Language: throw expression in assignment — $x = throw new Exception() (Zend zend_compile.c parity)

[PurHur]

Category

language

Problem

Throw expressions outside throw; statements are not lowered. Assignment RHS $x = throw new Exception('e') fails in php-cfg:

Unknown Expr Type Expr_Throw

Distinct from null-coalesce throw (#3462) and match throw arms (#3398).

php-src reference

• Zend/zend_compile.c — zend_compile_throw as expression (zend_ast throw expr)
• Zend/zend_execute.c — ZEND_THROW with unused result slot
• PHP RFC: Throw Expression (PHP 8.0)

Repro (today)

<?php
function f(): int {
    $x = throw new LogicException('abort');
    return $x;
}
try {
    f();
} catch (LogicException $e) {
    echo $e->getMessage();
}

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php repro.php'
php repro.php

Zend: prints abort (after #3371 / #195 register LogicException).
This compiler: compile fatal Unknown Expr Type Expr_Throw.

Requires #3371 / #195 for builtin exception classes before catch path is meaningful.

Scope (this repo)

Path	Notes
vendor/ircmaxell/php-cfg	Map Expr_Throw in assignment/return/comma contexts
lib/Compiler.php	Lower throw-expr → TYPE_THROW + unreachable merge
lib/VM.php	Propagate exception, no assign to LHS
Tests	test/compliance/cases/language/throw_expression_assign.phpt

Done when

• Repro compiles; catch prints abort once Language: Throwable / Error / TypeError / ValueError — builtin exception hierarchy (Zend zend_exceptions.c parity) #3371 green
• $x = throw ... never assigns to $x
• ./script/ci-fast.sh --filter throw_expression_assign green

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter throw_expression_assign'

Related

• Language: throw expressions and Exception object propagation #195 / Language: Throwable / Error / TypeError / ValueError — builtin exception hierarchy (Zend zend_exceptions.c parity) #3371 — exception hierarchy
• Language: null coalesce throw — ($x ?? throw new Exception()) (Zend zend_compile.c parity) #3462 — ?? throw
• Language: match expression throw arms — Expr_Throw in arm bodies (php-cfg + Zend parity) #3398 — match throw arms

[PurHur]

claim: worker-lane-c — starting this run

[PurHur]

claim: cursor-agent-lane-c — starting this run (rebase stale PR #3530 onto master, add compliance PHPT)