[3.0] Fix casting to Measurement and introduce custom AnyHashable support

lib/Sema/CSSimplify.cpp

@@ -4176,7 +4176,7 @@ ConstraintSystem::simplifyRestrictedConstraint(ConversionRestrictionKind restric
     }
 
     // If the bridged value type is generic, the generic arguments
-    // must match the 
+    // must either match or be bridged.
     // FIXME: This should be an associated type of the protocol.
     if (auto bgt1 = type2->getAs<BoundGenericType>()) {
       if (bgt1->getDecl() == TC.Context.getArrayDecl()) {
@@ -4219,7 +4219,7 @@ ConstraintSystem::simplifyRestrictedConstraint(ConversionRestrictionKind restric
                         locator.withPathElement(
                           LocatorPathElt::getGenericArgument(0))));
       } else {
-        llvm_unreachable("unhandled generic bridged type");
+        // Nothing special to do; matchTypes will match generic arguments.
       }
     }
 

stdlib/public/SDK/Foundation/Measurement.swift

@@ -227,10 +227,6 @@ extension Measurement : _ObjectiveCBridgeable {
     }
 }
 
-/*
-FIXME(id-as-any): can't write this code because of:
-<rdar://problem/27539951> "unhandled generic bridged type" when bridging NSMeasurement
-
 @available(OSX 10.12, iOS 10.0, watchOS 3.0, tvOS 10.0, *)
 extension NSMeasurement : _HasCustomAnyHashableRepresentation {
     // Must be @nonobjc to avoid infinite recursion during bridging.
@@ -239,7 +235,6 @@ extension NSMeasurement : _HasCustomAnyHashableRepresentation {
         return AnyHashable(self as Measurement)
     }
 }
-*/
 
 // This workaround is required for the time being, because Swift doesn't support covariance for Measurement (26607639)
 @available(OSX 10.12, iOS 10.0, watchOS 3.0, tvOS 10.0, *)

test/1_stdlib/TestMeasurement.swift

@@ -147,6 +147,34 @@ class TestMeasurement : TestMeasurementSuper {
         expectTrue(fiveKM < sevenThousandM)
         expectTrue(fiveKM <= fiveThousandM)
     }
+
+    func test_AnyHashableContainingMeasurement() {
+        let values: [Measurement<UnitLength>] = [
+          Measurement(value: 100, unit: UnitLength.meters),
+          Measurement(value: 100, unit: UnitLength.kilometers),
+          Measurement(value: 100, unit: UnitLength.kilometers),
+        ]
+        let anyHashables = values.map(AnyHashable.init)
+        expectEqual(Measurement<UnitLength>.self, type(of: anyHashables[0].base))
+        expectEqual(Measurement<UnitLength>.self, type(of: anyHashables[1].base))
+        expectEqual(Measurement<UnitLength>.self, type(of: anyHashables[2].base))
+        expectNotEqual(anyHashables[0], anyHashables[1])
+        expectEqual(anyHashables[1], anyHashables[2])
+    }
+
+    func test_AnyHashableCreatedFromNSMeasurement() {
+        let values: [NSMeasurement] = [
+            NSMeasurement(doubleValue: 100, unit: UnitLength.meters),
+            NSMeasurement(doubleValue: 100, unit: UnitLength.kilometers),
+            NSMeasurement(doubleValue: 100, unit: UnitLength.kilometers),
+        ]
+        let anyHashables = values.map(AnyHashable.init)
+        expectEqual(Measurement<Unit>.self, type(of: anyHashables[0].base))
+        expectEqual(Measurement<Unit>.self, type(of: anyHashables[1].base))
+        expectEqual(Measurement<Unit>.self, type(of: anyHashables[2].base))
+        expectNotEqual(anyHashables[0], anyHashables[1])
+        expectEqual(anyHashables[1], anyHashables[2])
+    }
 }
 
 #if !FOUNDATION_XCTEST
@@ -159,6 +187,8 @@ if #available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *) {
     MeasurementTests.test("testMeasurementFormatter") { TestMeasurement().testMeasurementFormatter() }
     MeasurementTests.test("testEquality") { TestMeasurement().testEquality() }
     MeasurementTests.test("testComparison") { TestMeasurement().testComparison() }
+    MeasurementTests.test("test_AnyHashableContainingMeasurement") { TestMeasurement().test_AnyHashableContainingMeasurement() }
+  MeasurementTests.test("test_AnyHashableCreatedFromNSMeasurement") { TestMeasurement().test_AnyHashableCreatedFromNSMeasurement() }
     runAllTests()
 }
 #endif

test/ClangModules/objc_bridging_custom.swift

@@ -211,3 +211,18 @@ class TestObjCProtoImpl : NSObject, TestObjCProto {
     return nil
   }
 }
+
+// Check explicit conversions for bridged generic types.
+// rdar://problem/27539951
+func testExplicitConversion(objc: APPManufacturerInfo<NSString>,
+                            swift: ManufacturerInfo<NSString>) {
+  // Bridging to Swift
+  let _ = objc as ManufacturerInfo<NSString>
+  let _ = objc as ManufacturerInfo<NSNumber> // expected-error{{cannot convert value of type 'APPManufacturerInfo<NSString>' to type 'ManufacturerInfo<NSNumber>' in coercion}}
+  let _ = objc as ManufacturerInfo<NSObject> // expected-error{{cannot convert value of type 'APPManufacturerInfo<NSString>' to type 'ManufacturerInfo<NSObject>' in coercion}}
+
+  // Bridging to Objective-C
+  let _ = swift as APPManufacturerInfo<NSString>
+  let _ = swift as APPManufacturerInfo<NSNumber> // expected-error{{cannot convert value of type 'ManufacturerInfo<NSString>' to type 'APPManufacturerInfo<NSNumber>' in coercion}}
+  let _ = swift as APPManufacturerInfo<NSObject> // expected-error{{cannot convert value of type 'ManufacturerInfo<NSString>' to type 'APPManufacturerInfo<NSObject>' in coercion}}
+}