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Rollup merge of #81608 - Aaron1011:macro-res-parse-err, r=davidtwco

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Improve handling of spans around macro result parse errors

Fixes #81543

After we expand a macro, we try to parse the resulting tokens as a AST
node. This commit makes several improvements to how we handle spans when
an error occurs:

* Only ovewrite the original `Span` if it's a dummy span. This preserves
  a more-specific span if one is available.
* Use `self.prev_token` instead of `self.token` when emitting an error
  message after encountering EOF, since an EOF token always has a dummy
  span
* Make `SourceMap::next_point` leave dummy spans unused. A dummy span
  does not have a logical 'next point', since it's a zero-length span.
  Re-using the span span preserves its 'dummy-ness' for other checks
This commit is contained in:
Jonas Schievink 2021-02-02 12:15:02 +01:00 • committed by GitHub
commit 255e0764c0
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6 changed files with 36 additions and 4 deletions
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4
compiler/rustc_parse/src/parser/diagnostics.rs
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@ -1104,7 +1104,7 @@ impl<'a> Parser<'a> {
let (prev_sp, sp) = match (&self.token.kind, self.subparser_name) {
// Point at the end of the macro call when reaching end of macro arguments.
(token::Eof, Some(_)) => {
let sp = self.sess.source_map().next_point(self.token.span);
let sp = self.sess.source_map().next_point(self.prev_token.span);
(sp, sp)
}
// We don't want to point at the following span after DUMMY_SP.
@ -1721,7 +1721,7 @@ impl<'a> Parser<'a> {
pub(super) fn expected_expression_found(&self) -> DiagnosticBuilder<'a> {
let (span, msg) = match (&self.token.kind, self.subparser_name) {
(&token::Eof, Some(origin)) => {
let sp = self.sess.source_map().next_point(self.token.span);
let sp = self.sess.source_map().next_point(self.prev_token.span);
(sp, format!("expected expression, found end of {}", origin))
}
_ => (