Merge pull request #660 from jskeet/throw-on-null

Throw on null for string/bytes single fields
9 years ago · bde01d5326
parent 7909b2edeb d18cc08456
commit bde01d5326
19 changed files with 169 additions and 149 deletions
--- a/Makefile.am
+++ b/Makefile.am
@ -107,6 +107,7 @@ csharp_EXTRA_DIST=                                                           \
  csharp/src/Google.Protobuf/LimitedInputStream.cs                           \
  csharp/src/Google.Protobuf/MessageExtensions.cs                            \
  csharp/src/Google.Protobuf/MessageParser.cs                                \
+  csharp/src/Google.Protobuf/Preconditions.cs                                \
  csharp/src/Google.Protobuf/Properties/AssemblyInfo.cs                      \
  csharp/src/Google.Protobuf/Reflection/DescriptorBase.cs                    \
  csharp/src/Google.Protobuf/Reflection/DescriptorPool.cs                    \
@ -133,7 +134,6 @@ csharp_EXTRA_DIST=                                                           \
  csharp/src/Google.Protobuf/Reflection/RepeatedFieldAccessor.cs             \
  csharp/src/Google.Protobuf/Reflection/ServiceDescriptor.cs                 \
  csharp/src/Google.Protobuf/Reflection/SingleFieldAccessor.cs               \
-  csharp/src/Google.Protobuf/ThrowHelper.cs                                  \
  csharp/src/Google.Protobuf/WellKnownTypes/Any.cs                           \
  csharp/src/Google.Protobuf/WellKnownTypes/Api.cs                           \
  csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs                      \
--- a/csharp/src/AddressBook/Addressbook.cs
+++ b/csharp/src/AddressBook/Addressbook.cs
@ -76,7 +76,7 @@ namespace Google.Protobuf.Examples.AddressBook {
    public string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -94,7 +94,7 @@ namespace Google.Protobuf.Examples.AddressBook {
    public string Email {
      get { return email_; }
      set {
-        email_ = value ?? "";
+        email_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -257,7 +257,7 @@ namespace Google.Protobuf.Examples.AddressBook {
        public string Number {
          get { return number_; }
          set {
-            number_ = value ?? "";
+            number_ = pb::Preconditions.CheckNotNull(value, "value");
          }
        }

--- a/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs
+++ b/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs
@ -111,6 +111,16 @@ namespace Google.Protobuf
            Assert.IsNull(message.OneofNestedMessage);
        }

