Regression: var_export($expr !== false, true) returns NULL — false literal misread as return flag (re-#13694, lib/Compiler.php) #17250

Category

Regression · php-src-strict · compile inline-arg wiring

Problem

var_dump($x !== false) was fixed in #13694, but var_export($expr !== false, true) still mis-compiles on master (2026-07-07): php-cfg hoists the false literal and the consumer pass treats it as var_export()’s return-mode flag instead of the comparison operand. Zend exports the boolean result; this compiler returns NULL, exports the LHS value, or prints the wrong boolean for loose != false.

php-src reference

• php/php-src ext/standard/var.c — php_var_export_ex() formats the first argument value; false in !== false is not a separate call argument
• php/php-src Zend/zend_compile.c — comparison result is arg #0; trailing true is arg Php stdlib specs implementation #1 only

PHP implementation target

• lib/Compiler.php — extend isComparisonInlineCallArgProducer() / resolveInlineCallArgProducer() so NotIdentical/NotEqual with false RHS feed arg #0 for var_export (mirror Language: comparison inside function call argument — var_dump($x !== false) binds as (var_dump($x)) !== false (Zend/zend_compile.c) #13694 var_dump path); do not hoist RHS false as return flag (Regression: array read with false key on string-keyed array returns false not NULL (re-#5275, Zend/zend_hash.c) #16738, Regression: var_export(arithmetic_expr, true) exports return flag not expression (lib/Compiler.php inline arg wiring) #17210 patterns)
• ext/standard/var_export.php / ext/standard/VmVarExport.php — VM formatter is fine once args are wired correctly

Repro

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

Done when

• test/repro/maintainer_gap_var_export_neq_false.php prints five true/false lines then ok on VM/JIT/AOT
• Compliance .phpt guard under test/compliance/cases/stdlib/var_export_comparison_neq_false.phpt
• InlineCallArgProducerSlotTest var_export comparison cases green
• php-src-strict; no php-compiler-strict shortcut