[embedded] Make Mirror present but unavailable

Author: kubamracek

stdlib/public/core/CMakeLists.txt

@@ -98,7 +98,7 @@ split_embedded_sources(
   EMBEDDED Integers.swift
     NORMAL Join.swift
   EMBEDDED KeyPath.swift
-    NORMAL KeyValuePairs.swift
+  EMBEDDED KeyValuePairs.swift
   EMBEDDED LazyCollection.swift
   EMBEDDED LazySequence.swift
     NORMAL LegacyABI.swift
@@ -227,7 +227,7 @@ split_embedded_sources(
   EMBEDDED FloatingPointRandom.swift
   EMBEDDED Instant.swift
   EMBEDDED Int128.swift
-    NORMAL Mirror.swift
+  EMBEDDED Mirror.swift
     NORMAL PlaygroundDisplay.swift
     NORMAL CommandLine.swift
   EMBEDDED SliceBuffer.swift

stdlib/public/core/EmbeddedStubs.swift

@@ -15,10 +15,9 @@ import SwiftShims
 /// String
 
 @_unavailableInEmbedded
-extension String {
-  public init<Subject>(describing instance: Subject) { fatalError() }
-  public init<Subject>(reflecting instance: Subject) { fatalError() }
-}
+internal func _print_unlocked<T>(_ value: T, _ target: inout String) { fatalError() }
+@_unavailableInEmbedded
+public func _debugPrint_unlocked<T>(_ value: T, _ target: inout String) { fatalError() }
 
 /// Codable
 

stdlib/public/core/KeyValuePairs.swift

@@ -125,13 +125,15 @@ extension KeyValuePairs: RandomAccessCollection {
   }
 }
 
+@_unavailableInEmbedded
 extension KeyValuePairs: CustomStringConvertible {
   /// A string that represents the contents of the dictionary.
   public var description: String {
     return _makeKeyValuePairDescription()
   }
 }
 
+@_unavailableInEmbedded
 extension KeyValuePairs: CustomDebugStringConvertible {
   /// A string that represents the contents of the dictionary, suitable for
   /// debugging.

stdlib/public/core/Mirror.swift

@@ -538,6 +538,7 @@ extension Mirror {
 
 //===--- General Utilities ------------------------------------------------===//
 
+@_unavailableInEmbedded
 extension String {
   /// Creates a string representing the given value.
   ///

test/embedded/mirror.swift

@@ -0,0 +1,14 @@
+// RUN: %target-swift-emit-ir -verify %s -enable-experimental-feature Embedded -wmo
+
+// REQUIRES: swift_in_compiler
+// REQUIRES: optimized_stdlib
+// REQUIRES: OS=macosx || OS=linux-gnu
+
+public struct MyStruct {
+  var a, b, c: Int
+}
+
+public func foo(s: MyStruct) {
+  let mirror = Mirror(reflecting: s) // expected-error {{'Mirror' is unavailable}}
+  _ = mirror.children
+}