fix: support class constants in defined()

[nahime0]

Summary

• resolve literal defined('Class::CONST') names through class, interface, trait-imported, and enum metadata instead of the global-constant table alone
• preserve PHP class/member casing, inheritance, implemented interfaces, visibility, lexical self::/parent::, named arguments, and runtime-called-class static:: behavior
• preserve the hidden called-class capture through class-scope closures and Closure::bind, bindTo, and call on every supported target
• compose trait constants in the frontend, accepting declarations with equivalent folded PHP values and rejecting incompatible trait/class compositions before canonical class metadata is built
• raise catchable PHP Errors for invalid relative scopes and mark defined() as potentially throwing so exception optimization preserves handlers
• document the behavior and demonstrate class and late-static probes in the classes example

Verification

• PHP 8 cross-checks for late-static, named, trait-imported, equivalent/conflicting trait, visibility, namespace/casing, and invalid-scope behavior
• cargo test --test codegen_tests test_defined_literal (10 passed)
• cargo test --test codegen_tests closure_bind (22 passed)
• focused trait-constant codegen/eval/reflection and conflict-diagnostic tests
• focused closure call, existing late-static constant, diagnostics, and EIR smoke tests
• optimizer-on/off parity for late-static and trait-imported probes
• emitter coverage for macOS AArch64, iOS ARM64, iOS Simulator ARM64, Linux AArch64, and Linux x86_64 closure-bind descriptors
• cargo build
• generated builtin docs/parity/EIR-boundary audit workflow
• assembly-comment and diff hygiene checks

Remaining limit

• eval-mode class-constant names and dynamic/first-class-callable defined() names remain outside this AOT lookup

Fixes #752
Fixes #1005
Fixes #1006

  

[greptile-apps]

Greptile Summary

This PR extends literal defined() handling to class-like constants and adds the metadata, late-static dispatch, closure capture preservation, trait composition, diagnostics, documentation, and regression coverage needed to support it.

• Resolves class, interface, enum, inherited, and trait-imported constants with PHP-compatible casing and visibility.
• Dispatches static:: probes using the runtime called class and preserves that state through closure binding.
• Detects incompatible trait-constant compositions and compares simple folded constant values.
• Marks invalid relative-scope probes as throwing and documents the supported AOT behavior.

Confidence Score: 4/5

The PR is not yet safe to merge because equivalent trait constants can still be rejected when equality requires resolving a named or scoped constant rather than folding literal arithmetic.

The previous equivalent-constant finding is only partially fixed: constants_compatible now normalizes expressions such as 3 + 4 and 7, but standalone folding leaves named constants and class/scoped constant accesses unresolved, so declarations whose evaluated PHP values are equal can remain structurally different and still trigger the incompatible-composition diagnostic.

Important Files Changed

Filename	Overview
src/types/defined.rs	Implements scope-aware class-like constant existence checks, relative-scope validation, inheritance, interfaces, enum cases, and PHP casing rules.
src/ir_lower/expr/scoped_values.rs	Adds runtime called-class dispatch for literal defined('static::CONST') probes.
src/ir_lower/expr/closures.rs	Captures the called-class identifier in class-scope closures so late-static behavior survives method return.
src/codegen_support/runtime/callables/closure_bind.rs	Extends closure binding to validate and copy descriptors containing the hidden called-class capture across all supported targets.
src/types/traits/merge.rs	Composes trait constants and compares duplicate values after standalone folding, but the previous equivalent-value finding remains only partly fixed.
tests/codegen/oop/constants.rs	Adds broad regression coverage for class-like defined() behavior, visibility, late-static dispatch, traits, enums, and invalid scopes.

_{Reviews (9): Last reviewed commit: "fix: compare folded trait constant value..." | Re-trigger Greptile}

[cursor]

Greptile P1 disposition after PHP 8.5 and compiler-path verification:

• P1a — DEFER-with-follow-up: valid late-static gap; runtime called-class work is #1005.
• P1b — VALID / fixed: invalid relative scopes now throw catchable Error; defined() is marked MAY_THROW so exception optimization preserves the handler.
• P1c — DEFER-with-follow-up: valid trait-composition gap; shared AOT trait-constant work is #1006.

Current HEAD: 000c2248e4bad2db47785e2561973bc92f0491c4. Focused class-constant, diagnostics, EIR smoke, PHP cross-check, build, generated builtin-docs, and hygiene checks pass.

[nahime0]

Follow-up for the residual Greptile 4/5 (named/scoped trait const equality before compare): #1007