+        [Test]
+        public void NullStringAndBytesRejected()
+        {
+            var message = new TestAllTypes();
+            Assert.Throws<ArgumentNullException>(() => message.SingleString = null);
+            Assert.Throws<ArgumentNullException>(() => message.OneofString = null);
+            Assert.Throws<ArgumentNullException>(() => message.SingleBytes = null);
+            Assert.Throws<ArgumentNullException>(() => message.OneofBytes = null);
+        }
+
        [Test]
        public void RoundTrip_Empty()
        {
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs
@ -426,7 +426,7 @@ namespace Google.Protobuf.TestProtos {
    public string SingleString {
      get { return singleString_; }
      set {
-        singleString_ = value ?? "";
+        singleString_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -435,7 +435,7 @@ namespace Google.Protobuf.TestProtos {
    public pb::ByteString SingleBytes {
      get { return singleBytes_; }
      set {
-        singleBytes_ = value ?? pb::ByteString.Empty;
+        singleBytes_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -700,7 +700,7 @@ namespace Google.Protobuf.TestProtos {
    public string OneofString {
      get { return oneofFieldCase_ == OneofFieldOneofCase.OneofString ? (string) oneofField_ : ""; }
      set {
-        oneofField_ = value ?? "";
+        oneofField_ = pb::Preconditions.CheckNotNull(value, "value");
        oneofFieldCase_ = OneofFieldOneofCase.OneofString;
      }
    }
@ -709,7 +709,7 @@ namespace Google.Protobuf.TestProtos {
    public pb::ByteString OneofBytes {
      get { return oneofFieldCase_ == OneofFieldOneofCase.OneofBytes ? (pb::ByteString) oneofField_ : pb::ByteString.Empty; }
      set {
-        oneofField_ = value ?? pb::ByteString.Empty;
+        oneofField_ = pb::Preconditions.CheckNotNull(value, "value");
        oneofFieldCase_ = OneofFieldOneofCase.OneofBytes;
      }
    }
@ -2703,7 +2703,7 @@ namespace Google.Protobuf.TestProtos {
    public string StringField {
      get { return stringField_; }
      set {
-        stringField_ = value ?? "";
+        stringField_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -2954,7 +2954,7 @@ namespace Google.Protobuf.TestProtos {
    public string MyString {
      get { return myString_; }
      set {
-        myString_ = value ?? "";
+        myString_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -3385,7 +3385,7 @@ namespace Google.Protobuf.TestProtos {
    public string Data {
      get { return data_; }
      set {
-        data_ = value ?? "";
+        data_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -3589,7 +3589,7 @@ namespace Google.Protobuf.TestProtos {
    public pb::ByteString Data {
      get { return data_; }
      set {
-        data_ = value ?? pb::ByteString.Empty;
+        data_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -3695,7 +3695,7 @@ namespace Google.Protobuf.TestProtos {
    public pb::ByteString Data {
      get { return data_; }
      set {
-        data_ = value ?? pb::ByteString.Empty;
+        data_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -4350,7 +4350,7 @@ namespace Google.Protobuf.TestProtos {
    public string FooString {
      get { return fooCase_ == FooOneofCase.FooString ? (string) foo_ : ""; }
      set {
-        foo_ = value ?? "";
+        foo_ = pb::Preconditions.CheckNotNull(value, "value");
        fooCase_ = FooOneofCase.FooString;
      }
    }
@ -5409,7 +5409,7 @@ namespace Google.Protobuf.TestProtos {
    public string A {
      get { return a_; }
      set {
-        a_ = value ?? "";
+        a_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

--- a/csharp/src/Google.Protobuf/Collections/MapField.cs
+++ b/csharp/src/Google.Protobuf/Collections/MapField.cs
@ -112,13 +112,13 @@ namespace Google.Protobuf.Collections

        public bool ContainsKey(TKey key)
        {
-            ThrowHelper.ThrowIfNull(key, "key");
+            Preconditions.CheckNotNullUnconstrained(key, "key");
            return map.ContainsKey(key);
        }

        public bool Remove(TKey key)
        {
-            ThrowHelper.ThrowIfNull(key, "key");
+            Preconditions.CheckNotNullUnconstrained(key, "key");
            LinkedListNode<KeyValuePair<TKey, TValue>> node;
            if (map.TryGetValue(key, out node))
            {
@ -151,7 +151,7 @@ namespace Google.Protobuf.Collections
        {
            get
            {
-                ThrowHelper.ThrowIfNull(key, "key");
+                Preconditions.CheckNotNullUnconstrained(key, "key");
                TValue value;
                if (TryGetValue(key, out value))
                {
@ -161,11 +161,11 @@ namespace Google.Protobuf.Collections
            }
            set
            {
-                ThrowHelper.ThrowIfNull(key, "key");
+                Preconditions.CheckNotNullUnconstrained(key, "key");
                // value == null check here is redundant, but avoids boxing.
                if (value == null && !allowNullValues)
                {
-                    ThrowHelper.ThrowIfNull(value, "value");
+                    Preconditions.CheckNotNullUnconstrained(value, "value");
                }
                LinkedListNode<KeyValuePair<TKey, TValue>> node;
                var pair = new KeyValuePair<TKey, TValue>(key, value);
@ -187,7 +187,7 @@ namespace Google.Protobuf.Collections

        public void Add(IDictionary<TKey, TValue> entries)
        {
-            ThrowHelper.ThrowIfNull(entries, "entries");
+            Preconditions.CheckNotNull(entries, "entries");
            foreach (var pair in entries)
            {
                Add(pair.Key, pair.Value);
@ -374,7 +374,7 @@ namespace Google.Protobuf.Collections

