bjoernager/rust
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Include macro name in 'local ambiguity' error

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Currently, we only point at the span of the macro argument. When the
macro call is itself generated by another macro, this can make it
difficult or impossible to determine which macro is responsible for
producing the error.
This commit is contained in:
Aaron Hill 2021-06-07 20:17:48 -05:00
parent e4a6032706
commit 822f800ad7
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GPG key ID: B4087E510E98B164
4 changed files with 13 additions and 7 deletions
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9
compiler/rustc_expand/src/mbe/macro_parser.rs
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@ -85,6 +85,7 @@ use smallvec::{smallvec, SmallVec};
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::sync::Lrc;
use rustc_span::symbol::Ident;
use std::borrow::Cow;
use std::collections::hash_map::Entry::{Occupied, Vacant};
use std::mem;
@ -615,7 +616,11 @@ fn inner_parse_loop<'root, 'tt>(
/// Use the given sequence of token trees (`ms`) as a matcher. Match the token
/// stream from the given `parser` against it and return the match.
pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> NamedParseResult {
pub(super) fn parse_tt(
parser: &mut Cow<'_, Parser<'_>>,
ms: &[TokenTree],
macro_name: Ident,
) -> NamedParseResult {
// A queue of possible matcher positions. We initialize it with the matcher position in which
// the "dot" is before the first token of the first token tree in `ms`. `inner_parse_loop` then
// processes all of these possible matcher positions and produces possible next positions into
@ -711,7 +716,7 @@ pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> Na
return Error(
parser.token.span,
format!(
"local ambiguity: multiple parsing options: {}",
"local ambiguity when calling macro `{macro_name}`: multiple parsing options: {}",
match next_items.len() {
0 => format!("built-in NTs {}.", nts),
1 => format!("built-in NTs {} or 1 other option.", nts),