Language: reject closure use($this) as Zend lexical fatal (#32152)

lib/Compiler.php

@@ -1079,6 +1079,26 @@ protected function assertReadonlyParamOnlyInConstructor(array $params, ?CfgFunc
         }
     }
 
+    /**
+     * php-src: Zend/zend_compile.c zend_compile_closure_binding() — $this is never a legal use() name (#32152).
+     *
+     * @param list<Operand\BoundVariable> $closureUseVars
+     */
+    protected function assertNoThisInClosureUseVars(array $closureUseVars, Op $source): void
+    {
+        foreach ($closureUseVars as $useVar) {
+            if ('this' !== $this->boundVariableName($useVar)) {
+                continue;
+            }
+            $detail = 'Cannot use $this as lexical variable';
+            $sourceFile = $source->getFile();
+            if ('' === $sourceFile) {
+                $sourceFile = 'unknown';
+            }
+            $this->throwCompileError($detail, $sourceFile, $source->getLine());
+        }
+    }
+
     /**
      * @param list<Operand\BoundVariable> $closureUseVars
      */
@@ -14819,6 +14839,7 @@ protected function compileAnonymousFunctionExpr($expr, Block $block): array
                     $closureUseVars[] = $useVar;
                 }
             }
+            $this->assertNoThisInClosureUseVars($closureUseVars, $expr);
         }
         try {
             $funcBlock = $this->compileCfgBlock($func->cfg, $func->params, $func, $closureUseVars);

phpunit.xml.dist

@@ -140,6 +140,8 @@
             <file>./test/compliance/TraitDiamondInsteadofRequiredNotAddedJITTest.php</file>
             <file>./test/compliance/TraitInsteadofParentVMTest.php</file>
             <file>./test/compliance/TraitInsteadofParentJITTest.php</file>
+            <file>./test/compliance/ClosureUseThis32152VMTest.php</file>
+            <file>./test/compliance/ClosureUseThis32152JITTest.php</file>
             <file>./test/compliance/UninitTypedArrayDimAssignVMTest.php</file>
             <file>./test/compliance/UninitTypedArrayDimAssignJITTest.php</file>
             <file>./test/compliance/UninitTypedArrayDimRwVMTest.php</file>

test/compliance/ClosureUseThis32152JITTest.php

@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PHPCompiler;
+
+require_once __DIR__.'/../BaseTest.php';
+
+/**
+ * JIT: closure use($this) is Zend compile fatal (#32152, zend_compile.c).
+ *
+ * Dedicated provider — path-slash data-set names break --filter on full JITTest.
+ *
+ * @group llvm
+ */
+final class ClosureUseThis32152JITTest extends BaseTest
+{
+    protected static string $DIR = __DIR__;
+
+    public static function providePHPTests(): \Generator
+    {
+        yield 'closure_use_this.phpt' => self::parsePHPT(
+            __DIR__.'/cases/language/closure_use_this.phpt',
+            'closure_use_this.phpt'
+        );
+        yield 'closure_use_this_method.phpt' => self::parsePHPT(
+            __DIR__.'/cases/language/closure_use_this_method.phpt',
+            'closure_use_this_method.phpt'
+        );
+    }
+
+    public function setUp(): void
+    {
+        $this->BIN = realpath(__DIR__.'/../../bin/jit.php');
+    }
+}

test/compliance/ClosureUseThis32152VMTest.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PHPCompiler;
+
+require_once __DIR__.'/../BaseTest.php';
+
+/**
+ * VM: closure use($this) is Zend compile fatal (#32152, zend_compile.c).
+ *
+ * Dedicated provider — path-slash data-set names break --filter on full VMTest.
+ */
+final class ClosureUseThis32152VMTest extends BaseTest
+{
+    protected static string $DIR = __DIR__;
+
+    public static function providePHPTests(): \Generator
+    {
+        yield 'closure_use_this.phpt' => self::parsePHPT(
+            __DIR__.'/cases/language/closure_use_this.phpt',
+            'closure_use_this.phpt'
+        );
+        yield 'closure_use_this_method.phpt' => self::parsePHPT(
+            __DIR__.'/cases/language/closure_use_this_method.phpt',
+            'closure_use_this_method.phpt'
+        );
+    }
+
+    public function setUp(): void
+    {
+        $this->BIN = realpath(__DIR__.'/../../bin/vm.php');
+    }
+}

