patch 8.2.0512: Vim9: no optional arguments in func typev8.2.0512

Problem:    Vim9: no optional arguments in func type.
Solution:   Check for question mark after type.  Find function reference
            without function().

13 files changed, 733 insertions, 459 deletions

diff --git a/src/globals.h b/src/globals.h
index 59f22d1af8..1a6a0d8d30 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -379,39 +379,39 @@ EXTERN sctx_T	current_sctx INIT4(0, 0, 0, 0);
 
 
 // Commonly used types.
-EXTERN type_T t_any INIT5(VAR_UNKNOWN, 0, 0, NULL, NULL);
-EXTERN type_T t_void INIT5(VAR_VOID, 0, 0, NULL, NULL);
-EXTERN type_T t_bool INIT5(VAR_BOOL, 0, 0, NULL, NULL);
-EXTERN type_T t_special INIT5(VAR_SPECIAL, 0, 0, NULL, NULL);
-EXTERN type_T t_number INIT5(VAR_NUMBER, 0, 0, NULL, NULL);
-EXTERN type_T t_float INIT5(VAR_FLOAT, 0, 0, NULL, NULL);
-EXTERN type_T t_string INIT5(VAR_STRING, 0, 0, NULL, NULL);
-EXTERN type_T t_blob INIT5(VAR_BLOB, 0, 0, NULL, NULL);
-EXTERN type_T t_job INIT5(VAR_JOB, 0, 0, NULL, NULL);
-EXTERN type_T t_channel INIT5(VAR_CHANNEL, 0, 0, NULL, NULL);
-
-EXTERN type_T t_func_void INIT5(VAR_FUNC, -1, 0, &t_void, NULL);
-EXTERN type_T t_func_any INIT5(VAR_FUNC, -1, 0, &t_any, NULL);
-EXTERN type_T t_func_number INIT5(VAR_FUNC, -1, 0, &t_number, NULL);
-EXTERN type_T t_func_string INIT5(VAR_FUNC, -1, 0, &t_string, NULL);
-EXTERN type_T t_func_0_void INIT5(VAR_FUNC, 0, 0, &t_void, NULL);
-EXTERN type_T t_func_0_any INIT5(VAR_FUNC, 0, 0, &t_any, NULL);
-EXTERN type_T t_func_0_number INIT5(VAR_FUNC, 0, 0, &t_number, NULL);
-EXTERN type_T t_func_0_string INIT5(VAR_FUNC, 0, 0, &t_string, NULL);
-
-EXTERN type_T t_list_any INIT5(VAR_LIST, 0, 0, &t_any, NULL);
-EXTERN type_T t_dict_any INIT5(VAR_DICT, 0, 0, &t_any, NULL);
-EXTERN type_T t_list_empty INIT5(VAR_LIST, 0, 0, &t_void, NULL);
-EXTERN type_T t_dict_empty INIT5(VAR_DICT, 0, 0, &t_void, NULL);
-
-EXTERN type_T t_list_bool INIT5(VAR_LIST, 0, 0, &t_bool, NULL);
-EXTERN type_T t_list_number INIT5(VAR_LIST, 0, 0, &t_number, NULL);
-EXTERN type_T t_list_string INIT5(VAR_LIST, 0, 0, &t_string, NULL);
-EXTERN type_T t_list_dict_any INIT5(VAR_LIST, 0, 0, &t_dict_any, NULL);
-
-EXTERN type_T t_dict_bool INIT5(VAR_DICT, 0, 0, &t_bool, NULL);
-EXTERN type_T t_dict_number INIT5(VAR_DICT, 0, 0, &t_number, NULL);
-EXTERN type_T t_dict_string INIT5(VAR_DICT, 0, 0, &t_string, NULL);
+EXTERN type_T t_any INIT6(VAR_UNKNOWN, 0, 0, 0, NULL, NULL);
+EXTERN type_T t_void INIT6(VAR_VOID, 0, 0, 0, NULL, NULL);
+EXTERN type_T t_bool INIT6(VAR_BOOL, 0, 0, 0, NULL, NULL);
+EXTERN type_T t_special INIT6(VAR_SPECIAL, 0, 0, 0, NULL, NULL);
+EXTERN type_T t_number INIT6(VAR_NUMBER, 0, 0, 0, NULL, NULL);
+EXTERN type_T t_float INIT6(VAR_FLOAT, 0, 0, 0, NULL, NULL);
+EXTERN type_T t_string INIT6(VAR_STRING, 0, 0, 0, NULL, NULL);
+EXTERN type_T t_blob INIT6(VAR_BLOB, 0, 0, 0, NULL, NULL);
+EXTERN type_T t_job INIT6(VAR_JOB, 0, 0, 0, NULL, NULL);
+EXTERN type_T t_channel INIT6(VAR_CHANNEL, 0, 0, 0, NULL, NULL);
+
+EXTERN type_T t_func_void INIT6(VAR_FUNC, -1, 0, 0, &t_void, NULL);
+EXTERN type_T t_func_any INIT6(VAR_FUNC, -1, 0, 0, &t_any, NULL);
+EXTERN type_T t_func_number INIT6(VAR_FUNC, -1, 0, 0, &t_number, NULL);
+EXTERN type_T t_func_string INIT6(VAR_FUNC, -1, 0, 0, &t_string, NULL);
+EXTERN type_T t_func_0_void INIT6(VAR_FUNC, 0, 0, 0, &t_void, NULL);
+EXTERN type_T t_func_0_any INIT6(VAR_FUNC, 0, 0, 0, &t_any, NULL);
+EXTERN type_T t_func_0_number INIT6(VAR_FUNC, 0, 0, 0, &t_number, NULL);
+EXTERN type_T t_func_0_string INIT6(VAR_FUNC, 0, 0, 0, &t_string, NULL);
+
+EXTERN type_T t_list_any INIT6(VAR_LIST, 0, 0, 0, &t_any, NULL);
+EXTERN type_T t_dict_any INIT6(VAR_DICT, 0, 0, 0, &t_any, NULL);
+EXTERN type_T t_list_empty INIT6(VAR_LIST, 0, 0, 0, &t_void, NULL);
+EXTERN type_T t_dict_empty INIT6(VAR_DICT, 0, 0, 0, &t_void, NULL);
+
+EXTERN type_T t_list_bool INIT6(VAR_LIST, 0, 0, 0, &t_bool, NULL);
+EXTERN type_T t_list_number INIT6(VAR_LIST, 0, 0, 0, &t_number, NULL);
+EXTERN type_T t_list_string INIT6(VAR_LIST, 0, 0, 0, &t_string, NULL);
+EXTERN type_T t_list_dict_any INIT6(VAR_LIST, 0, 0, 0, &t_dict_any, NULL);
+
+EXTERN type_T t_dict_bool INIT6(VAR_DICT, 0, 0, 0, &t_bool, NULL);
+EXTERN type_T t_dict_number INIT6(VAR_DICT, 0, 0, 0, &t_number, NULL);
+EXTERN type_T t_dict_string INIT6(VAR_DICT, 0, 0, 0, &t_string, NULL);
 
