Support `use`ing externally defined macros behind `#![feature(use_extern_macros)]`
With `#![feature(use_extern_macros)]`,
- A name collision between macros from different upstream crates is much less of an issue since we can `use` the macros in different submodules or rename with `as`.
- We can reexport macros with `pub use`, so `#![feature(macro_reexport)]` is no longer needed.
- These reexports are allowed in any module, so crates can expose a macro-modular interface.
If a macro invocation can resolve to both a `use` import and a `macro_rules!` or `#[macro_use]`, it is an ambiguity error.
r? @nrc
This commit is an implementation of [RFC 1721] which adds a new target feature
to the compiler, `crt-static`, which can be used to select how the C runtime for
a target is linked. Most targets dynamically linke the C runtime by default with
the notable exception of some of the musl targets.
[RFC 1721]: https://github.com/rust-lang/rfcs/blob/master/text/1721-crt-static.md
This commit first adds the new target-feature, `crt-static`. If enabled, then
the `cfg(target_feature = "crt-static")` will be available. Targets like musl
will have this enabled by default. This feature can be controlled through the
standard target-feature interface, `-C target-feature=+crt-static` or
`-C target-feature=-crt-static`.
Next this adds an gated and unstable `#[link(cfg(..))]` feature to enable the
`crt-static` semantics we want with libc. The exact behavior of this attribute
is a little squishy, but it's intended to be a forever-unstable
implementation detail of the liblibc crate.
Specifically the `#[link(cfg(..))]` annotation means that the `#[link]`
directive is only active in a compilation unit if that `cfg` value is satisfied.
For example when compiling an rlib, these directives are just encoded and
ignored for dylibs, and all staticlibs are continued to be put into the rlib as
usual. When placing that rlib into a staticlib, executable, or dylib, however,
the `cfg` is evaluated *as if it were defined in the final artifact* and the
library is decided to be linked or not.
Essentially, what'll happen is:
* On MSVC with `-C target-feature=-crt-static`, the `msvcrt.lib` library will be
linked to.
* On MSVC with `-C target-feature=+crt-static`, the `libcmt.lib` library will be
linked to.
* On musl with `-C target-feature=-crt-static`, the object files in liblibc.rlib
are removed and `-lc` is passed instead.
* On musl with `-C target-feature=+crt-static`, the object files in liblibc.rlib
are used and `-lc` is not passed.
This commit does **not** include an update to the liblibc module to implement
these changes. I plan to do that just after the 1.14.0 beta release is cut to
ensure we get ample time to test this feature.
cc #37406
Add foreign formatting directive detection.
This teaches `format_args!` how to interpret format printf- and
shell-style format directives. This is used in cases where there are
unused formatting arguments, and the reason for that *might* be because
the programmer is trying to use the wrong kind of formatting string.
This was prompted by an issue encountered by simulacrum on the #rust IRC
channel. In short: although `println!` told them that they weren't using
all of the conversion arguments, the problem was in using printf-syle
directives rather than ones `println!` would undertand.
Where possible, `format_args!` will tell the programmer what they should
use instead. For example, it will suggest replacing `%05d` with `{:0>5}`,
or `%2$.*3$s` with `{1:.3$}`. Even if it cannot suggest a replacement,
it will explicitly note that Rust does not support that style of directive,
and direct the user to the `std::fmt` documentation.
