Mark encoding param in StreamReader ctors to be nullable (#108542)

dotnet · Jan 10, 2025 · 5abf582 · 5abf582
1 parent 96613ae
commit 5abf582
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Showing 3 changed files with 29 additions and 24 deletions.
diff --git a/src/libraries/System.Private.CoreLib/src/System/IO/StreamReader.cs b/src/libraries/System.Private.CoreLib/src/System/IO/StreamReader.cs
@@ -111,12 +111,12 @@ public StreamReader(Stream stream, bool detectEncodingFromByteOrderMarks)
         {
         }
 
-        public StreamReader(Stream stream, Encoding encoding)
+        public StreamReader(Stream stream, Encoding? encoding)
             : this(stream, encoding, true, DefaultBufferSize, false)
         {
         }
 
-        public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks)
+        public StreamReader(Stream stream, Encoding? encoding, bool detectEncodingFromByteOrderMarks)
             : this(stream, encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize, false)
         {
         }
@@ -131,7 +131,7 @@ public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByt
         // unicode, and big endian unicode text, but that's it.  If neither
         // of those three match, it will use the Encoding you provided.
         //
-        public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
+        public StreamReader(Stream stream, Encoding? encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
             : this(stream, encoding, detectEncodingFromByteOrderMarks, bufferSize, false)
         {
         }
@@ -187,18 +187,18 @@ public StreamReader(string path, bool detectEncodingFromByteOrderMarks)
         {
         }
 
-        public StreamReader(string path, Encoding encoding)
+        public StreamReader(string path, Encoding? encoding)
             : this(path, encoding, true, DefaultBufferSize)
         {
         }
 
-        public StreamReader(string path, Encoding encoding, bool detectEncodingFromByteOrderMarks)
+        public StreamReader(string path, Encoding? encoding, bool detectEncodingFromByteOrderMarks)
             : this(path, encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize)
         {
         }
 
-        public StreamReader(string path, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
-            : this(ValidateArgsAndOpenPath(path, encoding, bufferSize), encoding, detectEncodingFromByteOrderMarks, bufferSize, leaveOpen: false)
+        public StreamReader(string path, Encoding? encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
+            : this(ValidateArgsAndOpenPath(path, bufferSize), encoding, detectEncodingFromByteOrderMarks, bufferSize, leaveOpen: false)
         {
         }
 
@@ -207,15 +207,14 @@ public StreamReader(string path, FileStreamOptions options)
         {
         }
 
-        public StreamReader(string path, Encoding encoding, bool detectEncodingFromByteOrderMarks, FileStreamOptions options)
-            : this(ValidateArgsAndOpenPath(path, encoding, options), encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize)
+        public StreamReader(string path, Encoding? encoding, bool detectEncodingFromByteOrderMarks, FileStreamOptions options)
+            : this(ValidateArgsAndOpenPath(path, options), encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize)
         {
         }
 
-        private static FileStream ValidateArgsAndOpenPath(string path, Encoding encoding, FileStreamOptions options)
+        private static FileStream ValidateArgsAndOpenPath(string path, FileStreamOptions options)
         {
             ArgumentException.ThrowIfNullOrEmpty(path);
-            ArgumentNullException.ThrowIfNull(encoding);
             ArgumentNullException.ThrowIfNull(options);
             if ((options.Access & FileAccess.Read) == 0)
             {
@@ -225,10 +224,9 @@ private static FileStream ValidateArgsAndOpenPath(string path, Encoding encoding
             return new FileStream(path, options);
         }
 
-        private static FileStream ValidateArgsAndOpenPath(string path, Encoding encoding, int bufferSize)
+        private static FileStream ValidateArgsAndOpenPath(string path, int bufferSize)
         {
             ArgumentException.ThrowIfNullOrEmpty(path);
-            ArgumentNullException.ThrowIfNull(encoding);
             ArgumentOutOfRangeException.ThrowIfNegativeOrZero(bufferSize);
 
             return new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read, DefaultFileStreamBufferSize);

