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, 11 insertions, 0 deletions

diff --git a/test/Mono.Linker.Tests/TestCasesRunner/ResultChecker.cs b/test/Mono.Linker.Tests/TestCasesRunner/ResultChecker.cs
index b4508e15e..18a32880d 100644
--- a/test/Mono.Linker.Tests/TestCasesRunner/ResultChecker.cs
+++ b/test/Mono.Linker.Tests/TestCasesRunner/ResultChecker.cs
@@ -707,6 +707,7 @@ namespace Mono.Linker.Tests.TestCasesRunner
 								string fileName = (string) attr.GetPropertyValue ("FileName");
 								int? sourceLine = (int?) attr.GetPropertyValue ("SourceLine");
 								int? sourceColumn = (int?) attr.GetPropertyValue ("SourceColumn");
+								bool? isCompilerGeneratedCode = (bool?) attr.GetPropertyValue ("CompilerGeneratedCode");
 
 								int expectedWarningCodeNumber = int.Parse (expectedWarningCode.Substring (2));
 								var actualMethod = attrProvider as MethodDefinition;
@@ -751,6 +752,16 @@ namespace Mono.Linker.Tests.TestCasesRunner
 											if (!actualOrigin.ToString ().EndsWith (expectedOrigin, StringComparison.OrdinalIgnoreCase))
 												return false;
 										}
+									} else if (isCompilerGeneratedCode == true) {
+										MethodDefinition methodDefinition = mc.Origin?.MemberDefinition as MethodDefinition;
+										if (methodDefinition != null) {
+											string actualName = methodDefinition.DeclaringType.FullName + "." + methodDefinition.Name;
+											if (actualName.StartsWith (attrProvider.DeclaringType.FullName) &&
+												actualName.Contains ("<" + attrProvider.Name + ">"))
+												return true;
+										}
+
+										return false;
 									} else {
 										if (mc.Origin?.MemberDefinition?.FullName == attrProvider.FullName)
 											return true;