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review comments: fix typo and add comments

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estebank committed May 6, 2019
1 parent f6a4b52 commit 54430ad53ab00bf86090a8d11844db1c40b2ca24
@@ -4174,7 +4174,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
oprnd_t,
);
let sp = tcx.sess.source_map().start_point(expr.span);
if let Some(sp) = tcx.sess.parse_sess.abiguous_block_expr_parse
if let Some(sp) = tcx.sess.parse_sess.ambiguous_block_expr_parse
.borrow().get(&sp)
{
tcx.sess.parse_sess.expr_parentheses_needed(
@@ -1918,7 +1918,7 @@ mod tests {
raw_identifier_spans: Lock::new(Vec::new()),
registered_diagnostics: Lock::new(ErrorMap::new()),
buffered_lints: Lock::new(vec![]),
abiguous_block_expr_parse: Lock::new(FxHashMap::default()),
ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
}
}

@@ -50,7 +50,7 @@ pub struct ParseSess {
/// Contains the spans of block expressions that could have been incomplete based on the
/// operation token that followed it, but that the parser cannot identify without further
/// analysis.
pub abiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
}

impl ParseSess {
@@ -74,7 +74,7 @@ impl ParseSess {
included_mod_stack: Lock::new(vec![]),
source_map,
buffered_lints: Lock::new(vec![]),
abiguous_block_expr_parse: Lock::new(FxHashMap::default()),
ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
}
}

@@ -2928,7 +2928,7 @@ impl<'a> Parser<'a> {
self.this_token_descr());
let mut err = self.fatal(&msg);
let sp = self.sess.source_map().start_point(self.span);
if let Some(sp) = self.sess.abiguous_block_expr_parse.borrow()
if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow()
.get(&sp)
{
self.sess.expr_parentheses_needed(&mut err, *sp, None);
@@ -3630,12 +3630,15 @@ impl<'a> Parser<'a> {
return Ok(lhs);
}
(false, _) => {} // continue parsing the expression
(true, Some(AssocOp::Multiply)) | // `{ 42 } *foo = bar;`
// An exhaustive check is done in the following block, but these are checked first
// because they *are* ambiguous but also reasonable looking incorrect syntax, so we
// want to keep their span info to improve diagnostics in these cases in a later stage.
(true, Some(AssocOp::Multiply)) | // `{ 42 } *foo = bar;` or `{ 42 } * 3`
(true, Some(AssocOp::Subtract)) | // `{ 42 } -5`
(true, Some(AssocOp::Add)) => { // `{ 42 } + 42
// These cases are ambiguous and can't be identified in the parser alone
let sp = self.sess.source_map().start_point(self.span);
self.sess.abiguous_block_expr_parse.borrow_mut().insert(sp, lhs.span);
self.sess.ambiguous_block_expr_parse.borrow_mut().insert(sp, lhs.span);
return Ok(lhs);
}
(true, Some(ref op)) if !op.can_continue_expr_unambiguously() => {
@@ -4968,7 +4971,7 @@ impl<'a> Parser<'a> {
let mut err = self.fatal(&msg);
err.span_label(self.span, format!("expected {}", expected));
let sp = self.sess.source_map().start_point(self.span);
if let Some(sp) = self.sess.abiguous_block_expr_parse.borrow().get(&sp) {
if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
self.sess.expr_parentheses_needed(&mut err, *sp, None);
}
return Err(err);
@@ -208,6 +208,10 @@ impl AssocOp {
}
}

/// This operator could be used to follow a block unambiguously.
///
/// This is used for error recovery at the moment, providing a suggestion to wrap blocks with
/// parentheses while having a high degree of confidence on the correctness of the suggestion.
pub fn can_continue_expr_unambiguously(&self) -> bool {
use AssocOp::*;
match self {
@@ -227,7 +231,6 @@ impl AssocOp {
Colon => true, // `{ 42 }: usize`
_ => false,
}

}
}

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