 
 #endif
diff --git a/src/structs.h b/src/structs.h
index efc74da175..4a5128171b 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1341,10 +1341,11 @@ typedef enum
 typedef struct type_S type_T;
 struct type_S {
     vartype_T	    tt_type;
-    short	    tt_argcount;    // for func, partial, -1 for unknown
-    short	    tt_flags;	    // TTFLAG_ values
+    char	    tt_argcount;    // for func, -1 for unknown
+    char	    tt_min_argcount; // number of non-optional arguments
+    char	    tt_flags;	    // TTFLAG_ values
     type_T	    *tt_member;	    // for list, dict, func return type
-    type_T	    **tt_args;	    // func arguments, allocated
+    type_T	    **tt_args;	    // func argument types, allocated
 };
 
 #define TTFLAG_VARARGS	1	    // func args ends with "..."
@@ -1520,7 +1521,7 @@ typedef struct
     int		uf_calls;	// nr of active calls
     int		uf_cleared;	// func_clear() was already called
     int		uf_dfunc_idx;	// >= 0 for :def function only
-    garray_T	uf_args;	// arguments
+    garray_T	uf_args;	// arguments, including optional arguments
     garray_T	uf_def_args;	// default argument expressions
 
     // for :def (for :function uf_ret_type is NULL)
@@ -1531,6 +1532,7 @@ typedef struct
 				// uf_def_args; length: uf_def_args.ga_len + 1
     char_u	*uf_va_name;	// name from "...name" or NULL
     type_T	*uf_va_type;	// type from "...name: type" or NULL
+    type_T	*uf_func_type;	// type of the function, &t_func_any if unknown
 
