Suppress AOT configuration-binding SYSLIB warnings in AotCompatibility test app

[Copilot]

The configuration binding source generator (EnableConfigurationBindingGenerator=true) recursively walks the X509Certificate2 type graph via MicrosoftIdentityApplicationOptions → ClientCredentials (IEnumerable<CredentialDescription>) → Certificate (X509Certificate2), producing 18 SYSLIB warnings on net10.0. Root cause is Microsoft.Identity.Abstractions 12 not being fully AOT-compatible. Certificates are never bound from IConfiguration—they are loaded programmatically—so the generated code silently skips those properties at runtime with no behavioral impact.

Changes

• tests/Microsoft.Identity.Web.AotCompatibility.TestApp/Microsoft.Identity.Web.AotCompatibility.TestApp.csproj — adds <NoWarn> to suppress the 18 warnings:

<NoWarn>$(NoWarn);SYSLIB1100;SYSLIB1101;SYSLIB0026;SYSLIB0027;SYSLIB0028</NoWarn>

Code	Count	Source
SYSLIB1100	7	Types with no/multiple constructors (X500DistinguishedName, PublicKey, X509Extension, AsymmetricAlgorithm, AsnEncodedData, unsupported collections)
SYSLIB1101	6	Unsupported bindable properties (Certificate, ClientCredentials, IssuerName, PrivateKey, PublicKey, Extensions, EncodedKeyValue)
SYSLIB0026/27/28	4	Obsolete APIs in generated BindingExtensions.g.cs (X509Certificate2(), PublicKey.Key, X509Certificate2.PrivateKey)

The longer-term fix belongs upstream in Microsoft.Identity.Abstractions—annotating CredentialDescription.Certificate and MicrosoftIdentityApplicationOptions.ClientCredentials to be excluded from configuration binding generation.

Original prompt

Problem

The Microsoft.Identity.Web.AotCompatibility.TestApp test project produces 18 SYSLIB warnings when building for net10.0 with PublishAot=true and EnableConfigurationBindingGenerator=true. These warnings are caused by the configuration binding source generator recursively walking the X509Certificate2 type graph through MicrosoftIdentityApplicationOptions → ClientCredentials (IEnumerable<CredentialDescription>) → Certificate (X509Certificate2).

The warnings originate from line 22 in Program.cs:

options => azureAdSection.Bind(options),

The affected types (X509Certificate2, X500DistinguishedName, PublicKey, AsymmetricAlgorithm, X509Extension, AsnEncodedData, X509ExtensionCollection) are never actually bound from configuration — certificates are loaded programmatically via DefaultCredentialsLoader and the various ICredentialSourceLoader implementations.

This is caused by referencing Microsoft.Identity.Abstractions 12 which is not fully AOT compatible.

Warnings to suppress

• SYSLIB1100 (7 warnings) — Types that can't be instantiated by the source generator
• SYSLIB1101 (6 warnings) — Unsupported properties on X509Certificate2 and related types
• SYSLIB0026 (1 warning) — Obsolete X509Certificate2() parameterless constructor
• SYSLIB0027 (1 warning) — Obsolete PublicKey.Key property
• SYSLIB0028 (2 warnings) — Obsolete X509Certificate2.PrivateKey property

Fix

Add a <NoWarn> entry to the <PropertyGroup> in tests/Microsoft.Identity.Web.AotCompatibility.TestApp/Microsoft.Identity.Web.AotCompatibility.TestApp.csproj:

<NoWarn>$(NoWarn);SYSLIB1100;SYSLIB1101;SYSLIB0026;SYSLIB0027;SYSLIB0028</NoWarn>

This should be added inside the first <PropertyGroup> alongside the other project properties.

Why this is safe

All 18 warnings trace back to the source generator recursively walking the X509Certificate2 type graph. Nobody configures certificates via IConfiguration binding — they're loaded programmatically. The generated binding code simply skips those unsupported properties at runtime, which is correct behavior. Suppressing these warnings just silences the noise without changing any runtime behavior.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: Build succeeded.

C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Program.cs(22,28): warning SYSLIB1100: Cannot create instance of type 'System.Security.Cryptography.X509Certificates.X500DistinguishedName' because it has multiple public parameterized constructors. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib1100) [C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Microsoft.Identity.Web.AotCompatibility.TestApp.csproj::TargetFramework=net10.0]
C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Program.cs(22,28): warning SYSLIB1101: Property 'IssuerName' on type 'System.Security.Cryptography.X509Certificates.X509Certificate2' is not supported. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib1101) [C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Microsoft.Identity.Web.AotCompatibility.TestApp.csproj::TargetFramework=net10.0]
C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Program.cs(22,28): warning SYSLIB1101: Property 'Certificate' on type 'Microsoft.Identity.Abstractions.CredentialDescription' is not supported. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib1101) [C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Microsoft.Identity.Web.AotCompatibility.TestApp.csproj::TargetFramework=net10.0]
C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Program.cs(22,28): warning SYSLIB1100: The collection element type is not supported: 'System.Collections.Generic.IEnumerable'. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib1100) [C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Microsoft.Identity.Web.AotCompatibility.TestApp.csproj::TargetFramework=net10.0]
C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Program.cs(22,28): warning SYSLIB1101: Property 'ClientCredentials' on type 'Microsoft.Identity.Abstractions.MicrosoftIdentityApplicationOptions' is not supported. (https://learn.microsoft.com/dotnet/fundamentals/syslib-diagnostics/syslib1101) [C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Microsoft.Identity.Web.AotCompatibility.TestApp.csproj::TargetFramework=net10.0]
C:__w\1\s\microsoft-identity-web\tests\Microsoft.Identity.Web.AotCompatibility.TestApp\Program.cs(22,28): warning ...

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