Change position of canOnlyMatchAtStart property

The order of this property in MEProgram seems to determine whether
or not it persists from the time it's stored to when it's accessed
in RegexDSLTests. Clearly something else is going on here, but this
works around the issue for now.

Author: natecook1000

Sources/_StringProcessing/Engine/MEBuilder.swift

@@ -395,6 +395,7 @@ extension MEProgram.Builder {
     regInfo.captures = nextCaptureRegister.rawValue
 
     return MEProgram(
+      canOnlyMatchAtStart: canOnlyMatchAtStart,
       instructions: InstructionList(instructions),
       staticElements: elements.stored,
       staticSequences: sequences.stored,
@@ -407,8 +408,7 @@ extension MEProgram.Builder {
       enableMetrics: enableMetrics,
       captureList: captureList,
       referencedCaptureOffsets: referencedCaptureOffsets,
-      initialOptions: initialOptions,
-      canOnlyMatchAtStart: canOnlyMatchAtStart)
+      initialOptions: initialOptions)
   }
 
   mutating func reset() { self = Self() }

Sources/_StringProcessing/Engine/MEProgram.swift

@@ -20,6 +20,8 @@ struct MEProgram {
   typealias MatcherFunction =
     (Input, Input.Index, Range<Input.Index>) throws -> (Input.Index, Any)?
 
+  var canOnlyMatchAtStart: Bool
+
   var instructions: InstructionList<Instruction>
 
   var staticElements: [Input.Element]
@@ -38,7 +40,6 @@ struct MEProgram {
   let referencedCaptureOffsets: [ReferenceID: Int]
 
   var initialOptions: MatchingOptions
-  var canOnlyMatchAtStart: Bool
 }
 
 extension MEProgram: CustomStringConvertible {

Sources/_StringProcessing/Regex/DSLTree.swift

@@ -724,7 +724,6 @@ extension DSLTree.Node {
   /// In particular, non-required groups and option-setting groups are
   /// inconclusive about where they can match.
   private func _canOnlyMatchAtStartImpl(_ options: inout MatchingOptions) -> Bool? {
-    print(self)
     switch self {
     // Defining cases
     case .atom(.assertion(.startOfSubject)):

Tests/RegexBuilderTests/RegexDSLTests.swift

@@ -985,28 +985,7 @@ class RegexDSLTests: XCTestCase {
     ) {
       let regex = content().regex
       let result = regex.program.loweredProgram.canOnlyMatchAtStart
-      print("""
-        canOnlyMatchAtStart: \(result)
-        expectation: \(expectation)
-        equal? \(result == expectation)
-        """)
-      
-      XCTAssertEqual(result ? 1 : 0, expectation ? 1 : 0, file: file, line: line)
-      
-      if expectation {
-        XCTAssertTrue(result, file: file, line: line)
-      } else {
-        XCTAssertFalse(result, file: file, line: line)
-      }
-      
-      XCTAssertTrue(expectation == result, file: file, line: line)
-
       XCTAssertEqual(result, expectation, file: file, line: line)
-      XCTAssertEqual(
-        result.baseValue,
-        expectation.baseValue,
-        file: file, line: line)
-      fflush(stdout)
     }
 
     expectCanOnlyMatchAtStart(true) {