     garray_T	uf_lines;	// function lines
 # ifdef FEAT_PROFILE
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index d0bfe1c7c7..1a47cfcda8 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -274,6 +274,7 @@ NEW_TESTS = \
 	test_vartabs \
 	test_vim9_disassemble \
 	test_vim9_expr \
+	test_vim9_func \
 	test_vim9_script \
 	test_viminfo \
 	test_vimscript \
@@ -483,6 +484,7 @@ NEW_TESTS_RES = \
 	test_vartabs.res \
 	test_vim9_disassemble.res \
 	test_vim9_expr.res \
+	test_vim9_func.res \
 	test_vim9_script.res \
 	test_viminfo.res \
 	test_vimscript.res \
diff --git a/src/testdir/test_vim9_disassemble.vim b/src/testdir/test_vim9_disassemble.vim
index e71782b970..0299df5f5b 100644
--- a/src/testdir/test_vim9_disassemble.vim
+++ b/src/testdir/test_vim9_disassemble.vim
@@ -87,8 +87,10 @@ enddef
 def Test_disassemble_store()
   let res = execute('disass s:ScriptFuncStore')
   assert_match('<SNR>\d*_ScriptFuncStore.*'
+        \ .. 'let localnr = 1.*'
         \ .. 'localnr = 2.*'
         \ .. ' STORE 2 in $0.*'
+        \ .. 'let localstr = ''abc''.*'
         \ .. 'localstr = ''xyz''.*'
         \ .. ' STORE $1.*'
         \ .. 'v:char = ''abc''.*'
@@ -360,22 +362,22 @@ def Test_disassemble_const_expr()
 enddef
 
 def WithFunc()
-  let funky1: func
-  let funky2: func = function("len")
-  let party2: func = funcref("UserFunc")
+  let Funky1: func
+  let Funky2: func = function("len")
+  let Party2: func = funcref("UserFunc")
 enddef
 
 def Test_disassemble_function()
   let instr = execute('disassemble WithFunc')
   assert_match('WithFunc.*'
-        \ .. 'let funky1: func.*'
+        \ .. 'let Funky1: func.*'
         \ .. '0 PUSHFUNC "\[none]".*'
         \ .. '1 STORE $0.*'
-        \ .. 'let funky2: func = function("len").*'
+        \ .. 'let Funky2: func = function("len").*'
         \ .. '2 PUSHS "len".*'
         \ .. '3 BCALL function(argc 1).*'
         \ .. '4 STORE $1.*'
-        \ .. 'let party2: func = funcref("UserFunc").*'
+        \ .. 'let Party2: func = funcref("UserFunc").*'
         \ .. '\d PUSHS "UserFunc".*'
         \ .. '\d BCALL funcref(argc 1).*'
         \ .. '\d STORE $2.*'
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index d9c20acb18..f11fc83893 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -460,8 +460,8 @@ func Test_expr4_fails()
 
   call CheckDefFailureMult(['let j: job', 'let chan: channel', 'let r = j == chan'], 'Cannot compare job with channel')
   call CheckDefFailureMult(['let j: job', 'let x: list<any>', 'let r = j == x'], 'Cannot compare job with list')
-  call CheckDefFailureMult(['let j: job', 'let x: func', 'let r = j == x'], 'Cannot compare job with func')
-  call CheckDefFailureMult(['let j: job', 'let x: func', 'let r = j == x'], 'Cannot compare job with func')
+  call CheckDefFailureMult(['let j: job', 'let Xx: func', 'let r = j == Xx'], 'Cannot compare job with func')
+  call CheckDefFailureMult(['let j: job', 'let Xx: func', 'let r = j == Xx'], 'Cannot compare job with func')
 endfunc
 
