[SILGen] Enable protocol extension version of _unconditionallyBridgeToObjectiveC

Author: DougGregor

lib/SILGen/SILGenBridging.cpp

@@ -131,6 +131,10 @@ emitBridgeObjectiveCToNative(SILGenFunction &gen,
     // Compute the substitutions.
     substitutions = valueTypeBGT->getSubstitutions(gen.SGM.SwiftModule,
                                                    nullptr);
+  } else {
+    // FIXME: We should always be using these substitutions, but they
+    // aren't reliable with specialized conformances.
+    substitutions = witness.getSubstitutions();
   }
 
   // Substitute into the witness function type.

stdlib/public/SDK/Foundation/Foundation.swift

@@ -213,12 +213,6 @@ extension Int : _ObjectiveCBridgeable {
     self._forceBridgeFromObjectiveC(x, result: &result)
     return true
   }
-
-  public static func _unconditionallyBridgeFromObjectiveC(
-    source: NSNumber?
-  ) -> Int {
-    return source!.integerValue
-  }
 }
 
 extension UInt : _ObjectiveCBridgeable {
@@ -253,12 +247,6 @@ extension UInt : _ObjectiveCBridgeable {
     self._forceBridgeFromObjectiveC(x, result: &result)
     return true
   }
-
-  public static func _unconditionallyBridgeFromObjectiveC(
-    source: NSNumber?
-  ) -> UInt {
-    return source!.unsignedIntegerValue
-  }
 }
 
 extension Float : _ObjectiveCBridgeable {
@@ -293,12 +281,6 @@ extension Float : _ObjectiveCBridgeable {
     self._forceBridgeFromObjectiveC(x, result: &result)
     return true
   }
-
-  public static func _unconditionallyBridgeFromObjectiveC(
-    source: NSNumber?
-  ) -> Float {
-    return source!.floatValue
-  }
 }
 
 extension Double : _ObjectiveCBridgeable {
@@ -333,12 +315,6 @@ extension Double : _ObjectiveCBridgeable {
     self._forceBridgeFromObjectiveC(x, result: &result)
     return true
   }
-
-  public static func _unconditionallyBridgeFromObjectiveC(
-    source: NSNumber?
-  ) -> Double {
-    return source!.doubleValue
-  }
 }
 
 extension Bool: _ObjectiveCBridgeable {
@@ -373,12 +349,6 @@ extension Bool: _ObjectiveCBridgeable {
     self._forceBridgeFromObjectiveC(x, result: &result)
     return true
   }
-
-  public static func _unconditionallyBridgeFromObjectiveC(
-    source: NSNumber?
-  ) -> Bool {
-    return source!.boolValue
-  }
 }
 
 // CGFloat bridging.
@@ -416,13 +386,6 @@ extension CGFloat : _ObjectiveCBridgeable {
     self._forceBridgeFromObjectiveC(x, result: &result)
     return true
   }
-
-  public static func _unconditionallyBridgeFromObjectiveC(
-    source: NSNumber?
-  ) -> CGFloat {
-    return CGFloat(
-             CGFloat.NativeType._unconditionallyBridgeFromObjectiveC(source))
-  }
 }
 
 // Literal support for NSNumber