Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
8b52f4e8f7
This PR fixes `FirstTokens.seq (.optTokens s) .unknown` to return `.unknown`. This occurs e.g. when an optional (with first tokens `.optTokens s`) is followed by a parser category (with first tokens `.unknown`). Previously `FirstTokens.seq` returned `.optTokens s`, ignoring the fact that the optional may be empty and then the parser category may have any first token. The correct behavior here is to return `.unknown`, which indicates that the first token may be anything. Closes #13203 |
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| lean-toolchain | ||
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