Add new syslib warnings (#23915)

docs/core/compatibility/syslib-obsoletions.md

@@ -1,9 +1,9 @@
 ---
 title: Obsolete features in .NET 5+
 description: Learn about APIs that are marked as obsolete in .NET 5 and later versions that produce SYSLIB compiler warnings.
-ms.date: 10/20/2020
+ms.date: 04/23/2021
 ---
-# Obsolete features in .NET 5
+# Obsolete features in .NET 5+
 
 Starting in .NET 5, some APIs that are newly marked as obsolete make use of two new properties on <xref:System.ObsoleteAttribute>.
 
@@ -31,6 +31,12 @@ The following table provides an index to the `SYSLIBxxxx` obsoletions in .NET 5+
 | [SYSLIB0010](syslib-warnings/syslib0010.md) | Some remoting APIs are not supported and throw <xref:System.PlatformNotSupportedException>. |
 | [SYSLIB0011](syslib-warnings/syslib0011.md) | <xref:System.Runtime.Serialization.Formatters.Binary.BinaryFormatter> serialization is obsolete and should not be used. |
 | [SYSLIB0012](syslib-warnings/syslib0012.md) | <xref:System.Reflection.Assembly.CodeBase?displayProperty=nameWithType> and <xref:System.Reflection.Assembly.EscapedCodeBase?displayProperty=nameWithType> are only included for .NET Framework compatibility. Use <xref:System.Reflection.Assembly.Location?displayProperty=nameWithType> instead. |
+| [SYSLIB0013](syslib-warnings/syslib0013.md) | <xref:System.Uri.EscapeUriString(System.String)?displayProperty=nameWithType> can corrupt the Uri string in some cases. Consider using <xref:System.Uri.EscapeDataString(System.String)?displayProperty=nameWithType> for query string components instead. |
+| [SYSLIB0014](syslib-warnings/syslib0014.md) | <xref:System.Net.WebRequest>, <xref:System.Net.HttpWebRequest>, <xref:System.Net.ServicePoint>, and <xref:System.Net.WebClient> are obsolete. Use <xref:System.Net.Http.HttpClient> instead. |
+| [SYSLIB0015](syslib-warnings/syslib0015.md) | <xref:System.Runtime.CompilerServices.DisablePrivateReflectionAttribute> has no effect in .NET 6+ applications. |
+| [SYSLIB0016](syslib-warnings/syslib0016.md) | Use the <xref:System.Drawing.Graphics.GetContextInfo%2A?displayProperty=nameWithType> overloads that accept arguments for better performance and fewer allocations. |
+| [SYSLIB0019](syslib-warnings/syslib0019.md) | The <xref:System.Runtime.InteropServices.RuntimeEnvironment?displayProperty=nameWithType> members <xref:System.Runtime.InteropServices.RuntimeEnvironment.SystemConfigurationFile>, <xref:System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeInterfaceAsIntPtr(System.Guid,System.Guid)>, and <xref:System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeInterfaceAsObject(System.Guid,System.Guid)> are no longer supported and throw <xref:System.PlatformNotSupportedException>. |
+| [SYSLIB0020](syslib-warnings/syslib0020.md) | <xref:System.Text.Json.JsonSerializerOptions.IgnoreNullValues?displayProperty=nameWithType> is obsolete. To ignore null values when serializing, set <xref:System.Text.Json.JsonSerializerOptions.DefaultIgnoreCondition> to <xref:System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull?displayProperty=nameWithType>. |
 
 ## Suppress warnings
 

docs/core/compatibility/syslib-warnings/syslib0013.md

@@ -0,0 +1,19 @@
+---
+title: SYSLIB0013 warning
+description: Learn about the EscapeUriString obsoletion that generates compile-time warning SYSLIB0013.
+ms.topic: reference
+ms.date: 04/24/2021
+---
+# SYSLIB0013: EscapeUriString is obsolete
+
+The <xref:System.Uri.EscapeUriString(System.String)?displayProperty=nameWithType> API is marked as obsolete, starting in .NET 6. Using it in code generates warning `SYSLIB0013` at compile time.
+
+<xref:System.Uri.EscapeUriString(System.String)?displayProperty=nameWithType> can corrupt the Uri string in some cases.
+
+For more information, see <https://github.com/dotnet/runtime/issues/31387>.
+
+## Workarounds
+
+Use <xref:System.Uri.EscapeDataString(System.String)?displayProperty=nameWithType> for query string components instead.
+
+[!INCLUDE [suppress-syslib-warning](../../../../includes/suppress-syslib-warning.md)]

docs/core/compatibility/syslib-warnings/syslib0014.md

@@ -0,0 +1,24 @@
+---
+title: SYSLIB0014 warning
+description: Learn about the System.Net obsoletions that generate compile-time warning SYSLIB0014.
+ms.topic: reference
+ms.date: 04/24/2021
+---
+# SYSLIB0014: WebRequest, HttpWebRequest, ServicePoint, WebClient are obsolete
+
+The following APIs are marked as obsolete, starting in .NET 6. Using them in code generates warning `SYSLIB0014` at compile time.
+
+- <xref:System.Net.WebRequest?displayProperty=fullName>
+- <xref:System.Net.HttpWebRequest?displayProperty=fullName>
+- <xref:System.Net.ServicePoint?displayProperty=fullName>
+- <xref:System.Net.WebClient?displayProperty=fullName>
+
+## Workarounds
+
+Use <xref:System.Net.Http.HttpClient> instead.
+
+[!INCLUDE [suppress-syslib-warning](../../../../includes/suppress-syslib-warning.md)]
+
+## See also
+
+- [WebRequest, WebClient, and ServicePoint are obsolete](../networking/6.0/webrequest-deprecated.md)

