Fix is_numeric() filtering in truthy condition

src/Rules/Comparison/ImpossibleCheckTypeHelper.php

@@ -63,6 +63,9 @@ public function findSpecifiedType(
 		) {
 			if ($node->name instanceof \PhpParser\Node\Name) {
 				$functionName = strtolower((string) $node->name);
+				if ($functionName === 'assert') {
+					return $this->findSpecifiedType($scope, $node->args[0]->value);
+				}
 				if (in_array($functionName, [
 					'class_exists',
 					'interface_exists',
@@ -77,6 +80,9 @@ public function findSpecifiedType(
 					if (count(TypeUtils::getConstantScalars($argType)) > 0) {
 						return !$argType->toNumber() instanceof ErrorType;
 					}
+					if (TypeUtils::containsGeneralString($argType)) {
+						return null;
+					}
 				} elseif ($functionName === 'defined') {
 					return null;
 				} elseif (

src/Type/Php/IsNumericFunctionTypeSpecifyingExtension.php

@@ -12,7 +12,6 @@
 use PHPStan\Type\FloatType;
 use PHPStan\Type\FunctionTypeSpecifyingExtension;
 use PHPStan\Type\IntegerType;
-use PHPStan\Type\MixedType;
 use PHPStan\Type\StringType;
 use PHPStan\Type\UnionType;
 
@@ -34,11 +33,6 @@ public function specifyTypes(FunctionReflection $functionReflection, FuncCall $n
 			throw new \PHPStan\ShouldNotHappenException();
 		}
 
-		$argType = $scope->getType($node->args[0]->value);
-		if ($context->truthy() && !(new StringType())->isSuperTypeOf($argType)->no() && !$argType instanceof MixedType) {
-			return new SpecifiedTypes([], []);
-		}
-
 		$numericTypes = [
 			new IntegerType(),
 			new FloatType(),

src/Type/TypeUtils.php

@@ -339,4 +339,21 @@ public static function containsCallable(Type $type): bool
 		return false;
 	}
 
+	public static function containsGeneralString(Type $type): bool
+	{
+		if ($type instanceof StringType && !$type instanceof ConstantType) {
+			return true;
+		}
+
+		if ($type instanceof UnionType) {
+			foreach ($type->getTypes() as $innerType) {
+				if ($innerType instanceof StringType && !$innerType instanceof ConstantType) {
+					return true;
+				}
+			}
+		}
+
+		return false;
+	}
+
 }

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -10033,6 +10033,11 @@ public function dataNonEmptyArrayKeyType(): array
 		return $this->gatherAssertTypes(__DIR__ . '/data/non-empty-array-key-type.php');
 	}
 
+	public function dataBug3133(): array
+	{
+		return $this->gatherAssertTypes(__DIR__ . '/data/bug-3133.php');
+	}
+
 	/**
 	 * @dataProvider dataBug2574
 	 * @dataProvider dataBug2577
@@ -10098,6 +10103,7 @@ public function dataNonEmptyArrayKeyType(): array
 	 * @dataProvider dataNativeStaticReturnType
 	 * @dataProvider dataClassPhpDocs
 	 * @dataProvider dataNonEmptyArrayKeyType
+	 * @dataProvider dataBug3133
 	 * @param string $assertType
 	 * @param string $file
 	 * @param mixed ...$args

tests/PHPStan/Analyser/data/bug-3133.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace Bug3133;
+
+use function PHPStan\Analyser\assertType;
+
+class Foo
+{
+
+	/**
+	 * @param string[]|string $arg
+	 */
+	public function doFoo($arg): void
+	{
+		if (!is_numeric($arg)) {
+			assertType('array<string>|string', $arg);
+			return;
+		}
+
+		assertType('string', $arg);
+	}
+
+	/**
+	 * @param string|bool|float|int|mixed[]|null $arg
+	 */
+	public function doBar($arg): void
+	{
+		if (\is_numeric($arg)) {
+			assertType('float|int|string', $arg);
+		}
+	}
+
+}

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php

@@ -206,10 +206,18 @@ public function testImpossibleCheckTypeFunctionCall(): void
 					677,
 					'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
 				],
+				[
+					'Call to function assert() with true will always evaluate to true.',
+					692,
+				],
 				[
 					'Call to function is_numeric() with \'123\' will always evaluate to true.',
 					692,
 				],
+				[
+					'Call to function assert() with false will always evaluate to false.',
+					693,
+				],
 				[
 					'Call to function is_numeric() with \'blabla\' will always evaluate to false.',
 					693,
@@ -326,6 +334,10 @@ public function testImpossibleCheckTypeFunctionCallWithoutAlwaysTrue(): void
 					'Call to function method_exists() with \'CheckTypeFunctionCall\\\\MethodExistsWithTrait\' and \'unknown\' will always evaluate to false.',
 					648,
 				],
+				[
+					'Call to function assert() with false will always evaluate to false.',
+					693,
+				],
 				[
 					'Call to function is_numeric() with \'blabla\' will always evaluate to false.',
 					693,