Handle empty mapping key separator as parse error#525
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Replace an assertion-only guard in KEY_SEPARATOR handling with a parse_error when the parser sees a mapping value separator without an active context. This prevents malformed input such as `: foo` from aborting on FK_YAML_ASSERT(!m_context_stack.empty()) and lets callers handle the failure through the normal exception path. Add regression coverage for the empty-key separator case and for the issue fktn-k#514 input to ensure it does not abort during deserialization.
sndth
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fktn-k
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Jul 7, 2026
Parse a root-level mapping value separator as an empty string key instead of throwing a parse_error. This supports YAML such as `: foo` as a mapping with `""` as the key, while leaving empty mapping keys inside block sequences unsupported for now. Update the key separator regression tests accordingly.
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This PR introduces a defensive fix for malformed mapping key separators.
The deserializer previously relied on
FK_YAML_ASSERT(!m_context_stack.empty())when handling aKEY_SEPARATORtoken. For malformed input such as:: foothe context stack can be empty, causing the process to abort instead of throwing a catchable exception.
This change replaces that assertion-only guard with a
parse_errorwhen a key separator is encountered without an active parsing context. This keeps malformed input on the normal error handling path and lets callers catch the failure.I could not reproduce the exact assertion failure from issue #514 locally with:
"\"\":\n port:not_a_scalar]\n"On my environment, that input is parsed as a mapping with an empty string key and a plain scalar value. I still added regression coverage for it to ensure deserialization does not abort.
Added regression coverage for:
: foo) throwingparse_errorPull Request Checklist
Read the CONTRIBUTING.md file for detailed information.
Please don't
#ifdefs or other means.