Language: catch (Exception $this) compiles — Zend "Cannot re-assign $this" (Zend/zend_compile.c)

[PurHur]

Category

language · php-src-strict · catch · compile-time fatal

Problem

php-src rejects $this as a catch variable at compile time (zend_compile_catch). This compiler accepts catch (Exception $this) — the illegal program runs and prints instead of aborting. VM and JIT both take the accept path.

rejectThisReassignment() already covers Assign / AssignRef / list-destruct / inc-dec, but catch binding does not go through those ops.

Repro	Zend 8.2+	VM/JIT (2026-08-18 @ af5eba395e)
try { throw new Exception('x'); } catch (Exception $this) { echo "accepted\n"; } (inside a method)	Fatal: Cannot re-assign $this (rc=255)	accepted (rc=0)

Silent accept is a php-src-strict miss, not an error-text nit. Sibling of #4865 ($this = …) and #32179 (function foo($this)).

php-src reference

• php/php-src Zend/zend_compile.c — zend_compile_catch(); catch variable named $this is Cannot re-assign $this

PHP implementation target

• lib/Compiler.php compile of Op\Stmt\TryCatch (resolveCatchVariableName around the catch-slot reserve) — when the catch name is this, emit Zend's compile fatal and abort
• AST visitor on PhpParser\Node\Stmt\Catch_ is also fine if it runs before php-cfg
• Same path for JIT/AOT; no new runtime/*.c logic

Repro

./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_catch_this.php 2>&1 | head -5'
./script/docker-exec.sh -- bash -lc 'php bin/jit.php test/repro/maintainer_gap_catch_this.php 2>&1 | head -5'

Done when

• VM and JIT compile-abort with Zend substring Cannot re-assign $this (rc≠0, no accepted output)
• Compliance .phpt guard under test/compliance/cases/language/ (e.g. catch_this_compile_fatal.phpt)
• php-src-strict; no php-compiler-strict shortcut

[PurHur]

claim: PHP Compiler Worker C — starting this run

[PurHur]

merged: #32216

VM and JIT compile-abort with Zend Cannot re-assign $this (rc=255, no accepted).

./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_catch_this.php'
# vm_rc=255
# PHP Fatal error:  Cannot re-assign $this in .../maintainer_gap_catch_this.php on line 9

./script/docker-exec.sh -- bash -lc 'php bin/jit.php test/repro/maintainer_gap_catch_this.php'
# jit_rc=255
# PHP Fatal error:  Cannot re-assign $this in .../maintainer_gap_catch_this.php on line 9

./script/phpunit.sh --filter 'CatchThisCompileFatalTest|CatchThis32204'
# OK (10 tests, 20 assertions)

php-src: Zend/zend_compile.c zend_compile_catch(). PHP: lib/Compiler.php assertNoThisAsCatchVariable().