Language: silence @ on assignment RHS (#29132)

lib/Compiler.php

@@ -12325,7 +12325,9 @@ private function isErrorSuppressInnerExpr(Op $child): bool
             || $child instanceof Op\Expr\Include_
             || $child instanceof Op\Expr\ArrayDimFetch
             || $child instanceof Op\Expr\Isset_
-            || $child instanceof Op\Expr\Empty_;
+            || $child instanceof Op\Expr\Empty_
+            // `@$cv` materializes via Assign under silence (#13587 / #29132).
+            || $child instanceof Op\Expr\Assign;
     }
 
     /**

patches/php-cfg-bare-variable-read-stmt.patch

@@ -18,18 +18,24 @@
      }
 
      protected function parseStmt_Class(Stmt\Class_ $node)
-@@ -1417,8 +1426,16 @@
+@@ -1417,8 +1426,24 @@
          $block->addParent($this->block);
          $this->block = $block;
          $result = $this->parseExprNode($expr->expr);
 -        // Evaluate reads inside the suppress region (issue #3546; Zend ZEND_COMPILE_SILENCE).
 -        $result = $this->readVariable($result);
 +        // Bare variable reads need a real fetch op for ZEND_CHECK_UNDEFINED_VAR (#13587).
++        // Materialize into a temp under silence so `$a = @$undef` does not re-fetch the CV
++        // after END_SILENCE (#29132). UnaryPlus would coerce null→int(0); Assign preserves null.
 +        if ($expr->expr instanceof Node\Expr\Variable) {
-+            $this->block->children[] = new Op\Expr\UnaryPlus(
++            $tmp = new Temporary();
++            $assign = new Op\Expr\Assign(
++                $tmp,
 +                $this->readVariable($result),
 +                $attrs
 +            );
++            $this->block->children[] = $assign;
++            $result = $assign->result;
 +        } else {
 +            // Evaluate reads inside the suppress region (issue #3546; Zend ZEND_COMPILE_SILENCE).
 +            $result = $this->readVariable($result);

test/compliance/ErrorSuppressJITTest.php

@@ -26,6 +26,10 @@ public static function providePHPTests(): \Generator
             __DIR__.'/cases/language/error_suppress_jit.phpt',
             'error_suppress_jit.phpt'
         );
+        yield 'at_silence_assign_undef_rhs.phpt' => self::parsePHPT(
+            __DIR__.'/cases/language/at_silence_assign_undef_rhs.phpt',
+            'at_silence_assign_undef_rhs.phpt'
+        );
     }
 
     public function setUp(): void

test/compliance/cases/language/at_silence_assign_undef_rhs.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Language: @$undef as assignment RHS is silenced; value remains null (#29132)
+--FILE--
+<?php
+error_reporting(E_ALL);
+$a = @$undef_assign_rhs_29132;
+var_dump($a);
+echo "ok\n";
+@$bare_undef_29132;
+$b = [];
+$c = @$b['missing_29132'];
+echo "ok2\n";
+--EXPECT--
+NULL
+ok
+ok2

test/unit/ErrorControlOperatorTest.php

@@ -22,5 +22,34 @@ public static function providePHPTests(): \Generator
             __DIR__.'/../compliance/cases/language/error_control_operator.phpt',
             'error_control_operator.phpt'
         );
+        yield 'at_silence_assign_undef_rhs.phpt' => self::parsePHPT(
+            __DIR__.'/../compliance/cases/language/at_silence_assign_undef_rhs.phpt',
+            'at_silence_assign_undef_rhs.phpt'
+        );
+    }
+
+    /** Issue #29132 — `$a = @$undef` must not print Undefined variable on stderr. */
+    public function testAssignUndefRhsSilenceLeavesStderrEmpty(): void
+    {
+        $code = <<<'PHP'
+        <?php
+        error_reporting(E_ALL);
+        $a = @$undef_assign_rhs_29132_stderr;
+        echo "ok\n";
+        PHP;
+        $repoRoot = dirname(__DIR__, 2);
+        $env = [];
+        foreach (array_merge($_ENV, $_SERVER) as $key => $value) {
+            if (is_string($value)) {
+                $env[$key] = $value;
+            }
+        }
+        self::applyLlvmToolchainEnv($env);
+        unset($env['PHP_COMPILER_SKIP_LLVM_PRELOAD']);
+        $cmd = array_merge(self::llvmEnvPrefix(), $this->phpCommand(), [$this->BIN]);
+        [$stdout, $exitCode, $stderr] = self::runVmSubprocess($cmd, $repoRoot, $env, $code, __FUNCTION__);
+        $this->assertSame(0, $exitCode, $stderr);
+        $this->assertSame("ok\n", $stdout);
+        $this->assertStringNotContainsString('Undefined variable', $stderr);
     }
 }