        void IDictionary.Remove(object key)
        {
-            ThrowHelper.ThrowIfNull(key, "key");
+            Preconditions.CheckNotNull(key, "key");
            if (!(key is TKey))
            {
                return;
@ -403,7 +403,7 @@ namespace Google.Protobuf.Collections
        {
            get
            {
-                ThrowHelper.ThrowIfNull(key, "key");
+                Preconditions.CheckNotNull(key, "key");
                if (!(key is TKey))
                {
                    return null;
--- a/csharp/src/Google.Protobuf/Google.Protobuf.csproj
+++ b/csharp/src/Google.Protobuf/Google.Protobuf.csproj
@ -96,7 +96,7 @@
    <Compile Include="Reflection\RepeatedFieldAccessor.cs" />
    <Compile Include="Reflection\ServiceDescriptor.cs" />
    <Compile Include="Reflection\SingleFieldAccessor.cs" />
-    <Compile Include="ThrowHelper.cs" />
+    <Compile Include="Preconditions.cs" />
    <Compile Include="WellKnownTypes\Any.cs" />
    <Compile Include="WellKnownTypes\Api.cs" />
    <Compile Include="WellKnownTypes\Duration.cs" />
--- a/csharp/src/Google.Protobuf/JsonFormatter.cs
+++ b/csharp/src/Google.Protobuf/JsonFormatter.cs
@ -120,7 +120,7 @@ namespace Google.Protobuf

        public string Format(IMessage message)
        {
-            ThrowHelper.ThrowIfNull(message, "message");
+            Preconditions.CheckNotNull(message, "message");
            StringBuilder builder = new StringBuilder();
            // TODO(jonskeet): Handle well-known types here.
            // Our reflection support needs improving so that we can get at the descriptor
--- a/csharp/src/Google.Protobuf/MessageExtensions.cs
+++ b/csharp/src/Google.Protobuf/MessageExtensions.cs
@ -41,8 +41,8 @@ namespace Google.Protobuf
    {
        public static void MergeFrom(this IMessage message, byte[] data)
        {
-            ThrowHelper.ThrowIfNull(message, "message");
-            ThrowHelper.ThrowIfNull(data, "data");
+            Preconditions.CheckNotNull(message, "message");
+            Preconditions.CheckNotNull(data, "data");
            CodedInputStream input = CodedInputStream.CreateInstance(data);
            message.MergeFrom(input);
            input.CheckLastTagWas(0);
@ -50,8 +50,8 @@ namespace Google.Protobuf

        public static void MergeFrom(this IMessage message, ByteString data)
        {
-            ThrowHelper.ThrowIfNull(message, "message");
-            ThrowHelper.ThrowIfNull(data, "data");
+            Preconditions.CheckNotNull(message, "message");
+            Preconditions.CheckNotNull(data, "data");
            CodedInputStream input = data.CreateCodedInput();
            message.MergeFrom(input);
            input.CheckLastTagWas(0);
@ -59,8 +59,8 @@ namespace Google.Protobuf

        public static void MergeFrom(this IMessage message, Stream input)
        {
-            ThrowHelper.ThrowIfNull(message, "message");
-            ThrowHelper.ThrowIfNull(input, "input");
+            Preconditions.CheckNotNull(message, "message");
+            Preconditions.CheckNotNull(input, "input");
            CodedInputStream codedInput = CodedInputStream.CreateInstance(input);
            message.MergeFrom(codedInput);
            codedInput.CheckLastTagWas(0);
@ -68,8 +68,8 @@ namespace Google.Protobuf

        public static void MergeDelimitedFrom(this IMessage message, Stream input)
        {
-            ThrowHelper.ThrowIfNull(message, "message");
-            ThrowHelper.ThrowIfNull(input, "input");
+            Preconditions.CheckNotNull(message, "message");
+            Preconditions.CheckNotNull(input, "input");
            int size = (int) CodedInputStream.ReadRawVarint32(input);
            Stream limitedStream = new LimitedInputStream(input, size);
            message.MergeFrom(limitedStream);
@ -77,7 +77,7 @@ namespace Google.Protobuf

        public static byte[] ToByteArray(this IMessage message)
        {
-            ThrowHelper.ThrowIfNull(message, "message");
+            Preconditions.CheckNotNull(message, "message");
            byte[] result = new byte[message.CalculateSize()];
            CodedOutputStream output = CodedOutputStream.CreateInstance(result);
            message.WriteTo(output);
@ -87,8 +87,8 @@ namespace Google.Protobuf