 " test addition, subtraction, concatenation
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
new file mode 100644
index 0000000000..6f61254f86
--- /dev/null
+++ b/src/testdir/test_vim9_func.vim
@@ -0,0 +1,400 @@
+" Test various aspects of the Vim9 script language.
+
+source check.vim
+source view_util.vim
+
+" Check that "lines" inside ":def" results in an "error" message.
+func CheckDefFailure(lines, error)
+  call writefile(['def Func()'] + a:lines + ['enddef'], 'Xdef')
+  call assert_fails('so Xdef', a:error, a:lines)
+  call delete('Xdef')
+endfunc
+
+func CheckScriptFailure(lines, error)
+  call writefile(a:lines, 'Xdef')
+  call assert_fails('so Xdef', a:error, a:lines)
+  call delete('Xdef')
+endfunc
+
+func Test_def_basic()
+  def SomeFunc(): string
+    return 'yes'
+  enddef
+  call assert_equal('yes', SomeFunc())
+endfunc
+
+def ReturnString(): string
+  return 'string'
+enddef
+
+def ReturnNumber(): number
+  return 123
+enddef
+
+let g:notNumber = 'string'
+
+def ReturnGlobal(): number
+  return g:notNumber
+enddef
+
+def Test_return_something()
+  assert_equal('string', ReturnString())
+  assert_equal(123, ReturnNumber())
+  assert_fails('call ReturnGlobal()', 'E1029: Expected number but got string')
+enddef
+
+let s:nothing = 0
+def ReturnNothing()
+  s:nothing = 1
+  if true
+    return
+  endif
+  s:nothing = 2
+enddef
+
+def Test_return_nothing()
+  ReturnNothing()
+  assert_equal(1, s:nothing)
+enddef
+
+func Increment()
+  let g:counter += 1
+endfunc
+
+def Test_call_ufunc_count()
+  g:counter = 1
+  Increment()
+  Increment()
+  Increment()
+  " works with and without :call
+  assert_equal(4, g:counter)
+  call assert_equal(4, g:counter)
+  unlet g:counter
+enddef
+
+def MyVarargs(arg: string, ...rest: list<string>): string
+  let res = arg
+  for s in rest
+    res ..= ',' .. s
+  endfor
+  return res
+enddef
+
+def Test_call_varargs()
+  assert_equal('one', MyVarargs('one'))
+  assert_equal('one,two', MyVarargs('one', 'two'))
+  assert_equal('one,two,three', MyVarargs('one', 'two', 'three'))
+enddef
+
+def MyDefaultArgs(name = 'string'): string
+  return name
+enddef
+
+def Test_call_default_args()
+  assert_equal('string', MyDefaultArgs())
+  assert_equal('one', MyDefaultArgs('one'))
+  assert_fails('call MyDefaultArgs("one", "two")', 'E118:')
+
+  call CheckScriptFailure(['def Func(arg: number = asdf)', 'enddef'], 'E1001:')
+enddef
+
+func Test_call_default_args_from_func()
+  call assert_equal('string', MyDefaultArgs())
+  call assert_equal('one', MyDefaultArgs('one'))
+  call assert_fails('call MyDefaultArgs("one", "two")', 'E118:')
+endfunc
+
+func TakesOneArg(arg)
+  echo a:arg
+endfunc
+
+def Test_call_wrong_args()
+  call CheckDefFailure(['TakesOneArg()'], 'E119:')
+  call CheckDefFailure(['TakesOneArg(11, 22)'], 'E118:')
+  call CheckDefFailure(['bufnr(xxx)'], 'E1001:')
+enddef
+
+" Default arg and varargs
+def MyDefVarargs(one: string, two = 'foo', ...rest: list<string>): string
+  let res = one .. ',' .. two
+  for s in rest
+    res ..= ',' .. s
+  endfor
+  return res
+enddef
+
+def Test_call_def_varargs()
+  call assert_fails('call MyDefVarargs()', 'E119:')
+  assert_equal('one,foo', MyDefVarargs('one'))
+  assert_equal('one,two', MyDefVarargs('one', 'two'))
+  assert_equal('one,two,three', MyDefVarargs('one', 'two', 'three'))
+enddef
+
+def Test_using_var_as_arg()
+  call writefile(['def Func(x: number)',  'let x = 234', 'enddef'], 'Xdef')
+  call assert_fails('so Xdef', 'E1006:')
+  call delete('Xdef')
+enddef
+
+def Test_call_func_defined_later()
+  call assert_equal('one', DefinedLater('one'))
+  call assert_fails('call NotDefined("one")', 'E117:')
+enddef
+
+func DefinedLater(arg)
+  return a:arg
+endfunc
+
+def FuncWithForwardCall()
+  return DefinedEvenLater("yes")
+enddef
+
+def DefinedEvenLater(arg: string): string
+  return arg
+enddef
+
+def Test_error_in_nested_function()
+  " Error in called function requires unwinding the call stack.
+  assert_fails('call FuncWithForwardCall()', 'E1029')
+enddef
+
+def Test_return_type_wrong()
+  CheckScriptFailure(['def Func(): number', 'return "a"', 'enddef'], 'expected number but got string')
+  CheckScriptFailure(['def Func(): string', 'return 1', 'enddef'], 'expected string but got number')
+  CheckScriptFailure(['def Func(): void', 'return "a"', 'enddef'], 'expected void but got string')
+  CheckScriptFailure(['def Func()', 'return "a"', 'enddef'], 'expected void but got string')
+
+  CheckScriptFailure(['def Func(): number', 'return', 'enddef'], 'E1003:')
+
+  CheckScriptFailure(['def Func(): list', 'return []', 'enddef'], 'E1008:')
+  CheckScriptFailure(['def Func(): dict', 'return {}', 'enddef'], 'E1008:')
+enddef
+
+def Test_arg_type_wrong()
+  CheckScriptFailure(['def Func3(items: list)', 'echo "a"', 'enddef'], 'E1008: Missing <type>')
+enddef
+
+def Test_vim9script_call()
+  let lines =<< trim END
+    vim9script
+    let var = ''
+    def MyFunc(arg: string)
+       var = arg
+    enddef
+    MyFunc('foobar')
+    assert_equal('foobar', var)
+
+    let str = 'barfoo'
+    str->MyFunc()
+    assert_equal('barfoo', var)
+
+    let g:value = 'value'
+    g:value->MyFunc()
+    assert_equal('value', var)
