Override custom Cargo `build-dir` in bootstrap
The context for this issue is in https://github.com/rust-lang/rust/issues/145107. The issue is that if people configure `build-dir`, it would break bootstrap. For now, we just hard-code it to our self-contained target directories inside the build directory.
Tested by putting the following:
```toml
[build]
build-dir = "/tmp/foo"
[unstable]
build-dir = true
```
into `<rustc-checkout>/.cargo/config.toml`. `x build` works with this PR, doesn't work without this PR.
Fixes: https://github.com/rust-lang/rust/issues/145107
[win][arm64ec] Add `/machine:arm64ec` when linking LLVM as Arm64EC
When the MSVC linker sees an Arm64EC object file, it needs to know if it's linking the final executable as Arm64EC or Arm64X.
This change adds the `/machine:arm64ec` flag to the linker when building LLVM as Arm64EC to avoid that ambiguity (and resulting linker error).
Improve error output when a command fails in bootstrap
I fixed this because it was being an issue for debugging CI failures.
We try to print as much information as possible, just with a slightly less verbose command description in non-verbose mode. The code is now more unified and hopefully simpler to understand.
I also fixed the `format_short_cmd` logic, it was a bit weird after some recent refactors.
Fixes: https://github.com/rust-lang/rust/issues/145002
r? `````````@jieyouxu`````````
CC `````````@Shourya742`````````
Simplify polonius location-sensitive analysis
This PR reworks the location-sensitive analysis into what we think is a worthwhile subset of the datalog analysis. A sort of polonius alpha analysis that handles NLL problem case 3 and more, but is still using the faster "reachability as an approximation of liveness", as well as the same loans-in-scope computation as NLLs -- and thus doesn't handle full flow-sensitivity like the datalog implementation.
In the last few months, we've identified this subset as being actionable:
- we believe we can make a stabilizable version of this analysis
- it is an improvement over the status quo
- it can also be modeled in a-mir-formality, or some other formalism, for assurances about soundness, and I believe ````````@nikomatsakis```````` is interested in looking into this during H2.
- and we've identified the areas of work we wish to explore later to gradually expand the supported cases: the differences between reachability and liveness, support of kills, and considerations of time-traveling, for example.
The approach in this PR is to try less to have the graph only represent live paths, by checking whether we reach a live region during traversal and recording the loan as live there, instead of equating traversal with liveness like today because it has subtleties with the typeck edges in statements (that could forward loans to the successor point without ensuring their liveness). We can then also simplify these typeck stmt edges. And we also can simplify traversal by removing looking at kills, because that's enough to handle a bunch of NLL problem 3 cases -- and we can gradually support them more and more in traversal in the future, to reduce the approximation of liveness.
There's still some in-progress pieces of work w/r/t opaque types that I'm expecting [lcnr's opaque types rework](https://github.com/rust-lang/rust/pull/139587), and [amanda's SCCs rework](https://github.com/rust-lang/rust/pull/130227) to handle. That didn't seem to show up in tests until I rebased today (and shows lack of test coverage once again) when https://github.com/rust-lang/rust/pull/142255 introduced a couple of test failures with the new captures rules from edition 2024. It's not unexpected since we know more work is needed with member constraints (and we're not even using SCCs in this prototype yet)
I'll look into these anyways, both for future work, and checking how these other 2 PRs would change things.
---
I'm not sure the following means a lot until we have some formalism in-place, but:
- I've changed the polonius compare-mode to use this analysis: the tests pass with it, except 2 cases with minor diagnostics differences, and the 2 edition 2024 opaque types one I mentioned above and need to investigate
- things that are expected to work still do work: it bootstraps, can run our rustc-perf benchmarks (and the results are not even that bad), and a crater run didn't find any regressions (forgetting that crater currently fails to test around a quarter of all crates 👼)
- I've added tests with improvements, like the NLL problem case 3 and others, as well as some that behave the same as NLLs today and are thus worse than the datalog implementation
r? ````````@jackh726````````
(no rush I know you're deep in phd work and "implmentating" the new trait solver for r-a :p <3)
This also fixesrust-lang/rust#135646, a diagnostics ICE from the previous implementation.
unstable-book: Add stubs for environment variables; document some of the important ones
This uses a very hacky regex that will probably miss some variables. But having some docs seems better than none at all.
