Improve type inference for $object::class === static::class

Author: rvanvelzen

src/Analyser/TypeSpecifier.php

@@ -198,6 +198,7 @@ public function specifyTypesInCondition(
 
 			$rightType = $scope->getType($expr->right);
 			if (
+				$context->true() &&
 				$expr->left instanceof ClassConstFetch &&
 				$expr->left->class instanceof Expr &&
 				$expr->left->name instanceof Node\Identifier &&
@@ -215,6 +216,41 @@ public function specifyTypesInCondition(
 					$rootExpr,
 				);
 			}
+			if (
+				$context->true()
+				&& $expr->left instanceof ClassConstFetch
+				&& $expr->left->class instanceof Expr
+				&& $expr->left->name instanceof Node\Identifier
+				&& $expr->right instanceof ClassConstFetch
+				&& $rightType instanceof GenericClassStringType
+				&& strtolower($expr->left->name->toString()) === 'class'
+			) {
+				return $this->create(
+					$expr->left->class,
+					$rightType->getGenericType(),
+					$context,
+					false,
+					$scope,
+					$rootExpr,
+				);
+			}
+			if (
+				$context->true()
+				&& $expr->left instanceof FuncCall
+				&& $expr->left->name instanceof Name
+				&& strtolower($expr->left->name->toString()) === 'get_class'
+				&& isset($expr->left->getArgs()[0])
+				&& $rightType instanceof GenericClassStringType
+			) {
+				return $this->create(
+					$expr->left->getArgs()[0]->value,
+					$rightType->getGenericType(),
+					$context,
+					false,
+					$scope,
+					$rootExpr,
+				);
+			}
 			if ($context->false()) {
 				$identicalType = $scope->getType($expr);
 				if ($identicalType instanceof ConstantBooleanType) {
@@ -1150,6 +1186,24 @@ private function specifyTypesForConstantStringBinaryExpression(
 			);
 		}
 
+		if (
+			$context->true()
+			&& $exprNode instanceof FuncCall
+			&& $exprNode->name instanceof Name
+			&& strtolower($exprNode->name->toString()) === 'get_class'
+			&& isset($exprNode->getArgs()[0])
+		) {
+			return $this->specifyTypesInCondition(
+				$scope,
+				new Instanceof_(
+					$exprNode->getArgs()[0]->value,
+					new Name($constantType->getValue()),
+				),
+				$context,
+				$rootExpr,
+			);
+		}
+
 		return null;
 	}
 
@@ -1391,7 +1445,7 @@ private function processBooleanConditionalTypes(Scope $scope, SpecifiedTypes $le
 	}
 
 	/**
-	 * @return (Expr|ConstantScalarType)[]|null
+	 * @return array{Expr, ConstantScalarType}|null
 	 */
 	private function findTypeExpressionsFromBinaryOperation(Scope $scope, Node\Expr\BinaryOp $binaryOperation): ?array
 	{

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -1099,6 +1099,8 @@ public function dataFileAsserts(): iterable
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/callable-object.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/callable-string.php');
+
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/static-class-const-equals.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/static-class-const-equals.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace StaticClassConstEquals;
+
+use function PHPStan\Testing\assertType;
+
+interface A {
+	public function equals(A $other): bool;
+}
+
+class B implements A {
+	public function equals(A $other): bool {
+		if ($other::class === static::class) {
+			assertType('static(StaticClassConstEquals\\B)', $other);
+			return true;
+		} else {
+			assertType('StaticClassConstEquals\\A', $other);
+			return false;
+		}
+	}
+}
+
+class C implements A {
+	public function equals(A $other): bool {
+		if (get_class($other) === static::class) {
+			assertType('static(StaticClassConstEquals\\C)', $other);
+			return true;
+		} else {
+			assertType('StaticClassConstEquals\\A', $other);
+			return false;
+		}
+	}
+}
+
+class D implements A {
+	public function equals(A $other): bool {
+		if ($other::class === self::class) {
+			assertType('StaticClassConstEquals\\D', $other);
+			return true;
+		} else {
+			assertType('StaticClassConstEquals\\A', $other);
+			return false;
+		}
+	}
+}
+
+class E implements A {
+	public function equals(A $other): bool {
+		if (get_class($other) === self::class) {
+			assertType('StaticClassConstEquals\\E', $other);
+			return true;
+		} else {
+			assertType('StaticClassConstEquals\\A', $other);
+			return false;
+		}
+	}
+}