From 0c036ecfcaa004fbadab340f161b9403c9d6b54c Mon Sep 17 00:00:00 2001
From: Stephen Toub <stoub@microsoft.com>
Date: Sat, 9 Jun 2018 16:34:46 -0400
Subject: [PATCH] Use nameof of Encoding classes (dotnet/coreclr#18395)

Commit migrated from https://github.com/dotnet/coreclr/commit/618f9c2d18e88566ac61f93529bac58123c50cba
---
 .../src/System/Text/ASCIIEncoding.cs               | 60 +++++++++++-----------
 .../src/System/Text/EncodingNLS.cs                 | 60 +++++++++++-----------
 .../src/System/Text/UTF32Encoding.cs               | 60 +++++++++++-----------
 .../src/System/Text/UTF7Encoding.cs                | 60 +++++++++++-----------
 .../src/System/Text/UTF8Encoding.cs                | 58 ++++++++++-----------
 .../src/System/Text/UnicodeEncoding.cs             | 60 +++++++++++-----------
 6 files changed, 179 insertions(+), 179 deletions(-)

diff --git a/src/libraries/System.Private.CoreLib/src/System/Text/ASCIIEncoding.cs b/src/libraries/System.Private.CoreLib/src/System/Text/ASCIIEncoding.cs
index 3d25228..7668f82 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Text/ASCIIEncoding.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Text/ASCIIEncoding.cs
@@ -59,13 +59,13 @@ namespace System.Text
         {
             // Validate input parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - index < count)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input, return 0, avoid fixed empty array problem
             if (count == 0)
@@ -85,7 +85,7 @@ namespace System.Text
         {
             // Validate input
             if (chars==null)
-                throw new ArgumentNullException("chars");
+                throw new ArgumentNullException(nameof(chars));
 
             fixed (char* pChars = chars)
                 return GetByteCount(pChars, chars.Length, null);
@@ -100,10 +100,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             // Call it with empty encoder
             return GetByteCount(chars, count, null);
@@ -118,16 +118,16 @@ namespace System.Text
                                               byte[] bytes, int byteIndex)
         {
             if (chars == null || bytes == null)
-                throw new ArgumentNullException((chars == null ? "chars" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((chars == null ? nameof(chars) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCount);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCount);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             int byteCount = bytes.Length - byteIndex;
 
@@ -154,16 +154,16 @@ namespace System.Text
         {
             // Validate parameters
             if (chars == null || bytes == null)
-                throw new ArgumentNullException((chars == null ? "chars" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((chars == null ? nameof(chars) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             // If nothing to encode return 0
             if (charCount == 0)
@@ -186,10 +186,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetBytes(chars, charCount, bytes, byteCount, null);
         }
@@ -206,13 +206,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input just return 0, fixed doesn't like 0 length arrays
             if (count == 0)
@@ -232,10 +232,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetCharCount(bytes, count, null);
         }
@@ -250,16 +250,16 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (byteIndex < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((byteIndex < 0 ? "byteIndex" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((byteIndex < 0 ? nameof(byteIndex) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if ( bytes.Length - byteIndex < byteCount)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (charIndex < 0 || charIndex > chars.Length)
-                throw new ArgumentOutOfRangeException("charIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(charIndex), SR.ArgumentOutOfRange_Index);
 
             // If no input, return 0 & avoid fixed problem
             if (byteCount == 0)
@@ -282,10 +282,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetChars(bytes, byteCount, chars, charCount, null);
         }
@@ -302,14 +302,14 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (byteIndex < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((byteIndex < 0 ? "byteIndex" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((byteIndex < 0 ? nameof(byteIndex) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
 
             if (bytes.Length - byteIndex < byteCount)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // Avoid problems with empty input buffer
             if (byteCount == 0) return string.Empty;
diff --git a/src/libraries/System.Private.CoreLib/src/System/Text/EncodingNLS.cs b/src/libraries/System.Private.CoreLib/src/System/Text/EncodingNLS.cs
index ce33354..bbd2dd6 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Text/EncodingNLS.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Text/EncodingNLS.cs
@@ -40,13 +40,13 @@ namespace System.Text
         {
             // Validate input parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - index < count)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input, return 0, avoid fixed empty array problem
             if (count == 0)
@@ -65,7 +65,7 @@ namespace System.Text
         {
             // Validate input
             if (s==null)
-                throw new ArgumentNullException("s");
+                throw new ArgumentNullException(nameof(s));
 
             fixed (char* pChars = s)
                 return GetByteCount(pChars, s.Length, null);
@@ -78,10 +78,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
             
