feat: type inference for generic associated types
This PR implements type inference for generic associated types. Basically, this PR lowers generic arguments for associated types in valid places and creates `Substitution`s for them.
I focused on the inference for correct Rust programs, so there are cases where we *accidentally* manage to infer things that are actually invalid (which would then be reported by flycheck so I deem them non-fatal). See the following tests and FIXME notes on them: `gats_with_dyn`, `gats_with_impl_trait`.
The added tests are rather arbitrary. Let me know if there are cases I'm missing or I should add.
Closes#9673
Remove `commit_if_ok` probe from NLL type relation
It was not really necessary to add the `commit_if_ok` in #100092 -- I added it to protect us against weird inference error messages due to recursive RPIT calls, but we are always on the error path when this happens anyways, and I can't come up with an example that makes this manifest.
Fixes#103599
r? `@oli-obk` since you reviewed #100092, feel free to re-roll.
🅱️📢 beta-nominating this since it's on beta (which forks in ~a week~ two days 😨) -- worst case we could revert the original PR on beta and land this on nightly, to give it some extra soak time...
Add Target Tier Policy notification.
This adds a notification posted to PRs when they add/modify a target spec.
This was hard-coded in highfive. I forgot to include this in https://github.com/rust-lang/rust/pull/103492.
Switch to upstream `positionEncoding`
Closes#13481
This drops support for the custom extension, but that's probably fine.
Draft because it's not tested yet.
fix: Test all generic args for trait when finding matching impl
Addresses https://github.com/rust-lang/rust-analyzer/pull/13463#issuecomment-1287816680
When finding matching impl for a trait method, we've been testing the unifiability of self type. However, there can be multiple impl of a trait for the same type with different generic arguments for the trait. This patch takes it into account and tests the unifiability of all type arguments for the trait (the first being the self type) thus enables rust-analyzer to find the correct impl even in such cases.
Shorten the `lookup_line` code slightly
The `match` looks like it's exactly the same as `checked_sub(1)`, so we might as well see if perf says we can just do that to save a couple lines.
Use ptr::metadata in <[T]>::len implementation
This avoids duplication of ptr::metadata code.
I believe this is acceptable as the previous approach essentially duplicated `ptr::metadata` because back then `rustc_allow_const_fn_unstable` annotation did not exist.
I would like somebody to ping `@rust-lang/wg-const-eval` as the documentation says:
> Always ping `@rust-lang/wg-const-eval` if you are adding more rustc_allow_const_fn_unstable attributes to any const fn.
Upgrade dist-mips*-linux to ubuntu:22.04 + crosstool-ng
These have no change in compatibility, still Linux 4.4 and glibc 2.23.
The main motivation for upgrading is that LLVM 16 will require at least GCC 7.1. Using crosstool-ng lets us choose our own toolchain versions, and then the Ubuntu version doesn't matter so much, just for the host compilation while we cross-compile.
Eliminate 280-byte memset from ReadDir iterator
This guy:
1536ab1b38/library/std/src/sys/unix/fs.rs (L589)
It turns out `libc::dirent64` is quite big—https://docs.rs/libc/0.2.135/libc/struct.dirent64.html. In #103135 this memset accounted for 0.9% of the runtime of iterating a big directory.
Almost none of the big zeroed value is ever used. We memcpy a tiny prefix (19 bytes) into it, and then read just 9 bytes (`d_ino` and `d_type`) back out. We can read exactly those 9 bytes we need directly from the original entry_ptr instead.
## History
This code got added in #93459 and tweaked in #94272 and #94750.
Prior to #93459, there was no memset but a full 280 bytes were being copied from the entry_ptr.
<table><tr><td>copy 280 bytes</td></tr></table>
This was not legal because not all of those bytes might be initialized, or even allocated, depending on the length of the directory entry's name, leading to a segfault. That PR fixed the segfault by creating a new zeroed dirent64 and copying just the guaranteed initialized prefix into it.
<table><tr><td>memset 280 bytes</td><td>copy 19 bytes</td></tr></table>
However this was still buggy because it used `addr_of!((*entry_ptr).d_name)`, which is considered UB by Miri in the case that the full extent of entry_ptr is not in bounds of the same allocation. (Arguably this shouldn't be a requirement, but here we are.)
The UB got fixed by #94272 by replacing `addr_of` with some pointer manipulation based on `offset_from`, but still fundamentally the same operation.
<table><tr><td>memset 280 bytes</td><td>copy 19 bytes</td></tr></table>
Then #94750 noticed that only 9 of those 19 bytes were even being used, so we could pick out only those 9 to put in the ReadDir value.
<table><tr><td>memset 280 bytes</td><td>copy 19 bytes</td><td>copy 9 bytes</td></tr></table>
After my PR we just grab the 9 needed bytes directly from entry_ptr.
<table><tr><td>copy 9 bytes</td></tr></table>
The resulting code is more complex but I believe still worthwhile to land for the following reason. This is an extremely straightforward thing to accomplish in C and clearly libc assumes that; literally just `entry_ptr->d_name`. The extra work in comparison to accomplish it in Rust is not an example of any actual safety being provided by Rust. I believe it's useful to have uncovered that and think about what could be done in the standard library or language to support this obvious operation better.
## References
- https://man7.org/linux/man-pages/man3/readdir.3.html
Implement invocation location config
This allows setting the working directory for build-scripts on flycheck
Complements https://github.com/rust-lang/rust-analyzer/pull/13128
This will be followed up by one more PR that adds a few simple interpolation vars for `overrideCommand`, with that we should cover the needs for most build systems I believe.
Support const generics for builtin derive macro
Fixes#13121
We have been treating every generic parameter as type parameter during builtin derive macro expansion. This patch adds support for const generics in such expansions.
