Expand variadic compilation tests

Author: natecook1000

Diff for: Tests/RegexBuilderTests/RegexDSLTests.swift

@@ -2029,6 +2029,78 @@ extension RegexDSLTests {
     XCTAssertEqual(match.output.2, "b")
     XCTAssertNil(match.output.3)
   }
+  
+  func testVariadicNesting_Compilation() {
+    let regex2_1 = Regex {
+      "a"
+      Optionally {
+        Capture { "b" }
+      }
+    }
+    let _: Regex<(Substring, Substring?)> = regex2_1
+    
+    let regex2_2 = Regex {
+      "a"
+      Optionally {
+        Capture { "b" }
+        Capture { "c" }
+      }
+    }
+    let _: Regex<(Substring, Substring?, Substring?)> = regex2_2
+
+    let regex3_1 = Regex {
+      Optionally {
+        regex2_1
+      }
+    }
+    let _: Regex<(Substring, Substring??)> = regex3_1
+    
+    let regex3_2 = Regex {
+      Optionally {
+        regex2_2
+      }
+    }
+    let _: Regex<(Substring, Substring??, Substring??)> = regex3_2
+
+    let regex3_1_1 = Regex {
+      Optionally {
+        regex2_1
+        regex2_1
+      }
+    }
+    let _: Regex<(Substring, Substring??, Substring??)> = regex3_1_1
+
+    let regex3_2_1 = Regex {
+      Optionally {
+        regex2_2
+        regex2_1
+      }
+    }
+    let _: Regex<(Substring, Substring??, Substring??, Substring??)> = regex3_2_1
+
+    let regex3_2_2 = Regex {
+      Optionally {
+        regex2_2
+        regex2_2
+      }
+    }
+    let _: Regex<(Substring, Substring??, Substring??, Substring??, Substring??)> = regex3_2_2
+    
+    let regexChoices = Regex {
+      ChoiceOf {
+        Capture { "A" }
+        "b"
+        "c"
+        Capture { "D" }
+        Optionally {
+          Capture {
+            "E"
+          }
+        }
+      }
+    }
+    let _: Regex<(Substring, Substring?, Substring?, Substring??)> = regexChoices
+  }
 }
 
 extension Unicode.Scalar {