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internal: Improve parser recovery a bunch

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This commit is contained in:
Lukas Wirth 2023-02-11 18:06:07 +01:00
parent 5fdf640fb3
commit 1be24e0899
14 changed files with 249 additions and 134 deletions
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29
crates/parser/src/grammar/expressions.rs
View file

@ -68,6 +68,12 @@ pub(super) fn stmt(p: &mut Parser<'_>, semicolon: Semicolon) {
Err(m) => m,
};
if !p.at_ts(EXPR_FIRST) {
p.err_and_bump("expected expression, item or let statement");
m.abandon(p);
return;
}
if let Some((cm, blocklike)) = expr_stmt(p, Some(m)) {
if !(p.at(T!['}']) || (semicolon != Semicolon::Required && p.at(EOF))) {
// test no_semi_after_block
@ -227,6 +233,12 @@ fn expr_bp(
attributes::outer_attrs(p);
m
});
if !p.at_ts(EXPR_FIRST) {
p.err_recover("expected expression", atom::EXPR_RECOVERY_SET);
m.abandon(p);
return None;
}
let mut lhs = match lhs(p, r) {
Some((lhs, blocklike)) => {
let lhs = lhs.extend_to(p, m);
@ -551,6 +563,12 @@ fn cast_expr(p: &mut Parser<'_>, lhs: CompletedMarker) -> CompletedMarker {
m.complete(p, CAST_EXPR)
}
// test_err arg_list_recovery
// fn main() {
// foo(bar::);
// foo(bar:);
// foo(bar+);
// }
fn arg_list(p: &mut Parser<'_>) {
assert!(p.at(T!['(']));
let m = p.start();
@ -563,8 +581,15 @@ fn arg_list(p: &mut Parser<'_>) {
if !expr(p) {
break;
}
if !p.at(T![')']) && !p.expect(T![,]) {
break;
if !p.at(T![,]) {
if p.at_ts(EXPR_FIRST) {
p.error("expected `,`");
continue;
} else {
break;
}
} else {
p.bump(T![,]);
}
}
p.eat(T![')']);

32
crates/parser/src/grammar/expressions/atom.rs
View file

@ -40,26 +40,28 @@ pub(super) const ATOM_EXPR_FIRST: TokenSet =
T!['{'],
T!['['],
T![|],
T![move],
T![box],
T![if],
T![while],
T![match],
T![unsafe],
T![return],
T![yield],
T![do],
T![break],
T![continue],
T![async],
T![try],
T![box],
T![break],
T![const],
T![loop],
T![continue],
T![do],
T![for],
T![if],
T![let],
T![loop],
T![match],
T![move],
T![return],
T![static],
T![try],
T![unsafe],
T![while],
T![yield],
LIFETIME_IDENT,
]));
const EXPR_RECOVERY_SET: TokenSet = TokenSet::new(&[T![let]]);
pub(super) const EXPR_RECOVERY_SET: TokenSet = TokenSet::new(&[T![')'], T![']']]);
pub(super) fn atom_expr(
p: &mut Parser<'_>,
@ -157,7 +159,7 @@ pub(super) fn atom_expr(
T![for] => for_expr(p, None),
_ => {
p.err_recover("expected expression", EXPR_RECOVERY_SET);
p.err_and_bump("expected expression");
return None;
}
};

11
crates/parser/src/grammar/paths.rs
View file

@ -67,6 +67,10 @@ fn path_for_qualifier(
}
}
const EXPR_PATH_SEGMENT_RECOVERY_SET: TokenSet =
items::ITEM_RECOVERY_SET.union(TokenSet::new(&[T![')'], T![,], T![let]]));
const TYPE_PATH_SEGMENT_RECOVERY_SET: TokenSet = types::TYPE_RECOVERY_SET;
fn path_segment(p: &mut Parser<'_>, mode: Mode, first: bool) {
let m = p.start();
// test qual_paths
@ -102,7 +106,12 @@ fn path_segment(p: &mut Parser<'_>, mode: Mode, first: bool) {
m.complete(p, NAME_REF);
}
_ => {
p.err_recover("expected identifier", items::ITEM_RECOVERY_SET);
let recover_set = match mode {
Mode::Use => items::ITEM_RECOVERY_SET,
Mode::Type => TYPE_PATH_SEGMENT_RECOVERY_SET,
Mode::Expr => EXPR_PATH_SEGMENT_RECOVERY_SET,
};
p.err_recover("expected identifier", recover_set);
if empty {
// test_err empty_segment
// use crate::;

3
crates/parser/src/grammar/types.rs
View file

@ -17,8 +17,9 @@ pub(super) const TYPE_FIRST: TokenSet = paths::PATH_FIRST.union(TokenSet::new(&[
T![Self],
]));
const TYPE_RECOVERY_SET: TokenSet = TokenSet::new(&[
pub(super) const TYPE_RECOVERY_SET: TokenSet = TokenSet::new(&[
T![')'],
T![>],
T![,],
// test_err struct_field_recover
// struct S { f pub g: () }