        public static void WriteTo(this IMessage message, Stream output)
        {
-            ThrowHelper.ThrowIfNull(message, "message");
-            ThrowHelper.ThrowIfNull(output, "output");
+            Preconditions.CheckNotNull(message, "message");
+            Preconditions.CheckNotNull(output, "output");
            CodedOutputStream codedOutput = CodedOutputStream.CreateInstance(output);
            message.WriteTo(codedOutput);
            codedOutput.Flush();
@ -96,8 +96,8 @@ namespace Google.Protobuf

        public static void WriteDelimitedTo(this IMessage message, Stream output)
        {
-            ThrowHelper.ThrowIfNull(message, "message");
-            ThrowHelper.ThrowIfNull(output, "output");
+            Preconditions.CheckNotNull(message, "message");
+            Preconditions.CheckNotNull(output, "output");
            CodedOutputStream codedOutput = CodedOutputStream.CreateInstance(output);
            codedOutput.WriteRawVarint32((uint)message.CalculateSize());
            message.WriteTo(codedOutput);
@ -106,7 +106,7 @@ namespace Google.Protobuf

        public static ByteString ToByteString(this IMessage message)
        {
-            ThrowHelper.ThrowIfNull(message, "message");
+            Preconditions.CheckNotNull(message, "message");
            return ByteString.AttachBytes(message.ToByteArray());
        }        
    }
--- a/csharp/src/Google.Protobuf/MessageParser.cs
+++ b/csharp/src/Google.Protobuf/MessageParser.cs
@ -84,7 +84,7 @@ namespace Google.Protobuf
        /// <returns>The newly parsed message.</returns>
        public T ParseFrom(byte[] data)
        {
-            ThrowHelper.ThrowIfNull(data, "data");
+            Preconditions.CheckNotNull(data, "data");
            T message = factory();
            message.MergeFrom(data);
            return message;
@ -92,7 +92,7 @@ namespace Google.Protobuf