+
+    let listvar = []
+    def ListFunc(arg: list<number>)
+       listvar = arg
+    enddef
+    [1, 2, 3]->ListFunc()
+    assert_equal([1, 2, 3], listvar)
+
+    let dictvar = {}
+    def DictFunc(arg: dict<number>)
+       dictvar = arg
+    enddef
+    {'a': 1, 'b': 2}->DictFunc()
+    assert_equal(#{a: 1, b: 2}, dictvar)
+    def CompiledDict()
+      {'a': 3, 'b': 4}->DictFunc()
+    enddef
+    CompiledDict()
+    assert_equal(#{a: 3, b: 4}, dictvar)
+
+    #{a: 3, b: 4}->DictFunc()
+    assert_equal(#{a: 3, b: 4}, dictvar)
+
+    ('text')->MyFunc()
+    assert_equal('text', var)
+    ("some")->MyFunc()
+    assert_equal('some', var)
+  END
+  writefile(lines, 'Xcall.vim')
+  source Xcall.vim
+  delete('Xcall.vim')
+enddef
+
+def Test_vim9script_call_fail_decl()
+  let lines =<< trim END
+    vim9script
+    let var = ''
+    def MyFunc(arg: string)
+       let var = 123
+    enddef
+  END
+  writefile(lines, 'Xcall_decl.vim')
+  assert_fails('source Xcall_decl.vim', 'E1054:')
+  delete('Xcall_decl.vim')
+enddef
+
+def Test_vim9script_call_fail_const()
+  let lines =<< trim END
+    vim9script
+    const var = ''
+    def MyFunc(arg: string)
+       var = 'asdf'
+    enddef
+  END
+  writefile(lines, 'Xcall_const.vim')
+  assert_fails('source Xcall_const.vim', 'E46:')
+  delete('Xcall_const.vim')
+enddef
+
+" Test that inside :function a Python function can be defined, :def is not
+" recognized.
+func Test_function_python()
+  CheckFeature python3
+  let py = 'python3'
+  execute py "<< EOF"
+def do_something():
+  return 1
+EOF
+endfunc
+
+def Test_delfunc()
+  let lines =<< trim END
+    vim9script
+    def GoneSoon()
+      echo 'hello'
+    enddef
+
+    def CallGoneSoon()
+      GoneSoon()
+    enddef
+
+    delfunc GoneSoon
+    CallGoneSoon()
+  END
+  writefile(lines, 'XToDelFunc')
+  assert_fails('so XToDelFunc', 'E933')
+  assert_fails('so XToDelFunc', 'E933')
+
+  delete('XToDelFunc')
+enddef
+
+def Test_redef_failure()
+  call writefile(['def Func0(): string',  'return "Func0"', 'enddef'], 'Xdef')
+  so Xdef
+  call writefile(['def Func1(): string',  'return "Func1"', 'enddef'], 'Xdef')
+  so Xdef
+  call writefile(['def! Func0(): string', 'enddef'], 'Xdef')
+  call assert_fails('so Xdef', 'E1027:')
+  call writefile(['def Func2(): string',  'return "Func2"', 'enddef'], 'Xdef')
+  so Xdef
+  call delete('Xdef')
+
+  call assert_equal(0, Func0())
+  call assert_equal('Func1', Func1())
+  call assert_equal('Func2', Func2())
+
+  delfunc! Func0
+  delfunc! Func1
+  delfunc! Func2
+enddef
+
+" Test for internal functions returning different types
+func Test_InternalFuncRetType()
+  let lines =<< trim END
+    def RetFloat(): float
+      return ceil(1.456)
+    enddef
+
+    def RetListAny(): list<any>
+      return items({'k' : 'v'})
+    enddef
+
+    def RetListString(): list<string>
+      return split('a:b:c', ':')
+    enddef
+
+    def RetListDictAny(): list<dict<any>>
+      return getbufinfo()
+    enddef
+
+    def RetDictNumber(): dict<number>
+      return wordcount()
+    enddef
+
+    def RetDictString(): dict<string>
+      return environ()
+    enddef
+  END
+  call writefile(lines, 'Xscript')
+  source Xscript
+
+  call assert_equal(2.0, RetFloat())
+  call assert_equal([['k', 'v']], RetListAny())
+  call assert_equal(['a', 'b', 'c'], RetListString())
+  call assert_notequal([], RetListDictAny())
+  call assert_notequal({}, RetDictNumber())
+  call assert_notequal({}, RetDictString())
+  call delete('Xscript')
+endfunc
+
+" Test for passing too many or too few arguments to internal functions
+func Test_internalfunc_arg_error()
+  let l =<< trim END
+    def! FArgErr(): float
+      return ceil(1.1, 2)
+    enddef
+  END
+  call writefile(l, 'Xinvalidarg')
+  call assert_fails('so Xinvalidarg', 'E118:')
+  let l =<< trim END
+    def! FArgErr(): float
+      return ceil()
+    enddef
+  END
+  call writefile(l, 'Xinvalidarg')
+  call assert_fails('so Xinvalidarg', 'E119:')
+  call delete('Xinvalidarg')
+endfunc
+
+let s:funcResult = 0
+
+def FuncNoArgNoRet()
+  funcResult = 11
+enddef
+
+def FuncNoArgRetNumber(): number
+  funcResult = 22
+  return 1234
+enddef
+
+def FuncOneArgNoRet(arg: number)
+  funcResult = arg
+enddef
+
+def FuncOneArgRetNumber(arg: number): number
+  funcResult = arg
+  return arg
+enddef
+
+def Test_func_type()
+  let Ref1: func()
+  funcResult = 0
+  Ref1 = FuncNoArgNoRet
+  Ref1()
+  assert_equal(11, funcResult)
+enddef
+
+def Test_func_type_fails()
+  CheckDefFailure(['let ref1: func()'], 'E704:')
+
+  CheckDefFailure(['let Ref1: func()', 'Ref1 = FuncNoArgRetNumber'], 'E1013: type mismatch, expected func() but got func(): number')
+  CheckDefFailure(['let Ref1: func()', 'Ref1 = FuncOneArgNoRet'], 'E1013: type mismatch, expected func() but got func(number)')
+  CheckDefFailure(['let Ref1: func()', 'Ref1 = FuncOneArgRetNumber'], 'E1013: type mismatch, expected func() but got func(number): number')
+enddef
+
+
+" vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index cf12e85bb7..01579a8a32 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -21,13 +21,6 @@ def Test_syntax()
   let other: list<string> = ['asdf']
 enddef
 