-----
**Example**: given:
```rust
fn main() {
println!("%.*3$s %s!\n", "Hello,", "World", 4);
println!("%1$*2$.*3$f", 123.456);
}
```
The compiler outputs the following:
```text
error: multiple unused formatting arguments
--> local/fmt.rs:2:5
|
2 | println!("%.*3$s %s!\n", "Hello,", "World", 4);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: argument never used
--> local/fmt.rs:2:30
|
2 | println!("%.*3$s %s!\n", "Hello,", "World", 4);
| ^^^^^^^^
note: argument never used
--> local/fmt.rs:2:40
|
2 | println!("%.*3$s %s!\n", "Hello,", "World", 4);
| ^^^^^^^
note: argument never used
--> local/fmt.rs:2:49
|
2 | println!("%.*3$s %s!\n", "Hello,", "World", 4);
| ^
= help: `%.*3$s` should be written as `{:.2$}`
= help: `%s` should be written as `{}`
= note: printf formatting not supported; see the documentation for `std::fmt`
= note: this error originates in a macro outside of the current crate
error: argument never used
--> local/fmt.rs:6:29
|
6 | println!("%1$*2$.*3$f", 123.456);
| ^^^^^^^
|
= help: `%1$*2$.*3$f` should be written as `{0:1$.2$}`
= note: printf formatting not supported; see the documentation for `std::fmt`
```
Don't provide hint to add lifetime on impl items
``` rust
use std::str::FromStr;
pub struct Foo<'a> {
field: &'a str,
}
impl<'a> FromStr for Foo<'a> {
type Err = ();
fn from_str(path: &str) -> Result<Self, ()> {
Ok(Foo { field: path })
}
}
```
would give the following hint:
``` nocode
help: consider using an explicit lifetime parameter as shown: fn from_str(path: &'a str) -> Result<Self, ()>
--> <anon>:9:5
|
9 | fn from_str(path: &str) -> Result<Self, ()> {
| ^
```
which is never correct, since then there will be a lifetime mismatch between the `impl` and the trait.
Remove this hint for all `impl` items.
Re: #37363.
Group unused import warnings per import list
Given a file
``` rust
use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
fn main() {}
```
Show a single warning, instead of three for each unused import:
``` nocode
warning: unused imports, #[warn(unused_imports)] on by default
--> file2.rs:1:24
|
1 | use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
| ^^^^^^^^^^ ^^^^^^^^ ^^^^^^^^
```
Include support for lints pointing at `MultilineSpan`s, instead of just
`Span`s.
Fixes#16132.
Show one error for duplicated type definitions
For the following code:
``` rustc
struct Bar;
struct Bar;
fn main () {
}
```
show
``` nocode
error[E0428]: a type named `Bar` has already been defined in this module
--> src/test/compile-fail/E0428.rs:12:1
|
11 | struct Bar;
| ----------- previous definition of `Bar` here
12 | struct Bar;
| ^^^^^^^^^^^
error: aborting due to previous error
```
instead of
``` nocode
error[E0428]: a type named `Bar` has already been defined in this module
--> src/test/compile-fail/E0428.rs:12:1
|
11 | struct Bar;
| ----------- previous definition of `Bar` here
12 | struct Bar;
| ^^^^^^^^^^^
error[E0428]: a value named `Bar` has already been defined in this module
--> src/test/compile-fail/E0428.rs:12:1
|
11 | struct Bar;
| ----------- previous definition of `Bar` here
12 | struct Bar;
| ^^^^^^^^^^^
error: aborting due to 2 previous errors
```
Fixes#35767.
Make E0243/E0244 message consistent with E0107
E0243/E0233 prints `expected {}, found {}` on the span note, while E0107 prints it on the first line. This is confusing when both error occur simultaneously.
This PR makes E0243/E0233 print `expected {}, found {}` on the first line.
Code:
``` rust
struct Foo<'a, 'b> {
s: &'a str,
t: &'b str,
}
type Bar<T, U> = Foo<T, U>;
```
rustc output (before):
```
error[E0107]: wrong number of lifetime parameters: expected 2, found 0
--> test.rs:6:18
|
6 | type Bar<T, U> = Foo<T, U>;
| ^^^^^^^^^ expected 2 lifetime parameters
error[E0244]: wrong number of type arguments
--> test.rs:6:18
|
6 | type Bar<T, U> = Foo<T, U>;
| ^^^^^^^^^ expected no type arguments, found 2
```
rustc output (after):
```
error[E0107]: wrong number of lifetime parameters: expected 2, found 0
--> /tmp/test.rs:6:18
|
6 | type Bar<T, U> = Foo<T, U>;
| ^^^^^^^^^ expected 2 lifetime parameters
error[E0244]: wrong number of type arguments: expected 0, found 2
--> /tmp/test.rs:6:18
|
6 | type Bar<T, U> = Foo<T, U>;
| ^^^^^^^^^ expected no type arguments
```
This teaches `format_args!` how to interpret format printf- and
shell-style format directives. This is used in cases where there are
unused formatting arguments, and the reason for that *might* be because
the programmer is trying to use the wrong kind of formatting string.
This was prompted by an issue encountered by simulacrum on the #rust IRC
channel. In short: although `println!` told them that they weren't using
all of the conversion arguments, the problem was in using printf-syle
directives rather than ones `println!` would undertand.
