Language: JIT new $class (variable classname) — LogicException resolveClassId (Zend/zend_compile.c) #27156

Category

Language · php-src-strict · JIT instantiation · pillar 4

Problem

new $class when $class is a runtime string works on Zend and VM (and is a common dynamic-instantiation pattern). JIT aborts in Object_::resolveClassId() with LogicException: JIT only supports constant named classes for class const fetch — the dynamic classname operand is rejected as if it were a class-const fetch.

Verified 2026-08-03 at e0e5e10c9 (Docker Zend 8.2.32):

Related closed work covered $class::CONST (#4095) and $var::class (#4179); this is the complementary new $var path.

php-src reference

• php/php-src Zend/zend_compile.c — zend_compile_new, ZEND_FETCH_CLASS for runtime classname
• php/php-src Zend/zend_execute.c — ZEND_NEW with fetched class entry

PHP implementation target

• lib/JIT/Builtin/Type/Object_.php — resolveClassId() / new lowering: runtime string classname → class table lookup (mirror Language: JIT class constant fetch with variable class operand ($class::CONST) #4095 pattern)
• lib/JIT.php — TYPE_NEW / instantiation when class operand is not Operand\Literal
• No new C runtime logic

Repro

./script/docker-exec.sh -- bash -lc 'cat > /tmp/new_var.php << \"PHP\"
<?php
$class = \"stdClass\";
$o = new $class;
echo get_class($o), \"\n\";
$class2 = \"Exception\";
try { throw new $class2(\"boom\"); } catch (Throwable $e) {
  echo get_class($e), \":\", $e->getMessage(), \"\n\";
}
PHP
php /tmp/new_var.php
php bin/vm.php /tmp/new_var.php
php bin/jit.php /tmp/new_var.php'

Expect stdClass / Exception:boom on all three.

Done when

• bin/jit.php prints stdClass + Exception:boom (no resolveClassId LogicException)
• Invalid classname throws Error matching Zend
• Compliance .phpt under test/compliance/cases/language/
• php-src-strict; no php-compiler-strict shortcut