make JitOptimizationsValidator work for .NET Core (needed properties are available now in 1.1)

src/BenchmarkDotNet.Core/Extensions/AssemblyExtensions.cs

@@ -6,28 +6,35 @@ namespace BenchmarkDotNet.Extensions
 {
     internal static class AssemblyExtensions
     {
-        internal static bool? IsJITOptimizationDisabled(this Assembly assembly)
-        {
-#if CORE
-            return null; // https://github.com/dotnet/coreclr/pull/6153
-#else
-            return assembly?.GetCustomAttributes(false)
-                .OfType<DebuggableAttribute>()
-                .SingleOrDefault()?.IsJITOptimizerDisabled;
-#endif
-        }
+        internal static bool? IsJitOptimizationDisabled(this Assembly assembly)
+            => GetDebuggableAttribute(assembly).IsJitOptimizerDisabled();
 
         internal static bool? IsDebug(this Assembly assembly)
-        {
-#if CORE
-            return null; // https://github.com/dotnet/coreclr/pull/6153
-#else
-            return assembly?.GetCustomAttributes(false)
-                .OfType<DebuggableAttribute>()
-                .SingleOrDefault()?.IsJITTrackingEnabled;
-#endif
-        }
+            => GetDebuggableAttribute(assembly).IsJitTrackingEnabled();
 
         internal static bool IsTrue(this bool? valueOrNothing) => valueOrNothing.HasValue && valueOrNothing.Value;
+
+        private static DebuggableAttribute GetDebuggableAttribute(Assembly assembly)
+        {
+            return assembly?.GetCustomAttributes()
+                            .OfType<DebuggableAttribute>()
+                            .SingleOrDefault();
+        }
+
+        static bool? IsJitOptimizerDisabled(this DebuggableAttribute attribute) => Read(attribute, "IsJITOptimizerDisabled");
+
+        static bool? IsJitTrackingEnabled(this DebuggableAttribute attribute) => Read(attribute, "IsJITTrackingEnabled");
+
+        private static bool? Read(DebuggableAttribute debuggableAttribute, string propertyName)
+        {
+            // the properties are implemented (https://github.com/dotnet/coreclr/pull/6153)
+            // but not exposed in corefx Contracs due to .NET Standard versioning problems (https://github.com/dotnet/corefx/issues/13717)
+            // so we need to use reflection to read this simple property...
+            var propertyInfo = typeof(DebuggableAttribute).GetProperty(propertyName);
+            if (debuggableAttribute == null || propertyInfo == null)
+                return null;
+
+            return (bool)propertyInfo.GetValue(debuggableAttribute);
+        }
     }
 }

src/BenchmarkDotNet.Core/Validators/JitOptimizationsValidator.cs

@@ -25,7 +25,7 @@ namespace BenchmarkDotNet.Validators
                 {
                     var referencedAssembly = Assembly.Load(referencedAssemblyName);
 
-                    if (referencedAssembly.IsJITOptimizationDisabled().IsTrue())
+                    if (referencedAssembly.IsJitOptimizationDisabled().IsTrue())
                     {
                         yield return new ValidationError(
                             TreatsWarningsAsErrors,
@@ -33,7 +33,7 @@ namespace BenchmarkDotNet.Validators
                     }
                 }
 
-                if (group.Key.IsJITOptimizationDisabled().IsTrue())
+                if (group.Key.IsJitOptimizationDisabled().IsTrue())
                 {
                     yield return new ValidationError(
                         TreatsWarningsAsErrors,