Build _RegexParser without implicit import of _StringProcessing

Explicitly ask the compiler not to implicitly import _StringProessing. This is to avoid a circular dependency when `-enable-experimental-string-processing` is enabled by default.

Author: rxwei

Package.swift

@@ -38,6 +38,7 @@ let package = Package(
             dependencies: [],
             swiftSettings: [
                 .unsafeFlags(["-enable-library-evolution"]),
+                .unsafeFlags(["-Xfrontend", "-disable-implicit-string-processing-module-import"]),
                 availabilityDefinition
             ]),
         .testTarget(

Sources/_RegexParser/Regex/AST/AST.swift

@@ -29,7 +29,6 @@ extension AST {
 
 extension AST {
   /// A node in the regex AST.
-  @frozen
   public indirect enum Node:
     Hashable, _TreeNode //, _ASTPrintable ASTValue, ASTAction
   {
@@ -247,7 +246,6 @@ extension AST {
   }
 
   public struct Reference: Hashable {
-    @frozen
     public enum Kind: Hashable {
       // \n \gn \g{n} \g<n> \g'n' (?n) (?(n)...
       // Oniguruma: \k<n>, \k'n'

Sources/_RegexParser/Regex/AST/Atom.swift

@@ -19,7 +19,6 @@ extension AST {
       self.location = loc
     }
 
-    @frozen
     public enum Kind: Hashable {
       /// Just a character
       ///
@@ -115,7 +114,6 @@ extension AST.Atom {
 
   // Characters, character types, literals, etc., derived from
   // an escape sequence.
-  @frozen
   public enum EscapedBuiltin: Hashable {
     // TODO: better doc comments
 
@@ -368,7 +366,6 @@ extension AST.Atom {
 }
 
 extension AST.Atom.CharacterProperty {
-  @frozen
   public enum Kind: Hashable {
     /// Matches any character, equivalent to Oniguruma's '\O'.
     case any
@@ -407,7 +404,6 @@ extension AST.Atom.CharacterProperty {
   }
 
   // TODO: erm, separate out or fold into something? splat it in?
-  @frozen
   public enum PCRESpecialCategory: String, Hashable {
     case alphanumeric     = "Xan"
     case posixSpace       = "Xps"
@@ -419,7 +415,6 @@ extension AST.Atom.CharacterProperty {
 
 extension AST.Atom {
   /// Anchors and other built-in zero-width assertions.
-  @frozen
   public enum AssertionKind: String {
     /// \A
     case startOfSubject = #"\A"#

Sources/_RegexParser/Regex/AST/CustomCharClass.swift

@@ -27,7 +27,6 @@ extension AST {
       self.location = sr
     }
 
-    @frozen
     public enum Member: Hashable {
       /// A nested custom character class `[[ab][cd]]`
       case custom(CustomCharacterClass)
@@ -59,13 +58,11 @@ extension AST {
         self.rhs = rhs
       }
     }
-    @frozen
     public enum SetOp: String, Hashable {
       case subtraction = "--"
       case intersection = "&&"
       case symmetricDifference = "~~"
     }
-    @frozen
     public enum Start: String {
       case normal = "["
       case inverted = "[^"

Sources/_RegexParser/Regex/AST/Quantification.swift

@@ -36,7 +36,6 @@ extension AST {
       self.trivia = trivia
     }
 
-    @frozen
     public enum Amount: Hashable {
       case zeroOrMore              // *
       case oneOrMore               // +
@@ -47,7 +46,6 @@ extension AST {
       case range(Located<Int>, Located<Int>) // {n,m}
     }
 
-    @frozen
     public enum Kind: String, Hashable {
       case eager      = ""
       case reluctant  = "?"

Sources/_RegexParser/Utility/MissingUnicode.swift

@@ -19,7 +19,6 @@ extension Unicode {
   // other script types.
 
   /// Character script types.
-  @frozen
   public enum Script: String, Hashable {
     case adlam = "Adlam"
     case ahom = "Ahom"
@@ -188,7 +187,6 @@ extension Unicode {
 
   /// POSIX character properties not already covered by general categories or
   /// binary properties.
-  @frozen
   public enum POSIXProperty: String, Hashable {
     case alnum = "alnum"
     case blank = "blank"
@@ -206,7 +204,6 @@ extension Unicode {
 
   /// Unicode.GeneralCategory + cases for "meta categories" such as "L", which
   /// encompasses Lu | Ll | Lt | Lm | Lo.
-  @frozen
   public enum ExtendedGeneralCategory: String, Hashable {
     case other = "C"
     case control = "Cc"
@@ -257,7 +254,6 @@ extension Unicode {
   /// A list of Unicode properties that can either be true or false.
   ///
   /// https://www.unicode.org/Public/UCD/latest/ucd/PropertyAliases.txt
-  @frozen
   public enum BinaryProperty: String, Hashable {
     case asciiHexDigit = "ASCII_Hex_Digit"
     case alphabetic = "Alphabetic"
@@ -333,7 +329,6 @@ extension Unicode {
 // property.
 
 /// Oniguruma properties that are not covered by Unicode spellings.
-@frozen
 public enum OnigurumaSpecialProperty: String, Hashable {
   case inBasicLatin = "In_Basic_Latin"
   case inLatin1Supplement = "In_Latin_1_Supplement"