Fix IsNetCore check for single-file apps without AOT, and IsNativeAOT check.

Author: timcassell

src/BenchmarkDotNet/Portability/RuntimeInformation.cs

@@ -50,22 +50,13 @@ internal static class RuntimeInformation
 
         public static readonly bool IsNetNative = FrameworkDescription.StartsWith(".NET Native", StringComparison.OrdinalIgnoreCase);
 
-        public static readonly bool IsNetCore =
-            ((Environment.Version.Major >= 5) || FrameworkDescription.StartsWith(".NET Core", StringComparison.OrdinalIgnoreCase))
-                && !string.IsNullOrEmpty(typeof(object).Assembly.Location);
-
 #if NET6_0_OR_GREATER
         [System.Runtime.Versioning.SupportedOSPlatformGuard("browser")]
         public static readonly bool IsWasm = OperatingSystem.IsBrowser();
 #else
         public static readonly bool IsWasm = IsOSPlatform(OSPlatform.Create("BROWSER"));
 #endif
 
-        public static readonly bool IsNativeAOT =
-            Environment.Version.Major >= 5
-                && string.IsNullOrEmpty(typeof(object).Assembly.Location) // it's merged to a single .exe and .Location returns null
-                && !IsWasm; // Wasm also returns "" for assembly locations
-
 #if NETSTANDARD2_0
         public static readonly bool IsAot = IsAotMethod();
 
@@ -88,6 +79,16 @@ private static bool IsAotMethod()
         public static readonly bool IsAot = !System.Runtime.CompilerServices.RuntimeFeature.IsDynamicCodeCompiled;
 #endif
 
+        public static bool IsNetCore
+            => ((Environment.Version.Major >= 5) || FrameworkDescription.StartsWith(".NET Core", StringComparison.OrdinalIgnoreCase))
+                && !IsAot;
+
+        public static bool IsNativeAOT
+            => Environment.Version.Major >= 5
+               && IsAot
+               && !IsWasm && !IsMono; // Wasm and MonoAOTLLVM are also AOT
+
+
         public static readonly bool IsTieredJitEnabled =
             IsNetCore
             && (Environment.Version.Major < 3
@@ -173,10 +174,21 @@ private static string GetNetCoreVersion()
             }
             else
             {
-                var coreclrAssemblyInfo = FileVersionInfo.GetVersionInfo(typeof(object).GetTypeInfo().Assembly.Location);
-                var corefxAssemblyInfo = FileVersionInfo.GetVersionInfo(typeof(Regex).GetTypeInfo().Assembly.Location);
+                string coreclrLocation = typeof(object).GetTypeInfo().Assembly.Location;
+                string corefxLocation = typeof(Regex).GetTypeInfo().Assembly.Location;
+
+                // Handle cases where assembly location is empty (e.g. single-file publish, AOT, some test runners)
+                if (string.IsNullOrEmpty(coreclrLocation) || string.IsNullOrEmpty(corefxLocation))
+                {
+                    return CoreRuntime.TryGetVersion(out var ver) && ver.Major >= 5
+                        ? $".NET {ver} (assembly location unavailable)"
+                        : $".NET Core {ver?.ToString() ?? Unknown} (assembly location unavailable)";
+                }
+
+                var coreclrAssemblyInfo = FileVersionInfo.GetVersionInfo(coreclrLocation);
+                var corefxAssemblyInfo = FileVersionInfo.GetVersionInfo(corefxLocation);
 
-                if (CoreRuntime.TryGetVersion(out var version) && version >= new Version(5, 0))
+                if (CoreRuntime.TryGetVersion(out var version) && version.Major >= 5)
                 {
                     // after the merge of dotnet/corefx and dotnet/coreclr into dotnet/runtime the version should always be the same
                     Debug.Assert(coreclrAssemblyInfo.FileVersion == corefxAssemblyInfo.FileVersion);