Improve error message for extern "C" unsafe fn()

This was handled correctly already for `extern unsafe fn()`.

Co-authored-by: Folkert <folkert@folkertdev.nl>
This commit is contained in:
Tamme Dittrich 2024-07-26 15:14:05 +02:00
parent 33dd288ef1
commit 3fdc99193e
5 changed files with 30 additions and 14 deletions

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@ -2483,12 +2483,15 @@ impl<'a> Parser<'a> {
/// `check_pub` adds additional `pub` to the checks in case users place it
/// wrongly, can be used to ensure `pub` never comes after `default`.
pub(super) fn check_fn_front_matter(&mut self, check_pub: bool, case: Case) -> bool {
const ALL_QUALS: &[Symbol] =
&[kw::Pub, kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Safe, kw::Extern];
// We use an over-approximation here.
// `const const`, `fn const` won't parse, but we're not stepping over other syntax either.
// `pub` is added in case users got confused with the ordering like `async pub fn`,
// only if it wasn't preceded by `default` as `default pub` is invalid.
let quals: &[Symbol] = if check_pub {
&[kw::Pub, kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Safe, kw::Extern]
ALL_QUALS
} else {
&[kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Safe, kw::Extern]
};
@ -2518,9 +2521,9 @@ impl<'a> Parser<'a> {
|| self.check_keyword_case(kw::Extern, case)
&& self.look_ahead(1, |t| t.can_begin_string_literal())
&& (self.look_ahead(2, |t| t.is_keyword_case(kw::Fn, case)) ||
// this branch is only for better diagnostic in later, `pub` is not allowed here
// this branch is only for better diagnostics; `pub`, `unsafe`, etc. are not allowed here
(self.may_recover()
&& self.look_ahead(2, |t| t.is_keyword(kw::Pub))
&& self.look_ahead(2, |t| ALL_QUALS.iter().any(|&kw| t.is_keyword(kw)))
&& self.look_ahead(3, |t| t.is_keyword_case(kw::Fn, case))))
}

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@ -1,6 +1,10 @@
trait T {
extern "Rust" unsafe fn foo();
//~^ ERROR expected `{`, found keyword `unsafe`
//~^ ERROR expected `fn`, found keyword `unsafe`
//~| NOTE expected `fn`
//~| HELP `unsafe` must come before `extern "Rust"`
//~| SUGGESTION unsafe extern "Rust"
//~| NOTE keyword order for functions declaration is `pub`, `default`, `const`, `async`, `unsafe`, `extern`
}
fn main() {}

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@ -1,13 +1,13 @@
error: expected `{`, found keyword `unsafe`
error: expected `fn`, found keyword `unsafe`
--> $DIR/issue-19398.rs:2:19
|
LL | trait T {
| - while parsing this item list starting here
LL | extern "Rust" unsafe fn foo();
| ^^^^^^ expected `{`
LL |
LL | }
| - the item list ends here
| --------------^^^^^^
| | |
| | expected `fn`
| help: `unsafe` must come before `extern "Rust"`: `unsafe extern "Rust"`
|
= note: keyword order for functions declaration is `pub`, `default`, `const`, `async`, `unsafe`, `extern`
error: aborting due to 1 previous error

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@ -7,6 +7,10 @@
// Visibilities are tested elsewhere.
extern "C" unsafe fn test() {}
//~^ ERROR
//~^ ERROR expected `fn`, found keyword `unsafe`
//~| NOTE expected `fn`
//~| HELP `unsafe` must come before `extern "C"`
//~| SUGGESTION unsafe extern "C"
//~| NOTE keyword order for functions declaration is `pub`, `default`, `const`, `async`, `unsafe`, `extern`
fn main() {}

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@ -1,8 +1,13 @@
error: expected `{`, found keyword `unsafe`
error: expected `fn`, found keyword `unsafe`
--> $DIR/wrong-unsafe-abi.rs:9:12
|
LL | extern "C" unsafe fn test() {}
| ^^^^^^ expected `{`
| -----------^^^^^^
| | |
| | expected `fn`
| help: `unsafe` must come before `extern "C"`: `unsafe extern "C"`
|
= note: keyword order for functions declaration is `pub`, `default`, `const`, `async`, `unsafe`, `extern`
error: aborting due to 1 previous error