patch 9.0.2057: Vim9: no strict type checks for funcrefs varargs

Problem:  Vim9: no strict type checks for funcrefs varargs
Solution: Perform strict type checking when declaring funcrefs
          with vararg declaration, add tests

closes: #13397

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Ernie Rael <errael@raelity.com>

runtime/doc/tags

@@ -11010,6 +11010,7 @@ vim9-differences	vim9.txt	/*vim9-differences*
 vim9-export	vim9.txt	/*vim9-export*
 vim9-false-true	vim9.txt	/*vim9-false-true*
 vim9-final	vim9.txt	/*vim9-final*
+vim9-func-declaration	vim9.txt	/*vim9-func-declaration*
 vim9-function-defined-later	vim9.txt	/*vim9-function-defined-later*
 vim9-gotchas	vim9.txt	/*vim9-gotchas*
 vim9-ignored-argument	vim9.txt	/*vim9-ignored-argument*

runtime/doc/vim9.txt

@@ -1468,7 +1468,7 @@ return value) results in error *E1031*  *E1186* .
 There is no array type, use list<{type}> instead.  For a list constant an
 efficient implementation is used that avoids allocating a lot of small pieces
 of memory.
-							*E1005* *E1007*
+				    *vim9-func-declaration* *E1005* *E1007*
 A partial and function can be declared in more or less specific ways:
 func				any kind of function reference, no type
 				checking for arguments or return value
@@ -1669,6 +1669,26 @@ Same for |extend()|, use |extendnew()| instead, and for |flatten()|, use
 |flattennew()| instead.  Since |flatten()| is intended to always change the
 type, it can not be used in Vim9 script.
 
+Assigning to a funcref with specified arguments (see |vim9-func-declaration|)
+does strict type checking of the arguments. For variable number of arguments
+the type must match: >
+	var FuncRef: func(string, number, bool): number
+	FuncRef = (v1: string, v2: number, v3: bool) => 777	# OK
+	FuncRef = (v1: string, v2: number, v3: number) => 777	# Error!
+	# variable number of arguments must have same type
+	var FuncVA: func(...list<string>): number
+	FuncVA = (...v: list<number>): number => v  # Error!
+	FuncVA = (...v: list<any>): number => v	    # OK, `any` runtime check
+	FuncVA = (v1: string, v: string2): number => 333     # Error!
+	FuncVA = (v: list<string>): number => 3	    # Error!
+
+If the destinataion funcref has no specified arguments, then there is no
+argument type checking: >
+	var FuncUnknownArgs: func: number
+	FuncUnknownArgs = (v): number => v			# OK
+	FuncUnknownArgs = (v1: string, v2: string): number => 3	# OK
+<	FuncUnknownArgs = (...v1: list<string>): number => 333	# OK
+
 			 *E1211* *E1217* *E1218* *E1219* *E1220* *E1221*
 			 *E1222* *E1223* *E1224* *E1225* *E1226* *E1227*
 			 *E1228* *E1238* *E1250* *E1251* *E1252* *E1256*

src/testdir/test_vim9_assign.vim

@@ -1890,7 +1890,7 @@ def Test_assign_funcref_args()
     var FuncAnyVA: func(...any): number
     FuncAnyVA = (v): number => v
   END
-  v9.CheckScriptFailure(lines, 'E1012: Type mismatch; expected func(...any): number but got func(any): number')
+  v9.CheckScriptFailure(lines, 'E1180: Variable arguments type must be a list: any')
 
   # varargs must match
   lines =<< trim END
@@ -1898,7 +1898,7 @@ def Test_assign_funcref_args()
     var FuncAnyVA: func(...any): number
     FuncAnyVA = (v1, v2): number => v1 + v2
   END
-  v9.CheckScriptFailure(lines, 'E1012: Type mismatch; expected func(...any): number but got func(any, any): number')
+  v9.CheckScriptFailure(lines, 'E1180: Variable arguments type must be a list: any')
 
   # varargs must match
   lines =<< trim END
@@ -1906,7 +1906,7 @@ def Test_assign_funcref_args()
     var FuncAnyVA: func(...any): number
     FuncAnyVA = (v1: list<any>): number => 3
   END
-  v9.CheckScriptFailure(lines, 'E1012: Type mismatch; expected func(...any): number but got func(list<any>): number')
+  v9.CheckScriptFailure(lines, 'E1180: Variable arguments type must be a list: any')
 enddef
 
 def Test_assign_funcref_arg_any()

src/testdir/test_vim9_func.vim

@@ -1995,7 +1995,7 @@ def Test_varargs_mismatch()
       var res = Map((v) => str2nr(v))
       assert_equal(12, res)
   END
-  v9.CheckScriptFailure(lines, 'E1013: Argument 1: type mismatch, expected func(...any): number but got func(any): number')
+  v9.CheckScriptFailure(lines, 'E1180: Variable arguments type must be a list: any')
 enddef
 
 def Test_using_var_as_arg()
@@ -2764,7 +2764,7 @@ def Test_func_type_fails()
   v9.CheckDefFailure(['var Ref1: func()', 'Ref1 = g:FuncOneArgRetNumber'], 'E1012: Type mismatch; expected func() but got func(number): number')
   v9.CheckDefFailure(['var Ref1: func(bool)', 'Ref1 = g:FuncTwoArgNoRet'], 'E1012: Type mismatch; expected func(bool) but got func(bool, number)')
   v9.CheckDefFailure(['var Ref1: func(?bool)', 'Ref1 = g:FuncTwoArgNoRet'], 'E1012: Type mismatch; expected func(?bool) but got func(bool, number)')
-  v9.CheckDefFailure(['var Ref1: func(...bool)', 'Ref1 = g:FuncTwoArgNoRet'], 'E1012: Type mismatch; expected func(...bool) but got func(bool, number)')
+  v9.CheckDefFailure(['var Ref1: func(...bool)', 'Ref1 = g:FuncTwoArgNoRet'], 'E1180: Variable arguments type must be a list: bool')
 
   v9.CheckDefFailure(['var RefWrong: func(string ,number)'], 'E1068:')
   v9.CheckDefFailure(['var RefWrong: func(string,number)'], 'E1069:')

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2057,
 /**/
     2056,
 /**/

src/vim9type.c

@@ -1231,6 +1231,15 @@ parse_type(char_u **arg, garray_T *type_gap, int give_error)
 			type = parse_type(&p, type_gap, give_error);
 			if (type == NULL)
 			    return NULL;
+			if ((flags & TTFLAG_VARARGS) != 0
+				&& type->tt_type != VAR_LIST)
+			{
+			    char *tofree;
+			    semsg(_(e_variable_arguments_type_must_be_list_str),
+				  type_name(type, &tofree));
+			    vim_free(tofree);
+			    return NULL;
+			}
 			arg_type[argcount++] = type;
 
 			// Nothing comes after "...{type}".