Feature gate clean
This PR does a bit of cleaning in the feature-gate-handling code of libsyntax. It also fixes two bugs (#32782 and #32648). Changes include:
* Change the way the existing features are declared in `feature_gate.rs`. The array of features and the `Features` struct are now defined together by a single macro. `featureck.py` has been updated accordingly. Note: there are now three different arrays for active, removed and accepted features instead of a single one with a `Status` item to tell wether a feature is active, removed, or accepted. This is mainly due to the way I implemented my macro in the first time and I can switch back to a single array if needed. But an advantage of the way it is now is that when an active feature is used, the parser only searches through the list of active features. It goes through the other arrays only if the feature is not found. I like to think that error checking (in this case, checking that an used feature is active) does not slow down compilation of valid code. :) But this is not very important...
* Feature-gate checking pass now use the `Features` structure instead of looking through a string vector. This should speed them up a bit. The construction of the `Features` struct should be faster too since it is build directly when parsing features instead of calling `has_feature` dozens of times.
* The MacroVisitor pass has been removed, it was mostly useless since the `#[cfg]-stripping` phase happens before (fixes#32648). The features that must actually be checked before expansion are now checked at the time they are used. This also allows us to check attributes that are generated by macro expansion and not visible to MacroVisitor, but are also removed by macro expansion and thus not visible to PostExpansionVisitor either. This fixes#32782. Note that in order for `#[derive_*]` to be feature-gated but still accepted when generated by `#[derive(Trait)]`, I had to do a little bit of trickery with spans that I'm not totally confident into. Please review that part carefully. (It's in `libsyntax_ext/deriving/mod.rs`.)::
Note: this is a [breaking change], since programs with feature-gated attributes on macro-generated macro invocations were not rejected before. For example:
```rust
macro_rules! bar (
() => ()
);
macro_rules! foo (
() => (
#[allow_internal_unstable] //~ ERROR allow_internal_unstable side-steps
bar!();
);
);
```
foo!();
report `const_err` on all expressions that can fail
also a drive-by fix for reporting an "overflow in shift *left*" when shifting an `i64` *right*
This increases the warning noise for shifting by more than the bitwidth and for `-T::MIN`. I can silence the bitwidth warnings explicitly and fix the const evaluator to make sure `--$expr` is treated exactly like `$expr` (which is kinda wrong, but mathematically right).
r? @eddyb
special-case #[derive(Copy, Clone)] with a shallow clone
If a type is Copy then its Clone implementation can be a no-op. Currently `#[derive(Clone)]` generates a deep clone anyway. This can lead to lots of code bloat.
This PR detects the case where Copy and Clone are both being derived (the general case of "is this type Copy" can't be determined by a syntax extension) and generates the shallow Clone impl. Right now this can only be done if there are no type parameters (see https://github.com/rust-lang/rust/issues/31085#issuecomment-178988663), but this restriction can be removed after specialization.
Fixes#31085.
Changes #[derive(Copy, Clone)] to use a faster impl of Clone when
both derives are present, and there are no generics in the type.
The faster impl is simply returning *self (which works because the
type is also Copy). See the comments in libsyntax_ext/deriving/clone.rs
for more details.
There are a few types which are Copy but not Clone, in violation
of the definition of Copy. These include large arrays and tuples. The
very existence of these types is arguably a bug, but in order for this
optimization not to change the applicability of #[derive(Copy, Clone)],
the faster Clone impl also injects calls to a new function,
core::clone::assert_receiver_is_clone, to verify that all members are
actually Clone.
This is not a breaking change, because pursuant to RFC 1521, any type
that implements Copy should not do any observable work in its Clone
impl.
Suppress fallback and ambiguity errors
If the infcx has observed other errors, then suppress both default type
parameter fallback (which can be unreliable, as the full constraint set
is not available) and errors related to unresovled
variables (annoyingly, integer type variables cannot currently be
unified with error, so that has to be a separate mechanism). Also add a
flag to `infcx` to allow us to independently indicate when we have
observed an error and hence should trigger this suppression mode.
