fix(array): reject scalar offset writes safely

phpunit/code/explicit-native-int-array-dim-write.php

@@ -0,0 +1,7 @@
+<?php
+
+function main(): void
+{
+    $value = std::int(1);
+    $value[0] = 'invalid';
+}

phpunit/code/native-bool-array-dim-write.php

@@ -0,0 +1,8 @@
+<?php
+use native_types;
+
+function main(): void
+{
+    $value = false;
+    $value[] = 'invalid';
+}

phpunit/code/native-float-array-dim-write.php

@@ -0,0 +1,8 @@
+<?php
+use native_types;
+
+function main(): void
+{
+    $value = 1.5;
+    $value[0] = 'invalid';
+}

phpunit/code/native-int-array-dim-write.php

@@ -0,0 +1,8 @@
+<?php
+use native_types;
+
+function main(): void
+{
+    $value = 1;
+    $value[] = 'invalid';
+}

phpunit/src/AssignTest.php

@@ -173,4 +173,18 @@ class AssignTest extends \BaseTest
     {
         $this->exec("declare(strict_types=0) is not allowed, only strict_types=1 is supported", 'declare-strict-types-zero.php');
     }
+
+    /** @dataProvider nativeScalarArrayDimWriteProvider */
+    public function testNativeScalarArrayDimWriteFailsInTypePhp(string $file): void
+    {
+        $this->exec('Cannot use [] for numbers', $file);
+    }
+
+    public static function nativeScalarArrayDimWriteProvider(): iterable
+    {
+        yield 'native int append' => ['native-int-array-dim-write.php'];
+        yield 'native float keyed write' => ['native-float-array-dim-write.php'];
+        yield 'native bool append' => ['native-bool-array-dim-write.php'];
+        yield 'explicit std::int keyed write' => ['explicit-native-int-array-dim-write.php'];
+    }
 }

src/Parser/ArrayExpressionTrait.php

@@ -216,17 +216,8 @@ trait ArrayExpressionTrait
                 } else {
                     $this->errorUndefinedVariable($node->var);
                 }
-            } else {
-                $type = $this->getVarType($var);
-                if ($type === Type::BOOL || $type === Type::INT || $type === Type::FLOAT) {
-                    $this->fatalError($node, 'Cannot use [] for numbers');
-                }
-            }
-            if ($this->getVarType($var) === Type::STR) {
-                if ($node->dim === null) {
-                    $this->fatalError($node, 'Cannot use [] for strings');
-                }
             }
+            $this->assertArrayDimVariableTypeIsSupported($node, $var);
         }
 
         if ($node->dim === null) {
@@ -267,6 +258,22 @@ trait ArrayExpressionTrait
         }
     }
 
+    /**
+     * Fixed native scalar variables cannot defer an offset operation to
+     * PHPX. Diagnose them here so invalid TypePHP does not become invalid C++.
+     * A php::Var remains runtime-checked because its value may have changed.
+     */
+    protected function assertArrayDimVariableTypeIsSupported(Expr\ArrayDimFetch $node, string $var): void
+    {
+        $type = $this->getVarType($var);
+        if ($type === Type::BOOL || $type === Type::INT || $type === Type::FLOAT) {
+            $this->fatalError($node, 'Cannot use [] for numbers');
+        }
+        if ($type === Type::STR && $node->dim === null) {
+            $this->fatalError($node, 'Cannot use [] for strings');
+        }
+    }
+
     private function parseArrayMixed(Expr\Array_ $node): string
     {
         $tmpVar = $this->genTmpVarName();

src/Parser/AssignOpTrait.php

@@ -666,9 +666,7 @@ trait AssignOpTrait
             return $this->parseAssignPropertyFetch($left, $right, $propertyWriteTarget, $resultUnused);
         } elseif ($this->isArrayDimFetch($left) and $this->isVarExpr($left->var)) {
             $tmp = $this->parseIdentifier($left->var);
-            if ($this->getVarType($tmp) === Type::STR and $left->dim === null) {
-                $this->fatalError($left, 'Cannot use [] for strings');
-            }
+            $this->assertArrayDimVariableTypeIsSupported($left, $tmp);
             if ($this->isStdContainerExpr($left)) {
                 return $this->parseStdContainerAssign($left, $right);
             }

tests/compiler/array/scalar-offset-write.phpt

@@ -0,0 +1,33 @@
+--TEST--
+Dynamic scalar offset writes fail instead of being silently ignored
+--FILE--
+<?php
+
+function expectOffsetWriteError(mixed $value, string $label): void
+{
+    try {
+        $value[] = 'invalid';
+        echo $label, ":missing-error\n";
+    } catch (Error $error) {
+        echo $label, ":error\n";
+    }
+}
+
+function main(): void
+{
+    expectOffsetWriteError(1, 'int');
+    expectOffsetWriteError(1.5, 'float');
+    expectOffsetWriteError(false, 'bool');
+    expectOffsetWriteError(new stdClass(), 'object');
+
+    $value = null;
+    $value[] = 'valid';
+    echo 'null:', $value[0], "\n";
+}
+?>
+--EXPECT--
+int:error
+float:error
+bool:error
+object:error
+null:valid