Implement `#[proc_macro_attribute]`
This implements `#[proc_macro_attribute]` as described in https://github.com/rust-lang/rfcs/pull/1566
The following major (hopefully non-breaking) changes are included:
* Refactor `proc_macro::TokenStream` to use `syntax::tokenstream::TokenStream`.
* `proc_macro::tokenstream::TokenStream` no longer emits newlines between items, this can be trivially restored if desired
* `proc_macro::TokenStream::from_str` does not try to parse an item anymore, moved to `impl MultiItemModifier for CustomDerive` with more informative error message
* Implement `#[proc_macro_attribute]`, which expects functions of the kind `fn(TokenStream, TokenStream) -> TokenStream`
* Reactivated `#![feature(proc_macro)]` and gated `#[proc_macro_attribute]` under it
* `#![feature(proc_macro)]` and `#![feature(custom_attribute)]` are mutually exclusive
* adding `#![feature(proc_macro)]` makes the expansion pass assume that any attributes that are not built-in, or introduced by existing syntax extensions, are proc-macro attributes
* Fix `feature_gate::find_lang_feature_issue()` to not use `unwrap()`
* This change wasn't necessary for this PR, but it helped debugging a problem where I was using the wrong feature string.
* Move "completed feature gate checking" pass to after "name resolution" pass
* This was necessary for proper feature-gating of `#[proc_macro_attribute]` invocations when the `proc_macro` feature flag isn't set.
Prototype/Litmus Test: [Implementation](https://github.com/abonander/anterofit/blob/proc_macro/service-attr/src/lib.rs#L13) -- [Usage](https://github.com/abonander/anterofit/blob/proc_macro/service-attr/examples/post_service.rs#L35)
* Add support for `#[proc_macro]`
* Reactivate `proc_macro` feature and gate `#[proc_macro_attribute]` under it
* Have `#![feature(proc_macro)]` imply `#![feature(use_extern_macros)]`,
error on legacy import of proc macros via `#[macro_use]`
syntax: enable attributes and cfg on struct fields
This enables conditional compilation of field initializers in a struct literal, simplifying construction of structs whose fields are themselves conditionally present. For example, the intializer for the constant in the following becomes legal, and has the intuitive effect:
```rust
struct Foo {
#[cfg(unix)]
bar: (),
}
const FOO: Foo = Foo {
#[cfg(unix)]
bar: (),
};
```
It's not clear to me whether this calls for the full RFC process, but the implementation was simple enough that I figured I'd begin the conversation with code.
Remove not(stage0) from deny(warnings)
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
This commit stabilizes the `proc_macro` and `proc_macro_lib` features in the
compiler to stabilize the "Macros 1.1" feature of the language. Many more
details can be found on the tracking issue, #35900.
Closes#35900
i128 and u128 support
Brings i128 and u128 support to nightly rust, behind a feature flag. The goal of this PR is to do the bulk of the work for 128 bit integer support. Smaller but just as tricky features needed for stabilisation like 128 bit enum discriminants are left for future PRs.
Rebased version of #37900, which in turn was a rebase + improvement of #35954 . Sadly I couldn't reopen#37900 due to github. There goes my premium position in the homu queue...
[plugin-breaking-change]
cc #35118 (tracking issue)
This commit introduces 128-bit integers. Stage 2 builds and produces a working compiler which
understands and supports 128-bit integers throughout.
The general strategy used is to have rustc_i128 module which provides aliases for iu128, equal to
iu64 in stage9 and iu128 later. Since nowhere in rustc we rely on large numbers being supported,
this strategy is good enough to get past the first bootstrap stages to end up with a fully working
128-bit capable compiler.
In order for this strategy to work, number of locations had to be changed to use associated
max_value/min_value instead of MAX/MIN constants as well as the min_value (or was it max_value?)
had to be changed to use xor instead of shift so both 64-bit and 128-bit based consteval works
(former not necessarily producing the right results in stage1).
This commit includes manual merge conflict resolution changes from a rebase by @est31.
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
Allow legacy custom derive authors to disable warnings in downstream crates
This PR allows legacy custom derive authors to use a pre-deprecated method `registry.register_custom_derive()` instead of `registry.register_syntax_extension()` to avoid downstream deprecation warnings.
r? @nrc
On fmt string with unescaped `{` note how to escape
On cases of malformed format strings where a `{` hasn't been properly escaped, like `println!("{");`, present a NOTE explaining how to escape the `{` char.
Fix#34300.
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$}`
= note: printf formatting not supported; see the documentation for `std::fmt`
```
On cases of malformed format strings where a `{` hasn't been properly
escaped, like `println!("{");`, present a note explaining how to escape
the `{` char.
This teaches `format_args!` how to interpret format printf- and
shell-style format directives. This is used in cases where there are
unused formatting arguments, and the reason for that *might* be because
the programmer is trying to use the wrong kind of formatting string.
This was prompted by an issue encountered by simulacrum on the #rust IRC
channel. In short: although `println!` told them that they weren't using
all of the conversion arguments, the problem was in using printf-syle
directives rather than ones `println!` would undertand.
Where possible, `format_args!` will tell the programmer what they should
use instead. For example, it will suggest replacing `%05d` with `{:0>5}`,
or `%2$.*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.
Fix regression involving custom derives on items with `$crate`
The regression was introduced in #37213.
I believe we cannot make the improvements from #37213 work with the current custom derive setup (c.f. https://github.com/rust-lang/rust/issues/37637#issuecomment-258959145) -- we'll have to wait for `TokenStream`'s API to improve.
Fixes#37637.
r? @nrc
macros 1.1: Allow proc_macro functions to declare attributes to be mark as used
This PR allows proc macro functions to declare attribute names that should be marked as used when attached to the deriving item. There are a few questions for this PR.
- Currently this uses a separate attribute named `#[proc_macro_attributes(..)]`, is this the best choice?
- In order to make this work, the `check_attribute` function had to be modified to not error on attributes marked as used. This is a pretty large change in semantics, is there a better way to do this?
- I've got a few clones where I don't know if I need them (like turning `item` into a `TokenStream`), can these be avoided?
- Is switching to `MultiItemDecorator` the right thing here?
Also fixes https://github.com/rust-lang/rust/issues/37563.
By using a second attribute `attributes(Bar)` on
proc_macro_derive, whitelist any attributes with
the name `Bar` in the deriving item. This allows
a proc_macro function to use custom attribtues
without a custom attribute error or unused attribute
lint.
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