In particular, this documents the following env vars explicitly (cc ````````@madsmtm```````` ````````@flba-eb```````` - do the docs for SDKROOT and QNX_TARGET look right?):
- COLORTERM
- QNX_TARGET
- SDKROOT
- TERM
and generates stubs for the following env vars:
- RUST_BACKTRACE
- RUSTC_BLESS
- RUSTC_BREAK_ON_ICE
- RUSTC_CTFE_BACKTRACE
- RUSTC_FORCE_RUSTC_VERSION
- RUSTC_GRAPHVIZ_FONT
- RUSTC_ICE
- RUSTC_LOG
- RUSTC_RETRY_LINKER_ON_SEGFAULT
- RUSTC_TRANSLATION_NO_DEBUG_ASSERT
- RUST_DEP_GRAPH_FILTER
- RUST_DEP_GRAPH
- RUST_FORBID_DEP_GRAPH_EDGE
- RUST_MIN_STACK
- RUST_TARGET_PATH
- UNSTABLE_RUSTDOC_TEST_LINE
- UNSTABLE_RUSTDOC_TEST_PATH
rendered: 
The rustc AST allows both `for<>` binders and `?` polarity
modifiers in trait bounds, but they are parsed in a specific
order and validated for correctness:
1. `for<>` binder is parsed first.
2. Polarity modifiers (`?`, `!`) are parsed second.
3. The parser validates that binders and polarity modifiers
do not conflict:
```rust
if let Some(binder_span) = binder_span {
match modifiers.polarity {
BoundPolarity::Maybe(polarity_span) => {
// Error: "for<...> binder not allowed with ? polarity"
}
}
}
```
This implies:
- `for<> ?Sized` → Valid syntax. Invalid semantics.
- `?for<> Sized` → Invalid syntax.
However, rust-analyzer incorrectly had special-case logic that
allowed `?for<>` as valid syntax. This fix removes that incorrect
special case, making rust-analyzer reject `?for<> Sized` as a
syntax error, matching rustc behavior.
This has caused confusion in other crates (such as syn) which
rely on these files to implement correct syntax evaluation.
Refactor codegen backends in bootstrap
This PR refactors the codegen backend steps, in preparation to make more progress on the integration of the GCC codegen backend in bootstrap. It does several things:
1) Splits the `CodegenBackend` step into two, one for clif and another one for gcc. Even though their code is mostly similar, that's IMO mostly fake similarity, and they do (or will) ultimately require different handling. This was already visible in the requirement of building GCC for cg_gcc, of course.
2) It is now possible to build both backends (and dist cranelift) even if they are not specified in `rust.codegen-backends`. It was quite weird that it wasn't possible to even invoke the corresponding codegen backend if the backend wasn't specified in that array, as that array should ideally only change defaults (see later below).
3) Changes the path specification of these steps to an alias. In other words, instead of `compiler/rustc_codegen_cranelift`, the step is now built only using `rustc_codegen_cranelift` or `cg_clif`. This is done to avoid an annoying clash with `x build compiler`, which would otherwise build both codegen backends after the 2) change.
4) Made the copying of codegen backend artifacts more explicit, in particular in the `Assemble` step.
5) Codifies the semantics of `rust.codegen-backends`, which now only affects the defaults of whether a codegen backend will be included in rustc's sysroot and whether it will be disted in `x dist` by default. We can change the behavior later, e.g. to dist cranelift by default in `x dist` once it becomes stabilized. Currently I left the existing behavior that we use on CI, I just tried to document it better.
