rustc_ast currently has a few dependencies on rustc_lexer. Ideally, an AST
would not have any dependency its lexer, for minimizing unnecessarily
design-time dependencies. Breaking this dependency would also have practical
benefits, since modifying rustc_lexer would not trigger a rebuild of rustc_ast.
This commit does not remove the rustc_ast --> rustc_lexer dependency,
but it does remove one of the sources of this dependency, which is the
code that handles fuzzy matching between symbol names for making suggestions
in diagnostics. Since that code depends only on Symbol, it is easy to move
it to rustc_span. It might even be best to move it to a separate crate,
since other tools such as Cargo use the same algorithm, and have simply
contain a duplicate of the code.
This changes the signature of find_best_match_for_name so that it is no
longer generic over its input. I checked the optimized binaries, and this
function was duplicated at nearly every call site, because most call sites
used short-lived iterator chains, generic over Map and such. But there's
no good reason for a function like this to be generic, since all it does
is immediately convert the generic input (the Iterator impl) to a concrete
Vec<Symbol>. This has all of the costs of generics (duplicated method bodies)
with no benefit.
Changing find_best_match_for_name to be non-generic removed about 10KB of
code from the optimized binary. I know it's a drop in the bucket, but we have
to start reducing binary size, and beginning to tame over-use of generics
is part of that.
Add note to use nightly when using expr in const generics
As recommended by `@Icnr` in #73899 and in zulip, I've added a note saying that const expressions can be used in nightly.
```
error: generic parameters may not be used in const operations
--> $DIR/issue-61935.rs:10:23
|
6 | Self:FooImpl<{N==0}>
| ^ cannot perform const operation using `N`
|
= help: const parameters may only be used as standalone arguments, i.e. `N`
= note: use feature(const_generics) and feature(const_evaluatable_checked) to enable this
error: aborting due to previous error
```
I hope the note is well written 😅
resolve: Do not put macros into `module.unexpanded_invocations` unless necessary
Macro invocations in modules <sup>(*)</sup> need to be tracked because they can produce named items when expanded.
We cannot give definite answer to queries like "does this module declare name `n`?" until all macro calls in that module are expanded.
Previously we marked too many macros as potentially producing named items.
E.g. in this example
```rust
mod m {
const C: u32 = line!();
}
```
`line!()` cannot emit any items into module `m`, but it was still marked.
This PR fixes that and marks macro calls as "unexpanded in module" only if they can actually emit named items into that module.
Diagnostics in UI test outputs have different order now because this change affects macro expansion order.
<sup>*</sup> Any containers for named items are called modules in resolve (that includes blocks, traits and enums in addition to `mod` items).
const_generics: assert resolve hack causes an error
prevent the min_const_generics `HACK`s in resolve from triggering a fallback path which successfully compiles so that we don't have to worry about future compat issues when removing it
r? `@eddyb` cc `@varkor`
Allow making `RUSTC_BOOTSTRAP` conditional on the crate name
Motivation: This came up in the [Zulip stream](https://rust-lang.zulipchat.com/#narrow/stream/233931-t-compiler.2Fmajor-changes/topic/Require.20users.20to.20confirm.20they.20know.20RUSTC_.E2.80.A6.20compiler-team.23350/near/208403962) for https://github.com/rust-lang/compiler-team/issues/350.
See also https://github.com/rust-lang/cargo/pull/6608#issuecomment-458546258; this implements https://github.com/rust-lang/cargo/issues/6627.
The goal is for this to eventually allow prohibiting setting `RUSTC_BOOTSTRAP` in build.rs (https://github.com/rust-lang/cargo/issues/7088).
## User-facing changes
- `RUSTC_BOOTSTRAP=1` still works; there is no current plan to remove this.
- Things like `RUSTC_BOOTSTRAP=0` no longer activate nightly features. In practice this shouldn't be a big deal, since `RUSTC_BOOTSTRAP` is the opposite of stable and everyone uses `RUSTC_BOOTSTRAP=1` anyway.
- `RUSTC_BOOTSTRAP=x` will enable nightly features only for crate `x`.
- `RUSTC_BOOTSTRAP=x,y` will enable nightly features only for crates `x` and `y`.
## Implementation changes
The main change is that `UnstableOptions::from_environment` now requires
an (optional) crate name. If the crate name is unknown (`None`), then the new feature is not available and you still have to use `RUSTC_BOOTSTRAP=1`. In practice this means the feature is only available for `--crate-name`, not for `#![crate_name]`; I'm interested in supporting the second but I'm not sure how.
Other major changes:
- Added `Session::is_nightly_build()`, which uses the `crate_name` of
the session
- Added `nightly_options::match_is_nightly_build`, a convenience method
for looking up `--crate-name` from CLI arguments.
`Session::is_nightly_build()`should be preferred where possible, since
it will take into account `#![crate_name]` (I think).
- Added `unstable_features` to `rustdoc::RenderOptions`
I'm not sure whether this counts as T-compiler or T-lang; _technically_ RUSTC_BOOTSTRAP is an implementation detail, but it's been used so much it seems like this counts as a language change too.
r? `@joshtriplett`
cc `@Mark-Simulacrum` `@hsivonen`
rustc_resolve: Use `#![feature(format_args_capture)]`
This is the best new sugar for quite some time.
