patch 8.2.3105: Vim9: type of partial is wrong when it has arguments

Problem:    Vim9: type of partial is wrong when it has arguments.
Solution:   Subtract arguments from the count. (issue #8492)

src/testdir/test_vim9_assign.vim

@@ -661,13 +661,16 @@ def Test_assignment_list()
   CheckDefExecAndScriptFailure(lines, 'E1012:', 5)
 enddef
 
-def PartFunc(b: bool): string
+def PartFuncBool(b: bool): string
   return 'done'
 enddef
 
 def Test_assignment_partial()
-  var Partial: func(): string = function(PartFunc, [true])
-  assert_equal('done', Partial())
+  var lines =<< trim END
+      var Partial: func(): string = function(PartFuncBool, [true])
+      assert_equal('done', Partial())
+  END
+  CheckDefAndScriptSuccess(lines)
 enddef
 
 def Test_assignment_list_any_index()

src/userfunc.c

@@ -3103,6 +3103,7 @@ call_func(
     int		argv_clear = 0;
     int		argv_base = 0;
     partial_T	*partial = funcexe->partial;
+    type_T	check_type;
 
     // Initialize rettv so that it is safe for caller to invoke clear_tv(rettv)
     // even when call_func() returns FAIL.
@@ -3146,6 +3147,16 @@ call_func(
 		argv[i + argv_clear] = argvars_in[i];
 	    argvars = argv;
 	    argcount = partial->pt_argc + argcount_in;
+
+	    if (funcexe->check_type != NULL)
+	    {
+		// Now funcexe->check_type is missing the added arguments, make
+		// a copy of the type with the correction.
+		check_type = *funcexe->check_type;
+		funcexe->check_type = &check_type;
+		check_type.tt_argcount += partial->pt_argc;
+		check_type.tt_min_argcount += partial->pt_argc;
+	    }
 	}
     }
 

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3105,
 /**/
     3104,
 /**/

src/vim9type.c

@@ -355,7 +355,20 @@ typval2type_int(typval_T *tv, int copyID, garray_T *type_gap, int do_member)
 	    if (ufunc->uf_func_type == NULL)
 		set_function_type(ufunc);
 	    if (ufunc->uf_func_type != NULL)
+	    {
+		if (tv->v_type == VAR_PARTIAL
+					    && tv->vval.v_partial->pt_argc > 0)
+		{
+		    type = get_type_ptr(type_gap);
+		    if (type == NULL)
+			return NULL;
+		    *type = *ufunc->uf_func_type;
+		    type->tt_argcount -= tv->vval.v_partial->pt_argc;
+		    type->tt_min_argcount -= tv->vval.v_partial->pt_argc;
+		    return type;
+		}
 		return ufunc->uf_func_type;
+	    }
 	}
     }