Mark array_filter(), array_map(), array_reduce() and sibling non-mutating callback functions as having no side effects

bin/functionMetadata_original.php

@@ -20,6 +20,8 @@
 	'apcu_key_info' => ['hasSideEffects' => true],
 	'apcu_sma_info' => ['hasSideEffects' => true],
 	'apcu_store' => ['hasSideEffects' => true],
+	'array_all' => ['hasSideEffects' => false],
+	'array_any' => ['hasSideEffects' => false],
 	'array_change_key_case' => ['hasSideEffects' => false],
 	'array_chunk' => ['hasSideEffects' => false],
 	'array_column' => ['hasSideEffects' => false],
@@ -32,6 +34,9 @@
 	'array_diff_ukey' => ['hasSideEffects' => false],
 	'array_fill' => ['hasSideEffects' => false],
 	'array_fill_keys' => ['hasSideEffects' => false],
+	'array_filter' => ['hasSideEffects' => false],
+	'array_find' => ['hasSideEffects' => false],
+	'array_find_key' => ['hasSideEffects' => false],
 	'array_flip' => ['hasSideEffects' => false],
 	'array_intersect' => ['hasSideEffects' => false],
 	'array_intersect_assoc' => ['hasSideEffects' => false],
@@ -42,13 +47,15 @@
 	'array_key_last' => ['hasSideEffects' => false],
 	'array_key_exists' => ['hasSideEffects' => false],
 	'array_keys' => ['hasSideEffects' => false],
+	'array_map' => ['hasSideEffects' => false],
 	'array_merge' => ['hasSideEffects' => false],
 	'array_merge_recursive' => ['hasSideEffects' => false],
 	'array_pad' => ['hasSideEffects' => false],
 	'array_pop' => ['hasSideEffects' => true],
 	'array_product' => ['hasSideEffects' => false],
 	'array_push' => ['hasSideEffects' => true],
 	'array_rand' => ['hasSideEffects' => false],
+	'array_reduce' => ['hasSideEffects' => false],
 	'array_replace' => ['hasSideEffects' => false],
 	'array_replace_recursive' => ['hasSideEffects' => false],
 	'array_reverse' => ['hasSideEffects' => false],
@@ -237,6 +244,8 @@
 	'output_reset_rewrite_vars' => ['hasSideEffects' => true],
 	'pclose' => ['hasSideEffects' => true],
 	'popen' => ['hasSideEffects' => true],
+	'preg_replace_callback' => ['hasSideEffects' => false],
+	'preg_replace_callback_array' => ['hasSideEffects' => false],
 	'readfile' => ['hasSideEffects' => true],
 	'rename' => ['hasSideEffects' => true],
 	'rewind' => ['hasSideEffects' => true],

