nandi.uk
Fork of daniellemaywood.uk/gleam — Wasm codegen work
🐛 Recognize missing pattern in alternative as syntax error
author
fruno
committer
Louis Pilfold
date
(Nov 18, 2025, 2:50 PM UTC)
commit
ea59a589
ea59a589f81dbc86ac2b10101b1b7da081de9b04
parent
f0cd3860
f0cd3860eaf9a32978724165ee57cf304c9ea388
+83
-4
+11
-4
compiler-core/src/parse.rs
+11
-4
compiler-core/src/parse.rs
···
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1609
match &patterns.first() {
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Some(lead) => {
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let mut alternative_patterns = vec![];
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-
loop {
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-
if self.maybe_one(&Token::Vbar).is_none() {
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-
break;
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+
while let Some((vbar_start, vbar_end)) = self.maybe_one(&Token::Vbar) {
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+
let patterns = self.parse_patterns(PatternPosition::CaseClause)?;
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if patterns.is_empty() {
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return parse_error(
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ParseErrorType::ExpectedPattern,
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SrcSpan {
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start: vbar_start,
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end: vbar_end,
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},
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+
);
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}
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-
alternative_patterns.push(self.parse_patterns(PatternPosition::CaseClause)?);
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alternative_patterns.push(patterns);
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}
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let guard = self.parse_case_clause_guard()?;
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let (arr_s, arr_e) = self
+20
compiler-core/src/parse/snapshots/gleam_core__parse__tests__case_alternative_clause_no_subject.snap
+20
compiler-core/src/parse/snapshots/gleam_core__parse__tests__case_alternative_clause_no_subject.snap
···
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+
---
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+
source: compiler-core/src/parse/tests.rs
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expression: "\nfn main() {\n case 1 {\n 1 | -> 1\n _ -> 1\n }\n}\n"
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+
---
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----- SOURCE CODE
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+
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fn main() {
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case 1 {
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1 | -> 1
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_ -> 1
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}
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}
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+
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+
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----- ERROR
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error: Syntax error
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┌─ /src/parse/error.gleam:4:9
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│
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4 │ 1 | -> 1
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│ ^ I was expecting a pattern after this
+24
compiler-core/src/parse/snapshots/gleam_core__parse__tests__case_clause_no_subject.snap
+24
compiler-core/src/parse/snapshots/gleam_core__parse__tests__case_clause_no_subject.snap
···
1
+
---
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source: compiler-core/src/parse/tests.rs
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expression: "\nfn main() {\n case 1 {\n -> 1\n _ -> 2\n }\n}\n"
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+
---
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----- SOURCE CODE
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+
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fn main() {
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case 1 {
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-> 1
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_ -> 2
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}
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}
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+
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+
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----- ERROR
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error: Syntax error
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┌─ /src/parse/error.gleam:4:7
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│
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4 │ -> 1
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│ ^^ I was not expecting this
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+
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Found `->`, expected one of:
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- `}`
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- a case clause
+28
compiler-core/src/parse/tests.rs
+28
compiler-core/src/parse/tests.rs
···
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}
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#[test]
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fn case_clause_no_subject() {
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assert_module_error!(
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"
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fn main() {
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case 1 {
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-> 1
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_ -> 2
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}
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+
}
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+
"
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+
);
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+
}
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+
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+
#[test]
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fn case_alternative_clause_no_subject() {
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assert_module_error!(
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"
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fn main() {
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case 1 {
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1 | -> 1
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_ -> 1
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}
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}
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"
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);
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}
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+
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#[test]
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fn use_invalid_assignments() {
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assert_module_error!(
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"