What it means. A string, rune, interpolated (s"…") or format (f"…") literal contains an escape sequence that is not one GALA accepts. New in GALA 0.72.2.
GALA’s accepted set is exactly Go’s set for an interpreted literal:
| Escape | Meaning |
|---|---|
\a \b \f \n \r \t \v |
bell, backspace, form feed, newline, carriage return, tab, vertical tab |
\\ |
a literal backslash |
\" |
a double quote (string literals only) |
\' |
a single quote (rune literals only) |
\xHH |
one byte, exactly 2 hexadecimal digits |
\uHHHH |
a code point, exactly 4 hexadecimal digits |
\UHHHHHHHH |
a code point, exactly 8 hexadecimal digits |
\OOO |
one byte, exactly 3 octal digits (0–7), value ≤ 255 |
Anything else after a backslash is rejected. The check also rejects a well-formed-looking escape whose value is out of range: an octal escape above 255, a \u/\U escape naming a surrogate half (U+D800–U+DFFF), or a \U escape above U+10FFFF.
Backtick raw strings are not affected — they have no escapes at all, so every backslash in them is already literal.
The usual offender is a regular expression whose backslash was not doubled:
package main
func main() {
val pattern = "(\d{4})"
Println(pattern)
}
error[GALA-E0038]: invalid escape sequence "\d" in string literal
--> esc.gala:4:21
|
4 | val pattern = "(\d{4})"
| ^^ valid escapes are \a \b \f \n \r \t \v \\ \" \xHH \uHHHH \UH…
|
= hint: valid escapes are \a \b \f \n \r \t \v \\ \" \xHH \uHHHH \UHHHHHHHH and \OOO (octal); to write a literal backslash (in a regular expression, for example) double it (\\) or use a backtick raw string
The caret spans exactly the offending escape sequence.
A malformed — rather than unrecognised — escape names the specific defect in the header:
error[GALA-E0038]: invalid escape sequence "\x4" in string literal: \x requires exactly 2 hexadecimal digits
error[GALA-E0038]: invalid escape sequence "\400" in string literal: the octal value 256 is above the maximum byte value 255
error[GALA-E0038]: invalid escape sequence "\uD800" in string literal: a surrogate half (U+D800-U+DFFF) is not a valid Unicode code point
error[GALA-E0038]: invalid escape sequence "\'" in string literal: \' is only valid in a rune literal; inside a string literal write '
Double the backslash, or switch to a backtick raw string:
val escaped = "(\\d{4})" // the string holds (\d{4})
val raw = `(\d{4})` // raw: every backslash is literal
Both print (\d{4}). For a regular expression the raw-string form is usually clearer, since a regex is full of backslashes that would each need doubling.
If you meant a control character, use its named escape (\n, \t, …) or a numeric one (\x0a, \012).
Rune literals are a narrower case: GALA’s lexer admits exactly one character after the backslash, so only the single-character escapes (\n, \t, \\, \', …) are writable in a 'x' literal at all. The numeric forms are a syntax error there rather than a GALA-E0038 — use a string if you need them.
A literal’s raw source text is copied verbatim into the generated Go literal. GALA’s lexer, however, accepted a backslash followed by any character — a strictly wider set than Go’s — so an unrecognised escape used to travel untouched into the emitted .gen.go, where it is also invalid.
Nothing downstream caught it. go/printer prints a string literal without parsing it, and the two later passes that do re-parse the buffer — the generator’s canonicalising format.Source step, and the source-map rewrite that lowers internal line markers into //line directives — both treated “the buffer does not parse” as tolerable and returned their input unchanged. The result was a file that still contained the transpiler’s internal markers, emitted with a success exit code; the failure only surfaced later as a Go compiler error about an undefined identifier the user never wrote.
Validating the literal where it is converted turns that whole chain into one diagnostic pointing at the offending escape in the .gala file. The marker rewrite now also fails loudly rather than degrading, so no future codegen defect can leak internal markers with a success status either.