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Rollup merge of #99030 - rust-lang:notriddle/field-recovery, r=petrochenkov

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diagnostics: error messages when struct literals fail to parse

If an expression is supplied where a field is expected, the parser can become convinced that it's a shorthand field syntax when it's not.

This PR addresses it by explicitly recording the permitted `:` token immediately after the identifier, and also adds a suggestion to insert the name of the field if it looks like a complex expression.

Fixes #98917
This commit is contained in:
Dylan DPC 2022-07-13 19:32:35 +05:30 • committed by GitHub
commit 980579a5e9
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5 changed files with 37 additions and 10 deletions
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18
compiler/rustc_parse/src/parser/expr.rs
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@ -3028,6 +3028,11 @@ impl<'a> Parser<'a> {
}
};
let is_shorthand = parsed_field.as_ref().map_or(false, |f| f.is_shorthand);
// A shorthand field can be turned into a full field with `:`.
// We should point this out.
self.check_or_expected(!is_shorthand, TokenType::Token(token::Colon));
match self.expect_one_of(&[token::Comma], &[token::CloseDelim(close_delim)]) {
Ok(_) => {
if let Some(f) = parsed_field.or(recovery_field) {
@ -3048,6 +3053,19 @@ impl<'a> Parser<'a> {
",",
Applicability::MachineApplicable,
);
} else if is_shorthand
&& (AssocOp::from_token(&self.token).is_some()
|| matches!(&self.token.kind, token::OpenDelim(_))
|| self.token.kind == token::Dot)
{
// Looks like they tried to write a shorthand, complex expression.
let ident = parsed_field.expect("is_shorthand implies Some").ident;
e.span_suggestion(
ident.span.shrink_to_lo(),
"try naming a field",
&format!("{ident}: "),
Applicability::HasPlaceholders,
);
}
}
if !recover {