test/compliance/cases/language/closure_use_this.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Language: closure use($this) is compile-time fatal (#32152, Zend/zend_compile.c)
+--FILE--
+<?php
+$f = function () use ($this) { return 1; };
+echo "accepted\n";
+--EXPECT_EXIT--
+255
+--EXPECTF--
+%APHP Fatal error:  Cannot use $this as lexical variable in %s on line %d

test/compliance/cases/language/closure_use_this_method.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Language: method-scope closure use($this) is compile-time fatal (#32152, Zend/zend_compile.c)
+--FILE--
+<?php
+class C {
+    public function m() {
+        $f = function () use ($this) { return 1; };
+        echo "accepted\n";
+        return $f;
+    }
+}
+(new C())->m();
+--EXPECT_EXIT--
+255
+--EXPECTF--
+%APHP Fatal error:  Cannot use $this as lexical variable in %s on line %d

test/repro/maintainer_gap_use_this.php

@@ -0,0 +1,8 @@
+<?php
+/**
+ * Maintainer gap #32152: function () use ($this) is accepted.
+ * Zend: compile fatal "Cannot use $this as lexical variable" (rc=255).
+ * php-src: Zend/zend_compile.c zend_compile_closure_binding().
+ */
+$f = function () use ($this) { return 1; };
+echo "accepted\n";

test/unit/ClosureUseThisCompileFatalTest.php

@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PHPCompiler\Test\Unit;
+
+use PHPCompiler\Runtime;
+use PHPUnit\Framework\TestCase;
+
+/** @covers issue #32152 — closure use($this) is a Zend compile-time fatal */
+final class ClosureUseThisCompileFatalTest extends TestCase
+{
+    /**
+     * @dataProvider illegalUseThisProvider
+     */
+    public function testUseThisFailsAtCompileTime(string $code): void
+    {
+        $runtime = new Runtime();
+        $this->expectException(\CompileError::class);
+        $this->expectExceptionMessage('Cannot use $this as lexical variable');
+        $runtime->parseAndCompile($code, 'closure_use_this.php');
+    }
+
+    /** @return iterable<string, array{string}> */
+    public static function illegalUseThisProvider(): iterable
+    {
+        yield 'file scope' => ['<?php $f = function () use ($this) { return 1; }; echo "accepted\n";'];
+        yield 'by-ref' => ['<?php $f = function () use (&$this) { return 1; }; echo "accepted\n";'];
+        yield 'method scope' => [
+            '<?php class C { public function m() { $f = function () use ($this) { return 1; }; echo "accepted\n"; } } (new C())->m();',
+        ];
+        yield 'mixed uses' => ['<?php $a = 1; $f = function () use ($a, $this) { return $a; }; echo "accepted\n";'];
+    }
+
+    public function testLegalUseStillCompiles(): void
+    {
+        $runtime = new Runtime();
+        $block = $runtime->parseAndCompile(
+            '<?php $a = 2; $f = function () use ($a) { return $a; }; echo $f();',
+            'closure_use_ok.php'
+        );
+        $this->assertNotNull($block);
+        ob_start();
+        $runtime->run($block);
+        $this->assertSame('2', ob_get_clean());
+    }
+
+    public function testMethodClosureAutoBindsThisWithoutUse(): void
+    {
+        $runtime = new Runtime();
+        $block = $runtime->parseAndCompile(
+            '<?php class C { public int $n = 7; public function m() { $f = function () { return $this->n; }; echo $f(); } } (new C())->m();',
+            'closure_this_ok.php'
+        );
+        $this->assertNotNull($block);
+        ob_start();
+        $runtime->run($block);
+        $this->assertSame('7', ob_get_clean());
+    }
+}