It is used in the case where a variable-length slice pattern is used to
match on an array of known size. This allows considering only those
entries in the array that are captured by one of the patterns.
As a side-effect, diagnostics improve a bit for those cases.
These helpers are resolved before their respective derives through a kind of look ahead into future expansions.
Some of these will migrate to proper resolution, others will be deprecated.
```
#[trait_helper] // Deprecate
#[derive(Trait)]
#[trait_helper] // Migrate to proper resolution
```
Update cc, git2, num_cpus.
This updates the `cc` crate, bringing in better parallel building support. Also updates `git2` which enables the parallel feature. (Note: I don't expect it will have a significant impact on build time, but seems good to update anyways.)
The main thorn is that `cc` gained knowledge about RISC-V architectures (https://github.com/alexcrichton/cc-rs/pull/428, https://github.com/alexcrichton/cc-rs/pull/429, https://github.com/alexcrichton/cc-rs/pull/430), but the builders on CI do not have the riscv C compiler installed. This means that bootstraps' cc detection was finding a C compiler that isn't installed, and fails.
The solution here is to override the cc detection to `false`. The C compiler isn't actually used on riscv platforms. AFAIK, the only location would be compiler_builtins, and it currently forces C support off (a533ae9c5a/build.rs (L49-L55)).
Other possible solutions:
- Add the override in cc_detect for riscv (or any "no-C" platform like wasm32 and nvptx)
- Install and use the appropriate c compiler. I tried this the `g++-riscv64-linux-gnu` package, but it failed missing some header file.
Closes#66232
Rollup of 5 pull requests
Successful merges:
- #66350 (protect creation of destructors by a mutex)
- #66407 (Add more tests for fixed ICEs)
- #66415 (Add --force-run-in-process unstable option to libtest)
- #66427 (Move the JSON error emitter to librustc_errors)
- #66441 (libpanic_unwind for Miri: make sure we have the SEH lang items when needed)
Failed merges:
r? @ghost
Refactor integer range handling in the usefulness algorithm
Integer range handling had accumulated a lot of debt. This cleans up a lot of it.
In particular this:
- removes unnecessary conversions between `Const` and `u128`, and between `Constructor` and `IntRange`
- clearly distinguishes between on the one hand ranges of integers that may or may not be matched exhaustively, and on the other hand ranges of non-integers that are never matched exhaustively and are compared using Const-based shenanigans
- cleans up some overly complicated code paths
- generally tries to be more idiomatic.
As a nice side-effect, I measured a 10% perf increase on `unicode_normalization`.
There's one thing that I feel remains to clean up: the [overlapping range check](https://github.com/rust-lang/rust/pull/64007), which is currently quite ad-hoc. But that is intricate enough that I'm leaving it out of this PR.
There's also one little thing I'm not sure I understand: can `try_eval_bits` fail for an integer constant value in that code ? What would that mean, and how do I construct a test case for this possibility ?
Now `mir_const_qualif` must be called for `static`s and `const fn`s as
well as `const`s since it is responsible for const-checking. We return
the qualifs in the return place for everything, even though they will
only be used for `const`s.
Unlike the original pass, we check *every* non-cleanup basic block
instead of stopping at `SwitchInt`. We use the `is_cfg_cyclic` function
to check for loops unlike the original checker which could not differentiate
between true cycles and basic blocks with more than two predecessors.
The last three functions are all copied verbatim from `qualify_consts`.
libpanic_unwind for Miri: make sure we have the SEH lang items when needed
r? @oli-obk @alexcrichton This is required to fix the Miri toolstate. Turns out rustc complains when doing codegen for MSVC and these lang items do not exist. For now `cfg(miri)` needs to still be able to codegen (we [plan to change that](https://github.com/rust-lang/miri/pull/1048#issuecomment-554108470) but that's a larger project requiring improvements to xargo and maybe also cargo; that should not block fixing the toolstate). Yes, this is a hack, but it is inside `cfg(miri)` so I hope this is okay.
Cc @Aaron1011
Move the JSON error emitter to librustc_errors
This is done both as a cleanup (it makes little sense for this emitter to be in libsyntax), but also as part of broader work to decouple Session from librustc itself.
Along the way, this also moves SourceMap to syntax_pos, which is also nice for the above reasons, as well as allowing dropping the SourceMapper trait from code. This had the unfortunate side-effect of moving `FatalError` to rustc_data_structures (it's needed in syntax_pos, due to SourceMap, but putting it there feels somehow worse).
Add --force-run-in-process unstable option to libtest
When running tests with `-Zpanic_abort_tests`, it's sometimes desirable to fall back to the old behavior of only running tests in-process. This comes in handy if the system process launcher is unavailable, or the test code somehow expects all tests to be run in the same process.
For example, in Fuchsia we have unit tests that actually test the process launcher itself, in which case we can't use the process launcher to run the tests :).
r? @alexcrichton
cc @cramertj,@petrhosek
Add more tests for fixed ICEs
Closes#36122 (fixed in 1.20.0)
Closes#58094 (fixed in #66054)
Also, fix mistaken test case, from #30904 to #30906 (cc @eddyb)
r? @Centril
