"Failed to parse macro invocation" when using crate "proconio" #8171
Comments
jonas-schievink
added
A-macro
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Some additional information: As for released versions of Rust Analyzer, version 2021-03-22 and 2021-03-15 both show the error for the repro code, but if fn main() {
input! {
n: isize,
}
let _x = n;
}As for versions of Visual Studio Code extension, I can confirm the same behavior with rust-analyzer 0.2.529 and 0.2.521. 0.2.529 behaves like 2021-03-22, 0.2.521 behaves like 2021-03-15. I'm not sure they are exactly the same version - I don't know how to check it.
The last one shows 0.2.521 can successfully parse the macro invocation ( |
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Thanks for the report, It seem like there's still have some bugs related to statements after #8044. I am investigating on it right now, but need sometimes. A no-deps version of reproducible example : macro_rules! input {
// terminator
(@from [$source:expr] @rest) => {};
// parse mutability
(@from [$source:expr] @rest mut $($rest:tt)*) => {
input! {
@from [$source]
@mut [mut]
@rest $($rest)*
}
};
(@from [$source:expr] @rest $($rest:tt)*) => {
input! {
@from [$source]
@mut []
@rest $($rest)*
}
};
// parse variable pattern
(@from [$source:expr] @mut [$($mut:tt)?] @rest $var:tt: $($rest:tt)*) => {
input! {
@from [$source]
@mut [$($mut)*]
@var $var
@kind []
@rest $($rest)*
}
};
// parse kind (type)
(@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [$($kind:tt)*] @rest) => {
let $($mut)* $var = 0;
};
(@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [$($kind:tt)*] @rest, $($rest:tt)*) => {
input!(@from [$source] @mut [$($mut)*] @var $var @kind [$($kind)*] @rest);
};
(@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [$($kind:tt)*] @rest $tt:tt $($rest:tt)*) => {
input!(@from [$source] @mut [$($mut)*] @var $var @kind [$($kind)* $tt] @rest $($rest)*);
};
($($rest:tt)*) => {
let mut _locked_stdin = "";
input! {
@from [&mut *locked_stdin]
@rest $($rest)*
}
drop(_locked_stdin); // release the lock
};
}
fn main() {
input! {
n: isize,
}
let a = n;
} |
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Smaller repro: macro_rules! ng {
([$($tts:tt)*]) => {
$($tts)*;
};
([$($tts:tt)*] $head:tt $($rest:tt)*) => {
ng! {
[$($tts)* $head] $($rest)*
}
};
}
fn main() {
ng!([] let _a = 3);
}This causes I'm not sure but recursive macro invocation with braces may be a part of cause: two macros below are both OK. macro_rules! ok1 {
([$($tts:tt)*]) => {
$($tts)*;
};
([$($tts:tt)*] $head:tt $($rest:tt)*) => {
// OK: using parens + semicolons instead of braces
ok1! (
[$($tts)* $head] $($rest)*
);
};
}macro_rules! ok2 {
([$($tts:tt)*]) => {
$($tts)*;
};
([$($tts:tt)*] $($rest:tt)+) => {
// OK: no recursive macro calls
ok2! {
[$($tts)* $($rest)*]
}
};
}Note: I have a lot of trouble trying them anyway. I need to restart rust-analyzer to get latest diagnostics (error highlights, semantic highlightings, type hints, diagnostics etc won't be updated) every time I change macro invocation (delete or change params, comment-out, etc). I think rust-analyzer enters some erroneous state when something goes wrong. Among them,
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proconio is easy IO library for competitive programming.
Error occur when using
input!macro.I can compile and run it, but I get "Failed to parse macro invocation" in rust-analyzer.
This error was confirmed in both vim and vscode.
rust-analyzer is nightly version(0.3.528).
Complete repro
cargo.toml:
main.rs
Thank you.
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