rustc: Separately feature gate repr(i128)
Brought up during the discussion of #35118, the support for this is still
somewhat buggy and so stabilization likely wants to be considered independently
of the type itself.
Brought up during the discussion of #35118, the support for this is still
somewhat buggy and so stabilization likely wants to be considered independently
of the type itself.
feature error span on attribute for fn_must_use, SIMD/align reprs, macro reëxport
There were several feature-gated attributes for which the feature-not-available
error spans would point to the item annotated with the gated attribute, when it
would make more sense for the span to point to the attribute itself: if the
attribute is removed, the function/struct/_&c._ likely still makes sense and the
program will compile. (Note that we decline to make the analogous change for
the `main`, `start`, and `plugin_registrar` features, for in those cases it
makes sense for the span to implicate the entire function, of which there is
little hope of using without the gated attribute.)
There were several feature-gated attributes for which the
feature-not-available error spans would point to the item annotated with
the gated attribute, when it would make more sense for the span to point
to the attribute itself: if the attribute is removed, the
function/struct/&c. likely still makes sense and the program will
compile. (Note that we decline to make the analogous change for the
`main`, `start`, and `plugin_registrar` features, for in those cases it
makes sense for the span to implicate the entire function, of which
there is little hope of using without the gated attribute.)
Before `#[must_use]` for functions was implemented, a `#[must_use]` attribute
on a function was a no-op. To avoid a breaking change in this behavior, we add
an option for "this-and-such feature is experimental" feature-gate messages to
be a mere warning rather than a compilation-halting failure (so old code that
used to have a useless no-op `#[must_use]` attribute now warns rather than
breaking). When we're on stable, we add a help note to clarify that the feature
isn't "on."
This is in support of #43302.
We'll actually want a new "soft" warning-only gate to maintain
backwards-compatibility, but it's cleaner to start out with the established,
well-understood gate before implementing the alternative warn-only behavior in
a later commit.
This is in the matter of #43302.
Expose all OS-specific modules in libstd doc.
1. Uses the special `--cfg dox` configuration passed by rustbuild when running `rustdoc`. Changes the `#[cfg(platform)]` into `#[cfg(any(dox, platform))]` so that platform-specific API are visible to rustdoc.
2. Since platform-specific implementations often won't compile correctly on other platforms, `rustdoc` is changed to apply `everybody_loops` to the functions during documentation and doc-test harness.
3. Since platform-specific code are documented on all platforms now, it could confuse users who found a useful API but is non-portable. Also, their examples will be doc-tested, so must be excluded when not testing on the native platform. An undocumented attribute `#[doc(cfg(...))]` is introduced to serve the above purposed.
Fixes#24658 (Does _not_ fully implement #1998).
This attribute has two effects:
1. Items with this attribute and their children will have the "This is
supported on **** only" message attached in the documentation.
2. The items' doc tests will be skipped if the configuration does not
match.
It's more pleasing to use the inner-attribute syntax (`#!` rather than
`#`) in the error message, as that is how `feature` attributes in
particular will be declared (as they apply to the entire crate).
Fix feature gate for `#[link_args(..)]` attribute
Fix feature gate for `#[link_args(..)]` attribute so that it will fire regardless of context of attribute.
See also #29596 and #43106
rustc: Implement the #[global_allocator] attribute
This PR is an implementation of [RFC 1974] which specifies a new method of
defining a global allocator for a program. This obsoletes the old
`#![allocator]` attribute and also removes support for it.
[RFC 1974]: https://github.com/rust-lang/rfcs/pull/1974
The new `#[global_allocator]` attribute solves many issues encountered with the
`#![allocator]` attribute such as composition and restrictions on the crate
graph itself. The compiler now has much more control over the ABI of the
allocator and how it's implemented, allowing much more freedom in terms of how
this feature is implemented.
cc #27389
This PR is an implementation of [RFC 1974] which specifies a new method of
defining a global allocator for a program. This obsoletes the old
`#![allocator]` attribute and also removes support for it.
[RFC 1974]: https://github.com/rust-lang/rfcs/pull/197
The new `#[global_allocator]` attribute solves many issues encountered with the
`#![allocator]` attribute such as composition and restrictions on the crate
graph itself. The compiler now has much more control over the ABI of the
allocator and how it's implemented, allowing much more freedom in terms of how
this feature is implemented.
cc #27389
This change allows the user to add an `#[allow_fail]` attribute to
tests that will cause the test to compile & run, but if the test fails
it will not cause the entire test run to fail. The test output will
show the failure, but in yellow instead of red, and also indicate that
it was an allowed failure.
add thiscall calling convention support
This support is needed for bindgen to work well on 32-bit Windows, and also enables people to begin experimenting with C++ FFI support on that platform.
Fixes#42044.
Initial implementation of declarative macros 2.0
Implement declarative macros 2.0 (rust-lang/rfcs#1584) behind `#![feature(decl_macro)]`.
Differences from `macro_rules!` include:
- new syntax: `macro m(..) { .. }` instead of `macro_rules! m { (..) => { .. } }`
- declarative macros are items:
```rust
// crate A:
pub mod foo {
m!(); // use before definition; declaration order is irrelevant
pub macro m() {} // `pub`, `pub(super)`, etc. work
}
fn main() {
foo::m!(); // named like other items
{ use foo::m as n; n!(); } // imported like other items
}
pub use foo::m; // re-exported like other items
// crate B:
extern crate A; // no need for `#[macro_use]`
A::foo::m!(); A::m!();
```
- Racket-like hygiene for items, imports, methods, fields, type parameters, privacy, etc.
- Intuitively, names in a macro definition are resolved in the macro definition's scope, not the scope in which the macro is used.
- This [explaination](http://beautifulracket.com/explainer/hygiene.html) of hygiene for Racket applies here (except for the "Breaking Hygiene" section). I wrote a similar [explanation](https://github.com/jseyfried/rfcs/blob/hygiene/text/0000-hygiene.md) for Rust.
- Generally speaking, if `fn f() { <body> }` resolves, `pub macro m() { <body> } ... m!()` also resolves, even if `m!()` is in a separate crate.
- `::foo::bar` in a `macro` behaves like `$crate::foo::bar` in a `macro_rules!`, except it can access everything visible from the `macro` (thus more permissive).
- See [`src/test/{run-pass, compile-fail}/hygiene`](https://github.com/rust-lang/rust/pull/40847/commits/afe7d89858fd72b983e24727d6f4058293153c19) for examples. Small example:
```rust
mod foo {
fn f() { println!("hello world"); }
pub macro m() { f(); }
}
fn main() { foo::m!(); }
```
Limitations:
- This does not address planned changes to matchers (`expr`,`ty`, etc.), c.f. #26361.
- Lints (including stability and deprecation) and `unsafe` are not hygienic.
- adding hygiene here will be mostly or entirely backwards compatible
- Nested macro definitions (a `macro` inside another `macro`) don't always work correctly when invoked from external crates.
- pending improvements in how we encode macro definitions in crate metadata
- There is no way to "escape" hygiene without using a procedural macro.
r? @nrc
This support is needed for bindgen to work well on 32-bit Windows, and
also enables people to begin experimenting with C++ FFI support on that
platform.
Fixes#42044.
Correct some stability versions
These were found by running tidy on stable versions of rust and finding
features stabilised with the wrong version numbers.