Where possible, `format_args!` will tell the programmer what they should
use instead. For example, it will suggest replacing `%05d` with `{:0>5}`,
or `%2$.*3$s` with `{1:.3$}`. Even if it cannot suggest a replacement,
it will explicitly note that Rust does not support that style of directive,
and direct the user to the `std::fmt` documentation.
Don't provide hint to add lifetime on impl items that implement a trait.
```rust
use std::str::FromStr;
pub struct Foo<'a> {
field: &'a str,
}
impl<'a> FromStr for Foo<'a> {
type Err = ();
fn from_str(path: &str) -> Result<Self, ()> {
Ok(Foo { field: path })
}
}
```
would give the following hint:
```nocode
help: consider using an explicit lifetime parameter as shown: fn from_str(path: &'a str) -> Result<Self, ()>
--> <anon>:9:5
|
9 | fn from_str(path: &str) -> Result<Self, ()> {
| ^
```
which is never correct, since then there will be a lifetime mismatch
between the impl and the trait.
Remove this hint for impl items that implement a trait.
For the following code:
```rustc
struct Bar;
struct Bar;
fn main () {
}
```
show
```nocode
error[E0428]: a type named `Bar` has already been defined in this module
--> src/test/compile-fail/E0428.rs:12:1
|
11 | struct Bar;
| ----------- previous definition of `Bar` here
12 | struct Bar;
| ^^^^^^^^^^^
error: aborting due to previous error
```
instead of
```nocode
error[E0428]: a type named `Bar` has already been defined in this module
--> src/test/compile-fail/E0428.rs:12:1
|
11 | struct Bar;
| ----------- previous definition of `Bar` here
12 | struct Bar;
| ^^^^^^^^^^^
error[E0428]: a value named `Bar` has already been defined in this module
--> src/test/compile-fail/E0428.rs:12:1
|
11 | struct Bar;
| ----------- previous definition of `Bar` here
12 | struct Bar;
| ^^^^^^^^^^^
error: aborting due to 2 previous errors
```
_match: correct max_slice_length logic
The logic used to be wildly wrong, but before the HAIR patch its wrongness was in most cases hidden by another bug.
Fixes#37598.
r? @nikomatsakis
Point to type argument span when used as trait
Given the following code:
``` rust
struct Foo<T: Clone>(T);
use std::ops::Add;
impl<T: Clone, Add> Add for Foo<T> {
type Output = usize;
fn add(self, rhs: Self) -> Self::Output {
unimplemented!();
}
}
```
present the following output:
``` nocode
error[E0404]: `Add` is not a trait
--> file3.rs:5:21
|
5 | impl<T: Clone, Add> Add for Okok<T> {
| --- ^^^ expected trait, found type parameter
| |
| type parameter defined here
```
Fixes#35987.
Include type of missing trait methods in error
Provide either a span pointing to the original definition of missing
trait items, or a message with the inferred definitions.
Fixes#24626. Follow up to PR #36371.
If PR #37369 lands, missing trait items that present a multiline span will be able to show the entirety of the item definition on the error itself, instead of just the first line.
Reword error when data-less enum variant called as function
Given a file like:
``` rust
enum Test {
Variant,
Variant2 {a: u32},
}
fn main(){
let x = Test::Variant("Hello");
let y = Test::Variant2("World");
}
```
Both errors now look similar:
``` bash
error[E0423]: `Test::Variant2` is the name of a struct or struct variant, but this expression uses it like a function name
--> file3.rs:10:13
|
10 | let y = Test::Variant2("Hello");
| ^^^^^^^^^^^^^^ struct called like a function
|
= help: did you mean to write: `Test::Variant2 { /* fields */ }`?
error: `Test::Variant` is the name of a data-less enum, but this expression uses it like a function name
--> file3.rs:9:13
|
9 | let x = Test::Variant("World");
| ^^^^^^^^^^^^^^^^^^^^^^ data-less enum called like a function
|
= help: did you mean to write: `Test::Variant`?
note: defined here
--> file3.rs:2:5
|
2 | Variant,
| ^^^^^^^
error: aborting due to previous error
```
Re: #28533
Given a file
```rust
use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
fn main() {}
```
Show a single warning, instead of three for each unused import:
```nocode
warning: unused imports, #[warn(unused_imports)] on by default
--> foo.rs:1:24
|
1 | use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
| ^^^^^^^^^^ ^^^^^^^^ ^^^^^^^^
```
Include support for lints pointing at `MultilineSpan`s, instead of just
`Span`s.
