nandi.uk
Fork of daniellemaywood.uk/gleam — Wasm codegen work
Update wording for suffix concat match error
author
Gavin Morrow
committer
Louis Pilfold
date
(Jun 3, 2026, 3:38 PM +0100)
commit
ad6dc782
ad6dc7829f9fcffad51c95199264ed05ba688e45
parent
dc25ba5a
dc25ba5a29fb8450edc04adc93a92af92e38b4de
change-id
znxzmrym
znxzmrymotqlxqosupkpuwoszknuvwpr
+106
-18
+31
-9
compiler-core/src/parse.rs
+31
-9
compiler-core/src/parse.rs
···
1366
1366
self.advance();
1367
1367
let (r_start, right, r_end) = self.expect_assign_name()?;
1368
1368
1369
-
// Can't match on prefix and suffix
1370
-
if let Some((_, Token::Concatenate, _)) = self.tok0 {
1371
-
return concat_pattern_variable_in_infix_position_error(
1372
-
r_start, r_end,
1369
+
// Can't match on suffix literal
1370
+
if let Some((
1371
+
second_concat_start,
1372
+
Token::Concatenate,
1373
+
second_concat_end,
1374
+
)) = self.tok0
1375
+
{
1376
+
let suffix_end = match &self.tok1 {
1377
+
Some((_start, Token::String { .. }, end)) => *end,
1378
+
_ => second_concat_end,
1379
+
};
1380
+
return concat_pattern_variable_with_suffix(
1381
+
second_concat_start,
1382
+
right.name().clone(),
1383
+
suffix_end,
1373
1384
);
1374
1385
}
1375
1386
···
1408
1419
self.advance();
1409
1420
let (r_start, right, r_end) = self.expect_assign_name()?;
1410
1421
1411
-
// Can't match on prefix and suffix
1412
-
if let Some((_, Token::Concatenate, _)) = self.tok0 {
1413
-
return concat_pattern_variable_in_infix_position_error(r_start, r_end);
1422
+
// Can't match on suffix literal
1423
+
if let Some((second_concat_start, Token::Concatenate, second_concat_end)) =
1424
+
self.tok0
1425
+
{
1426
+
let suffix_end = match &self.tok1 {
1427
+
Some((_start, Token::String { .. }, end)) => *end,
1428
+
_ => second_concat_end,
1429
+
};
1430
+
return concat_pattern_variable_with_suffix(
1431
+
second_concat_start,
1432
+
right.name().clone(),
1433
+
suffix_end,
1434
+
);
1414
1435
}
1415
1436
1416
1437
Pattern::StringPrefix {
···
4664
4685
})
4665
4686
}
4666
4687
4667
-
fn concat_pattern_variable_in_infix_position_error<T>(
4688
+
fn concat_pattern_variable_with_suffix<T>(
4668
4689
start: u32,
4690
+
name: EcoString,
4669
4691
end: u32,
4670
4692
) -> Result<T, ParseError> {
4671
4693
Err(ParseError {
4672
-
error: ParseErrorType::ConcatPatternVariableInInfixPosition,
4694
+
error: ParseErrorType::ConcatPatternVariableWithSuffix { name },
4673
4695
location: SrcSpan::new(start, end),
4674
4696
})
4675
4697
}
+7
-7
compiler-core/src/parse/error.rs
+7
-7
compiler-core/src/parse/error.rs
···
110
110
ConcatPatternVariableLeftHandSide,
111
111
/// A variable was assigned as infix between prefix and suffix string
112
112
/// patterns using <>
113
-
ConcatPatternVariableInInfixPosition,
113
+
ConcatPatternVariableWithSuffix {
114
+
name: EcoString,
115
+
},
114
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ListSpreadWithoutTail, // let x = [1, ..]
