Fix async desugaring providing wrong input to procedural macros.
Fixes#60674.
This PR fixes a minor oversight introduced by #60535 where unused `mut` binding modes were removed from the arguments to an `async fn` (as they were added to the statement that we insert into the closure body). However, this meant that the input to procedural macros was incorrect. This removes that and instead fixes the `unused_mut` error that it avoided.
r? @cramertj
cc @taiki-e
Comment ext::tt::transcribe
Also did a bit of minor cleanup (remove unidiomatic use of `Add` and an unneeded `clone`). No functionality changes.
r? @petrochenkov
Identify when a stmt could have been parsed as an expr
There are some expressions that can be parsed as a statement without
a trailing semicolon depending on the context, which can lead to
confusing errors due to the same looking code being accepted in some
places and not others. Identify these cases and suggest enclosing in
parenthesis making the parse non-ambiguous without changing the
accepted grammar.
Fix#54186, cc #54482, fix#59975, fix#47287.
This commit removes the modification of the mutability of simple
bindings. While the mutability isn't used, it is important that it is
kept so that the input to procedural macros matches what the user wrote.
This commit also modifies the span of the binding mode so that it is
considered a compiler desugaring and won't be linted against for being
unused..
Adds support for .await under the existing async_await feature gate.
Moves macro-like await! syntax to the await_macro feature gate.
Removes support for `await` as a non-keyword under the `async_await`
feature.
introduce unescape module
A WIP PR to gauge early feedback
Currently, we deal with escape sequences twice: once when we [lex](112f7e9ac5/src/libsyntax/parse/lexer/mod.rs (L928-L1065)) a string, and a second time when we [unescape](112f7e9ac5/src/libsyntax/parse/mod.rs (L313-L366)) literals. Note that we also produce different sets of diagnostics in these two cases.
This PR aims to remove this duplication, by introducing a new `unescape` module as a single source of truth for character escaping rules.
I think this would be a useful cleanup by itself, but I also need this for https://github.com/rust-lang/rust/pull/59706.
In the current state, the PR has `unescape` module which fully (modulo bugs) deals with string and char literals. I am quite happy about the state of this module
What this PR doesn't have yet are:
* [x] handling of byte and byte string literals (should be simple to add)
* [x] good diagnostics
* [x] actual removal of code from lexer (giant `scan_char_or_byte` should go away completely)
* [x] performance check
* [x] general cleanup of the new code
Diagnostics will be the most labor-consuming bit here, but they are mostly a question of just correctly adjusting spans to sub-tokens. The current setup for diagnostics is that `unescape` produces a plain old `enum` with various problems, and they are rendered into `Handler` separately. This bit is not actually required (it is possible to just pass the `Handler` in), but I like the separation between diagnostics and logic this approach imposes, and such separation should again be useful for #59706
cc @eddyb , @petrochenkov
Account for paths in incorrect pub qualifier help
Handle case where incorrect pub qualifier with a mod path is used and provide the same help given for all other incorrect qualifiers by making the `pub(crate)` parse check more specific.
Currently, we deal with escape sequences twice: once when we lex a
string, and a second time when we unescape literals. This PR aims to
remove this duplication, by introducing a new `unescape` mode as a
single source of truth for character escaping rules
Ensure that drop order of `async fn` matches `fn` and that users cannot refer to generated arguments.
Fixes#60236 and fixes#60438.
This PR modifies the lowering of `async fn` arguments so that the
drop order matches the equivalent `fn`.
Previously, async function arguments were lowered as shown below:
async fn foo(<pattern>: <ty>) {
async move {
}
} // <-- dropped as you "exit" the fn
// ...becomes...
fn foo(__arg0: <ty>) {
async move {
let <pattern> = __arg0;
} // <-- dropped as you "exit" the async block
}
After this PR, async function arguments will be lowered as:
async fn foo(<pattern>: <ty>, <pattern>: <ty>, <pattern>: <ty>) {
async move {
}
} // <-- dropped as you "exit" the fn
// ...becomes...
fn foo(__arg0: <ty>, __arg1: <ty>, __arg2: <ty>) {
async move {
let __arg2 = __arg2;
let <pattern> = __arg2;
let __arg1 = __arg1;
let <pattern> = __arg1;
let __arg0 = __arg0;
let <pattern> = __arg0;
} // <-- dropped as you "exit" the async block
}
If `<pattern>` is a simple ident, then it is lowered to a single
`let <pattern> = <pattern>;` statement as an optimization.
This PR also stops users from referring to the generated `__argN`
identifiers.
r? @nikomatsakis
Added an explanation for the E0704 error.
# Description
Adds an explanation on the E0704 error. I tried to stick as closely to the message that the compiler generates. It's the first time I am fixing error messages here, so if there is something I did wrong or should improve, please let me know.
closes#55398
This commit gensyms the generated ident for replacement arguments so
that users cannot refer to them. It also ensures that levenshtein
distance suggestions do not suggest gensymed identifiers.
This commit modifies the lowering of `async fn` arguments so that the
drop order matches the equivalent `fn`.
Previously, async function arguments were lowered as shown below:
async fn foo(<pattern>: <ty>) {
async move {
}
} // <-- dropped as you "exit" the fn
// ...becomes...
fn foo(__arg0: <ty>) {
async move {
let <pattern> = __arg0;
} // <-- dropped as you "exit" the async block
}
After this PR, async function arguments will be lowered as:
async fn foo(<pattern>: <ty>, <pattern>: <ty>, <pattern>: <ty>) {
async move {
}
} // <-- dropped as you "exit" the fn
// ...becomes...
fn foo(__arg0: <ty>, __arg1: <ty>, __arg2: <ty>) {
async move {
let __arg2 = __arg2;
let <pattern> = __arg2;
let __arg1 = __arg1;
let <pattern> = __arg1;
let __arg0 = __arg0;
let <pattern> = __arg0;
} // <-- dropped as you "exit" the async block
}
If `<pattern>` is a simple ident, then it is lowered to a single
`let <pattern> = <pattern>;` statement as an optimization.
