Razor requires referencing two different versions of Roslyn
Razor compiler (rzc) that ships as part of the SDK. rzc ships copies of compiler binaries (Microsoft.CodeAnalysis.CSharp and Microsoft.CodeAnalysis.Common).
Razor runtime compilation is shipped as a NuGet package and needs to reference a version of Roslyn that ships as a NuGet package.
Roslyn doesn't follow the runtime ship schedule so to reliably the 2nd item, ASP.NET Core manually updates this package version. As part of 5.0.1, it was discovered that there's two different versions of these binaries in the SDK (a 3.8.0 version carried by the compiler and a 3.7.0 version carried by Razor). This is a bit vexxing, more so in source build which only builds the newer version.
Fixes#28096
Description
Update the Roslyn version referenced by Razor to 3.8.0
Customer impact
Razor compilation uses a newer version of the compiler consistent with the rest of the SDK.
Users updating to the 5.0.1 version of runtime compilation package will now use a newer version of the compiler. While it's slightly unusual to update a reference by a minor version as part of a patch release, we do not see users taking a hard dependency on the compiler version to be affected by this.
Regression
No
Risk
Low.
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