        public T ParseFrom(ByteString data)
        {
-            ThrowHelper.ThrowIfNull(data, "data");
+            Preconditions.CheckNotNull(data, "data");
            T message = factory();
            message.MergeFrom(data);
            return message;
--- a/csharp/src/Google.Protobuf/Preconditions.cs
+++ b/csharp/src/Google.Protobuf/Preconditions.cs
@ -37,17 +37,38 @@ namespace Google.Protobuf
    /// <summary>
    /// Helper methods for throwing exceptions
    /// </summary>
-    internal static class ThrowHelper
+    public static class Preconditions
    {
        /// <summary>
-        /// Throws an ArgumentNullException if the given value is null.
+        /// Throws an ArgumentNullException if the given value is null, otherwise
+        /// return the value to the caller.
        /// </summary>
-        internal static void ThrowIfNull(object value, string name)
+        public static T CheckNotNull<T>(T value, string name) where T : class
        {
            if (value == null)
            {
                throw new ArgumentNullException(name);
            }
+            return value;
+        }
+
+        /// <summary>
+        /// Throws an ArgumentNullException if the given value is null, otherwise
+        /// return the value to the caller.
+        /// </summary>
+        /// <remarks>
+        /// This is equivalent to <see cref="CheckNotNull"/> but without the type parameter
+        /// constraint. In most cases, the constraint is useful to prevent you from calling CheckNotNull
+        /// with a value type - but it gets in the way if either you want to use it with a nullable
+        /// value type, or you want to use it with an unconstrained type parameter.
+        /// </remarks>
+        internal static T CheckNotNullUnconstrained<T>(T value, string name)
+        {
+            if (value == null)
+            {
+                throw new ArgumentNullException(name);
+            }
+            return value;
        }
    }
 }
--- a/csharp/src/Google.Protobuf/Reflection/DescriptorProtoFile.cs
+++ b/csharp/src/Google.Protobuf/Reflection/DescriptorProtoFile.cs
@ -301,7 +301,7 @@ namespace Google.Protobuf.Reflection {
    internal string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -310,7 +310,7 @@ namespace Google.Protobuf.Reflection {
    internal string Package {
      get { return package_; }
      set {
-        package_ = value ?? "";
+        package_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -393,7 +393,7 @@ namespace Google.Protobuf.Reflection {
    internal string Syntax {
      get { return syntax_; }
      set {
-        syntax_ = value ?? "";
+        syntax_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -649,7 +649,7 @@ namespace Google.Protobuf.Reflection {
    internal string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -1200,7 +1200,7 @@ namespace Google.Protobuf.Reflection {
    internal string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -1236,7 +1236,7 @@ namespace Google.Protobuf.Reflection {
    internal string TypeName {
      get { return typeName_; }
      set {
-        typeName_ = value ?? "";
+        typeName_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -1245,7 +1245,7 @@ namespace Google.Protobuf.Reflection {
    internal string Extendee {
      get { return extendee_; }
      set {
-        extendee_ = value ?? "";
+        extendee_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -1254,7 +1254,7 @@ namespace Google.Protobuf.Reflection {
    internal string DefaultValue {
      get { return defaultValue_; }
      set {
-        defaultValue_ = value ?? "";
+        defaultValue_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -1545,7 +1545,7 @@ namespace Google.Protobuf.Reflection {
    internal string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -1653,7 +1653,7 @@ namespace Google.Protobuf.Reflection {
    internal string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -1809,7 +1809,7 @@ namespace Google.Protobuf.Reflection {
    internal string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -1973,7 +1973,7 @@ namespace Google.Protobuf.Reflection {
    internal string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -2132,7 +2132,7 @@ namespace Google.Protobuf.Reflection {
    internal string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -2141,7 +2141,7 @@ namespace Google.Protobuf.Reflection {
    internal string InputType {
      get { return inputType_; }
      set {
-        inputType_ = value ?? "";
+        inputType_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -2150,7 +2150,7 @@ namespace Google.Protobuf.Reflection {
    internal string OutputType {
      get { return outputType_; }
      set {
-        outputType_ = value ?? "";
+        outputType_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -2383,7 +2383,7 @@ namespace Google.Protobuf.Reflection {
    internal string JavaPackage {
      get { return javaPackage_; }
      set {
-        javaPackage_ = value ?? "";
+        javaPackage_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -2392,7 +2392,7 @@ namespace Google.Protobuf.Reflection {
    internal string JavaOuterClassname {
      get { return javaOuterClassname_; }
      set {
-        javaOuterClassname_ = value ?? "";
+        javaOuterClassname_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -2437,7 +2437,7 @@ namespace Google.Protobuf.Reflection {
    internal string GoPackage {
      get { return goPackage_; }
      set {
-        goPackage_ = value ?? "";
+        goPackage_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -2491,7 +2491,7 @@ namespace Google.Protobuf.Reflection {
    internal string ObjcClassPrefix {
      get { return objcClassPrefix_; }
      set {
-        objcClassPrefix_ = value ?? "";
+        objcClassPrefix_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -2500,7 +2500,7 @@ namespace Google.Protobuf.Reflection {
    internal string CsharpNamespace {
      get { return csharpNamespace_; }
      set {
-        csharpNamespace_ = value ?? "";
+        csharpNamespace_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -3853,7 +3853,7 @@ namespace Google.Protobuf.Reflection {
    internal string IdentifierValue {
      get { return identifierValue_; }
      set {
-        identifierValue_ = value ?? "";
+        identifierValue_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -3889,7 +3889,7 @@ namespace Google.Protobuf.Reflection {
    internal pb::ByteString StringValue {
      get { return stringValue_; }
      set {
-        stringValue_ = value ?? pb::ByteString.Empty;
+        stringValue_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -3898,7 +3898,7 @@ namespace Google.Protobuf.Reflection {
    internal string AggregateValue {
      get { return aggregateValue_; }
      set {
-        aggregateValue_ = value ?? "";
+        aggregateValue_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -4095,7 +4095,7 @@ namespace Google.Protobuf.Reflection {
        internal string NamePart_ {
          get { return namePart_; }
          set {
-            namePart_ = value ?? "";
+            namePart_ = pb::Preconditions.CheckNotNull(value, "value");
          }
        }

@ -4350,7 +4350,7 @@ namespace Google.Protobuf.Reflection {
        internal string LeadingComments {
          get { return leadingComments_; }
          set {
-            leadingComments_ = value ?? "";
+            leadingComments_ = pb::Preconditions.CheckNotNull(value, "value");
          }
        }

