add sameShape constraint kind (#103)

rdar://129338238

Author: QuietMisdreavus

Sources/SymbolKit/SymbolGraph/Symbol/Swift/GenericConstraint.swift

@@ -1,7 +1,7 @@
 /*
  This source file is part of the Swift.org open source project
 
- Copyright (c) 2021-2023 Apple Inc. and the Swift project authors
+ Copyright (c) 2021-2025 Apple Inc. and the Swift project authors
  Licensed under Apache License v2.0 with Runtime Library Exception
 
  See https://swift.org/LICENSE.txt for license information
@@ -46,6 +46,17 @@ extension SymbolGraph.Symbol.Swift {
              ```
              */
             case sameType
+
+            /**
+             A same-shape constraint, such as:
+
+             ```swift
+             public func function<each Element0, each Element1>(
+               _: (repeat (each Element0, each Element1))
+             ) { }
+             ```
+             */
+            case sameShape
         }
 
         enum CodingKeys: String, CodingKey {

Tests/SymbolKitTests/SymbolGraph/Symbol/Swift/GenericConstraintTests.swift

@@ -1,7 +1,7 @@
 /*
  This source file is part of the Swift.org open source project
 
- Copyright (c) 2023 Apple Inc. and the Swift project authors
+ Copyright (c) 2023-2025 Apple Inc. and the Swift project authors
  Licensed under Apache License v2.0 with Runtime Library Exception
 
  See https://swift.org/LICENSE.txt for license information
@@ -66,4 +66,22 @@ class GenericConstraintTests: XCTestCase {
         )
         XCTAssertEqual(jsonConstraint, constraint)
     }
+
+    func testInitializeSameShape() throws {
+        let jsonString = """
+        {
+            "kind": "sameShape",
+            "lhs": "T1",
+            "rhs": "T2",
+        }
+        """
+        let jsonData = Data(jsonString.utf8)
+        let jsonConstraint = try JSONDecoder().decode(SymbolGraph.Symbol.Swift.GenericConstraint.self, from: jsonData)
+        let constraint = SymbolGraph.Symbol.Swift.GenericConstraint(
+            kind: .sameShape,
+            leftTypeName: "T1",
+            rightTypeName: "T2"
+        )
+        XCTAssertEqual(jsonConstraint, constraint)
+    }
 }