gleam-lang/gleam · error

segment referenced in a check before being created

Error message

segment referenced in a check before being created

What it means

Error "segment referenced in a check before being created" thrown in gleam-lang/gleam.

Source

Thrown at compiler-core/src/javascript/decision.rs:1824

    ) -> Document<'a, 'doc> {
        if offset.is_zero() {
            return ZERO_DOCUMENT;
        }

        let mut pieces = vec![];
        if offset.constant != BigInt::ZERO {
            pieces.push(eco_string_int(arena, offset.constant.to_string().into()));
        }

        for (variable, times) in offset
            .variables
            .iter()
            .sorted_by(|(one, _), (other, _)| one.name().cmp(other.name()))
        {
            let mut variable = match variable {
                VariableUsage::PatternSegment(segment_name, _) => self
                    .get_segment_value(arena, segment_name)
                    .expect("segment referenced in a check before being created"),
                VariableUsage::OutsideVariable(name) => self.local_var(name).to_doc(arena),
            };
            if *times != 1 {
                variable = variable
                    .append(arena, SPACE_TIMES_SPACE_DOCUMENT)
                    .append(arena, *times);
            }
            pieces.push(variable.to_doc(arena));
        }

        for calculation in offset.calculations.iter() {
            let left = self.offset_to_doc(arena, &calculation.left, true);
            let right = self.offset_to_doc(arena, &calculation.right, true);

            let calculation = self.expression_generator.bin_op_with_doc_operands(
                arena,
                calculation.operator.to_bin_op(),
                left,

View on GitHub (pinned to 7e623aa83d)

When it happens

Trigger: Thrown at compiler-core/src/javascript/decision.rs:1824 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of gleam-lang/gleam@7e623aa83d (2026-08-17). Data as JSON: /api/errors/7a04fb6b6a70bceb. Report an issue: GitHub.