[ABI] Clean up StringCreate, remove unused _HasContiguousBytes

conformance from String/Substring.

Author: karwa

stdlib/public/core/AssertCommon.swift

@@ -115,7 +115,7 @@ internal func _assertionFailure(
 ) -> Never {
   prefix.withUTF8Buffer {
     (prefix) -> Void in
-    message._withUnsafeBufferPointerToUTF8 {
+    message._withUTF8 {
       (messageUTF8) -> Void in
       file.withUTF8Buffer {
         (file) -> Void in
@@ -145,7 +145,7 @@ internal func _assertionFailure(
 ) -> Never {
   prefix.withUTF8Buffer {
     (prefix) -> Void in
-    message._withUnsafeBufferPointerToUTF8 {
+    message._withUTF8 {
       (messageUTF8) -> Void in
       _swift_stdlib_reportFatalError(
         prefix.baseAddress!, CInt(prefix.count),

stdlib/public/core/ContiguouslyStored.swift

@@ -73,11 +73,7 @@ extension UnsafeMutableRawBufferPointer: _HasContiguousBytes {
     return try body(UnsafeRawBufferPointer(self))
   }
 }
-extension String: _HasContiguousBytes {
-  @inlinable
-  internal var _providesContiguousBytesNoCopy: Bool {
-    @inline(__always) get { return self._guts.isFastUTF8 }
-  }
+extension String {
 
   @inlinable @inline(__always)
   internal func _withUTF8<R>(
@@ -93,20 +89,9 @@ extension String: _HasContiguousBytes {
       try body($0)
     }
   }
-
-  @inlinable @inline(__always)
-  internal func withUnsafeBytes<R>(
-    _ body: (UnsafeRawBufferPointer) throws -> R
-  ) rethrows -> R {
-    return try self._withUTF8 { return try body(UnsafeRawBufferPointer($0)) }
-  }
 }
-extension Substring: _HasContiguousBytes {
-  @inlinable
-  internal var _providesContiguousBytesNoCopy: Bool {
-    @inline(__always) get { return self._wholeGuts.isFastUTF8 }
-  }
-
+extension Substring {
+  
   @inlinable @inline(__always)
   internal func _withUTF8<R>(
     _ body: (UnsafeBufferPointer<UInt8>) throws -> R
@@ -121,11 +106,4 @@ extension Substring: _HasContiguousBytes {
       try body($0)
     }
   }
-
-  @inlinable @inline(__always)
-  internal func withUnsafeBytes<R>(
-    _ body: (UnsafeRawBufferPointer) throws -> R
-  ) rethrows -> R {
-    return try self._withUTF8 { return try body(UnsafeRawBufferPointer($0)) }
-  }
 }

stdlib/public/core/StringCreate.swift

@@ -58,13 +58,7 @@ extension String {
     _ input: UnsafeBufferPointer<UInt8>
   ) -> String {
     _internalInvariant(_allASCII(input), "not actually ASCII")
-
-    if let smol = _SmallString(input) {
-      return String(_StringGuts(smol))
-    }
-
-    let storage = __StringStorage.create(initializingFrom: input, isASCII: true)
-    return storage.asString
+    return _uncheckedFromUTF8(UnsafeRawBufferPointer(input), isASCII: true)
   }
 
   // UTF8 from typed memory.
@@ -113,8 +107,7 @@ extension String {
     }
   }
 
-  @usableFromInline
-  internal static func _uncheckedFromUTF8(
+  private static func _uncheckedFromUTF8(
     _ input: UnsafeRawBufferPointer,
     isASCII: Bool
   ) -> String {
@@ -127,15 +120,6 @@ extension String {
     return storage.asString
   }
 
-  // If we've already pre-scanned for ASCII, just supply the result
-  @usableFromInline
-  internal static func _uncheckedFromUTF8(
-    _ input: UnsafeBufferPointer<UInt8>, asciiPreScanResult: Bool
-  ) -> String {
-    return _uncheckedFromUTF8(UnsafeRawBufferPointer(input),
-                              isASCII: asciiPreScanResult)
-  }
-
   // Other encodings.
 
   @usableFromInline
@@ -159,12 +143,6 @@ extension String {
     return contents.withUnsafeBufferPointer { String._uncheckedFromUTF8($0) }
   }
 
-  internal func _withUnsafeBufferPointerToUTF8<R>(
-    _ body: (UnsafeBufferPointer<UTF8.CodeUnit>) throws -> R
-  ) rethrows -> R {
-    return try self._withUTF8(body)
-  }
-
   @usableFromInline @inline(never) // slow-path
   internal static func _fromCodeUnits<
     Input: Collection,

test/api-digester/Outputs/stability-stdlib-abi.swift.expected

@@ -86,5 +86,12 @@ Subscript Substring.subscript(_:) has been removed
 
 Func Collection.makeIterator() has self access kind changing from NonMutating to __Consuming
 
-Func String._uncheckedFromUTF8(_:isASCII:) has parameter 0 type change from UnsafeBufferPointer<UInt8> to UnsafeRawBufferPointer
+Func String._uncheckedFromUTF8(_:isASCII:) has been removed
 Func _bytesToUInt64(_:_:) has parameter 0 type change from UnsafePointer<UInt8> to UnsafeRawPointer
+Func String._uncheckedFromUTF8(_:asciiPreScanResult:) has been removed
+Func String.withUnsafeBytes(_:) has been removed
+Func Substring.withUnsafeBytes(_:) has been removed
+Struct String has removed conformance to _HasContiguousBytes
+Struct Substring has removed conformance to _HasContiguousBytes
+Var String._providesContiguousBytesNoCopy has been removed
+Var Substring._providesContiguousBytesNoCopy has been removed