Fixes#31997
cc @alexcrichton
r? @arielb1
syntax: Merge PathParsingMode::NoTypesAllowed and PathParsingMode::ImportPrefix
syntax: Rename PathParsingMode and its variants to better express their purpose
syntax: Remove obsolete error message about 'self lifetime
syntax: Remove ALLOW_MODULE_PATHS workaround
syntax/resolve: Adjust some error messages
resolve: Compare unhygienic (not renamed) names with keywords::Invalid, invalid identifiers may appear to be valid after renaming
This pass was supposed to check use of gated features before
`#[cfg]`-stripping but this was not the case since it in fact happens
after. Checks that are actually important and must be done before macro
expansion are now made where the features are actually used. Close#32648.
Also ensure that attributes on macro-generated macro invocations are
checked as well. Close#32782 and #32655.
This uncovered a lot of bugs in compiletest and also some shortcomings
of our existing JSON output. We had to add information to the JSON
output, such as suggested text and macro backtraces. We also had to fix
various bugs in the existing tests.
Joint work with jntrnr.
This commit adds support in rustbuild for running all of the compiletest test
suites as part of `make check`. The `compiletest` program was moved to
`src/tools` (like `rustbook` and others) and is now just compiled like any other
old tool. Each test suite has a pretty standard set of dependencies and just
tweaks various parameters to the final compiletest executable.
Note that full support is lacking in terms of:
* Once a test suite has passed, that's not remembered. When a test suite is
requested to be run, it's always run.
* The arguments to compiletest probably don't work for every possible
combination of platforms and testing environments just yet. There will likely
need to be future updates to tweak various pieces here and there.
* Cross compiled test suites probably don't work just yet, support for that will
come in a follow-up patch.
Implement `pub(restricted)` privacy (RFC 1422)
This implements `pub(restricted)` privacy from RFC 1422 (cc #32409) behind a feature gate.
`pub(restricted)` paths currently cannot use re-exported modules both for simplicity of implementation and for future compatibility with RFC 1560 (cf #31783).
r? @nikomatsakis
Fix macro hygiene bug
This fixes#32922 (EDIT: and fixes#31856), macro hygiene bugs.
It is a [breaking-change]. For example, the following would break:
```rust
fn main() {
let x = true;
macro_rules! foo { () => {
let x = 0;
macro_rules! bar { () => {x} }
let _: bool = bar!();
//^ `bar!()` used to resolve the first `x` (a bool),
//| but will now resolve to the second x (an i32).
}}
foo! {};
}
```
r? @nrc
don't report errors in constants at every use site
partially fixes#32842
r? @arielb1
cc @retep998
I chose this way of implementing it, because the alternative (checking if the error span is inside the constant's expressions's span) would get confusing when combined with expression generating macros.
A next step would be to re-enable the re-reporting of errors if the original erroneous constant is in another crate.
Replace consider_unification_despite_ambiguity with new obligation variant
Is work towards #32730. Addresses part one of #32286. Addresses #24210 and #26046 to some degree.
r? @nikomatsakis
resolve: Improve duplicate glob detection
This fixes a bug introduced in #31726 in which we erroneously allow multiple imports of the same item under some circumstances.
More specifically, we erroneously allow a module that is in a cycle of glob re-exports to have other re-exports (besides the glob from the cycle).
For example,
```rust
pub fn f() {}
mod foo {
pub use f; // (1) This defines `foo::f`.
pub use bar::*; // (3) This also defines `foo::f`, which should be a duplicate error but is currently allowed.
}
mod bar {
pub use foo::*; // (2) This defines `bar::f`.
}
```
A module in a glob re-export cycle can still have `pub` items after this PR. For example,
```rust
mod foo {
pub fn f() {}; // (1) This defines `foo::f`.
pub use bar::*; // (3) This is not a duplicate error since items shadow glob-imported re-exports (cf #31337).
}
mod bar {
pub use foo::*; // (2) This defines `bar::f`.
}
```
r? @nikomatsakis
If the infcx has observed other errors, then suppress both default type
parameter fallback (which can be unreliable, as the full constraint set
is not available) and errors related to unresovled
variables (annoyingly, integer type variables cannot currently be
unified with error, so that has to be a separate mechanism). Also add a
flag to `infcx` to allow us to independently indicate when we have
observed an error and hence should trigger this suppression mode.
This commit rewrites all of the tidy checks we have, namely:
* featureck
* errorck
* tidy
* binaries
into Rust under a new `tidy` tool inside of the `src/tools` directory. This at
the same time deletes all the corresponding Python tidy checks so we can be sure
to only have one source of truth for all the tidy checks.
cc #31590
