Avoid duplicate in Union type description

src/Type/UnionType.php

@@ -27,6 +27,8 @@
 use PHPStan\Type\Generic\TemplateTypeVariance;
 use PHPStan\Type\Generic\TemplateUnionType;
 use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
+use function array_diff_assoc;
+use function array_fill_keys;
 use function array_map;
 use function array_merge;
 use function array_slice;
@@ -293,6 +295,22 @@ public function describe(VerbosityLevel $level): string
 				}
 			}
 
+			if ($level->isPrecise()) {
+				$duplicates = array_diff_assoc($typeNames, array_unique($typeNames));
+				if (count($duplicates) > 0) {
+					$indexByDuplicate = array_fill_keys($duplicates, 0);
+					foreach ($typeNames as $key => $typeName) {
+						if (!isset($indexByDuplicate[$typeName])) {
+							continue;
+						}
+
+						$typeNames[$key] = $typeName . '#' . ++$indexByDuplicate[$typeName];
+					}
+				}
+			} else {
+				$typeNames = array_unique($typeNames);
+			}
+
 			if (count($typeNames) > 1024) {
 				return implode('|', array_slice($typeNames, 0, 1024)) . "|\u{2026}";
 			}

src/Type/VerbosityLevel.php

@@ -78,6 +78,11 @@ public function isValue(): bool
 		return $this->value === self::VALUE;
 	}
 
+	public function isPrecise(): bool
+	{
+		return $this->value === self::PRECISE;
+	}
+
 	/** @api */
 	public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acceptedType = null): self
 	{

tests/PHPStan/Type/UnionTypeTest.php

@@ -717,11 +717,13 @@ public function dataDescribe(): array
 				new UnionType([new IntegerType(), new StringType()]),
 				'int|string',
 				'int|string',
+				'int|string',
 			],
 			[
 				new UnionType([new IntegerType(), new StringType(), new NullType()]),
 				'int|string|null',
 				'int|string|null',
+				'int|string|null',
 			],
 			[
 				new UnionType([
@@ -742,6 +744,7 @@ public function dataDescribe(): array
 					new ConstantStringType('1'),
 				]),
 				"1|2|2.2|10|'1'|'10'|'10aaa'|'11aaa'|'1aaa'|'2'|'2aaa'|'foo'|stdClass|true|null",
+				"1|2|2.2|10|'1'|'10'|'10aaa'|'11aaa'|'1aaa'|'2'|'2aaa'|'foo'|stdClass|true|null",
 				'float|int|stdClass|string|true|null',
 			],
 			[
@@ -763,6 +766,7 @@ public function dataDescribe(): array
 					new ConstantStringType('aaa'),
 				),
 				'\'aaa\'|array{a: int, b: float}|array{a: string, b: bool}',
+				'\'aaa\'|array{a: int, b: float}|array{a: string, b: bool}',
 				'array<string, bool|float|int|string>|string',
 			],
 			[
@@ -784,6 +788,7 @@ public function dataDescribe(): array
 					new ConstantStringType('aaa'),
 				),
 				'\'aaa\'|array{a: string, b: bool}|array{b: int, c: float}',
+				'\'aaa\'|array{a: string, b: bool}|array{b: int, c: float}',
 				'array<string, bool|float|int|string>|string',
 			],
 			[
@@ -805,6 +810,7 @@ public function dataDescribe(): array
 					new ConstantStringType('aaa'),
 				),
 				'\'aaa\'|array{a: string, b: bool}|array{c: int, d: float}',
+				'\'aaa\'|array{a: string, b: bool}|array{c: int, d: float}',
 				'array<string, bool|float|int|string>|string',
 			],
 			[
@@ -825,6 +831,7 @@ public function dataDescribe(): array
 					]),
 				),
 				'array{int, bool, float}|array{string}',
+				'array{int, bool, float}|array{string}',
 				'array<int, bool|float|int|string>',
 			],
 			[
@@ -837,6 +844,7 @@ public function dataDescribe(): array
 					]),
 				),
 				'array{}|array{foooo: \'barrr\'}',
+				'array{}|array{foooo: \'barrr\'}',
 				'array<string, string>',
 			],
 			[
@@ -848,6 +856,7 @@ public function dataDescribe(): array
 					]),
 				),
 				'int|numeric-string',
+				'int|numeric-string',
 				'int|string',
 			],
 			[
@@ -857,6 +866,7 @@ public function dataDescribe(): array
 				),
 				'int<0, 4>|int<6, 10>',
 				'int<0, 4>|int<6, 10>',
+				'int<0, 4>|int<6, 10>',
 			],
 			[
 				TypeCombinator::union(
@@ -868,6 +878,7 @@ public function dataDescribe(): array
 					),
 					new NullType(),
 				),
+				'TFoo of int (class foo, parameter)|null',
 				'(TFoo of int)|null',
 				'(TFoo of int)|null',
 			],
@@ -881,6 +892,7 @@ public function dataDescribe(): array
 					),
 					new GenericClassStringType(new ObjectType('Abc')),
 				),
+				'class-string<Abc>|TFoo of int (class foo, parameter)',
 				'class-string<Abc>|TFoo of int',
 				'class-string<Abc>|TFoo of int',
 			],
@@ -894,6 +906,7 @@ public function dataDescribe(): array
 					),
 					new NullType(),
 				),
+				'TFoo (class foo, parameter)|null',
 				'TFoo|null',
 				'TFoo|null',
 			],
@@ -912,9 +925,16 @@ public function dataDescribe(): array
 					),
 					new NullType(),
 				),
+				'TFoo of TBar (class foo, parameter) (class foo, parameter)|null',
 				'(TFoo of TBar)|null',
 				'(TFoo of TBar)|null',
 			],
+			[
+				new UnionType([new ObjectType('Foo'), new ObjectType('Foo')]),
+				'Foo#1|Foo#2',
+				'Foo',
+				'Foo',
+			],
 		];
 	}
 
@@ -923,10 +943,12 @@ public function dataDescribe(): array
 	 */
 	public function testDescribe(
 		Type $type,
+		string $expectedPreciseDescription,
 		string $expectedValueDescription,
 		string $expectedTypeOnlyDescription,
 	): void
 	{
+		$this->assertSame($expectedPreciseDescription, $type->describe(VerbosityLevel::precise()));
 		$this->assertSame($expectedValueDescription, $type->describe(VerbosityLevel::value()));
 		$this->assertSame($expectedTypeOnlyDescription, $type->describe(VerbosityLevel::typeOnly()));
 	}