Language: unimplemented trait abstract method — fatal text/stream vs Zend (Zend/zend_compile.c)

Problem

A concrete class that uses a trait with an unimplemented abstract method must compile-fatal like Zend. VM exits 255 but:

Omits the PHP Fatal error: prefix
Writes the message to stdout (Zend: stderr)
Fails during whole-file compile so preceding statements (e.g. echo \"before\") never run — Zend runs bind-time check when the class declaration executes

Probed 2026-07-31 Zend 8.2.32 vs VM @ fad4609ee.

Repro	Zend 8.2	VM
`echo \"before\"; class C { use TAbs; }` (trait has `abstract function f()`)	stdout `before`; stderr `PHP Fatal error: Class C contains 1 abstract method...`	only `Class C contains 1 abstract method...` on stdout; no `before`

php-src reference

php/php-src Zend/zend_compile.c — trait abstract method verification at class bind
php/php-src Zend/zend_inheritance.c — abstract method residual checks

PHP implementation target

Match Zend bind timing for trait abstract residuals (so prior opcodes run)
Emit PHP Fatal error: ... on stderr with exit 255
PHP-in-PHP compile/VM path; no new C

Repro

./script/docker-exec.sh -- bash -lc 'php test/repro/maintainer_gap_trait_abstract_unimplemented_fatal.php; php bin/vm.php test/repro/maintainer_gap_trait_abstract_unimplemented_fatal.php'

Done when

stdout includes before; stderr has PHP Fatal error: Class … abstract method
exit 255; no accepted
Compliance / repro guard; php-src-strict

claim: lane-B implementer (Composer) — starting this run

Pre-claim gates: user_release_ready: yes; inventory OK 6647/6647; north-star5-fast ok on master. gen-0 seed stale (warning only).

Branch: agent/issue-25912-trait-abstract-unimplemented-fatal

claim: lane-B implementer (Composer) — continuing this run (branch reset to current master; implementing)

Gate snapshot:

docker: ok
release-readiness: north-star5-fast ok; inventory doc construct-flag drift (SessionGcRuntime); gen-0 seed stale (warning)
user_release_ready: checking in-branch

Language: trait abstract residuals fatal at DECLARE after prior stmts (…

Merged via #25922

Verification

Repro: VM stdout before; stderr PHP Fatal error: Class C contains 1 abstract method… (C::f); exit 255; no accepted (matches Zend).
TraitAbstractUnimplementedFatalTest OK (2)
compliance language/trait_abstract_unimplemented_fatal OK
related trait_abstract_* / enum_trait_abstract_* OK (4)

Root cause: DECLARE_CLASS was hoisted before prior stmts; ClassValidator threw LogicException to stdout. Fix: source-order trait-using classes + CompileError → raiseClassDeclareCompileFatal.

Lane B verification (post-merge)

Confirmed on master after #25922:

VM exit 255
stdout: before
stderr: PHP Fatal error:  Class C contains 1 abstract method … (C::f)

Compliance language/trait_abstract_unimplemented_fatal OK. No further work on this issue.

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Language: unimplemented trait abstract method — fatal text/stream vs Zend (Zend/zend_compile.c) #25912

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php-src reference

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Repro

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Lane B verification (post-merge)

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Language: unimplemented trait abstract method — fatal text/stream vs Zend (Zend/zend_compile.c) #25912

Description

Category

Problem

php-src reference

PHP implementation target

Repro

Done when

Activity

PurHur commented on Jul 31, 2026

PurHur commented on Jul 31, 2026

PurHur commented on Jul 31, 2026

PurHur commented on Jul 31, 2026

Lane B verification (post-merge)

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