diff --git a/lib/Demangling/Demangler.cpp b/lib/Demangling/Demangler.cpp
index 642df88..f9211dd 100644
--- a/lib/Demangling/Demangler.cpp
+++ b/lib/Demangling/Demangler.cpp
@@ -442,6 +442,10 @@
   int RepeatCount = -1;
   while (true) {
     char c = nextChar();
+    if (c == 0) {
+      // End of text.
+      return nullptr;
+    }
     if (isLowerLetter(c)) {
       // It's a substitution with an index < 26.
       NodePointer Nd = pushMultiSubstitutions(RepeatCount, c - 'a');
@@ -1322,7 +1326,8 @@
       case FunctionSigSpecializationParamKind::ClosureProp: {
         size_t FixedChildren = Param->getNumChildren();
         while (NodePointer Ty = popNode(Node::Kind::Type)) {
-          assert(ParamKind == FunctionSigSpecializationParamKind::ClosureProp);
+          if (ParamKind != FunctionSigSpecializationParamKind::ClosureProp)
+            return nullptr;
           Param = addChild(Param, Ty);
         }
         NodePointer Name = popNode(Node::Kind::Identifier);
diff --git a/lib/PrintAsObjC/PrintAsObjC.cpp b/lib/PrintAsObjC/PrintAsObjC.cpp
index b311794..a95e869 100644
--- a/lib/PrintAsObjC/PrintAsObjC.cpp
+++ b/lib/PrintAsObjC/PrintAsObjC.cpp
@@ -825,7 +825,7 @@
     if (!attr || !attr->isSwift3Inferred())
       return;
 
-    os << " SWIFT_DEPRECATED_MSG(\"Swift ";
+    os << " SWIFT_DEPRECATED_OBJC(\"Swift ";
     if (isa<VarDecl>(VD))
       os << "property";
     else if (isa<SubscriptDecl>(VD))
@@ -2337,6 +2337,7 @@
     out << "// Generated by " << version::getSwiftFullVersion(
       M.getASTContext().LangOpts.EffectiveLanguageVersion) << "\n"
            "#pragma clang diagnostic push\n"
+           "#pragma clang diagnostic ignored \"-Wgcc-compat\"\n"
            "\n"
            "#if !defined(__has_include)\n"
            "# define __has_include(x) 0\n"
@@ -2528,6 +2529,11 @@
            "#if !defined(SWIFT_DEPRECATED_MSG)\n"
            "# define SWIFT_DEPRECATED_MSG(...) __attribute__((deprecated(__VA_ARGS__)))\n"
            "#endif\n"
+           "#if __has_feature(attribute_diagnose_if_objc)\n"
+           "# define SWIFT_DEPRECATED_OBJC(Msg) __attribute__((diagnose_if(1, Msg, \"warning\")))\n"
+           "#else\n"
+           "# define SWIFT_DEPRECATED_OBJC(Msg) SWIFT_DEPRECATED_MSG(Msg)\n"
+           "#endif\n"
            ;
     static_assert(SWIFT_MAX_IMPORTED_SIMD_ELEMENTS == 4,
                 "need to add SIMD typedefs here if max elements is increased");
diff --git a/stdlib/public/core/ArrayType.swift b/stdlib/public/core/ArrayType.swift
index b79e5c6..645ad3a 100644
--- a/stdlib/public/core/ArrayType.swift
+++ b/stdlib/public/core/ArrayType.swift
@@ -70,3 +70,15 @@
   // For testing.
   var _buffer: _Buffer { get }
 }
+
+extension _ArrayProtocol {
+  // Since RangeReplaceableCollection now has a version of filter that is less
+  // efficient, we should make the default implementation coming from Sequence
+  // preferred.
+  @_inlineable
+  public func filter(
+    _ isIncluded: (Element) throws -> Bool
+  ) rethrows -> [Element] {
+    return try _filter(isIncluded)
+  }
+}
diff --git a/stdlib/public/core/Arrays.swift.gyb b/stdlib/public/core/Arrays.swift.gyb
index 4aeed18d..f2310c7 100644
--- a/stdlib/public/core/Arrays.swift.gyb
+++ b/stdlib/public/core/Arrays.swift.gyb
@@ -1574,16 +1574,6 @@
     }
   }
 
-  // Since RangeReplaceableCollection now has a version of filter that is less
-  // efficient, we should make the default implementation coming from Sequence
-  // preferred.
-  @_inlineable
-  public func filter(
-    _ isIncluded: (Element) throws -> Bool
-  ) rethrows -> [Element] {
-    return try _filter(isIncluded)
-  }
-
   //===--- algorithms -----------------------------------------------------===//
 
