Playground - ArrayDimCastRule

Author: ondrejmirtes

issue-bot/playground.neon

@@ -1,4 +1,5 @@
 rules:
+	- PHPStan\Rules\Playground\ArrayDimCastRule
 	- PHPStan\Rules\Playground\FunctionNeverRule
 	- PHPStan\Rules\Playground\LiteralArrayKeyCastRule
 	- PHPStan\Rules\Playground\MethodNeverRule

src/Rules/Playground/ArrayDimCastRule.php

@@ -0,0 +1,62 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Playground;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr\ArrayDimFetch;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use PHPStan\Type\GeneralizePrecision;
+use PHPStan\Type\VerbosityLevel;
+use function sprintf;
+
+/**
+ * @implements Rule<ArrayDimFetch>
+ */
+final class ArrayDimCastRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return ArrayDimFetch::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if ($node->dim === null) {
+			return [];
+		}
+
+		$varType = $scope->getType($node->var);
+		if ($varType->isArray()->no()) {
+			return [];
+		}
+
+		$dimType = $scope->getType($node->dim);
+		if (!$dimType->isConstantScalarValue()->yes()) {
+			return [];
+		}
+
+		$constantScalars = $dimType->getConstantScalarTypes();
+		$errors = [];
+		foreach ($constantScalars as $constantScalar) {
+			$arrayKeyType = $constantScalar->toArrayKey();
+			if ($arrayKeyType->equals($constantScalar)) {
+				continue;
+			}
+
+			$errors[] = RuleErrorBuilder::message(sprintf(
+				'Key %s (%s) will be cast to %s (%s) in the array access.',
+				$constantScalar->describe(VerbosityLevel::value()),
+				$constantScalar->generalize(GeneralizePrecision::lessSpecific())->describe(VerbosityLevel::typeOnly()),
+				$arrayKeyType->describe(VerbosityLevel::value()),
+				$arrayKeyType->describe(VerbosityLevel::typeOnly()),
+			))->identifier('phpstanPlayground.arrayDimFetchCast')
+				->build();
+		}
+
+		return $errors;
+	}
+
+}

tests/PHPStan/Rules/Playground/ArrayDimCastRuleTest.php

@@ -0,0 +1,53 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Playground;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/**
+ * @extends RuleTestCase<ArrayDimCastRule>
+ */
+final class ArrayDimCastRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new ArrayDimCastRule();
+	}
+
+	public function testRule(): void
+	{
+		$this->analyse([__DIR__ . '/data/array-dim-fetch-cast.php'], [
+			[
+				"Key '1' (string) will be cast to 1 (int) in the array access.",
+				13,
+			],
+			[
+				"Key null (null) will be cast to '' (string) in the array access.",
+				14,
+			],
+			[
+				'Key 2.5 (float) will be cast to 2 (int) in the array access.',
+				15,
+			],
+			[
+				'Key true (bool) will be cast to 1 (int) in the array access.',
+				17,
+			],
+			[
+				'Key false (bool) will be cast to 0 (int) in the array access.',
+				18,
+			],
+			[
+				"Key '10' (string) will be cast to 10 (int) in the array access.",
+				20,
+			],
+			[
+				"Key '1' (string) will be cast to 1 (int) in the array access.",
+				26,
+			],
+		]);
+	}
+
+}

tests/PHPStan/Rules/Playground/data/array-dim-fetch-cast.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace ArrayDimFetchCast;
+
+class Foo
+{
+
+	public function doFoo(array $a): void
+	{
+		$partiallyCast = rand(0,1) ? '10' : 10;
+		echo $a['a'];
+		echo $a['+1'];
+		echo $a['1']; // cast to 1
+		echo $a[null]; // cast to ''
+		echo $a[2.5]; // cast to 2
+		echo $a['1.2'];
+		echo $a[true]; // cast to 1
+		echo $a[false]; // cast to 0
+		echo $a['08'];
+		echo $a[$partiallyCast]; // one part of the union is cast to 10
+	}
+
+	public function doBar($mixed): void
+	{
+		echo $mixed['a'];
+		echo $mixed['1'];
+	}
+
+}