(I only changed places that already used named arguments.)
The main change is that `UnstableOptions::from_environment` now requires
an (optional) crate name. If the crate name is unknown (`None`), then the new feature is not available and you still have to use `RUSTC_BOOTSTRAP=1`. In practice this means the feature is only available for `--crate-name`, not for `#![crate_name]`; I'm interested in supporting the second but I'm not sure how.
Other major changes:
- Added `Session::is_nightly_build()`, which uses the `crate_name` of
the session
- Added `nightly_options::match_is_nightly_build`, a convenience method
for looking up `--crate-name` from CLI arguments.
`Session::is_nightly_build()`should be preferred where possible, since
it will take into account `#![crate_name]` (I think).
- Added `unstable_features` to `rustdoc::RenderOptions`
There is a user-facing change here: things like `RUSTC_BOOTSTRAP=0` no
longer active nightly features. In practice this shouldn't be a big
deal, since `RUSTC_BOOTSTRAP` is the opposite of stable and everyone
uses `RUSTC_BOOTSTRAP=1` anyway.
- Add tests
Check against `Cheat`, not whether nightly features are allowed.
Nightly features are always allowed on the nightly channel.
- Only call `is_nightly_build()` once within a function
- Use booleans consistently for rustc_incremental
Sessions can't be passed through threads, so `read_file` couldn't take a
session. To be consistent, also take a boolean in `write_file_header`.
Suggest calling associated `fn` inside `trait`s
When calling a function that doesn't exist inside of a trait's
associated `fn`, and another associated `fn` in that trait has that
name, suggest calling it with the appropriate fully-qualified path.
Expand the label to be more descriptive.
Prompted by the following user experience:
https://users.rust-lang.org/t/cannot-find-function/50663
[resolve] Use `unwrap_or_else` instead of `unwrap_or` in a hot path
This improves the performance of the `resolve_crate` function by 30% for
a very large single file crate with auto-generated C bindings.
cc `@rylev`
min_const_generics: allow ty param in repeat expr
implements https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/repeat.20expressions
Even with `min_const_generics` active, now keeps resulting in future compat warnings instead of hard errors.
Const parameters, for example `[0; N + 1]`, still result in hard errors during resolve.
```rust
#![allow(dead_code)]
fn foo<T>() {
[0; std::mem::size_of::<*mut T>()];
}
struct Foo<T>(T);
impl<T> Foo<T> {
const ASSOC: usize = 4;
fn test() {
[0; Self::ASSOC];
}
}
```
r? @varkor cc @petrochenkov
When calling a function that doesn't exist inside of a trait's
associated `fn`, and another associated `fn` in that trait has that
name, suggest calling it with the appropriate fully-qualified path.
Expand the label to be more descriptive.
Prompted by the following user experience:
https://users.rust-lang.org/t/cannot-find-function/50663
This commit improves the diagnostic emitted when a tuple struct is being
constructed which has private fields so that private fields are
labelled and the message is improved.
Signed-off-by: David Wood <david@davidtw.co>
Compute proper module parent during resolution
Fixes#75982
The direct parent of a module may not be a module
(e.g. `const _: () = { #[path = "foo.rs"] mod foo; };`).
To find the parent of a module for purposes of resolution, we need to
walk up the tree until we hit a module or a crate root.
fix def collector for impl trait
fixes#77329
We now consistently make `impl Trait` a hir owner, requiring some special casing for synthetic generic params.
r? `@eddyb`
Fixes#75982
The direct parent of a module may not be a module
(e.g. `const _: () = { #[path = "foo.rs"] mod foo; };`).
To find the parent of a module for purposes of resolution, we need to
walk up the tree until we hit a module or a crate root.
Use `DroplessArena` where we know the type doesn't need drop
This PR uses a single `DroplessArena` in resolve instead of three separate `TypedArena`s.
`DroplessArena` checks that the type indeed doesn't need drop, so in case the types change, this will result in visible failures.
Suggest correct place to add `self` parameter when inside closure
It would incorrectly suggest adding it as a parameter to the closure instead of the containing function.
[For example](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=1936bcd1e5f981573386e0cee985c3c0):
```
help: add a `self` receiver parameter to make the associated `fn` a method
|
5 | let _ = || self&self;
| ^^^^^
```
`DiagnosticMetadata.current_function` is only used for these messages so tweaking its behavior should be ok.
resolve: further improvements to "try using the enum's variant" diagnostic
Follow-up on https://github.com/rust-lang/rust/pull/77341#issuecomment-702738281.
This PR improves the diagnostic modified in #77341 to suggest not only those variants which do not have fields, but those with fields (by suggesting with placeholders). In addition, the wording of the tuple-variant-only case is improved slightly.
I've not made further changes to the tuple-variant-only case (e.g. to only suggest variants with the correct number of fields) because I don't think I have enough information to do so reliably (e.g. in the case where there is an attempt to construct a tuple variant, I have no information on how many fields were provided; and in the case of pattern matching, I only have a slice of spans and would need to check for things like `..` in those spans, which doesn't seem worth it).
r? @estebank