resources/functionMetadata.php

@@ -725,6 +725,8 @@
 	'apcu_key_info' => ['hasSideEffects' => true],
 	'apcu_sma_info' => ['hasSideEffects' => true],
 	'apcu_store' => ['hasSideEffects' => true],
+	'array_all' => ['hasSideEffects' => false],
+	'array_any' => ['hasSideEffects' => false],
 	'array_change_key_case' => ['hasSideEffects' => false],
 	'array_chunk' => ['hasSideEffects' => false],
 	'array_column' => ['hasSideEffects' => false],
@@ -737,6 +739,9 @@
 	'array_diff_ukey' => ['hasSideEffects' => false],
 	'array_fill' => ['hasSideEffects' => false],
 	'array_fill_keys' => ['hasSideEffects' => false],
+	'array_filter' => ['hasSideEffects' => false],
+	'array_find' => ['hasSideEffects' => false],
+	'array_find_key' => ['hasSideEffects' => false],
 	'array_first' => ['hasSideEffects' => false],
 	'array_flip' => ['hasSideEffects' => false],
 	'array_intersect' => ['hasSideEffects' => false],
@@ -750,13 +755,15 @@
 	'array_key_last' => ['hasSideEffects' => false],
 	'array_keys' => ['hasSideEffects' => false],
 	'array_last' => ['hasSideEffects' => false],
+	'array_map' => ['hasSideEffects' => false],
 	'array_merge' => ['hasSideEffects' => false],
 	'array_merge_recursive' => ['hasSideEffects' => false],
 	'array_pad' => ['hasSideEffects' => false],
 	'array_pop' => ['hasSideEffects' => true],
 	'array_product' => ['hasSideEffects' => false],
 	'array_push' => ['hasSideEffects' => true],
 	'array_rand' => ['hasSideEffects' => false],
+	'array_reduce' => ['hasSideEffects' => false],
 	'array_replace' => ['hasSideEffects' => false],
 	'array_replace_recursive' => ['hasSideEffects' => false],
 	'array_reverse' => ['hasSideEffects' => false],
@@ -1616,6 +1623,8 @@
 	'preg_last_error' => ['hasSideEffects' => true],
 	'preg_last_error_msg' => ['hasSideEffects' => true],
 	'preg_quote' => ['hasSideEffects' => false],
+	'preg_replace_callback' => ['hasSideEffects' => false],
+	'preg_replace_callback_array' => ['hasSideEffects' => false],
 	'preg_split' => ['hasSideEffects' => false],
 	'property_exists' => ['hasSideEffects' => false],
 	'quoted_printable_decode' => ['hasSideEffects' => false],

tests/PHPStan/Analyser/data/discussion-7124.php

@@ -33,30 +33,30 @@ function filter(array $array, ?callable $callback = null, int $mode = ARRAY_FILT
 
 function () {
 	// This one does fail, as both the value + key is asked and the key + value is used
-	filter(
+	echo count(filter(
 		[false, true, false],
 		static fn (int $key, bool $value): bool => 0 === $key % 2 && $value,
 		mode: ARRAY_FILTER_USE_BOTH,
-	);
+	));
 
 	// This one should fail, as both the value + key is asked but only the key is used
-	filter(
+	echo count(filter(
 		[false, true, false],
 		static fn (int $key): bool => 0 === $key % 2,
 		mode: ARRAY_FILTER_USE_BOTH,
-	);
+	));
 
 	// This one should fail, as only the key is asked but the value is used
-	filter(
+	echo count(filter(
 		[false, true, false],
 		static fn (bool $value): bool => $value,
 		mode: ARRAY_FILTER_USE_KEY,
-	);
+	));
 
 	// This one should fail, as only the value is asked but the key is used
-	filter(
+	echo count(filter(
 		[false, true, false],
 		static fn (int $key): bool => 0 === $key % 2,
 		mode: 0,
-	);
+	));
 };

tests/PHPStan/Command/data/file-without-errors.php

@@ -1,3 +1,3 @@
 <?php
 
-array_filter([0, 1, 2]);
+echo count(array_filter([0, 1, 2]));

tests/PHPStan/Rules/Functions/CallToFunctionStatementWithoutSideEffectsRuleTest.php

@@ -91,6 +91,65 @@ public function testBug12224(): void
 		$this->analyse([__DIR__ . '/data/bug-12224.php'], []);
 	}
 
+	public function testBug11101(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-11101.php'], [
+			[
+				'Call to function array_filter() on a separate line has no effect.',
+				8,
+			],
+			[
+				'Call to function array_map() on a separate line has no effect.',
+				9,
+			],
+			[
+				'Call to function array_reduce() on a separate line has no effect.',
+				10,
+			],
+			[
+				'Call to function array_filter() on a separate line has no effect.',
+				13,
+			],
+			[
+				'Call to function preg_replace_callback() on a separate line has no effect.',
+				14,
+			],
+			[
+				'Call to function preg_replace_callback_array() on a separate line has no effect.',
+				15,
+			],
+		]);
+	}
+
+	#[RequiresPhp('>= 8.4.0')]
+	public function testBug11101Php84(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-11101-php84.php'], [
+			[
+				'Call to function array_any() on a separate line has no effect.',
+				8,
+			],
+			[
+				'Call to function array_all() on a separate line has no effect.',
+				9,
+			],
+			[
+				'Call to function array_any() on a separate line has no effect.',
+				31,
+			],
+		]);
+	}
+
+	public function testBug11101PureClosure(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-11101-pure-closure.php'], [
+			[
+				'Call to function array_map() on a separate line has no effect.',
+				17,
+			],
+		]);
+	}
+
 	public function testBug4455(): void
 	{
 		require_once __DIR__ . '/data/bug-4455.php';

