Back-to-back metadata blocks triggers misleading parse error

[johanfylling]

If a policy has two METADATA blocks declared back-to-back, with no empty lines in-between, e.g.:

package play

# METADATA
# title: Ps
# scope: document
# METADATA
# title: P
p := rego.metadata.chain()

A hard to understand, and possibly misleading error is generated:

policy.rego:7: rego_parse_error: yaml: line 4: could not find expected ':'

Presumably, this error is rooted in the second METADATA header being interpreted as a yaml attribute, and is expected to be followed by a :. This is however not very helpful to the author, as they clearly intended to start a new set of annotations, and not to add another annotation to the first block.

[johanfylling]

Opinion: although it can be argued it's more readable to separate METADATA blocks with newlines, there is no real reason to disallow this in the parser; and should instead be seen as something a linter (like Regal) should have opinions about.

[stale]

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