             // Call it with empty encoder
             return GetByteCount(chars, count, null);
@@ -95,16 +95,16 @@ namespace System.Text
                                               byte[] bytes, int byteIndex)
         {
             if (s == null || bytes == null)
-                throw new ArgumentNullException((s == null ? "s" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((s == null ? nameof(s) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (s.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("s", SR.ArgumentOutOfRange_IndexCount);
+                throw new ArgumentOutOfRangeException(nameof(s), SR.ArgumentOutOfRange_IndexCount);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             int byteCount = bytes.Length - byteIndex;
 
@@ -130,16 +130,16 @@ namespace System.Text
         {
             // Validate parameters
             if (chars == null || bytes == null)
-                throw new ArgumentNullException((chars == null ? "chars" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((chars == null ? nameof(chars) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             // If nothing to encode return 0, avoid fixed problem
             if (charCount == 0)
@@ -160,10 +160,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"),  SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)),  SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetBytes(chars, charCount, bytes, byteCount, null);
         }
@@ -179,13 +179,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
                                    
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input just return 0, fixed doesn't like 0 length arrays
             if (count == 0)
@@ -203,10 +203,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
             
             return GetCharCount(bytes, count, null);
         }
@@ -220,16 +220,16 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (byteIndex < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((byteIndex < 0 ? "byteIndex" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((byteIndex < 0 ? nameof(byteIndex) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if ( bytes.Length - byteIndex < byteCount)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (charIndex < 0 || charIndex > chars.Length)
-                throw new ArgumentOutOfRangeException("charIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(charIndex), SR.ArgumentOutOfRange_Index);
 
             // If no input, return 0 & avoid fixed problem
             if (byteCount == 0)
@@ -250,10 +250,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
             
             return GetChars(bytes, byteCount, chars, charCount, null);
         }
@@ -269,13 +269,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // Avoid problems with empty input buffer
             if (count == 0) return string.Empty;
diff --git a/src/libraries/System.Private.CoreLib/src/System/Text/UTF32Encoding.cs b/src/libraries/System.Private.CoreLib/src/System/Text/UTF32Encoding.cs
index 00ac666..185eef1 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Text/UTF32Encoding.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Text/UTF32Encoding.cs
@@ -103,13 +103,13 @@ namespace System.Text
         {
             // Validate input parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - index < count)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input, return 0, avoid fixed empty array problem
             if (count == 0)
@@ -129,7 +129,7 @@ namespace System.Text
         {
             // Validate input
             if (s==null)
-                throw new ArgumentNullException("s");
+                throw new ArgumentNullException(nameof(s));
 
             fixed (char* pChars = s)
                 return GetByteCount(pChars, s.Length, null);
@@ -144,10 +144,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             // Call it with empty encoder
             return GetByteCount(chars, count, null);
@@ -162,16 +162,16 @@ namespace System.Text
                                               byte[] bytes, int byteIndex)
         {
             if (s == null || bytes == null)
-                throw new ArgumentNullException((s == null ? "s" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((s == null ? nameof(s) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (s.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("s", SR.ArgumentOutOfRange_IndexCount);
+                throw new ArgumentOutOfRangeException(nameof(s), SR.ArgumentOutOfRange_IndexCount);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             int byteCount = bytes.Length - byteIndex;
 
@@ -198,16 +198,16 @@ namespace System.Text
         {
             // Validate parameters
             if (chars == null || bytes == null)
-                throw new ArgumentNullException((chars == null ? "chars" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((chars == null ? nameof(chars) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             // If nothing to encode return 0, avoid fixed problem
             if (charCount == 0)
@@ -230,10 +230,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetBytes(chars, charCount, bytes, byteCount, null);
         }
@@ -250,13 +250,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input just return 0, fixed doesn't like 0 length arrays.
             if (count == 0)
@@ -276,10 +276,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetCharCount(bytes, count, null);
         }
@@ -294,16 +294,16 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (byteIndex < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((byteIndex < 0 ? "byteIndex" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((byteIndex < 0 ? nameof(byteIndex) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if ( bytes.Length - byteIndex < byteCount)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (charIndex < 0 || charIndex > chars.Length)
-                throw new ArgumentOutOfRangeException("charIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(charIndex), SR.ArgumentOutOfRange_Index);
 
