Annotate methods that get MethodBase from a stackwalk as RUC (#59851)

Fixes #53242. Saddened this didn't make .NET 6.0. Stack traces in trimmed apps look ugly without this fix: ``` Unhandled exception. System.ArgumentNullException: Value cannot be null. (Parameter 'id') at System.TimeZoneInfo.ValidateTimeZoneInfo(String , TimeSpan , AdjustmentRule[] , Boolean& ) at System.TimeZoneInfo..ctor(String , TimeSpan , String , String , String , AdjustmentRule[] , Boolean , Boolean ) at System.TimeZoneInfo.CreateCustomTimeZone(String , TimeSpan , String , String ) at Program.<Main>$(String[] args) in C:\stacktrace\Program.cs:line 3 ```
dotnet · Oct 4, 2021 · b72b8a2 · b72b8a2
1 parent e118d3f
commit b72b8a2
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Showing 11 changed files with 40 additions and 5 deletions.
diff --git a/src/coreclr/System.Private.CoreLib/src/System/Exception.CoreCLR.cs b/src/coreclr/System.Private.CoreLib/src/System/Exception.CoreCLR.cs
@@ -3,6 +3,7 @@
 
 using System.Collections;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -69,6 +70,7 @@ private IDictionary CreateDataContainer()
 
         public MethodBase? TargetSite
         {
+            [RequiresUnreferencedCode("Metadata for the method might be incomplete or removed")]
             get
             {
                 if (_exceptionMethod != null)
@@ -85,13 +87,17 @@ private IDictionary CreateDataContainer()
             }
         }
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+            Justification = "The API will return null if the metadata for current method cannot be established.")]
         private string? CreateSourceName()
         {
             StackTrace st = new StackTrace(this, fNeedFileInfo: false);
             if (st.FrameCount > 0)
             {
                 StackFrame sf = st.GetFrame(0)!;
-                MethodBase method = sf.GetMethod()!;
+                MethodBase? method = sf.GetMethod();
+                if (method == null)
+                    return null;
 
                 Module module = method.Module;
 

diff --git a/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBase.CoreCLR.cs b/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBase.CoreCLR.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Runtime.InteropServices;
 using System.Threading;
@@ -36,6 +37,7 @@ public abstract partial class MethodBase : MemberInfo
             return RuntimeType.GetMethodBase(declaringType.GetRuntimeType(), handle.GetMethodInfo());
         }
 
+        [RequiresUnreferencedCode("Metadata for the method might be incomplete or removed")]
         [System.Security.DynamicSecurityMethod] // Methods containing StackCrawlMark local var has to be marked DynamicSecurityMethod
         public static MethodBase? GetCurrentMethod()
         {

diff --git a/src/libraries/System.Diagnostics.StackTrace/ref/System.Diagnostics.StackTrace.cs b/src/libraries/System.Diagnostics.StackTrace/ref/System.Diagnostics.StackTrace.cs
@@ -19,6 +19,7 @@ public partial class StackFrame
         public virtual int GetFileLineNumber() { throw null; }
         public virtual string? GetFileName() { throw null; }
         public virtual int GetILOffset() { throw null; }
+        [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Metadata for the method might be incomplete or removed")]
         public virtual System.Reflection.MethodBase? GetMethod() { throw null; }
         public virtual int GetNativeOffset() { throw null; }
         public override string ToString() { throw null; }

diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Contracts/Contracts.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Contracts/Contracts.cs
@@ -619,6 +619,9 @@ public static bool Exists<T>(IEnumerable<T> collection, Predicate<T> predicate)
         /// This method is used internally to trigger a failure indicating to the "programmer" that they are using the interface incorrectly.
         /// It is NEVER used to indicate failure of actual contracts at runtime.
         /// </summary>
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+            Justification = "StackFrame.GetMethod is only used to help diagnosing incorrect use of contracts. " +
+                "It handles missing or incomplete metadata.")]
         private static void AssertMustUseRewriter(ContractFailureKind kind, string contractKind)
         {
             // For better diagnostics, report which assembly is at fault.  Walk up stack and

diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/StackFrame.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/StackFrame.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics.CodeAnalysis;
 using System.Text;
 using System.Reflection;
 using System.Runtime.CompilerServices;
@@ -136,6 +137,7 @@ public StackFrame(string? fileName, int lineNumber, int colNumber)
         /// <summary>
         /// Returns the method the frame is executing
         /// </summary>
+        [RequiresUnreferencedCode("Metadata for the method might be incomplete or removed")]
         public virtual MethodBase? GetMethod()
         {
             return _method;

diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/StackFrameExtensions.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/StackFrameExtensions.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 
 namespace System.Diagnostics
 {
@@ -12,6 +13,8 @@ public static bool HasNativeImage(this StackFrame stackFrame)
             return stackFrame.GetNativeImageBase() != IntPtr.Zero;
         }
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+            Justification = "StackFrame.GetMethod is used to establish if method is available.")]
         public static bool HasMethod(this StackFrame stackFrame)
         {
             return stackFrame.GetMethod() != null;

diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/StackTrace.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/StackTrace.cs
@@ -203,6 +203,8 @@ internal string ToString(TraceFormat traceFormat)
         }
 