-func Test_def_basic()
-  def SomeFunc(): string
-    return 'yes'
-  enddef
-  call assert_equal('yes', SomeFunc())
-endfunc
-
 let s:appendToMe = 'xxx'
 let s:addToMe = 111
 let g:existing = 'yes'
@@ -66,9 +59,9 @@ def Test_assignment()
   if has('float')
     let float1: float = 3.4
   endif
-  let funky1: func
-  let funky2: func = function('len')
-  let party2: func = funcref('Test_syntax')
+  let Funky1: func
+  let Funky2: func = function('len')
+  let Party2: func = funcref('Test_syntax')
 
   " type becomes list<any>
   let somelist = rand() > 0 ? [1, 2, 3] : ['a', 'b', 'c']
@@ -134,6 +127,9 @@ def Test_assignment()
   assert_equal('noneagain', v:errmsg)
   call CheckDefFailure(['v:errmsg += "more"'], 'E1013:')
   call CheckDefFailure(['v:errmsg += 123'], 'E1013:')
+enddef
+
+def Test_assignment_default()
 
   " Test default values.
   let thebool: bool
@@ -153,8 +149,8 @@ def Test_assignment()
   let theblob: blob
   assert_equal(0z, theblob)
 
-  let thefunc: func
-  assert_equal(test_null_function(), thefunc)
+  let Thefunc: func
+  assert_equal(test_null_function(), Thefunc)
 
   let thelist: list<any>
   assert_equal([], thelist)
@@ -264,157 +260,6 @@ def Test_cmd_modifier()
 enddef
 