             // If no input, return 0 & avoid fixed problem
             if (byteCount == 0)
@@ -326,10 +326,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetChars(bytes, byteCount, chars, charCount, null);
         }
@@ -346,13 +346,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // Avoid problems with empty input buffer
             if (count == 0) return string.Empty;
diff --git a/src/libraries/System.Private.CoreLib/src/System/Text/UTF7Encoding.cs b/src/libraries/System.Private.CoreLib/src/System/Text/UTF7Encoding.cs
index cfd6c4d..568e1d2 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Text/UTF7Encoding.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Text/UTF7Encoding.cs
@@ -133,13 +133,13 @@ namespace System.Text
         {
             // Validate input parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - index < count)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input, return 0, avoid fixed empty array problem
             if (count == 0)
@@ -159,7 +159,7 @@ namespace System.Text
         {
             // Validate input
             if (s==null)
-                throw new ArgumentNullException("s");
+                throw new ArgumentNullException(nameof(s));
 
             fixed (char* pChars = s)
                 return GetByteCount(pChars, s.Length, null);
@@ -174,10 +174,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             // Call it with empty encoder
             return GetByteCount(chars, count, null);
@@ -192,16 +192,16 @@ namespace System.Text
                                               byte[] bytes, int byteIndex)
         {
             if (s == null || bytes == null)
-                throw new ArgumentNullException((s == null ? "s" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((s == null ? nameof(s) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (s.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("s", SR.ArgumentOutOfRange_IndexCount);
+                throw new ArgumentOutOfRangeException(nameof(s), SR.ArgumentOutOfRange_IndexCount);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             int byteCount = bytes.Length - byteIndex;
 
@@ -228,16 +228,16 @@ namespace System.Text
         {
             // Validate parameters
             if (chars == null || bytes == null)
-                throw new ArgumentNullException((chars == null ? "chars" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((chars == null ? nameof(chars) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             // If nothing to encode return 0, avoid fixed problem
             if (charCount == 0)
@@ -260,10 +260,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetBytes(chars, charCount, bytes, byteCount, null);
         }
@@ -280,13 +280,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input just return 0, fixed doesn't like 0 length arrays.
             if (count == 0)
@@ -306,10 +306,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetCharCount(bytes, count, null);
         }
@@ -324,16 +324,16 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (byteIndex < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((byteIndex < 0 ? "byteIndex" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((byteIndex < 0 ? nameof(byteIndex) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if ( bytes.Length - byteIndex < byteCount)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (charIndex < 0 || charIndex > chars.Length)
-                throw new ArgumentOutOfRangeException("charIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(charIndex), SR.ArgumentOutOfRange_Index);
 
             // If no input, return 0 & avoid fixed problem
             if (byteCount == 0)
@@ -356,10 +356,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetChars(bytes, byteCount, chars, charCount, null);
         }
@@ -376,13 +376,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // Avoid problems with empty input buffer
             if (count == 0) return string.Empty;
diff --git a/src/libraries/System.Private.CoreLib/src/System/Text/UTF8Encoding.cs b/src/libraries/System.Private.CoreLib/src/System/Text/UTF8Encoding.cs
index 877010a..115163f 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Text/UTF8Encoding.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Text/UTF8Encoding.cs
@@ -130,13 +130,13 @@ namespace System.Text
         {
             // Validate input parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - index < count)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input, return 0, avoid fixed empty array problem
             if (count == 0)
@@ -171,10 +171,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             // Call it with empty encoder
             return GetByteCount(chars, count, null);
@@ -189,16 +189,16 @@ namespace System.Text
                                               byte[] bytes, int byteIndex)
         {
             if (s == null || bytes == null)
-                throw new ArgumentNullException((s == null ? "s" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((s == null ? nameof(s) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (s.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("s", SR.ArgumentOutOfRange_IndexCount);
+                throw new ArgumentOutOfRangeException(nameof(s), SR.ArgumentOutOfRange_IndexCount);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             int byteCount = bytes.Length - byteIndex;
 
@@ -225,16 +225,16 @@ namespace System.Text
         {
             // Validate parameters
             if (chars == null || bytes == null)
-                throw new ArgumentNullException((chars == null ? "chars" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((chars == null ? nameof(chars) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             // If nothing to encode return 0, avoid fixed problem
             if (charCount == 0)
@@ -257,10 +257,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetBytes(chars, charCount, bytes, byteCount, null);
         }
@@ -277,13 +277,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input just return 0, fixed doesn't like 0 length arrays.
             if (count == 0)
@@ -303,10 +303,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetCharCount(bytes, count, null);
         }
@@ -321,16 +321,16 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (byteIndex < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((byteIndex < 0 ? "byteIndex" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((byteIndex < 0 ? nameof(byteIndex) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if ( bytes.Length - byteIndex < byteCount)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (charIndex < 0 || charIndex > chars.Length)
-                throw new ArgumentOutOfRangeException("charIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(charIndex), SR.ArgumentOutOfRange_Index);
 
