autoindex: capture PHP enums and class constants - #286

Written by an AI coding agent (Claude Opus 5 via Claude Code), run by @pradaev.
@pradaev has signed the CLA (#289) and approved this for review.

Defect

PHP_Q matched functions, methods, classes, interfaces and traits.
enum_declaration was absent, and so was every form of named constant.

The enum gap is the severe one, because it is not a missing kind on an
otherwise-indexed file. A PHP 8.1 enum declares no class, no interface and no
trait, so a file holding one extracted zero symbols — the type could not be
found by its own name through symbol search at all. That is #170's failure mode.
Backed enums are the idiomatic way to express a closed set of values in modern
PHP, and they are exactly what a caller looks up by name.

Class constants are PHP's only way to write a named constant inside a type.
Without them, a class made mostly of constants — a limits table, a status
registry — carried only its own name into defs, and the constant the caller was
searching for was not there.

Fix

(enum_declaration name: (name) @enum)
(enum_case name: (name) @const)
(const_declaration (const_element (name) @const))

• One const_declaration pattern serves both a class/interface/enum constant and
  a file-scope const — the grammar uses the same node for both, with
  const_element holding the name. Verified against to_sexp() output, including
  the modifier-and-type form public const int X = 1, where the name still sits
  in const_element.
• Deliberately not anchored, unlike the C, Go and Rust queries. PHP has no
  function-local const statement, so there is no locals trap to guard against,
  and anchoring would only cost recall on constants declared inside a namespace
  block. define() is a function call — a different node — and stays uncaptured.
• Enum cases are @const, matching how Go's const_spec members are treated: a
  case is a named constant of the enum type, and it is what a caller greps for
  when they know the value but not the type.

Failing test first

php_enum_and_const, run against unfixed main. Note what is in the output: the
class and the interface, and nothing else — the enum Suit is absent entirely,
along with all five constants:

---- extract::code::tests::php_enum_and_const stdout ----
thread 'extract::code::tests::php_enum_and_const' panicked at
crates/xerj-autoindex/src/extract/code.rs:513:9:
got [("C", "class", 3), ("I", "interface", 4)]

test result: FAILED. 24 passed; 3 failed

Verified — commands run in this environment, output observed

• cargo test -p xerj-autoindex --lib extract::code on unfixed main → the failure above
• cargo test -p xerj-autoindex --lib extract::code on this branch → ok. 25 passed; 0 failed
• cargo clippy -p xerj-autoindex --all-targets -- -D warnings → clean
• cargo fmt --all -- --check → clean
• ES-YAML conformance suite, on this branch's tree:
  ./target/release/es-yaml-runner --dir tests/es-compat-yaml/yaml
  -> 1366 passed · 0 failed · 3 skipped · 1369 total, runner exit 0
  (release binary built from this branch, node started on a fresh mktemp -d)
• Node shapes confirmed by dumping to_sexp() before writing the patterns:
  (enum_declaration name: (name) … body: (enum_declaration_list (enum_case name: (name) …)))
  and (const_declaration (visibility_modifier) type: (primitive_type) (const_element (name) …)).

Assumed — NOT tested

• Enum cases of a pure enum (no backing type) are assumed to use the same
  enum_case node as a backed enum. The test covers the backed form only.
  Falsified by a grammar that gives pure cases a different node.
• Capturing every enum case is assumed to be net-positive rather than noise. A
  very large enum will now contribute many @const entries. Go's grouped
  const (…) sets the precedent, but I did not measure the distribution of PHP
  enum sizes.

Evidence boundary

First observed while indexing a private PHP monolith: 571 files whose top-level
declaration is an enum produced no defs/symbols, confirmed by fetching one
such document from a running node and finding language: php with both fields
absent. That corpus is not shareable, so the committed test is the reproducible
evidence.

Not run

• Pre-existing macOS-only failure in the crate's wider suite
  (content::tests::lossy_display_collisions_keep_distinct_alias_identities,
  Os { code: 92, "Illegal byte sequence" }), reproduced on unmodified main
  in this environment and unrelated to this change.