 
-def ReturnString(): string
-  return 'string'
-enddef
-
-def ReturnNumber(): number
-  return 123
-enddef
-
-let g:notNumber = 'string'
-
-def ReturnGlobal(): number
-  return g:notNumber
-enddef
-
-def Test_return_something()
-  assert_equal('string', ReturnString())
-  assert_equal(123, ReturnNumber())
-  assert_fails('call ReturnGlobal()', 'E1029: Expected number but got string')
-enddef
-
-let s:nothing = 0
-def ReturnNothing()
-  s:nothing = 1
-  if true
-    return
-  endif
-  s:nothing = 2
-enddef
-
-def Test_return_nothing()
-  ReturnNothing()
-  assert_equal(1, s:nothing)
-enddef
-
-func Increment()
-  let g:counter += 1
-endfunc
-
-def Test_call_ufunc_count()
-  g:counter = 1
-  Increment()
-  Increment()
-  Increment()
-  " works with and without :call
-  assert_equal(4, g:counter)
-  call assert_equal(4, g:counter)
-  unlet g:counter
-enddef
-
-def MyVarargs(arg: string, ...rest: list<string>): string
-  let res = arg
-  for s in rest
-    res ..= ',' .. s
-  endfor
-  return res
-enddef
-
-def Test_call_varargs()
-  assert_equal('one', MyVarargs('one'))
-  assert_equal('one,two', MyVarargs('one', 'two'))
-  assert_equal('one,two,three', MyVarargs('one', 'two', 'three'))
-enddef
-
-def MyDefaultArgs(name = 'string'): string
-  return name
-enddef
-
-def Test_call_default_args()
-  assert_equal('string', MyDefaultArgs())
-  assert_equal('one', MyDefaultArgs('one'))
-  assert_fails('call MyDefaultArgs("one", "two")', 'E118:')
-
-  call CheckScriptFailure(['def Func(arg: number = asdf)', 'enddef'], 'E1001:')
-enddef
-
-func Test_call_default_args_from_func()
-  call assert_equal('string', MyDefaultArgs())
-  call assert_equal('one', MyDefaultArgs('one'))
-  call assert_fails('call MyDefaultArgs("one", "two")', 'E118:')
-endfunc
-
-func TakesOneArg(arg)
-  echo a:arg
-endfunc
-
-def Test_call_wrong_args()
-  call CheckDefFailure(['TakesOneArg()'], 'E119:')
-  call CheckDefFailure(['TakesOneArg(11, 22)'], 'E118:')
-  call CheckDefFailure(['bufnr(xxx)'], 'E1001:')
-enddef
-
-" Default arg and varargs
-def MyDefVarargs(one: string, two = 'foo', ...rest: list<string>): string
-  let res = one .. ',' .. two
-  for s in rest
-    res ..= ',' .. s
-  endfor
-  return res
-enddef
-
-def Test_call_def_varargs()
-  call assert_fails('call MyDefVarargs()', 'E119:')
-  assert_equal('one,foo', MyDefVarargs('one'))
-  assert_equal('one,two', MyDefVarargs('one', 'two'))
-  assert_equal('one,two,three', MyDefVarargs('one', 'two', 'three'))
-enddef
-
-def Test_using_var_as_arg()
-  call writefile(['def Func(x: number)',  'let x = 234', 'enddef'], 'Xdef')
-  call assert_fails('so Xdef', 'E1006:')
-  call delete('Xdef')
-enddef
-
-def Test_call_func_defined_later()
-  call assert_equal('one', DefinedLater('one'))
-  call assert_fails('call NotDefined("one")', 'E117:')
-enddef
-
-func DefinedLater(arg)
-  return a:arg
-endfunc
-
-def FuncWithForwardCall()
-  return DefinedEvenLater("yes")
-enddef
-
-def DefinedEvenLater(arg: string): string
-  return arg
-enddef
-
-def Test_error_in_nested_function()
-  " Error in called function requires unwinding the call stack.
-  assert_fails('call FuncWithForwardCall()', 'E1029')
-enddef
-
-def Test_return_type_wrong()
-  CheckScriptFailure(['def Func(): number', 'return "a"', 'enddef'], 'expected number but got string')
-  CheckScriptFailure(['def Func(): string', 'return 1', 'enddef'], 'expected string but got number')
-  CheckScriptFailure(['def Func(): void', 'return "a"', 'enddef'], 'expected void but got string')
-  CheckScriptFailure(['def Func()', 'return "a"', 'enddef'], 'expected void but got string')
-
-  CheckScriptFailure(['def Func(): number', 'return', 'enddef'], 'E1003:')
-
-  CheckScriptFailure(['def Func(): list', 'return []', 'enddef'], 'E1008:')
-  CheckScriptFailure(['def Func(): dict', 'return {}', 'enddef'], 'E1008:')
-enddef
-
-def Test_arg_type_wrong()
-  CheckScriptFailure(['def Func3(items: list)', 'echo "a"', 'enddef'], 'E1008: Missing <type>')
-enddef
-
 def Test_try_catch()
   let l = []
   try
@@ -732,82 +577,6 @@ def Test_vim9script_fails()
   assert_fails('export something', 'E1042')
 enddef
 
