fix: parse errors show meaningful messages instead of internal 'fail' label#1022
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stephenamar-db merged 1 commit intoJun 24, 2026
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Motivation:
Parse errors exposed fastparse's internal combinator name "fail"
(e.g., "Expected fail:1:12"), which is meaningless to users.
Root cause: Several parser rules used bare `Fail` instead of
`Fail.opaque("descriptive message")`, causing fastparse to use
the default "fail" label in error messages.
Fix: Replace bare `Fail` with descriptive `Fail.opaque(...)`:
- String literal parsing: "string literal"
- Verbatim string (@): "verbatim string literal (@\" or @')"
- Expression parsing: "expression"
Result:
- Before: "Expected fail:1:12, found ..."
- After: "Expected expression:1:12, found ..."
Also includes error test files for format %c validation (from PR databricks#1015).
Cross-implementation comparison (local x = ; x):
| Implementation | Error message |
|---|---|
| C++ jsonnet | "unexpected: \";\" while parsing terminal" |
| go-jsonnet | "Unexpected: \";\" while parsing terminal" |
| sjsonnet (before) | "Expected fail:1:12" |
| sjsonnet (after) | "Expected expression:1:12" ✅ |
stephenamar-db
approved these changes
Jun 24, 2026
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fix: parse errors show meaningful messages instead of internal "fail" label
Motivation
Parse errors exposed fastparse's internal combinator name
"fail"(e.g.,Expected fail:1:12), which is meaningless to users. Root cause: several parser rules used bareFailinstead ofFail.opaque("descriptive message").Modification
Parser.scala: Replaced 5 bareFailwith descriptiveFail.opaque(...):"string literal"@) →"verbatim string literal (@\" or @')""expression"Result
local x = ; xExpected fail:1:12❌Expected expression:1:12✅@helloExpected fail:1:2❌Expected verbatim string literal✅{a: }Expected fail:1:6❌Expected expression:1:6✅