v1.108.267 - Kotlin and Bash constants are extracted, and a declared pattern must now prove itself

Reported by @mussonking (#428) against Rust, confirmed across six languages.

The defect

A LanguageSpec can declare constant_patterns, the walker can dispatch on them, and _extract_constant can have no branch for any of them. It falls through to return None.

There is no signal, and that is the actual harm. A declared-but-unimplemented pattern is indistinguishable from a language that genuinely has no constants: search_symbols returns nothing and the caller concludes the symbol does not exist, which is the one thing an index must never let you conclude wrongly. The reporter only caught it because he knew for a fact his file held 935 of them.

Six languages declare a constant surface and extract nothing: Rust, Go, Java, PHP, Kotlin, Bash. Membership in constant_patterns predicts nothing in either direction, because Scala and Gleam also declare patterns with no branch and work anyway by routing through symbol_node_types instead.

Fixed here: Kotlin and Bash

Kotlin was a different and nastier failure than a missing branch. There is a property_declaration branch, but it is written against Swift's grammar: it requires a value_binding_pattern child with mutability == let. Kotlin spells the same thing binding_pattern_kind > val, with the name under variable_declaration > simple_identifier, so the branch returned None on every possible Kotlin input while reading as coverage. It is now keyed on language as well as node type, because a branch keyed only on node type is how it went unreachable in the first place. const val is a constant by declaration; a bare val is merely immutable, so it takes the naming convention the other extractors use.

Bash settled the multi-symbol question. readonly FIRST="x" SECOND="y" is one declaration_command carrying two variable_assignment children, and Optional[Symbol] cannot express that. A new plural _extract_constants handles multi-binding node types and delegates everything else to _extract_constant unchanged, so Go's const ( ... ) and Java's multi-declarator field_declaration have their plumbing already in place. Only the read-only forms count: local and a bare declare declare a variable, so the declaration itself is the evidence and no naming heuristic is needed.

The part that outlives the instance

tests/test_constant_extraction_guard.py walks every spec declaring constant_patterns, feeds it a minimal sample, and asserts at least one constant comes back. Rust, Go, Java and PHP are exempt by name with #428 and a reason, never as a category, and a ratchet asserts each still extracts nothing, so a fix cannot land without deleting its own exemption. Those four are left for the PR @mussonking offered.

The guard isolates config, and it has to. parse_file consults is_language_enabled, so an unisolated run reports the developer's config.jsonc rather than the parser. A first sweep here showed a seventh affected language, arduino, extracting zero symbols; it was disabled locally and the parser was fine. Same failure mode as #411, where a test read the real ~/.code-index/config.jsonc.

Guard proven non-vacuous against unmodified HEAD in an isolated worktree: 5 fail before the fix, 19 pass, and the passing set includes the exemption ratchet and a control asserting the measurement can return empty.

Full suite 7428 passed, 7 skipped, ruff clean. The delta from .266's 7404 is exactly the 24 new guard tests; nothing else moved.