Support arrays with union value-types in implode()

Author: staabm

Diff for: phpstan-baseline.neon

@@ -1367,11 +1367,6 @@ parameters:
 			count: 1
 			path: src/Type/Php/FunctionExistsFunctionTypeSpecifyingExtension.php
 
-		-
-			message: "#^Doing instanceof PHPStan\\\\Type\\\\ConstantScalarType is error\\-prone and deprecated\\. Use Type\\:\\:isConstantScalarValue\\(\\) or Type\\:\\:getConstantScalarTypes\\(\\) or Type\\:\\:getConstantScalarValues\\(\\) instead\\.$#"
-			count: 1
-			path: src/Type/Php/ImplodeFunctionReturnTypeExtension.php
-
 		-
 			message: """
 				#^Call to deprecated method getConstantScalars\\(\\) of class PHPStan\\\\Type\\\\TypeUtils\\:

Diff for: src/Type/Php/ImplodeFunctionReturnTypeExtension.php

@@ -4,6 +4,7 @@
 
 use PhpParser\Node\Expr\FuncCall;
 use PHPStan\Analyser\Scope;
+use PHPStan\Internal\CombinationsHelper;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
 use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
@@ -12,7 +13,6 @@
 use PHPStan\Type\Accessory\AccessoryUppercaseStringType;
 use PHPStan\Type\Constant\ConstantArrayType;
 use PHPStan\Type\Constant\ConstantStringType;
-use PHPStan\Type\ConstantScalarType;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
 use PHPStan\Type\IntersectionType;
 use PHPStan\Type\StringType;
@@ -115,13 +115,17 @@ private function inferConstantType(ConstantArrayType $arrayType, ConstantStringT
 
 			$arrayValues = [];
 			foreach ($valueTypes as $valueType) {
-				if (!$valueType instanceof ConstantScalarType) {
+				$constScalars = $valueType->getConstantScalarValues();
+				if (count($constScalars) === 0) {
 					return null;
 				}
-				$arrayValues[] = $valueType->getValue();
+				$arrayValues[] = $constScalars;
 			}
 
-			$strings[] = new ConstantStringType(implode($separatorType->getValue(), $arrayValues));
+			$combinations = CombinationsHelper::combinations($arrayValues);
+			foreach ($combinations as $combination) {
+				$strings[] = new ConstantStringType(implode($separatorType->getValue(), $combination));
+			}
 		}
 
 		return TypeCombinator::union(...$strings);

Diff for: tests/PHPStan/Analyser/nsrt/implode.php

@@ -21,4 +21,29 @@ public function constants() {
 		assertType("'x,345'", join(',', [self::X, '345']));
 		assertType("'1,345'", join(',', [self::ONE, '345']));
 	}
+
+	/** @param array{0: 1|2, 1: 'a'|'b'} $constArr */
+	public function constArrays($constArr) {
+		assertType("'1a'|'1b'|'2a'|'2b'", implode('', $constArr));
+	}
+
+	/** @param array{0: 1|2|3, 1: 'a'|'b'|'c'} $constArr */
+	public function constArrays2($constArr) {
+		assertType("'1a'|'1b'|'1c'|'2a'|'2b'|'2c'|'3a'|'3b'|'3c'", implode('', $constArr));
+	}
+
+	/** @param array{0: 1, 1: 'a'|'b', 2: 'x'|'y'} $constArr */
+	public function constArrays3($constArr) {
+		assertType("'1ax'|'1ay'|'1bx'|'1by'", implode('', $constArr));
+	}
+
+	/** @param array{0: 1, 1: 'a'|'b', 2?: 'x'|'y'} $constArr */
+	public function constArrays4($constArr) {
+		assertType("'1a'|'1ax'|'1ay'|'1b'|'1bx'|'1by'", implode('', $constArr));
+	}
+
+	/** @param array{10: 1|2|3, xy: 'a'|'b'|'c'} $constArr */
+	public function constArrays5($constArr) {
+		assertType("'1a'|'1b'|'1c'|'2a'|'2b'|'2c'|'3a'|'3b'|'3c'", implode('', $constArr));
+	}
 }