Fix un-buildable main: ParameterInfo[]/Type[] mismatch in generator instance stubs (re-enables #723/#737/#738/#739)

Compilation/ILCompiler.AsyncGenerators.cs

@@ -371,9 +371,12 @@
 
         // #725: instantiate the function display class and seed any captured-and-mutated parameter
         // into it (instance methods carry 'this' at arg 0, so user params start at arg 1). The stub
-        // params are typed, so value types are boxed before the store. No-op when no function DC.
+        // params are typed, so value types are boxed before the store. No-op when no function DC. Pass
+        // the CLR boxing types from the method's ACTUAL IL signature (same source as the field-seeding
+        // loop above), so widened/all-object slots are not spuriously boxed.
         if (funcDCKey != null)
-            EmitGeneratorFunctionDCInit(il, smBuilder.FunctionDCField, method, funcDCKey, paramOffset: 1, paramTypes);
+            EmitGeneratorFunctionDCInit(il, smBuilder.FunctionDCField, method, funcDCKey, paramOffset: 1,
+                paramTypes.Select(p => p.ParameterType).ToArray());
 
         // Return the state machine (which implements IAsyncEnumerable<object>)
         il.Emit(OpCodes.Ret);

Compilation/ILCompiler.Generators.cs

@@ -552,10 +552,13 @@
         // into it so an arrow that writes that parameter shares the generator's storage. Instance
         // methods carry 'this' at arg 0, so user params start at arg 1 (paramOffset: 1). The stub
         // params are typed, so EmitGeneratorFunctionDCInit boxes value types before the store. No-op
-        // when the method has no function DC.
+        // when the method has no function DC. Pass the CLR boxing types from the method's ACTUAL IL
+        // signature (same source as the field-seeding loop above), so widened/all-object slots are not
+        // spuriously boxed.
         if (funcDCKey != null)
-            EmitGeneratorFunctionDCInit(il, smBuilder.FunctionDCField, method, funcDCKey, paramOffset: 1, paramTypes);
+            EmitGeneratorFunctionDCInit(il, smBuilder.FunctionDCField, method, funcDCKey, paramOffset: 1,
+                paramTypes.Select(p => p.ParameterType).ToArray());
 
         // Captured outer-scope variables are NOT copied into the state machine (#541): see the
         // free-function stub above. MoveNext reads/writes them live from their backing storage,
         // wired through the CompilationContext in EmitGeneratorMethodBody.