Document ProviderAliasAttribute breaking change (#46274)

Author: gewarren

docs/core/compatibility/10.0.md

@@ -34,6 +34,12 @@ If you're migrating an app to .NET 10, the breaking changes listed here might af
 | [MacCatalyst version normalization](core-libraries/10.0/maccatalyst-version-normalization.md)                              | Behavioral change   | Preview 1          |
 | [System.Linq.AsyncEnumerable included in core libraries](core-libraries/10.0/asyncenumerable.md)                           | Source incompatible | Preview 1          |
 
+## Extensions
+
+| Title                                                                                                     | Type of change      | Introduced version |
+|-----------------------------------------------------------------------------------------------------------|---------------------|--------------------|
+| [ProviderAliasAttribute moved to Microsoft.Extensions.Logging.Abstractions assembly](extensions/10.0/provideraliasattribute-moved-assembly.md) | Source incompatible | Preview 4          |
+
 ## Globalization
 
 | Title                                                                                                 | Type of change    | Introduced version |

docs/core/compatibility/extensions/10.0/provideraliasattribute-moved-assembly.md

@@ -0,0 +1,39 @@
+---
+title: "Breaking change: ProviderAliasAttribute moved to Microsoft.Extensions.Logging.Abstractions assembly"
+description: Learn about the breaking change in .NET 10 where the ProviderAliasAttribute class moved from the Microsoft.Extensions.Logging assembly to the Microsoft.Extensions.Logging.Abstractions assembly.
+ms.date: 05/19/2025
+---
+
+# ProviderAliasAttribute moved to Microsoft.Extensions.Logging.Abstractions
+
+The <xref:Microsoft.Extensions.Logging.ProviderAliasAttribute> attribute has been moved from the `Microsoft.Extensions.Logging` assembly to the `Microsoft.Extensions.Logging.Abstractions` assembly.
+
+## Version introduced
+
+.NET 10 Preview 4
+
+## Previous behavior
+
+In previous versions of .NET, <xref:Microsoft.Extensions.Logging.ProviderAliasAttribute> was defined in the `Microsoft.Extensions.Logging` assembly.
+
+## New behavior
+
+Starting in .NET 10, <xref:Microsoft.Extensions.Logging.ProviderAliasAttribute> is defined in `Microsoft.Extensions.Logging.Abstractions` and, to maintain compatibility, is type-forwarded from `Microsoft.Extensions.Logging`.
+
+## Type of breaking change
+
+This change can affect [source compatibility](../../categories.md#source-compatibility).
+
+## Reason for change
+
+This change allows applications that depend on [Microsoft.Extensions.Logging.Abstractions](https://www.nuget.org/packages/Microsoft.Extensions.Logging.Abstractions) and that use <xref:Microsoft.Extensions.Logging.ProviderAliasAttribute> to avoid taking a dependency on the full [Microsoft.Extensions.Logging package](https://www.nuget.org/packages/Microsoft.Extensions.Logging).
+
+## Recommended action
+
+In most scenarios, no action is required. The type is [type-forwarded](../../../../standard/assembly/type-forwarding.md) from `Microsoft.Extensions.Logging` to `Microsoft.Extensions.Logging.Abstractions`, which allows existing code to continue to work without modification.
+
+The only potential breaking scenario occurs when your project references an older version of `Microsoft.Extensions.Logging` alongside the .NET 10 version of `Microsoft.Extensions.Logging.Abstractions`. In this situation, a compilation error might occur due to <xref:Microsoft.Extensions.Logging.ProviderAliasAttribute> being defined in both assemblies. To resolve the error, upgrade to the .NET 10 version of `Microsoft.Extensions.Logging`.
+
+## Affected APIs
+
+- <xref:Microsoft.Extensions.Logging.ProviderAliasAttribute?displayProperty=fullName>

docs/core/compatibility/toc.yml

@@ -38,6 +38,10 @@ items:
                 href: cryptography/10.0/x509-publickey-null.md
               - name: Environment variable renamed to DOTNET_OPENSSL_VERSION_OVERRIDE
                 href: cryptography/10.0/version-override.md
+          - name: Extensions
+            items:
+              - name: "ProviderAliasAttribute moved to Microsoft.Extensions.Logging.Abstractions assembly"
+                href: extensions/10.0/provideraliasattribute-moved-assembly.md
           - name: Globalization
             items:
               - name: Environment variable renamed to DOTNET_ICU_VERSION_OVERRIDE
@@ -1746,6 +1750,10 @@ items:
             href: /ef/core/what-is-new/ef-core-3.x/breaking-changes?toc=/dotnet/core/compatibility/toc.json&bc=/dotnet/breadcrumb/toc.json
       - name: Extensions
         items:
+          - name: .NET 10
+            items:
+              - name: "ProviderAliasAttribute moved to Microsoft.Extensions.Logging.Abstractions assembly"
+                href: extensions/10.0/provideraliasattribute-moved-assembly.md
           - name: .NET 8
             items:
               - name: ActivatorUtilities.CreateInstance behaves consistently