tests/PHPStan/Rules/Functions/data/bug-11101-php84.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace Bug11101Php84;
+
+function doFoo(array $array): void
+{
+	// pure callbacks - reported as no effect
+	array_any($array, 'is_string');
+	array_all($array, 'is_string');
+}
+
+function doBar(array $array): void
+{
+	// impure callbacks - NOT reported
+	array_any($array, function ($v) {
+		echo $v;
+		return true;
+	});
+	array_all($array, function ($v) {
+		echo $v;
+		return true;
+	});
+}
+
+function maybeImpure(array $array): void
+{
+	$cb = rand(0,1) ? 'is_string' : function ($v) {
+		echo $v;
+		return true;
+	};
+	array_any($array, $cb);
+
+}

tests/PHPStan/Rules/Functions/data/bug-11101-pure-closure.php

@@ -0,0 +1,20 @@
+<?php declare(strict_types = 1);
+
+namespace Bug11101PureClosure;
+
+class Foo
+{
+
+	/** @param list<string> $args */
+	public function test(array $args): void
+	{
+		$pureFx = static function (string $v): void {};
+
+		assert(isset($args[0]));
+
+		$pureFx($args[0]);
+
+		array_map($pureFx, $args);
+	}
+
+}

tests/PHPStan/Rules/Functions/data/bug-11101.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace Bug11101;
+
+function doFoo(array $array): void
+{
+	// pure callbacks - reported as no effect
+	array_filter($array, 'is_string');
+	array_map('is_string', $array);
+	array_reduce($array, function ($carry, $item) {
+		return $carry + $item;
+	}, 0);
+	array_filter($array);
+	preg_replace_callback('/\d/', 'strtoupper', 'abc');
+	preg_replace_callback_array(['/\d/' => 'strtoupper'], 'abc');
+}
+
+function doBar(array $array, callable $cb): void
+{
+	// impure callbacks - NOT reported
+	array_filter($array, function ($v) {
+		echo $v;
+		return true;
+	});
+	array_map(function ($v) {
+		echo $v;
+		return $v;
+	}, $array);
+	array_reduce($array, function ($carry, $item) {
+		echo $item;
+		return $carry;
+	}, 0);
+	array_map('printf', $array);
+
+	// unknown callable purity - NOT reported
+	array_map($cb, $array);
+	array_filter($array, $cb);
+}

tests/PHPStan/Rules/Pure/PureMethodRuleTest.php

@@ -276,6 +276,12 @@ public function testBug12048(): void
 		$this->analyse([__DIR__ . '/data/bug-12048.php'], []);
 	}
 
+	public function testBug11100(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-11100.php'], []);
+	}
+
 	public function testBug12224(): void
 	{
 		$this->treatPhpDocTypesAsCertain = true;

tests/PHPStan/Rules/Pure/data/bug-11100.php

@@ -0,0 +1,30 @@
+<?php // lint >= 8.0
+
+namespace Bug11100;
+
+final class FooClass
+{
+	/**
+	 * @param array<string, string|int> $getParams
+	 *
+	 * @phpstan-pure
+	 */
+	public function build(array $getParams, string $trailingSlash, bool $useSlashSeparator): string
+	{
+		if ($getParams === []) {
+			return '';
+		}
+
+		if ($useSlashSeparator) {
+			return '/' . implode('/', array_map(
+				static function (string $key, string|int $value): string {
+					return rawurlencode($key) . '/' . rawurlencode((string) $value);
+				},
+				array_keys($getParams),
+				$getParams
+			)) . $trailingSlash;
+		}
+
+		return $trailingSlash . '?' . http_build_query($getParams);
+	}
+}