 #if !CORERT
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+            Justification = "ToString is best effort when it comes to available information.")]
         internal void ToString(TraceFormat traceFormat, StringBuilder sb)
         {
             // Passing a default string for "at" in case SR.UsingResourceKeys() is true
@@ -301,8 +303,12 @@ internal void ToString(TraceFormat traceFormat, StringBuilder sb)
                             if (pi[j].ParameterType != null)
                                 typeName = pi[j].ParameterType.Name;
                             sb.Append(typeName);
-                            sb.Append(' ');
-                            sb.Append(pi[j].Name);
+                            string? parameterName = pi[j].Name;
+                            if (parameterName != null)
+                            {
+                                sb.Append(' ');
+                                sb.Append(parameterName);
+                            }
                         }
                         sb.Append(')');
                     }

diff --git a/src/libraries/System.Runtime/ref/System.Runtime.cs b/src/libraries/System.Runtime/ref/System.Runtime.cs
@@ -2839,7 +2839,7 @@ public partial class Exception : System.Runtime.Serialization.ISerializable
         public virtual string Message { get { throw null; } }
         public virtual string? Source { get { throw null; } set { } }
         public virtual string? StackTrace { get { throw null; } }
-        public System.Reflection.MethodBase? TargetSite { get { throw null; } }
+        public System.Reflection.MethodBase? TargetSite { [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Metadata for the method might be incomplete or removed")] get { throw null; } }
         [System.ObsoleteAttribute("BinaryFormatter serialization is obsolete and should not be used. See https://aka.ms/binaryformatter for more information.", DiagnosticId = "SYSLIB0011", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
         protected event System.EventHandler<System.Runtime.Serialization.SafeSerializationEventArgs>? SerializeObjectState { add { } remove { } }
         public virtual System.Exception GetBaseException() { throw null; }
@@ -11873,6 +11873,7 @@ public abstract partial class MethodBase : System.Reflection.MemberInfo
         public abstract System.RuntimeMethodHandle MethodHandle { get; }
         public virtual System.Reflection.MethodImplAttributes MethodImplementationFlags { get { throw null; } }
         public override bool Equals(object? obj) { throw null; }
+        [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Metadata for the method might be incomplete or removed")]
         public static System.Reflection.MethodBase? GetCurrentMethod() { throw null; }
         public virtual System.Type[] GetGenericArguments() { throw null; }
         public override int GetHashCode() { throw null; }

diff --git a/src/mono/System.Private.CoreLib/src/System/Diagnostics/StackTrace.Mono.cs b/src/mono/System.Private.CoreLib/src/System/Diagnostics/StackTrace.Mono.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -35,6 +36,8 @@ public partial class StackTrace
         [MethodImplAttribute(MethodImplOptions.InternalCall)]
         internal static extern MonoStackFrame[] get_trace(Exception e, int skipFrames, bool needFileInfo);
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+            Justification = "StackFrame.GetMethod is getting compared to null but nothing else on it is touched.")]
         [MethodImplAttribute(MethodImplOptions.NoInlining)]
         private void InitializeForCurrentThread(int skipFrames, bool needFileInfo)
         {

diff --git a/src/mono/System.Private.CoreLib/src/System/Exception.Mono.cs b/src/mono/System.Private.CoreLib/src/System/Exception.Mono.cs
@@ -3,6 +3,7 @@
 
 using System.Collections;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using System.Runtime.InteropServices;
 using System.Diagnostics.Tracing;
@@ -50,6 +51,7 @@ public DispatchState(MonoStackFrame[]? stackFrames)
 
         public MethodBase? TargetSite
         {
+            [RequiresUnreferencedCode("Metadata for the method might be incomplete or removed")]
             get
             {
                 StackTrace st = new StackTrace(this, true);
@@ -107,15 +109,19 @@ private bool CanSetRemoteStackTrace()
             return true; // mono runtime doesn't have immutable agile exceptions, always return true
         }
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+            Justification = "The API will return null if the metadata for current method cannot be established.")]
         private string? CreateSourceName()
         {
             var st = new StackTrace(this, fNeedFileInfo: false);
             if (st.FrameCount > 0)
             {
                 StackFrame sf = st.GetFrame(0)!;
                 MethodBase? method = sf.GetMethod();
+                if (method == null)
+                    return null;
 
-                Module? module = method?.Module;
+                Module module = method.Module;
                 RuntimeModule? rtModule = module as RuntimeModule;
 
                 if (rtModule == null)

diff --git a/src/mono/System.Private.CoreLib/src/System/Reflection/MethodBase.Mono.cs b/src/mono/System.Private.CoreLib/src/System/Reflection/MethodBase.Mono.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 
 namespace System.Reflection
@@ -34,6 +35,7 @@ public partial class MethodBase
             return m;
         }
 
+        [RequiresUnreferencedCode("Metadata for the method might be incomplete or removed")]
         [MethodImplAttribute(MethodImplOptions.InternalCall)]
         public static extern MethodBase? GetCurrentMethod();