Fix Environment.GetCommandLineArg for AOT compiled libraries

src/coreclr/System.Private.CoreLib/src/System/Environment.CoreCLR.cs

@@ -61,28 +61,6 @@ public static extern int ExitCode
         [MethodImpl(MethodImplOptions.InternalCall)]
         internal static extern void FailFast(string? message, Exception? exception, string? errorMessage);
 
-        private static string[]? s_commandLineArgs;
-
-        public static string[] GetCommandLineArgs()
-        {
-            // There are multiple entry points to a hosted app. The host could
-            // use ::ExecuteAssembly() or ::CreateDelegate option:
-            //
-            // ::ExecuteAssembly() -> In this particular case, the runtime invokes the main
-            // method based on the arguments set by the host, and we return those arguments
-            //
-            // ::CreateDelegate() -> In this particular case, the host is asked to create a
-            // delegate based on the appDomain, assembly and methodDesc passed to it.
-            // which the caller uses to invoke the method. In this particular case we do not have
-            // any information on what arguments would be passed to the delegate.
-            // So our best bet is to simply use the commandLine that was used to invoke the process.
-            // in case it is present.
-
-            return s_commandLineArgs != null ?
-                (string[])s_commandLineArgs.Clone() :
-                GetCommandLineArgsNative();
-        }
-
         private static unsafe string[] InitializeCommandLineArgs(char* exePath, int argc, char** argv) // invoked from VM
         {
             string[] commandLineArgs = new string[argc + 1];

src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/CompilerHelpers/StartupCode/StartupCodeHelpers.Extensions.cs

@@ -26,7 +26,7 @@ internal static unsafe void InitializeCommandLineArgsW(int argc, char** argv)
             {
                 args[i] = new string(argv[i]);
             }
-            Environment.SetCommandLineArgs(args);
+            Environment.s_commandLineArgs = args;
         }
 
         internal static unsafe void InitializeCommandLineArgs(int argc, sbyte** argv)
@@ -36,14 +36,16 @@ internal static unsafe void InitializeCommandLineArgs(int argc, sbyte** argv)
             {
                 args[i] = new string(argv[i]);
             }
-            Environment.SetCommandLineArgs(args);
+            Environment.s_commandLineArgs = args;
         }
 
         private static string[] GetMainMethodArguments()
         {
-            // GetCommandLineArgs includes the executable name, Main() arguments do not.
-            string[] args = Environment.GetCommandLineArgs();
+            // Environment.s_commandLineArgs includes the executable name, Main() arguments do not.
+            string[]? args = Environment.s_commandLineArgs;
 
+            // Environment.s_commandLineArgs is expected to initialized during startup.
+            Debug.Assert(args != null);
             Debug.Assert(args.Length > 0);
 
             string[] mainArgs = new string[args.Length - 1];

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Environment.NativeAot.cs

@@ -63,18 +63,5 @@ internal static void ShutdownCore()
         }
 
         public static int TickCount => (int)TickCount64;
-
-        private static string[]? s_commandLineArgs;
-
-        public static string[] GetCommandLineArgs()
-        {
-            Debug.Assert(s_commandLineArgs != null, "VM did not properly setup application.");
-            return (string[])s_commandLineArgs.Clone();
-        }
-
-        internal static void SetCommandLineArgs(string[] cmdLineArgs)
-        {
-            s_commandLineArgs = cmdLineArgs;
-        }
     }
 }

src/libraries/System.Private.CoreLib/src/System/Environment.cs

@@ -86,6 +86,19 @@ public static void SetEnvironmentVariable(string variable, string? value, Enviro
             SetEnvironmentVariableFromRegistry(variable, value, fromMachine: fromMachine);
         }
 
+#if !MONO
+        internal static string[]? s_commandLineArgs;
+
+        public static string[] GetCommandLineArgs()
+        {
+            // s_commandLineArgs is expected to be initialize with application command line arguments
+            // during startup. GetCommandLineArgsNative fallback is used for hosted libraries.
+            return s_commandLineArgs != null ?
+                (string[])s_commandLineArgs.Clone() :
+                GetCommandLineArgsNative();
+        }
+#endif
+
         public static string CommandLine => PasteArguments.Paste(GetCommandLineArgs(), pasteFirstArgumentUsingArgV0Rules: true);
 
         public static string CurrentDirectory