Runtime: ternary with function call in test/alternate — wrong branch value (Zend zend_compile.c parity)

[PurHur]

Category

runtime

Problem

When a ternary (?:) uses a function call in the condition and again in the alternate arm, the VM prints the wrong branch value. A minimal getenv() repro shows the consequent string "unset" is replaced by the function name "getenv" even when the condition is true.

This breaks idiomatic env checks like getenv('VAR') === false ? 'unset' : getenv('VAR') used in bootstrap and CLI tooling.

php-src reference

• php/php-src Zend/zend_compile.c — zend_compile_short_circuit / ternary zend_ast lowering
• php/php-src Zend/zend_execute.c — ZEND_JMP_SET / ZEND_JMP_SET_VAR, short-circuit evaluation order

Repro (failure today)

<?php
putenv('FOO=bar');
putenv('FOO'); // unset
echo getenv('FOO') === false ? 'unset' : getenv('FOO');

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

Runtime	Output
Zend PHP 8.x	unset
bin/vm.php	getenv

Note: assigning to a temp works — $r = getenv('FOO'); echo $r === false ? 'unset' : 'val'; prints unset. Bug is specific to inline ternary with repeated call.

Scope (this repo)

Layer	Path	Notes
Compiler	lib/Compiler.php	Ternary/?? branch merge may reuse wrong operand slot for call results
VM	lib/VM.php	Verify TYPE_JUMP/assign phi for ternary arms
Tests	test/compliance/cases/language/ternary_func_call.phpt	getenv repro + generic foo() stub

Done when

• Repro prints unset on VM
• Condition evaluated once; alternate call evaluated only when condition false
• ./script/ci-fast.sh --filter ternary_func_call green
• No regression on ?? / ?: with literals (Language: Null coalescing operator (??) in compiler pipeline #99, Language: ??= null coalescing assignment #1235)

Verification

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

Links

• Coalesce/ternary merge: Language: Null coalescing operator (??) in compiler pipeline #99, Language: ??= null coalescing assignment #1235
• getenv parity: Stdlib: getenv() — local_only second argument (ext/standard/basic_functions.c parity) #3710 (separate local_only arg)
• North star: Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: runforge-worker-lane-c — lane C had no unclaimed non-stdlib issues; implementing this VM parity gap (ternary merge slot unification).

[PurHur]

Verification (runforge-worker-lane-c)

VM repro green after merge-slot fix:

• putenv('FOO'); echo getenv('FOO') === false ? 'unset' : getenv('FOO'); → unset
• putenv('FOO=bar'); echo … → bar
• vendor/bin/phpunit --filter ternary_func_call OK (VMTest)

PR incoming on agent/issue-3790-ternary-func-call. JIT execute deferred (merge scope in MCJIT).