Add issue links and reasons to tool-specific test attributes

[Copilot]

Description

The illink test framework requires [ExpectedWarning] and [UnexpectedWarning] attributes with Tool.XXX parameters to include either an issue link (for bugs) or a reason string (for intentional differences). 563 attributes across 34 test files had empty placeholder strings.

Changes

Issue links added (69 attributes):

• IL2091 generic parameter dataflow → Trim analyzer: Doesn't produce warnings due to annotated generic parameter in various situations #95121
• IL2072/IL2068/IL2073/IL2089 ByRef tracking → Data flow incorrectly handles out and ref parameters #101734
• IL2072 extension methods → ILLink analyzer doesn't see operator method annotations #119110

Reason strings added (494 attributes):

• 314× "NativeAOT specific warning" (IL3002/IL3050)
• 23× "Analyzer follows different virtual method hierarchy validation rules" (IL2092/IL2093/IL2095)
• 18× "Analyzer does not support compiler-generated code warning suppression" (IL2026)
• 16× "Analyzer limitation in requires attribute validation" (IL2046/IL3003/IL3051)
• Plus other patterns with specific explanations

Fix applied based on code review:

• Corrected 4 ExpectedWarning attributes in FeatureGuardSubstitutions.cs where the Tool parameter was incorrectly changed from Tool.Trimmer | Tool.NativeAot to Tool.Analyzer (lines 294, 315, 336, 362). The correct tool parameter has been restored while keeping the appropriate message.

Example changes:

// Before
[ExpectedWarning("IL2091", "RequiresParameterlessCtor", Tool.Trimmer | Tool.NativeAot, "")]

// After
[ExpectedWarning("IL2091", "RequiresParameterlessCtor", Tool.Trimmer | Tool.NativeAot, "https://github.com/dotnet/runtime/issues/95121")]

Testing

All changes are string replacements in test attributes - no logic modified. CodeQL and code review passed.

Original prompt

Problem

In src/tools/illink/test/Mono.Linker.Tests.Cases, there are [ExpectedWarning] and [UnexpectedWarning] attributes that specify Tool.XXX (like Tool.Trimmer, Tool.NativeAot, Tool.Analyzer, or combinations thereof), indicating that warnings are not consistent among all 3 tools.

According to the test framework design, when warnings differ between tools, they should have either:

1. An issue link (like "https://github.com/dotnet/runtime/issues/XXXXX") - for bugs/inconsistencies that should be fixed
2. A reason string (like "NativeAOT-specific warning") - explaining why the difference is expected/intentional

Task

1. Search thoroughly through the test files in src/tools/illink/test/Mono.Linker.Tests.Cases for [ExpectedWarning] and [UnexpectedWarning] attributes that:

   • Specify a Tool.XXX parameter (meaning they're tool-specific)
   • Do NOT already have an issue link or reason string

2. For each missing link/reason:

   • Search existing GitHub issues in dotnet/runtime to see if there's an issue tracking the inconsistency
   • If an issue exists, add the issue link
   • If no issue exists and the behavior difference is a bug, create a new issue and add that link
   • If the behavior difference is intentional/expected, add an appropriate reason string

Reference

The attribute signatures that require issue links or reasons are:

// From ExpectedWarningAttribute.cs
public ExpectedWarningAttribute(string warningCode, Tool producedBy, string issueLinkOrReason)
public ExpectedWarningAttribute(string warningCode, string messageContains, Tool producedBy, string issueLinkOrReason)
public ExpectedWarningAttribute(string warningCode, string[] messageContains, Tool producedBy, string issueLinkOrReason)

// From UnexpectedWarningAttribute.cs - same patterns, inherits from ExpectedWarningAttribute

The overloads that only take params string[] messageContains (without Tool parameter) are for warnings expected from ALL tools and don't need issue links.

Examples of correct usage

// With issue link for bug/inconsistency:
[ExpectedWarning("IL2091", "'T'", Tool.Trimmer | Tool.NativeAot, "https://github.com/dotnet/runtime/issues/87596")]
[UnexpectedWarning("IL2111", Tool.Trimmer, "https://github.com/dotnet/runtime/issues/101195")]

// With reason string for intentional difference:
[ExpectedWarning("IL3050", "Microsoft.CSharp.RuntimeBinder.Binder.GetMember", Tool.NativeAot | Tool.Analyzer, "NativeAOT Specific Warning")]
[ExpectedWarning("IL3002", "--Method--", Tool.Analyzer | Tool.NativeAot, "NativeAOT-specific warning")]

Relevant issues to search

Some known issues that may be relevant:

• Dataflow analysis taking forever #87596 - Dataflow analysis taking forever (affects value tracking limits)
• ILLink: Trimmer, NativeAOT, and Trim analyzer have inconsistent UnsafeAccessor behavior #101195 - Trimmer, NativeAOT, and Trim analyzer have inconsistent UnsafeAccessor behavior
• ILC: Duplicate warnings for attribute on property dataflow #120004 - ILC: Duplicate warnings for attribute on property dataflow
• Linker doesn't track references/addresses for ldind.ref and always push an UnknownValue to the stack #85465 - Linker doesn't track references/addresses for ldind.ref
• NativeAOT doesnt have a way to remove all occurences of an attribute #80466 - NativeAOT doesn't support wildcard * in XML
• GetType() behave strange #93720 - GetType on isinst result
• ILLink: FormatException when building a diagnostic message #93800 - Nullable MakeGenericType warnings
• Postpone marking DAM members until type allocated #110563 - NativeAOT generic instantiation tracking
• ILLink analyzer doesn't see operator method annotations #119110 - Extension member operators dataflow
• Data flow incorrectly handles out and ref parameters #101734 - ByRef parameter annotation tracking
• ILLink: Trim analyzer doesn't warn on dataflow through multidimensional array #101951 - Multi-dimensional array tracking
• [ILLink analyzer] Analyzer doesn't produce RequiresDynamicCode warnings for dynamic objects #94427 - CallSite dynamic code warning

PR #116799 recently added many issue links - use that as a reference for the expected format and approach.

This pull request was created from Copilot chat.

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