I don't think that this requires a change tracker entry, because the defaults should work the same as before. It is just now possible to do `x build/dist rustc_codegen_cranelift` even if CLIF is not in the `codegen-backends` array. It is no longer possible to do `./x build compiler/rustc_codegen_cranelift` though, not sure if that requires a change tracker entry.
There is one thing that I didn't touch yet, and that is the fact that `rust.codegen-backends` not only affects the default behavior of `x dist` w.r.t. Cranelift, but also of `x test`. In other words, `x test rustc_codegen_cranelift` still does not hing if cranelift isn't in `rust.codegen-backends`. I plan to take a look at this once I get to refactoring the test steps.
r? `@jieyouxu`
Fix cross-compilation of Cargo
Regressed in https://github.com/rust-lang/rust/pull/144303. I guess this wasn't seen in other `ToolTarget` tools, because they are more dependent on the compiler and are ~always built together with other stuff that also built the std, while Cargo is relatively self-contained.
Fixes: https://github.com/rust-lang/rust/issues/145059
r? ``@jieyouxu``
update enzyme submodule to handle llvm 21
This currently has a fix / workaround in our local rust-lang/Enzyme fork, which is needed to unblock a few people contributing to std::autodiff. It also permanently disables a component (BCLoader) which we shouldn't need on the rust side, hence saving a bit of compile time and disk space.
Once upstream Enzyme (EnzymeAD/Enzyme) fixed llvm-21 support I'll probably make another pr to drop our local patch.
rustdoc search: prefer stable items in search results
fixes https://github.com/rust-lang/rust/issues/138067
this does add a new field to the search index, but since we're only listing unstable items instead of adding a boolean flag to every item, it should only increase the search index size of sysroot crates, since those are the only ones using the `staged_api` feature, at least as far as the rust project is concerned.
Rollup of 8 pull requests
Successful merges:
- rust-lang/rust#139451 (Add `target_env = "macabi"` and `target_env = "sim"`)
- rust-lang/rust#144039 (Use `tcx.short_string()` in more diagnostics)
- rust-lang/rust#144192 (atomicrmw on pointers: move integer-pointer cast hacks into backend)
- rust-lang/rust#144545 (In rustc_pattern_analysis, put `true` witnesses before `false` witnesses)
- rust-lang/rust#144579 (Implement declarative (`macro_rules!`) attribute macros (RFC 3697))
- rust-lang/rust#144649 (Account for bare tuples and `Pin` methods in field searching logic)
- rust-lang/rust#144775 (more strongly dissuade use of `skip_binder`)
- rust-lang/rust#144987 (Enable f16 and f128 on targets that were fixed in LLVM21)
r? `@ghost`
`@rustbot` modify labels: rollup
Implement declarative (`macro_rules!`) attribute macros (RFC 3697)
This implements [RFC 3697](https://github.com/rust-lang/rust/issues/143547), "Declarative (`macro_rules!`) attribute macros".
I would suggest reading this commit-by-commit. This first introduces the
feature gate, then adds parsing for attribute rules (doing nothing with them),
then adds the ability to look up and apply `macro_rules!` attributes by path,
then adds support for local attributes, then adds a test, and finally makes
various improvements to errors.
atomicrmw on pointers: move integer-pointer cast hacks into backend
Conceptually, we want to have atomic operations on pointers of the form `fn atomic_add(ptr: *mut T, offset: usize, ...)`. However, LLVM does not directly support such operations (https://github.com/llvm/llvm-project/issues/120837), so we have to cast the `offset` to a pointer somewhere.
This PR moves that hack into the LLVM backend, so that the standard library, intrinsic, and Miri all work with the conceptual operation we actually want. Hopefully, one day LLVM will gain a way to represent these operations without integer-pointer casts, and then the hack will disappear entirely.
Cc ```@nikic``` -- this is the best we can do right now, right?
Fixes https://github.com/rust-lang/rust/issues/134617