   @_inlineable
diff --git a/test/Demangle/Inputs/manglings.txt b/test/Demangle/Inputs/manglings.txt
index 438d750..1eedde0 100644
--- a/test/Demangle/Inputs/manglings.txt
+++ b/test/Demangle/Inputs/manglings.txt
@@ -254,4 +254,6 @@
 _T04test6testitSiyt_tF ---> test.testit(()) -> Swift.Int
 _T0Rml ---> _T0Rml
 _T0Tk ---> _T0Tk
+_T0A8 ---> _T0A8
+_T0s30ReversedRandomAccessCollectionVyxGTfq3nnpf_nTfq1cn_nTfq4x_n ---> _T0s30ReversedRandomAccessCollectionVyxGTfq3nnpf_nTfq1cn_nTfq4x_n
 
diff --git a/test/PrintAsObjC/swift3_deprecated_objc_inference.swift b/test/PrintAsObjC/swift3_deprecated_objc_inference.swift
index c56d5ce..38929f1 100644
--- a/test/PrintAsObjC/swift3_deprecated_objc_inference.swift
+++ b/test/PrintAsObjC/swift3_deprecated_objc_inference.swift
@@ -32,15 +32,15 @@
 }
 
 // CHECK-LABEL: @interface A2{{$}}
-// CHECK-NEXT: - (nonnull instancetype)initWithA2:(A2 * _Nonnull)a2 OBJC_DESIGNATED_INITIALIZER SWIFT_DEPRECATED_MSG("Swift initializer 'A2.init(a2:)' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
-// CHECK-NEXT: - (void)foo SWIFT_DEPRECATED_MSG("Swift method 'A2.foo()' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
-// CHECK-NEXT: + (void)bar SWIFT_DEPRECATED_MSG("Swift method 'A2.bar()' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
-// CHECK-NEXT: @property (nonatomic, strong) A2 * _Nullable property SWIFT_DEPRECATED_MSG("Swift property 'A2.property' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
-// CHECK-NEXT: SWIFT_CLASS_PROPERTY(@property (nonatomic, class, strong) A2 * _Nullable static_property SWIFT_DEPRECATED_MSG("Swift property 'A2.static_property' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");)
-// CHECK-NEXT: + (A2 * _Nullable)static_property SWIFT_WARN_UNUSED_RESULT SWIFT_DEPRECATED_MSG("Swift property 'A2.static_property' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
-// CHECK-NEXT: + (void)setStatic_property:(A2 * _Nullable)value SWIFT_DEPRECATED_MSG("Swift property 'A2.static_property' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
-// CHECK-NEXT: - (A2 * _Nonnull)objectAtIndexedSubscript:(NSInteger)i SWIFT_WARN_UNUSED_RESULT SWIFT_DEPRECATED_MSG("Swift subscript 'A2.subscript(_:)' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
-// CHECK-NEXT: - (void)setObject:(A2 * _Nonnull)newValue atIndexedSubscript:(NSInteger)i SWIFT_DEPRECATED_MSG("Swift subscript 'A2.subscript(_:)' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
+// CHECK-NEXT: - (nonnull instancetype)initWithA2:(A2 * _Nonnull)a2 OBJC_DESIGNATED_INITIALIZER SWIFT_DEPRECATED_OBJC("Swift initializer 'A2.init(a2:)' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
+// CHECK-NEXT: - (void)foo SWIFT_DEPRECATED_OBJC("Swift method 'A2.foo()' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
+// CHECK-NEXT: + (void)bar SWIFT_DEPRECATED_OBJC("Swift method 'A2.bar()' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
+// CHECK-NEXT: @property (nonatomic, strong) A2 * _Nullable property SWIFT_DEPRECATED_OBJC("Swift property 'A2.property' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
+// CHECK-NEXT: SWIFT_CLASS_PROPERTY(@property (nonatomic, class, strong) A2 * _Nullable static_property SWIFT_DEPRECATED_OBJC("Swift property 'A2.static_property' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");)
+// CHECK-NEXT: + (A2 * _Nullable)static_property SWIFT_WARN_UNUSED_RESULT SWIFT_DEPRECATED_OBJC("Swift property 'A2.static_property' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
+// CHECK-NEXT: + (void)setStatic_property:(A2 * _Nullable)value SWIFT_DEPRECATED_OBJC("Swift property 'A2.static_property' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
+// CHECK-NEXT: - (A2 * _Nonnull)objectAtIndexedSubscript:(NSInteger)i SWIFT_WARN_UNUSED_RESULT SWIFT_DEPRECATED_OBJC("Swift subscript 'A2.subscript(_:)' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
+// CHECK-NEXT: - (void)setObject:(A2 * _Nonnull)newValue atIndexedSubscript:(NSInteger)i SWIFT_DEPRECATED_OBJC("Swift subscript 'A2.subscript(_:)' uses '@objc' inference deprecated in Swift 4; add '@objc' to provide an Objective-C entrypoint");
 
 // CHECK-NEXT: @end
 @objc class A2 {
diff --git a/test/stdlib/RangeReplaceableFilterCompatibility.swift b/test/stdlib/RangeReplaceableFilterCompatibility.swift
index 169654f..37ac3d1 100644
--- a/test/stdlib/RangeReplaceableFilterCompatibility.swift
+++ b/test/stdlib/RangeReplaceableFilterCompatibility.swift
@@ -35,5 +35,10 @@
   expectEqualSequence("HW", filtered)
 }
 
+tests.test("lazy.flatMap.filter ambiguity") {
+  // this expression should compile without ambiguity
+  _ = Array(0..<10).lazy.flatMap { .some($0) }.filter { _ in false }
+}
+
 runAllTests()