Validate NoInlining in the benchmark process.

Author: timcassell

src/BenchmarkDotNet/Templates/BenchmarkType.txt

@@ -17,7 +17,7 @@
             host.WriteLine($"// Job: {job.DisplayInfo}");
             host.WriteLine();
 
-            System.Collections.Generic.IEnumerable<BenchmarkDotNet.Validators.ValidationError> errors = BenchmarkDotNet.Environments.BenchmarkEnvironmentInfo.Validate(job);
+            System.Collections.Generic.IEnumerable<BenchmarkDotNet.Validators.ValidationError> errors = BenchmarkDotNet.Validators.BenchmarkProcessValidator.Validate(job, instance);
             if (BenchmarkDotNet.Validators.ValidationErrorReporter.ReportIfAny(errors, host))
                 return;
 

src/BenchmarkDotNet/Toolchains/InProcess/Emit/Implementation/Runnable/RunnableReuse.cs

@@ -24,7 +24,7 @@ public static (Job, EngineParameters, IEngineFactory) PrepareForRun<T>(T instanc
             var job = CreateJob(benchmarkCase);
             DumpJob(host, job);
 
-            var errors = BenchmarkEnvironmentInfo.Validate(job);
+            var errors = BenchmarkProcessValidator.Validate(job, instance);
             if (ValidationErrorReporter.ReportIfAny(errors, host))
                 return default;
 

src/BenchmarkDotNet/Validators/BenchmarkProcessValidator.cs

@@ -0,0 +1,33 @@
+using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Environments;
+using BenchmarkDotNet.Extensions;
+using BenchmarkDotNet.Jobs;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+
+namespace BenchmarkDotNet.Validators
+{
+    public static class BenchmarkProcessValidator
+    {
+        public static IEnumerable<ValidationError> Validate(Job job, object benchmarkInstance)
+        {
+            foreach (var validationError in BenchmarkEnvironmentInfo.Validate(job))
+            {
+                yield return validationError;
+            }
+
+            var inlineableBenchmarks = benchmarkInstance.GetType().BaseType
+                .GetMethods(BindingFlags.Static | BindingFlags.Instance | BindingFlags.Public)
+                .Where(method => method.HasAttribute<BenchmarkAttribute>() && !method.MethodImplementationFlags.HasFlag(MethodImplAttributes.NoInlining));
+            foreach (var benchmark in inlineableBenchmarks)
+            {
+                yield return new ValidationError(
+                    true,
+                    $"Benchmark method `{benchmark.Name}` does not have MethodImplOptions.NoInlining flag set." +
+                    $" You may need to rebuild your project, or apply it manually if you are not using MSBuild to build your project."
+                );
+            }
+        }
+    }
+}