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Improve error messages around invalid literals in attribute arguments

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Signed-off-by: Jonathan Brouwer <jonathantbrouwer@gmail.com>
This commit is contained in:
Jonathan Brouwer
2025-08-28 20:03:58 +02:00
parent 2c7dfa91b5
commit f328709276
3 changed files with 52 additions and 35 deletions
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59
compiler/rustc_attr_parsing/src/parser.rs
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@@ -10,11 +10,11 @@ use rustc_ast::token::{self, Delimiter, MetaVarKind};
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::{AttrArgs, DelimArgs, Expr, ExprKind, LitKind, MetaItemLit, NormalAttr, Path};
use rustc_ast_pretty::pprust;
use rustc_errors::PResult;
use rustc_errors::{Diag, PResult};
use rustc_hir::{self as hir, AttrPath};
use rustc_parse::exp;
use rustc_parse::parser::{Parser, PathStyle, token_descr};
use rustc_session::errors::report_lit_error;
use rustc_session::errors::{create_lit_error, report_lit_error};
use rustc_session::parse::ParseSess;
use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol, sym};
use thin_vec::ThinVec;
@@ -379,22 +379,23 @@ struct MetaItemListParserContext<'a, 'sess> {
impl<'a, 'sess> MetaItemListParserContext<'a, 'sess> {
fn parse_unsuffixed_meta_item_lit(&mut self) -> PResult<'sess, MetaItemLit> {
let uninterpolated_span = self.parser.token_uninterpolated_span();
let Some(token_lit) = self.parser.eat_token_lit() else {
return self.parser.handle_missing_lit(Parser::mk_meta_item_lit_char);
};
let Some(token_lit) = self.parser.eat_token_lit() else { return Err(self.expected_lit()) };
self.unsuffixed_meta_item_from_lit(token_lit)
}
fn unsuffixed_meta_item_from_lit(
&mut self,
token_lit: token::Lit,
) -> PResult<'sess, MetaItemLit> {
let lit = match MetaItemLit::from_token_lit(token_lit, self.parser.prev_token.span) {
Ok(lit) => lit,
Err(err) => {
let guar =
report_lit_error(&self.parser.psess, err, token_lit, uninterpolated_span);
// Pack possible quotes and prefixes from the original literal into
// the error literal's symbol so they can be pretty-printed faithfully.
let suffixless_lit = token::Lit::new(token_lit.kind, token_lit.symbol, None);
let symbol = Symbol::intern(&suffixless_lit.to_string());
let token_lit = token::Lit::new(token::Err(guar), symbol, token_lit.suffix);
MetaItemLit::from_token_lit(token_lit, uninterpolated_span).unwrap()
return Err(create_lit_error(
&self.parser.psess,
err,
token_lit,
self.parser.prev_token_uninterpolated_span(),
));
}
};
@@ -448,16 +449,28 @@ impl<'a, 'sess> MetaItemListParserContext<'a, 'sess> {
}
fn parse_meta_item_inner(&mut self) -> PResult<'sess, MetaItemOrLitParser<'static>> {
match self.parse_unsuffixed_meta_item_lit() {
Ok(lit) => return Ok(MetaItemOrLitParser::Lit(lit)),
Err(err) => err.cancel(), // we provide a better error below
}
match self.parse_attr_item() {
Ok(mi) => return Ok(MetaItemOrLitParser::MetaItemParser(mi)),
Err(err) => err.cancel(), // we provide a better error below
if let Some(token_lit) = self.parser.eat_token_lit() {
// If a literal token is parsed, we commit to parsing a MetaItemLit for better errors
Ok(MetaItemOrLitParser::Lit(self.unsuffixed_meta_item_from_lit(token_lit)?))
} else {
let prev_pros = self.parser.approx_token_stream_pos();
match self.parse_attr_item() {
Ok(item) => Ok(MetaItemOrLitParser::MetaItemParser(item)),
Err(err) => {
// If `parse_attr_item` made any progress, it likely has a more precise error we should prefer
// If it didn't make progress we use the `expected_lit` from below
if self.parser.approx_token_stream_pos() != prev_pros {
Err(err)
} else {
err.cancel();
Err(self.expected_lit())
}
}
}
}
}
fn expected_lit(&mut self) -> Diag<'sess> {
let mut err = InvalidMetaItem {
span: self.parser.token.span,
descr: token_descr(&self.parser.token),
@@ -492,7 +505,7 @@ impl<'a, 'sess> MetaItemListParserContext<'a, 'sess> {
self.parser.bump();
}
Err(self.parser.dcx().create_err(err))
self.parser.dcx().create_err(err)
}
fn parse(