@ -4359,7 +4359,7 @@ namespace Google.Protobuf.Reflection {
        internal string TrailingComments {
          get { return trailingComments_; }
          set {
-            trailingComments_ = value ?? "";
+            trailingComments_ = pb::Preconditions.CheckNotNull(value, "value");
          }
        }

--- a/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
@ -71,7 +71,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string TypeUrl {
      get { return typeUrl_; }
      set {
-        typeUrl_ = value ?? "";
+        typeUrl_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -80,7 +80,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public pb::ByteString Value {
      get { return value_; }
      set {
-        value_ = value ?? pb::ByteString.Empty;
+        value_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

--- a/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
@ -84,7 +84,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -109,7 +109,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string Version {
      get { return version_; }
      set {
-        version_ = value ?? "";
+        version_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -285,7 +285,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -294,7 +294,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string RequestTypeUrl {
      get { return requestTypeUrl_; }
      set {
-        requestTypeUrl_ = value ?? "";
+        requestTypeUrl_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -312,7 +312,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string ResponseTypeUrl {
      get { return responseTypeUrl_; }
      set {
-        responseTypeUrl_ = value ?? "";
+        responseTypeUrl_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

--- a/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs
@ -71,7 +71,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string FileName {
      get { return fileName_; }
      set {
-        fileName_ = value ?? "";
+        fileName_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

--- a/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
@ -224,7 +224,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string StringValue {
      get { return kindCase_ == KindOneofCase.StringValue ? (string) kind_ : ""; }
      set {
-        kind_ = value ?? "";
+        kind_ = pb::Preconditions.CheckNotNull(value, "value");
        kindCase_ = KindOneofCase.StringValue;
      }
    }
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
@ -105,7 +105,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -327,7 +327,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -336,7 +336,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string TypeUrl {
      get { return typeUrl_; }
      set {
-        typeUrl_ = value ?? "";
+        typeUrl_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -610,7 +610,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -783,7 +783,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -932,7 +932,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string Name {
      get { return name_; }
      set {
-        name_ = value ?? "";
+        name_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

--- a/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
@ -822,7 +822,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public string Value {
      get { return value_; }
      set {
-        value_ = value ?? "";
+        value_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

@ -928,7 +928,7 @@ namespace Google.Protobuf.WellKnownTypes {
    public pb::ByteString Value {
      get { return value_; }
      set {
-        value_ = value ?? pb::ByteString.Empty;
+        value_ = pb::Preconditions.CheckNotNull(value, "value");
      }
    }

--- a/src/google/protobuf/compiler/csharp/csharp_field_base.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_field_base.cc
@ -127,17 +127,6 @@ void FieldGeneratorBase::AddDeprecatedFlag(io::Printer* printer) {
  }
 }

-void FieldGeneratorBase::AddNullCheck(io::Printer* printer) {
-  AddNullCheck(printer, "value");
-}
-
-void FieldGeneratorBase::AddNullCheck(io::Printer* printer, const std::string& name) {
-  if (is_nullable_type()) {
-    printer->Print("  pb::ThrowHelper.ThrowIfNull($name$, \"$name$\");\n",
-                   "name", name);
-  }
-}
-
 void FieldGeneratorBase::AddPublicMemberAttributes(io::Printer* printer) {
  AddDeprecatedFlag(printer);
 }
--- a/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc
@ -81,7 +81,7 @@ void PrimitiveFieldGenerator::GenerateMembers(io::Printer* printer) {
  } else {
    printer->Print(
      variables_,
-      "    $name$_ = value ?? $default_value$;\n");
+      "    $name$_ = pb::Preconditions.CheckNotNull(value, \"value\");\n");
  }
  printer->Print(
    "  }\n"
@ -183,7 +183,7 @@ void PrimitiveOneofFieldGenerator::GenerateMembers(io::Printer* printer) {
    } else {
      printer->Print(
        variables_,
-        "    $oneof_name$_ = value ?? $default_value$;\n");
+        "    $oneof_name$_ = pb::Preconditions.CheckNotNull(value, \"value\");\n");
    }
    printer->Print(
      variables_,