporary path in the configure place which, again, is the
wrong place to do it.
Instead, the WriteFile step has been updated with more functionality:
tmp mode: In this mode, the directory will be placed inside "tmp" rather
than "o", and caching will be skipped. During the `make` phase, the step
will always do all the file system operations, and on successful build
completion, the dir will be deleted along with all other tmp
directories. The directory is therefore eligible to be used for
mutations by other steps. `Build.addTempFiles` is introduced to
initialize a WriteFile step with this mode.
mutate mode: The operations will not be performed against a freshly
created directory, but instead act against a temporary directory.
`Build.addMutateFiles` is introduced to initialize a WriteFile step with
this mode.
`Build.tmpPath` is introduced, which is a shortcut for
`Build.addTempFiles` followed by `WriteFile.getDirectory`.
* give Cache a gpa rather than arena because that's what it asks for
