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Parse alternative incorrect uses of await and recover

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This commit is contained in:
Esteban Küber 2019-05-15 19:47:18 -07:00
parent 1962adea6a
commit d763faf921
12 changed files with 428 additions and 37 deletions
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113
src/libsyntax/parse/parser.rs
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@ -2629,14 +2629,94 @@ impl<'a> Parser<'a> {
db.note("variable declaration using `let` is a statement");
return Err(db);
} else if self.span.rust_2018() && self.eat_keyword(keywords::Await) {
// FIXME: remove this branch when `await!` is no longer supported
// https://github.com/rust-lang/rust/issues/60610
self.expect(&token::Not)?;
self.expect(&token::OpenDelim(token::Paren))?;
let expr = self.parse_expr()?;
self.expect(&token::CloseDelim(token::Paren))?;
hi = self.prev_span;
ex = ExprKind::Await(ast::AwaitOrigin::MacroLike, expr);
let await_sp = self.prev_span;
match self.token {
token::Not => {
// FIXME: make this an error when `await!` is no longer supported
// https://github.com/rust-lang/rust/issues/60610
self.expect(&token::Not)?;
self.expect(&token::OpenDelim(token::Paren))?;
let expr = self.parse_expr().map_err(|mut err| {
err.span_label(
await_sp,
"while parsing this await macro call",
);
err
})?;
self.expect(&token::CloseDelim(token::Paren))?;
ex = ExprKind::Await(ast::AwaitOrigin::MacroLike, expr);
}
token::Question => {
// Handle `await? <expr>`
self.bump(); // `?`
let expr = self.parse_expr().map_err(|mut err| {
err.span_label(
await_sp,
"while parsing this incorrect await statement",
);
err
})?;
let sp = lo.to(expr.span);
let expr_str = self.sess.source_map().span_to_snippet(expr.span)
.unwrap_or_else(|_| pprust::expr_to_string(&expr));
let expr = self.mk_expr(
sp,
ExprKind::Await(ast::AwaitOrigin::FieldLike, expr),
ThinVec::new(),
);
hi = sp;
ex = ExprKind::Try(expr);
let mut err = self.struct_span_err(
await_sp,
"incorrect use of `await`",
);
err.span_suggestion(
sp,
"`await` is not a statement",
format!("{}.await?", expr_str),
Applicability::MachineApplicable,
);
err.emit();
}
ref t => {
// Handle `await <expr>`
let expr = if t == &token::OpenDelim(token::Brace) {
// Handle `await { <expr> }`
// this needs to be handled separatedly from the next arm to avoid
// interpreting `await { <expr> }?` as `<expr>?.await`
self.parse_block_expr(
None,
self.span,
BlockCheckMode::Default,
ThinVec::new(),
)
} else {
self.parse_expr()
}.map_err(|mut err| {
err.span_label(
await_sp,
"while parsing this incorrect await statement",
);
err
})?;
let expr_str = self.sess.source_map().span_to_snippet(expr.span)
.unwrap_or_else(|_| pprust::expr_to_string(&expr));
let sp = lo.to(expr.span);
hi = sp;
ex = ExprKind::Await(ast::AwaitOrigin::FieldLike, expr);
let mut err = self.struct_span_err(
await_sp,
"incorrect use of `await`",
);
err.span_suggestion(
sp,
"`await` is not a statement",
format!("{}.await", expr_str),
Applicability::MachineApplicable,
);
err.emit();
}
}
} else if self.token.is_path_start() {
let path = self.parse_path(PathStyle::Expr)?;
@ -2913,6 +2993,23 @@ impl<'a> Parser<'a> {
ExprKind::Await(ast::AwaitOrigin::FieldLike, self_arg),
ThinVec::new(),
);
if self.token == token::OpenDelim(token::Paren) &&
self.look_ahead(1, |t| t == &token::CloseDelim(token::Paren))
{
// future.await()
let lo = self.span;
self.bump(); // (
let sp = lo.to(self.span);
self.bump(); // )
let mut err = self.struct_span_err(span, "incorrect use of `await`");
err.span_suggestion(
sp,
"`await` is not a method call, remove the parentheses",
String::new(),
Applicability::MachineApplicable,
);
err.emit()
}
return Ok(await_expr);
}
let segment = self.parse_path_segment(PathStyle::Expr)?;