docs/core/compatibility/syslib-warnings/syslib0015.md

@@ -0,0 +1,17 @@
+---
+title: SYSLIB0015 warning
+description: Learn about the obsoletion of DisablePrivateReflectionAttribute that generates compile-time warning SYSLIB0015.
+ms.topic: reference
+ms.date: 04/24/2021
+---
+# SYSLIB0015: DisablePrivateReflectionAttribute is obsolete
+
+Starting in .NET 6, the <xref:System.Runtime.CompilerServices.DisablePrivateReflectionAttribute?displayProperty=nameWithType> type is marked as obsolete. This attribute has no effect in .NET Core 2.1 and later apps. Using it in code generates warning `SYSLIB0015` at compile time for .NET 6 and later apps.
+
+For more information, see <https://github.com/dotnet/runtime/issues/11811>.
+
+## Workarounds
+
+None.
+
+[!INCLUDE [suppress-syslib-warning](../../../../includes/suppress-syslib-warning.md)]

docs/core/compatibility/syslib-warnings/syslib0016.md

@@ -0,0 +1,17 @@
+---
+title: SYSLIB0016 warning
+description: Learn about the GetContextInfo obsoletion that generates compile-time warning SYSLIB0016.
+ms.topic: reference
+ms.date: 04/24/2021
+---
+# SYSLIB0016: GetContextInfo() is obsolete
+
+The <xref:System.Drawing.Graphics.GetContextInfo?displayProperty=nameWithType> method that takes no arguments is marked as obsolete, starting in .NET 6. Using it in code generates warning `SYSLIB0016` at compile time.
+
+For more information, see <https://github.com/dotnet/runtime/issues/47880>.
+
+## Workarounds
+
+For better performance and fewer allocations, use the <xref:System.Drawing.Graphics.GetContextInfo%2A?displayProperty=nameWithType> overloads that accept arguments.
+
+[!INCLUDE [suppress-syslib-warning](../../../../includes/suppress-syslib-warning.md)]

docs/core/compatibility/syslib-warnings/syslib0019.md

@@ -0,0 +1,21 @@
+---
+title: SYSLIB0019 warning
+description: Learn about the RuntimeEnvironment obsoletions that generate compile-time warning SYSLIB0019.
+ms.topic: reference
+ms.date: 04/24/2021
+---
+# SYSLIB0019: Some RuntimeEnvironment APIs are obsolete
+
+The following APIs are marked as obsolete, starting in .NET 6. Using them in code generates warning `SYSLIB0019` at compile time.
+
+- <xref:System.Runtime.InteropServices.RuntimeEnvironment.SystemConfigurationFile?displayProperty=nameWithType> property
+- <xref:System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeInterfaceAsIntPtr(System.Guid,System.Guid)?displayProperty=nameWithType> method
+- <xref:System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeInterfaceAsObject(System.Guid,System.Guid)?displayProperty=nameWithType> method
+
+These APIs always throw a <xref:System.PlatformNotSupportedException> at run time.
+
+## Workarounds
+
+None.
+
+[!INCLUDE [suppress-syslib-warning](../../../../includes/suppress-syslib-warning.md)]

docs/core/compatibility/syslib-warnings/syslib0020.md

@@ -0,0 +1,15 @@
+---
+title: SYSLIB0020 warning
+description: Learn about the IgnoreNullValues obsoletion that generates compile-time warning SYSLIB0020.
+ms.topic: reference
+ms.date: 04/24/2021
+---
+# SYSLIB0020: IgnoreNullValues is obsolete
+
+The <xref:System.Text.Json.JsonSerializerOptions.IgnoreNullValues?displayProperty=nameWithType> property is marked as obsolete, starting in .NET 6. Using it in code generates warning `SYSLIB0020` at compile time.
+
+## Workarounds
+
+To ignore null values when serializing, set <xref:System.Text.Json.JsonSerializerOptions.DefaultIgnoreCondition> to <xref:System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull?displayProperty=nameWithType>. For more information, see <https://github.com/dotnet/runtime/issues/39152>.
+
+[!INCLUDE [suppress-syslib-warning](../../../../includes/suppress-syslib-warning.md)]

docs/core/compatibility/toc.yml

@@ -730,3 +730,15 @@ items:
       href: syslib-warnings/syslib0011.md
     - name: SYSLIB0012
       href: syslib-warnings/syslib0012.md
+    - name: SYSLIB0013
+      href: syslib-warnings/syslib0013.md
+    - name: SYSLIB0014
+      href: syslib-warnings/syslib0014.md
+    - name: SYSLIB0015
+      href: syslib-warnings/syslib0015.md
+    - name: SYSLIB0016
+      href: syslib-warnings/syslib0016.md
+    - name: SYSLIB0019
+      href: syslib-warnings/syslib0019.md
+    - name: SYSLIB0020
+      href: syslib-warnings/syslib0020.md