Warning suppressions in compiler generated code (#2075)

This change implements the following high-level functionality:
* `UnconditionalSuppressMessage` applies to the entire method body even for iterators, async methods
* `RequiresUnreferencedCode` automatically suppresses trim analysis warnings from entire method body for iterators, async methods

Solution approach:
* Detect compiler generated code by using the `IteratorStateMachineAttribute`, `AsyncStateMachineAttribute` and `AyncIteratorStateMachineAttribute`.
  * When a method which is compiler generated (detected by looing for `<` in its name) is processed the original "user method" is determined by looking for a method with the "state machine" attribute pointing to the compiler generated type.
  * This information is cached to avoid duplication of relatively expensive detection logic.
* Looks for `UnconditionalSuppressMessage` and `RequriesUnreferencedCode` in:
  * If the warning origin is not a compiler generated code - simply use the warning origin (method) - existing behavior
  * If the warning origin is compiler generated use both the origin as well as the user defined method (non-compiler-generated) which is the source of the code for the compiler generated origin

This is done by storing additional `SuppressionContextMember` on `MessageOrigin` which should always point to non-compiler-generated item.

Added lot of new tests for these scenarios.

This implements warning suppression part of https://github.com/mono/linker/issues/2001 for state machines.

1 files changed, 10 insertions, 8 deletions

diff --git a/src/linker/Linker.Dataflow/ReflectionMethodBodyScanner.cs b/src/linker/Linker.Dataflow/ReflectionMethodBodyScanner.cs
index a453702d0..582bde492 100644
--- a/src/linker/Linker.Dataflow/ReflectionMethodBodyScanner.cs
+++ b/src/linker/Linker.Dataflow/ReflectionMethodBodyScanner.cs
@@ -59,9 +59,12 @@ namespace Mono.Linker.Dataflow
 			return context.Annotations.FlowAnnotations.RequiresDataFlowAnalysis (fieldDefinition);
 		}
 
-		bool ShouldEnableReflectionPatternReporting (MethodDefinition method)
+		bool ShouldEnableReflectionPatternReporting ()
 		{
-			return !_context.Annotations.HasLinkerAttribute<RequiresUnreferencedCodeAttribute> (method);
+			if (_markStep.ShouldSuppressAnalysisWarningsForRequiresUnreferencedCode ())
+				return false;
+
+			return true;
 		}
 
 		public ReflectionMethodBodyScanner (LinkContext context, MarkStep parent, MarkScopeStack scopeStack)
@@ -79,7 +82,7 @@ namespace Mono.Linker.Dataflow
 				var method = methodBody.Method;
 				var requiredMemberTypes = _context.Annotations.FlowAnnotations.GetReturnParameterAnnotation (method);
 				if (requiredMemberTypes != 0) {
-					var reflectionContext = new ReflectionPatternContext (_context, ShouldEnableReflectionPatternReporting (method), _scopeStack.CurrentScope.Origin, method.MethodReturnType);
+					var reflectionContext = new ReflectionPatternContext (_context, ShouldEnableReflectionPatternReporting (), _scopeStack.CurrentScope.Origin, method.MethodReturnType);
 					reflectionContext.AnalyzingPattern ();
 					RequireDynamicallyAccessedMembers (ref reflectionContext, requiredMemberTypes, MethodReturnValue, method.MethodReturnType);
 					reflectionContext.Dispose ();
@@ -151,9 +154,8 @@ namespace Mono.Linker.Dataflow
 
 			ValueNode valueNode = GetTypeValueNodeFromGenericArgument (genericArgument);
 			var currentScopeOrigin = _scopeStack.CurrentScope.Origin;
-			bool enableReflectionPatternReporting = !(currentScopeOrigin.MemberDefinition is MethodDefinition sourceMethod) || ShouldEnableReflectionPatternReporting (sourceMethod);
 
-			var reflectionContext = new ReflectionPatternContext (_context, enableReflectionPatternReporting, currentScopeOrigin, genericParameter);
+			var reflectionContext = new ReflectionPatternContext (_context, ShouldEnableReflectionPatternReporting (), currentScopeOrigin, genericParameter);
 			reflectionContext.AnalyzingPattern ();
 			RequireDynamicallyAccessedMembers (ref reflectionContext, annotation, valueNode, genericParameter);
 			reflectionContext.Dispose ();
@@ -228,7 +230,7 @@ namespace Mono.Linker.Dataflow
 			var requiredMemberTypes = _context.Annotations.FlowAnnotations.GetFieldAnnotation (field);
 			if (requiredMemberTypes != 0) {
 				_scopeStack.UpdateCurrentScopeInstructionOffset (operation.Offset);
-				var reflectionContext = new ReflectionPatternContext (_context, ShouldEnableReflectionPatternReporting (method), _scopeStack.CurrentScope.Origin, field, operation);
+				var reflectionContext = new ReflectionPatternContext (_context, ShouldEnableReflectionPatternReporting (), _scopeStack.CurrentScope.Origin, field, operation);
 				reflectionContext.AnalyzingPattern ();
 				RequireDynamicallyAccessedMembers (ref reflectionContext, requiredMemberTypes, valueToStore, field);
 				reflectionContext.Dispose ();
@@ -241,7 +243,7 @@ namespace Mono.Linker.Dataflow
 			if (requiredMemberTypes != 0) {
 				ParameterDefinition parameter = method.Parameters[index - (method.HasImplicitThis () ? 1 : 0)];
 				_scopeStack.UpdateCurrentScopeInstructionOffset (operation.Offset);
-				var reflectionContext = new ReflectionPatternContext (_context, ShouldEnableReflectionPatternReporting (method), _scopeStack.CurrentScope.Origin, parameter, operation);
+				var reflectionContext = new ReflectionPatternContext (_context, ShouldEnableReflectionPatternReporting (), _scopeStack.CurrentScope.Origin, parameter, operation);
 				reflectionContext.AnalyzingPattern ();
 				RequireDynamicallyAccessedMembers (ref reflectionContext, requiredMemberTypes, valueToStore, parameter);
 				reflectionContext.Dispose ();
@@ -649,7 +651,7 @@ namespace Mono.Linker.Dataflow
 			_scopeStack.UpdateCurrentScopeInstructionOffset (operation.Offset);
 			var reflectionContext = new ReflectionPatternContext (
 				_context,
-				ShouldEnableReflectionPatternReporting (callingMethodDefinition),
+				ShouldEnableReflectionPatternReporting (),
 				_scopeStack.CurrentScope.Origin,
 				calledMethodDefinition,
 				operation);