Merge pull request #1839 from etcwilde/ewilde/variant-triple-to-variant-module-job

Add `contains(subsequence:)` on any bidirectional sequence instead of just arrays

Author: etcwilde

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -4182,7 +4182,7 @@ final class SwiftDriverTests: XCTestCase {
         "-emit-module-path", "target.swiftmodule",
         "-emit-variant-module-path", "variant.swiftmodule",
         "-Xfrontend", "-emit-module-doc-path", "-Xfrontend", "target.swiftdoc",
-        "-Xfrontend", "-emit-variant-module-doc-path", "variant.swiftdoc",
+        "-Xfrontend", "-emit-variant-module-doc-path", "-Xfrontend", "variant.swiftdoc",
         "-emit-module-source-info-path", "target.sourceinfo",
         "-emit-variant-module-source-info-path", "variant.sourceinfo",
         "-emit-package-module-interface-path", "target.package.swiftinterface",
@@ -8323,7 +8323,7 @@ func assertString(
                 """, file: file, line: line)
 }
 
-extension Array where Element: Equatable {
+extension BidirectionalCollection where Element: Equatable, Index: Strideable, Index.Stride: SignedInteger {
   /// Returns true if the receiver contains the given elements as a subsequence
   /// (i.e., all elements are present, contiguous, and in the same order).
   ///
@@ -8337,10 +8337,15 @@ extension Array where Element: Equatable {
   {
     precondition(!subsequence.isEmpty,  "Subsequence may not be empty")
 
-    let subsequenceCount = subsequence.count
-    for index in 0...(self.count - subsequence.count) {
-      let subsequenceEnd = index + subsequenceCount
-      if self[index..<subsequenceEnd].elementsEqual(subsequence) {
+    guard self.count >= subsequence.count else {
+      return false
+    }
+
+    for index in self.startIndex...self.index(self.endIndex,
+                                              offsetBy: -subsequence.count) {
+      if self[index..<self.index(index,
+                                 offsetBy: subsequence.count)]
+                          .elementsEqual(subsequence) {
         return true
       }
     }