Given the following code:
```rust
struct Foo<T: Clone>(T);
use std::ops::Add;
impl<T: Clone, Add> Add for Foo<T> {
type Output = usize;
fn add(self, rhs: Self) -> Self::Output {
unimplemented!();
}
}
```
present the following output:
```nocode
error[E0404]: `Add` is not a trait
--> file3.rs:5:21
|
5 | impl<T: Clone, Add> Add for Okok<T> {
| --- ^^^ expected trait, found type parameter
| |
| type parameter defined here
```
Stabilize `..` in tuple (struct) patterns
I'd like to nominate `..` in tuple and tuple struct patterns for stabilization.
This feature is a relatively small extension to existing stable functionality and doesn't have known blockers.
The feature first appeared in Rust 1.10 6 months ago.
An example of use: https://github.com/rust-lang/rust/pull/36203
Closes https://github.com/rust-lang/rust/issues/33627
r? @nikomatsakis
macros: improve shadowing checks
This PR improves macro-expanded shadowing checks to work with out-of-(pre)order expansion.
Out-of-order expansion became possible in #37084, so this technically a [breaking-change] for nightly.
The regression test from this PR is an example of code that would break.
r? @nrc
Fix ICE when querying DefId on Def::Err.
Also moves computations into check that `kind_id` is `Ok(_)`, which is in theory an optimization, though I expect it's minor.
Fixes#37534.
r? @eddyb.
rustc: Add knowledge of Windows subsystems.
This commit is an implementation of [RFC 1665] which adds support for the
`#![windows_subsystem]` attribute. This attribute allows specifying either the
"windows" or "console" subsystems on Windows to the linker.
[RFC 1665]: https://github.com/rust-lang/rfcs/blob/master/text/1665-windows-subsystem.md
Previously all Rust executables were compiled as the "console" subsystem which
meant that if you wanted a graphical application it would erroneously pop up a
console whenever opened. When compiling an application, however, this is
undesired behavior and the "windows" subsystem is used instead to have control
over user interactions.
This attribute is validated, but ignored on all non-Windows platforms.
cc #37499
detect extra region requirements in impls
The current "compare method" check fails to check for the "region obligations" that accrue in the fulfillment context. This branch switches that code to create a `FnCtxt` so that it can invoke the regionck code. Previous crater runs (I haven't done one with the latest tip) have found some small number of affected crates, so I went ahead and introduced a warning cycle. I will kick off a crater run with this branch shortly.
This is a [breaking-change] because previously unsound code was accepted. The crater runs also revealed some cases where legitimate code was no longer type-checking, so the branch contains one additional (but orthogonal) change. It improves the elaborator so that we elaborate region requirements more thoroughly. In particular, if we know that `&'a T: 'b`, we now deduce that `T: 'b` and `'a: 'b`.
I invested a certain amount of effort in getting a good error message. The error message looks like this:
```
error[E0276]: impl has stricter requirements than trait
--> traits-elaborate-projection-region.rs:33:5
|
21 | fn foo() where T: 'a;
| --------------------- definition of `foo` from trait
...
33 | fn foo() where U: 'a { }
| ^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `U: 'a`
|
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #18937 <https://github.com/rust-lang/rust/issues/18937>
note: lint level defined here
--> traits-elaborate-projection-region.rs:12:9
|
12 | #![deny(extra_requirement_in_impl)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^
```
Obviously the warning only prints if this is a _new_ error (that resulted from the bugfix). But all existing errors that fit this description are updated to follow the general template. In order to get the lint to preserve the span-labels and the error code, I separate out the core `Diagnostic` type (which encapsulates the error code, message, span, and children) from the `DiagnosticBuilder` (which layers on a `Handler` that can be used to report errors). I also extended `add_lint` with an alternative `add_lint_diagnostic` that takes in a full diagnostic (cc @jonathandturner for those changes). This doesn't feel ideal but feels like it's moving in the right direction =).
r? @pnkfelix
cc @arielb1
Fixes#18937