             // If no input, return 0 & avoid fixed problem
             if (byteCount == 0)
@@ -353,10 +353,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetChars(bytes, byteCount, chars, charCount, null);
         }
@@ -373,13 +373,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // Avoid problems with empty input buffer
             if (count == 0) return string.Empty;
diff --git a/src/libraries/System.Private.CoreLib/src/System/Text/UnicodeEncoding.cs b/src/libraries/System.Private.CoreLib/src/System/Text/UnicodeEncoding.cs
index 8386c49..5e2c098 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Text/UnicodeEncoding.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Text/UnicodeEncoding.cs
@@ -94,13 +94,13 @@ namespace System.Text
         {
             // Validate input parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - index < count)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input, return 0, avoid fixed empty array problem
             if (count == 0)
@@ -120,7 +120,7 @@ namespace System.Text
         {
             // Validate input
             if (s==null)
-                throw new ArgumentNullException("s");
+                throw new ArgumentNullException(nameof(s));
 
             fixed (char* pChars = s)
                 return GetByteCount(pChars, s.Length, null);
@@ -135,10 +135,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (chars == null)
-                throw new ArgumentNullException("chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(chars), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             // Call it with empty encoder
             return GetByteCount(chars, count, null);
@@ -153,16 +153,16 @@ namespace System.Text
                                               byte[] bytes, int byteIndex)
         {
             if (s == null || bytes == null)
-                throw new ArgumentNullException((s == null ? "s" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((s == null ? nameof(s) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (s.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("s", SR.ArgumentOutOfRange_IndexCount);
+                throw new ArgumentOutOfRangeException(nameof(s), SR.ArgumentOutOfRange_IndexCount);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             int byteCount = bytes.Length - byteIndex;
 
@@ -189,16 +189,16 @@ namespace System.Text
         {
             // Validate parameters
             if (chars == null || bytes == null)
-                throw new ArgumentNullException((chars == null ? "chars" : "bytes"), SR.ArgumentNull_Array);
+                throw new ArgumentNullException((chars == null ? nameof(chars) : nameof(bytes)), SR.ArgumentNull_Array);
 
             if (charIndex < 0 || charCount < 0)
-                throw new ArgumentOutOfRangeException((charIndex < 0 ? "charIndex" : "charCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charIndex < 0 ? nameof(charIndex) : nameof(charCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (chars.Length - charIndex < charCount)
-                throw new ArgumentOutOfRangeException("chars", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(chars), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (byteIndex < 0 || byteIndex > bytes.Length)
-                throw new ArgumentOutOfRangeException("byteIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(byteIndex), SR.ArgumentOutOfRange_Index);
 
             // If nothing to encode return 0, avoid fixed problem
             if (charCount == 0)
@@ -221,10 +221,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetBytes(chars, charCount, bytes, byteCount, null);
         }
@@ -241,13 +241,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // If no input just return 0, fixed doesn't like 0 length arrays
             if (count == 0)
@@ -267,10 +267,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (count < 0)
-                throw new ArgumentOutOfRangeException("count", SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetCharCount(bytes, count, null);
         }
@@ -285,16 +285,16 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (byteIndex < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((byteIndex < 0 ? "byteIndex" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((byteIndex < 0 ? nameof(byteIndex) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if ( bytes.Length - byteIndex < byteCount)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             if (charIndex < 0 || charIndex > chars.Length)
-                throw new ArgumentOutOfRangeException("charIndex", SR.ArgumentOutOfRange_Index);
+                throw new ArgumentOutOfRangeException(nameof(charIndex), SR.ArgumentOutOfRange_Index);
 
             // If no input, return 0 & avoid fixed problem
             if (byteCount == 0)
@@ -317,10 +317,10 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null || chars == null)
-                throw new ArgumentNullException(bytes == null ? "bytes" : "chars", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(bytes == null ? nameof(bytes) : nameof(chars), SR.ArgumentNull_Array);
 
             if (charCount < 0 || byteCount < 0)
-                throw new ArgumentOutOfRangeException((charCount < 0 ? "charCount" : "byteCount"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((charCount < 0 ? nameof(charCount) : nameof(byteCount)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             return GetChars(bytes, byteCount, chars, charCount, null);
         }
@@ -337,13 +337,13 @@ namespace System.Text
         {
             // Validate Parameters
             if (bytes == null)
-                throw new ArgumentNullException("bytes", SR.ArgumentNull_Array);
+                throw new ArgumentNullException(nameof(bytes), SR.ArgumentNull_Array);
 
             if (index < 0 || count < 0)
-                throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), SR.ArgumentOutOfRange_NeedNonNegNum);
+                throw new ArgumentOutOfRangeException((index < 0 ? nameof(index) : nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
 
             if (bytes.Length - index < count)
-                throw new ArgumentOutOfRangeException("bytes", SR.ArgumentOutOfRange_IndexCountBuffer);
+                throw new ArgumentOutOfRangeException(nameof(bytes), SR.ArgumentOutOfRange_IndexCountBuffer);
 
             // Avoid problems with empty input buffer
             if (count == 0) return string.Empty;
-- 
2.7.4