Make IntegerRangeType represent open intervals properly

This removes the usage of PHP_INT_MIN and PHP_INT_MAX to mark open-ended
intervals and instead uses null for that purpose.  Since using getMin() and
getMax() now became slightly more complicated for callers, a lot of
IntegerRangeType related logic has been moved into the class itself.

Author: jlherren

src/Analyser/MutatingScope.php

@@ -1472,11 +1472,7 @@ private function resolveType(Expr $node): Type
 				}
 				return TypeCombinator::union(...$newTypes);
 			} elseif ($varType instanceof IntegerRangeType) {
-				$shift = $node instanceof Expr\PreInc ? +1 : -1;
-				return IntegerRangeType::fromInterval(
-					$varType->getMin() === PHP_INT_MIN ? PHP_INT_MIN : $varType->getMin() + $shift,
-					$varType->getMax() === PHP_INT_MAX ? PHP_INT_MAX : $varType->getMax() + $shift
-				);
+				return $varType->shift($node instanceof Expr\PreInc ? +1 : -1);
 			}
 
 			$stringType = new StringType();

src/Rules/Functions/RandomIntParametersRule.php

@@ -9,7 +9,6 @@
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\IntegerRangeType;
-use PHPStan\Type\IntegerType;
 use PHPStan\Type\VerbosityLevel;
 
 /**
@@ -45,35 +44,25 @@ public function processNode(Node $node, Scope $scope): array
 
 		$minType = $scope->getType($node->args[0]->value)->toInteger();
 		$maxType = $scope->getType($node->args[1]->value)->toInteger();
-		$integerType = new IntegerType();
 
-		if ($minType->equals($integerType) || $maxType->equals($integerType)) {
+		if (
+			!$minType instanceof ConstantIntegerType && !$minType instanceof IntegerRangeType
+			|| !$maxType instanceof ConstantIntegerType && !$maxType instanceof IntegerRangeType
+		) {
 			return [];
 		}
 
-		if ($minType instanceof ConstantIntegerType || $minType instanceof IntegerRangeType) {
-			if ($minType instanceof ConstantIntegerType) {
-				$maxPermittedType = IntegerRangeType::fromInterval($minType->getValue(), PHP_INT_MAX);
-			} else {
-				$maxPermittedType = IntegerRangeType::fromInterval($minType->getMax(), PHP_INT_MAX);
-			}
-
-			if (!$maxPermittedType->isSuperTypeOf($maxType)->yes()) {
-				$message = 'Parameter #1 $min (%s) of function random_int expects lower number than parameter #2 $max (%s).';
-
-				// True if sometimes the parameters conflict.
-				$isMaybe = !$maxType->isSuperTypeOf($minType)->no();
-
-				if (!$isMaybe || $this->reportMaybes) {
-					return [
-						RuleErrorBuilder::message(sprintf(
-							$message,
-							$minType->describe(VerbosityLevel::value()),
-							$maxType->describe(VerbosityLevel::value())
-						))->build(),
-					];
-				}
-			}
+		$isSmaller = $maxType->isSmallerThan($minType);
+
+		if ($isSmaller->yes() || $isSmaller->maybe() && $this->reportMaybes) {
+			$message = 'Parameter #1 $min (%s) of function random_int expects lower number than parameter #2 $max (%s).';
+			return [
+				RuleErrorBuilder::message(sprintf(
+					$message,
+					$minType->describe(VerbosityLevel::value()),
+					$maxType->describe(VerbosityLevel::value())
+				))->build(),
+			];
 		}
 
 		return [];

src/Type/Constant/ConstantIntegerType.php

@@ -37,7 +37,9 @@ public function isSuperTypeOf(Type $type): TrinaryLogic
 		}
 
 		if ($type instanceof IntegerRangeType) {
-			if ($type->getMin() <= $this->value && $this->value <= $type->getMax()) {
+			$min = $type->getMin();
+			$max = $type->getMax();
+			if (($min === null || $min <= $this->value) && ($max === null || $this->value <= $max)) {
 				return TrinaryLogic::createMaybe();
 			}