Improve the error message when forwarding a matched fragment to another macro
Adds a link to [Forwarding a matched fragment](https://doc.rust-lang.org/nightly/reference/macros-by-example.html#forwarding-a-matched-fragment) section of the Rust Reference, and suggests a possible fix (using `:tt` instead in the macro definition).
Also removes typos from the original message, it should be `:lifetime` instead of `$lifetime`.
## Motivation
When trying to write a macro which uses a literal in the matcher from the outer macro, like the following one, using a fragment specified that isn't one of `:ident`, `:lifetime`, or `:tt` currently results in a hard to understand message.
```rs
macro_rules! make_t_for_all_tokens {
($($name:literal as $variant:expr,)*) => {
macro_rules! t {
$(
($name) => {
$variant
};
)*
}
};
}
make_t_for_all_tokens! {
"fn" as Token::Fn,
"return" as Token::Return,
"let" as Token::Let,
}
// This creates
//
// macro_rules! t {
// ("fn") => {
// Token::Fn
// };
// ("return") => {
// Token::Return
// };
// ("let") => {
// Token::Let
// };
// }
t!["fn"];
```
### Before
```
error: no rules expected the token `"fn"`
--> src/main.rs:103:10
|
32 | macro_rules! t {
| -------------- when calling this macro
...
103 | t!["fn"];
| ^^^^ no rules expected this token in macro call
|
note: while trying to match `"fn"`
--> src/main.rs:34:6
|
34 | ($name) => {
| ^^^^^
...
58 | / make_t_for_all_tokens! {
59 | | "fn" as Token::Fn,
60 | | "return" as Token::Return,
61 | | "let" as Token::Let,
62 | | }
| |_- in this macro invocation
= note: captured metavariables except for `$tt`, `$ident` and `$lifetime` cannot be compared to other tokens
= note: this error originates in the macro `make_t_for_all_tokens` (in Nightly builds, run with -Z macro-backtrace for more info)
```
### After
```
error: no rules expected the token `"fn"`
--> src/main.rs:103:10
|
32 | macro_rules! t {
| -------------- when calling this macro
...
103 | t!["fn"];
| ^^^^ no rules expected this token in macro call
|
note: while trying to match `"fn"`
--> src/main.rs:34:6
|
34 | ($name) => {
| ^^^^^
...
58 | / make_t_for_all_tokens! {
59 | | "fn" as Token::Fn,
60 | | "return" as Token::Return,
61 | | "let" as Token::Let,
62 | | }
| |_- in this macro invocation
= note: captured metavariables except for `:tt`, `:ident` and `:lifetime` cannot be compared to other tokens
= note: see https://doc.rust-lang.org/nightly/reference/macros-by-example.html#forwarding-a-matched-fragment for more information
= help: try using `:tt` instead in the macro definition
= note: this error originates in the macro `make_t_for_all_tokens` (in Nightly builds, run with -Z macro-backtrace for more info)
```
## Unresolved questions
- Preferrably the suggestion should be attached to the `$name:literal` part of the outer macro, instead of being in the notes section at the end. But I'm not familiar with how the compiler works at all, and I have no idea how to approach this kind of solution.
- `@Nilstrieb` raised a question that the suggestion of adding `:tt` isn't accurate when there's more than `tt` being matched, for example when the input is an `item`.
Adds a link to the relevant part of The Rust Reference in the eror
message, and suggests a possible fix (replacing the fragment specifier
with :tt in the macro definition).
Fixes typos in the original message.
Signed-off-by: Lena Milizé <me@lvmn.org>
It partially expands crate attributes before the main expansion pass (without modifying the crate), and the produced preliminary crate attribute list is used for querying a few attributes that are required very early.
Crate-level cfg attributes are then expanded normally during the main expansion pass, like attributes on any other nodes.
This makes it easier to open the messages file while developing on features.
The commit was the result of automatted changes:
for p in compiler/rustc_*; do mv $p/locales/en-US.ftl $p/messages.ftl; rmdir $p/locales; done
for p in compiler/rustc_*; do sed -i "s#\.\./locales/en-US.ftl#../messages.ftl#" $p/src/lib.rs; done
Rollup of 9 pull requests
Successful merges:
- #104363 (Make `unused_allocation` lint against `Box::new` too)
- #106633 (Stabilize `nonzero_min_max`)
- #106844 (allow negative numeric literals in `concat!`)
- #108071 (Implement goal caching with the new solver)
- #108542 (Force parentheses around `match` expression in binary expression)
- #108690 (Place size limits on query keys and values)
- #108708 (Prevent overflow through Arc::downgrade)
- #108739 (Prevent the `start_bx` basic block in codegen from having two `Builder`s at the same time)
- #108806 (Querify register_tools and post-expansion early lints)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Querify register_tools and post-expansion early lints
The 2 extra queries correspond to code that happen before and after macro expansion, and don't need the resolver to exist.
After removing the `map_in_place` method, which isn't much use because
modifying every element in a collection such as a `Vec` can be done
trivially with iteration.
Extend `CodegenBackend` trait with a function returning the translation
resources from the codegen backend, which can be added to the complete
list of resources provided to the emitter.
Signed-off-by: David Wood <david.wood@huawei.com>
Instead of loading the Fluent resources for every crate in
`rustc_error_messages`, each crate generates typed identifiers for its
own diagnostics and creates a static which are pulled together in the
`rustc_driver` crate and provided to the diagnostic emitter.
Signed-off-by: David Wood <david.wood@huawei.com>
Introduce `-Zterminal-urls` to use OSC8 for error codes
Terminals supporting the OSC8 Hyperlink Extension can support inline anchors where the text is user defineable but clicking on it opens a browser to a specified URLs, just like `<a href="URL">` does in HTML.
https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
Terminals supporting the OSC8 Hyperlink Extension can support inline
anchors where the text is user defineable but clicking on it opens a
browser to a specified URLs, just like `<a href="URL">` does in HTML.
https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