diff --git a/src/libraries/System.Runtime/ref/System.Runtime.cs b/src/libraries/System.Runtime/ref/System.Runtime.cs
@@ -10769,17 +10769,17 @@ public partial class StreamReader : System.IO.TextReader
         public static readonly new System.IO.StreamReader Null;
         public StreamReader(System.IO.Stream stream) { }
         public StreamReader(System.IO.Stream stream, bool detectEncodingFromByteOrderMarks) { }
-        public StreamReader(System.IO.Stream stream, System.Text.Encoding encoding) { }
-        public StreamReader(System.IO.Stream stream, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks) { }
-        public StreamReader(System.IO.Stream stream, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize) { }
+        public StreamReader(System.IO.Stream stream, System.Text.Encoding? encoding) { }
+        public StreamReader(System.IO.Stream stream, System.Text.Encoding? encoding, bool detectEncodingFromByteOrderMarks) { }
+        public StreamReader(System.IO.Stream stream, System.Text.Encoding? encoding, bool detectEncodingFromByteOrderMarks, int bufferSize) { }
         public StreamReader(System.IO.Stream stream, System.Text.Encoding? encoding = null, bool detectEncodingFromByteOrderMarks = true, int bufferSize = -1, bool leaveOpen = false) { }
         public StreamReader(string path) { }
         public StreamReader(string path, bool detectEncodingFromByteOrderMarks) { }
         public StreamReader(string path, System.IO.FileStreamOptions options) { }
-        public StreamReader(string path, System.Text.Encoding encoding) { }
-        public StreamReader(string path, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks) { }
-        public StreamReader(string path, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize) { }
-        public StreamReader(string path, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, System.IO.FileStreamOptions options) { }
+        public StreamReader(string path, System.Text.Encoding? encoding) { }
+        public StreamReader(string path, System.Text.Encoding? encoding, bool detectEncodingFromByteOrderMarks) { }
+        public StreamReader(string path, System.Text.Encoding? encoding, bool detectEncodingFromByteOrderMarks, int bufferSize) { }
+        public StreamReader(string path, System.Text.Encoding? encoding, bool detectEncodingFromByteOrderMarks, System.IO.FileStreamOptions options) { }
         public virtual System.IO.Stream BaseStream { get { throw null; } }
         public virtual System.Text.Encoding CurrentEncoding { get { throw null; } }
         public bool EndOfStream { get { throw null; } }

diff --git a/...braries/System.Runtime/tests/System.IO.Tests/StreamReader/StreamReader.StringCtorTests.cs b/...braries/System.Runtime/tests/System.IO.Tests/StreamReader/StreamReader.StringCtorTests.cs
@@ -19,10 +19,6 @@ public static void NullArgs_ThrowsArgumentNullException()
             AssertExtensions.Throws<ArgumentNullException>("path", () => new StreamReader((string)null, null, true));
             AssertExtensions.Throws<ArgumentNullException>("path", () => new StreamReader((string)null, null, true, null));
             AssertExtensions.Throws<ArgumentNullException>("path", () => new StreamReader((string)null, null, true, -1));
-            AssertExtensions.Throws<ArgumentNullException>("encoding", () => new StreamReader("path", (Encoding)null));
-            AssertExtensions.Throws<ArgumentNullException>("encoding", () => new StreamReader("path", null, true));
-            AssertExtensions.Throws<ArgumentNullException>("encoding", () => new StreamReader("path", null, true, null));
-            AssertExtensions.Throws<ArgumentNullException>("encoding", () => new StreamReader("path", null, true, -1));
             AssertExtensions.Throws<ArgumentNullException>("options", () => new StreamReader("path", (FileStreamOptions)null));
             AssertExtensions.Throws<ArgumentNullException>("options", () => new StreamReader("path", Encoding.UTF8, true, null));
 
@@ -40,6 +36,17 @@ public static void EmptyPath_ThrowsArgumentException()
             AssertExtensions.Throws<ArgumentException>("path", () => new StreamReader("", Encoding.UTF8, true, -1));
         }
 
+        [Fact]
+        public static void NullEncodingParamInCtor_ShouldNotThrowException()
+        {
+            // Call the constructor with overloads that has Stream and null encoding parameters.
+            // It should not throw exception, to test passing the nullable encoding parameter..
+            StreamReader streamReaderTest = new StreamReader(new MemoryStream(), null);
+            streamReaderTest = new StreamReader(new MemoryStream(), null, false);
+            streamReaderTest = new StreamReader(new MemoryStream(), null, false, 100);
+            streamReaderTest = new StreamReader(new MemoryStream(), null, false, 100, false);
+        }
+
         [Fact]
         public static void NegativeBufferSize_ThrowsArgumentOutOfRangeException()
         {