115
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ExpectedFunctionBody, // let x = fn()
116
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RedundantInternalAttribute, // for a private definition marked as internal
···
557
559
extra_labels: vec![],
558
560
},
559
561
560
-
ParseErrorType::ConcatPatternVariableInInfixPosition => ParseErrorDetails {
562
+
ParseErrorType::ConcatPatternVariableWithSuffix { name}=> ParseErrorDetails {
561
563
text: [
562
-
"We can't tell what size this infix should be so we don't know",
563
-
"how to handle this pattern.",
564
+
"A string pattern can only match on a literal string prefix.",
564
565
"",
565
-
"If you want to match one character consider using `pop_grapheme`",
566
-
"from the stdlib's `gleam/string` module.",
566
+
&format!("Matching on a literal suffix is not possible, because `{}` would have an unknown size.", name),
567
567
]
568
568
.join("\n"),
569
569
hint: None,
570
-
label_text: "This must be a string literal prefix".into(),
570
+
label_text: "This pattern is not allowed".into(),
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571
extra_labels: vec![],
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572
},
573
573
+19
compiler-core/src/parse/snapshots/gleam_core__parse__tests__assign_infix_and_match_suffix_of_concat_pattern.snap
+19
compiler-core/src/parse/snapshots/gleam_core__parse__tests__assign_infix_and_match_suffix_of_concat_pattern.snap
···
1
+
---
2
+
source: compiler-core/src/parse/tests.rs
3
+
expression: "case \"\" {\n \"prefix\" <> infix <> \"suffix\" -> infix\n}"
4
+
---
5
+
----- SOURCE CODE
6
+
case "" {
7
+
"prefix" <> infix <> "suffix" -> infix
8
+
}
9
+
10
+
----- ERROR
11
+
error: Syntax error
12
+
┌─ /src/parse/error.gleam:2:23
13
+
│
14
+
2 │ "prefix" <> infix <> "suffix" -> infix
15
+
│ ^^^^^^^^^^^ This pattern is not allowed
16
+
17
+
A string pattern can only match on a literal string prefix.
18
+
19
+
Matching on a literal suffix is not possible, because `infix` would have an unknown size.
+19
compiler-core/src/parse/snapshots/gleam_core__parse__tests__discard_infix_and_match_suffix_of_concat_pattern.snap
+19
compiler-core/src/parse/snapshots/gleam_core__parse__tests__discard_infix_and_match_suffix_of_concat_pattern.snap
···
1
+
---
2
+
source: compiler-core/src/parse/tests.rs
3
+
expression: "case \"\" {\n \"prefix\" <> _ <> \"suffix\" -> Nil\n}"
4
+
---
5
+
----- SOURCE CODE
6
+
case "" {
7
+
"prefix" <> _ <> "suffix" -> Nil
8
+
}
9
+
10
+
----- ERROR
11
+
error: Syntax error
12
+
┌─ /src/parse/error.gleam:2:19
13
+
│
14
+
2 │ "prefix" <> _ <> "suffix" -> Nil
15
+
│ ^^^^^^^^^^^ This pattern is not allowed
16
+
17
+
A string pattern can only match on a literal string prefix.
18
+
19
+
Matching on a literal suffix is not possible, because `_` would have an unknown size.
+19
compiler-core/src/parse/snapshots/gleam_core__parse__tests__incomplete_suffix_match_in_concat_pattern.snap
+19
compiler-core/src/parse/snapshots/gleam_core__parse__tests__incomplete_suffix_match_in_concat_pattern.snap
···
1
+
---
2
+
source: compiler-core/src/parse/tests.rs
3
+
expression: "case \"\" {\n \"prefix\" <> wibble <> -> wibble\n}"
4
+
---
5
+
----- SOURCE CODE
6
+
case "" {
7
+
"prefix" <> wibble <> -> wibble
8
+
}
9
+
10
+
----- ERROR
11
+
error: Syntax error
12
+
┌─ /src/parse/error.gleam:2:24
13
+
│
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+
2 │ "prefix" <> wibble <> -> wibble
15
+
│ ^^ This pattern is not allowed
16
+
17
+
A string pattern can only match on a literal string prefix.
18
+
19
+
Matching on a literal suffix is not possible, because `wibble` would have an unknown size.
+11
-2
compiler-core/src/parse/tests.rs
+11
-2
compiler-core/src/parse/tests.rs
···
635
635
}
636
636
637
637
#[test]
638
-
fn discard_infix_of_concat_pattern() {
638
+
fn discard_infix_and_match_suffix_of_concat_pattern() {
639
639
assert_error!(
640
640
r#"case "" {
641
641
"prefix" <> _ <> "suffix" -> Nil
···
644
644
}
645
645
646
646
#[test]
647
-
fn assign_infix_of_concat_pattern() {
647
+
fn assign_infix_and_match_suffix_of_concat_pattern() {
648
648
assert_error!(
649
649
r#"case "" {
650
650
"prefix" <> infix <> "suffix" -> infix
651
+
}"#
652
+
);
653
+
}
654
+
655
+
#[test]
656
+
fn incomplete_suffix_match_in_concat_pattern() {
657
+
assert_error!(
658
+
r#"case "" {
659
+
"prefix" <> wibble <> -> wibble
651
660
}"#
652
661
);
653
662
}