bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

parse guard patterns

Browse source 
Co-authored-by: Max Niederman <max@maxniederman.com>
This commit is contained in:
Nadrieril 2024-11-24 17:36:52 +01:00
parent f86915a682
commit 962c0140c7
17 changed files with 248 additions and 63 deletions
Download patch file Download diff file Expand all files Collapse all files

52
compiler/rustc_parse/src/parser/expr.rs
View file

@ -2776,7 +2776,7 @@ impl<'a> Parser<'a> {
};
// Try to parse the pattern `for ($PAT) in $EXPR`.
let pat = match (
self.parse_pat_no_top_guard(
self.parse_pat_allow_top_guard(
None,
RecoverComma::Yes,
RecoverColon::Yes,
@ -3313,39 +3313,33 @@ impl<'a> Parser<'a> {
fn parse_match_arm_pat_and_guard(&mut self) -> PResult<'a, (P<Pat>, Option<P<Expr>>)> {
if self.token == token::OpenDelim(Delimiter::Parenthesis) {
// Detect and recover from `($pat if $cond) => $arm`.
let left = self.token.span;
match self.parse_pat_no_top_guard(
let pat = self.parse_pat_no_top_guard(
None,
RecoverComma::Yes,
RecoverColon::Yes,
CommaRecoveryMode::EitherTupleOrPipe,
) {
Ok(pat) => Ok((pat, self.parse_match_arm_guard()?)),
Err(err)
if let prev_sp = self.prev_token.span
&& let true = self.eat_keyword(kw::If) =>
{
// We know for certain we've found `($pat if` so far.
let mut cond = match self.parse_match_guard_condition() {
Ok(cond) => cond,
Err(cond_err) => {
cond_err.cancel();
return Err(err);
}
};
err.cancel();
CondChecker::new(self).visit_expr(&mut cond);
self.eat_to_tokens(&[&token::CloseDelim(Delimiter::Parenthesis)]);
self.expect(&token::CloseDelim(Delimiter::Parenthesis))?;
let right = self.prev_token.span;
self.dcx().emit_err(errors::ParenthesesInMatchPat {
span: vec![left, right],
sugg: errors::ParenthesesInMatchPatSugg { left, right },
});
Ok((self.mk_pat(left.to(prev_sp), ast::PatKind::Wild), Some(cond)))
}
Err(err) => Err(err),
)?;
if let ast::PatKind::Paren(subpat) = &pat.kind
&& let ast::PatKind::Guard(..) = &subpat.kind
{
// Detect and recover from `($pat if $cond) => $arm`.
// FIXME(guard_patterns): convert this to a normal guard instead
let span = pat.span;
let ast::PatKind::Paren(subpat) = pat.into_inner().kind else { unreachable!() };
let ast::PatKind::Guard(_, mut cond) = subpat.into_inner().kind else {
unreachable!()
};
self.psess.gated_spans.ungate_last(sym::guard_patterns, cond.span);
CondChecker::new(self).visit_expr(&mut cond);
let right = self.prev_token.span;
self.dcx().emit_err(errors::ParenthesesInMatchPat {
span: vec![left, right],
sugg: errors::ParenthesesInMatchPatSugg { left, right },
});
Ok((self.mk_pat(span, ast::PatKind::Wild), Some(cond)))
} else {
Ok((pat, self.parse_match_arm_guard()?))
}
} else {
// Regular parser flow:

39
compiler/rustc_parse/src/parser/pat.rs
View file

@ -95,6 +95,31 @@ pub enum PatternLocation {
}
impl<'a> Parser<'a> {
/// Parses a pattern.
///
/// Corresponds to `Pattern` in RFC 3637 and admits guard patterns at the top level.
/// Used when parsing patterns in all cases where neither `PatternNoTopGuard` nor
/// `PatternNoTopAlt` (see below) are used.
pub fn parse_pat_allow_top_guard(
&mut self,
expected: Option<Expected>,
rc: RecoverComma,
ra: RecoverColon,
rt: CommaRecoveryMode,
) -> PResult<'a, P<Pat>> {
let pat = self.parse_pat_no_top_guard(expected, rc, ra, rt)?;
if self.eat_keyword(kw::If) {
let cond = self.parse_expr()?;
// Feature-gate guard patterns
self.psess.gated_spans.gate(sym::guard_patterns, cond.span);
let span = pat.span.to(cond.span);
Ok(self.mk_pat(span, PatKind::Guard(pat, cond)))
} else {
Ok(pat)
}
}
/// Parses a pattern.
///
/// Corresponds to `PatternNoTopAlt` in RFC 3637 and does not admit or-patterns
@ -111,8 +136,8 @@ impl<'a> Parser<'a> {
/// Parses a pattern.
///
/// Corresponds to `PatternNoTopGuard` in RFC 3637 and allows or-patterns, but not
/// guard patterns, at the top level. Used for parsing patterns in `pat` fragments and
/// `let`, `if let`, and `while let` expressions.
/// guard patterns, at the top level. Used for parsing patterns in `pat` fragments (until
/// the next edition) and `let`, `if let`, and `while let` expressions.
///
/// Note that after the FCP in <https://github.com/rust-lang/rust/issues/81415>,
/// a leading vert is allowed in nested or-patterns, too. This allows us to
@ -697,7 +722,7 @@ impl<'a> Parser<'a> {
} else if self.check(&token::OpenDelim(Delimiter::Bracket)) {
// Parse `[pat, pat,...]` as a slice pattern.
let (pats, _) = self.parse_delim_comma_seq(Delimiter::Bracket, |p| {
p.parse_pat_no_top_guard(
p.parse_pat_allow_top_guard(
None,
RecoverComma::No,
RecoverColon::No,
@ -945,7 +970,7 @@ impl<'a> Parser<'a> {
let open_paren = self.token.span;
let (fields, trailing_comma) = self.parse_paren_comma_seq(|p| {
p.parse_pat_no_top_guard(
p.parse_pat_allow_top_guard(
None,
RecoverComma::No,
RecoverColon::No,
@ -1360,7 +1385,7 @@ impl<'a> Parser<'a> {
path: Path,
) -> PResult<'a, PatKind> {
let (fields, _) = self.parse_paren_comma_seq(|p| {
p.parse_pat_no_top_guard(
p.parse_pat_allow_top_guard(
None,
RecoverComma::No,
RecoverColon::No,
@ -1395,7 +1420,7 @@ impl<'a> Parser<'a> {
self.parse_builtin(|self_, _lo, ident| {
Ok(match ident.name {
// builtin#deref(PAT)
sym::deref => Some(ast::PatKind::Deref(self_.parse_pat_no_top_guard(
sym::deref => Some(ast::PatKind::Deref(self_.parse_pat_allow_top_guard(
None,
RecoverComma::Yes,
RecoverColon::Yes,
@ -1670,7 +1695,7 @@ impl<'a> Parser<'a> {
// Parsing a pattern of the form `fieldname: pat`.
let fieldname = self.parse_field_name()?;
self.bump();
let pat = self.parse_pat_no_top_guard(
let pat = self.parse_pat_allow_top_guard(
None,
RecoverComma::No,
RecoverColon::No,

2
compiler/rustc_parse/src/parser/path.rs
View file

@ -469,7 +469,7 @@ impl<'a> Parser<'a> {
PathStyle::Pat
if let Ok(_) = self
.parse_paren_comma_seq(|p| {
p.parse_pat_no_top_guard(
p.parse_pat_allow_top_guard(
None,
RecoverComma::No,
RecoverColon::No,