-def Test_vim9script_call()
-  let lines =<< trim END
-    vim9script
-    let var = ''
-    def MyFunc(arg: string)
-       var = arg
-    enddef
-    MyFunc('foobar')
-    assert_equal('foobar', var)
-
-    let str = 'barfoo'
-    str->MyFunc()
-    assert_equal('barfoo', var)
-
-    let g:value = 'value'
-    g:value->MyFunc()
-    assert_equal('value', var)
-
-    let listvar = []
-    def ListFunc(arg: list<number>)
-       listvar = arg
-    enddef
-    [1, 2, 3]->ListFunc()
-    assert_equal([1, 2, 3], listvar)
-
-    let dictvar = {}
-    def DictFunc(arg: dict<number>)
-       dictvar = arg
-    enddef
-    {'a': 1, 'b': 2}->DictFunc()
-    assert_equal(#{a: 1, b: 2}, dictvar)
-    def CompiledDict()
-      {'a': 3, 'b': 4}->DictFunc()
-    enddef
-    CompiledDict()
-    assert_equal(#{a: 3, b: 4}, dictvar)
-
-    #{a: 3, b: 4}->DictFunc()
-    assert_equal(#{a: 3, b: 4}, dictvar)
-
-    ('text')->MyFunc()
-    assert_equal('text', var)
-    ("some")->MyFunc()
-    assert_equal('some', var)
-  END
-  writefile(lines, 'Xcall.vim')
-  source Xcall.vim
-  delete('Xcall.vim')
-enddef
-
-def Test_vim9script_call_fail_decl()
-  let lines =<< trim END
-    vim9script
-    let var = ''
-    def MyFunc(arg: string)
-       let var = 123
-    enddef
-  END
-  writefile(lines, 'Xcall_decl.vim')
-  assert_fails('source Xcall_decl.vim', 'E1054:')
-  delete('Xcall_decl.vim')
-enddef
-
-def Test_vim9script_call_fail_const()
-  let lines =<< trim END
-    vim9script
-    const var = ''
-    def MyFunc(arg: string)
-       var = 'asdf'
-    enddef
-  END
-  writefile(lines, 'Xcall_const.vim')
-  assert_fails('source Xcall_const.vim', 'E46:')
-  delete('Xcall_const.vim')
-enddef
-
 def Test_vim9script_reload()
   let lines =<< trim END
     vim9script
@@ -926,17 +695,6 @@ def Test_fixed_size_list()
   assert_equal([2, 99, 3, 4, 5], l)
 enddef
 
-" Test that inside :function a Python function can be defined, :def is not
-" recognized.
-func Test_function_python()
-  CheckFeature python3
-  let py = 'python3'
-  execute py "<< EOF"
-def do_something():
-  return 1
-EOF
-endfunc
-
 def IfElse(what: number): string
   let res = ''
   if what == 1
@@ -1087,27 +845,6 @@ def Test_if_const_expr_fails()
   call CheckDefFailure(["if has('aaa') ? true false"], 'E109:')
 enddef
 
-def Test_delfunc()
-  let lines =<< trim END
-    vim9script
-    def GoneSoon()
-      echo 'hello'
-    enddef
-
-    def CallGoneSoon()
-      GoneSoon()
-    enddef
-
-    delfunc GoneSoon
-    CallGoneSoon()
-  END
-  writefile(lines, 'XToDelFunc')
-  assert_fails('so XToDelFunc', 'E933')
-  assert_fails('so XToDelFunc', 'E933')
-
-  delete('XToDelFunc')
-enddef
-
 def Test_execute_cmd()
   new
   setline(1, 'default')
@@ -1222,83 +959,6 @@ def Test_interrupt_loop()
   assert_true(caught, 'should have caught an exception')
 enddef
 
-def Test_redef_failure()
-  call writefile(['def Func0(): string',  'return "Func0"', 'enddef'], 'Xdef')
-  so Xdef
-  call writefile(['def Func1(): string',  'return "Func1"', 'enddef'], 'Xdef')
-  so Xdef
-  call writefile(['def! Func0(): string', 'enddef'], 'Xdef')
-  call assert_fails('so Xdef', 'E1027:')
-  call writefile(['def Func2(): string',  'return "Func2"', 'enddef'], 'Xdef')
-  so Xdef
-  call delete('Xdef')
-
-  call assert_equal(0, Func0())
-  call assert_equal('Func1', Func1())
-  call assert_equal('Func2', Func2())
-
-  delfunc! Func0
-  delfunc! Func1
-  delfunc! Func2
-enddef
-
-" Test for internal functions returning different types
-func Test_InternalFuncRetType()
-  let lines =<< trim END
-    def RetFloat(): float
-      return ceil(1.456)
-    enddef
-
-    def RetListAny(): list<any>
-      return items({'k' : 'v'})
-    enddef
-
-    def RetListString(): list<string>
-      return split('a:b:c', ':')
-    enddef
-
-    def RetListDictAny(): list<dict<any>>
-      return getbufinfo()
-    enddef
-
-    def RetDictNumber(): dict<number>
-      return wordcount()
-    enddef
-
-    def RetDictString(): dict<string>
-      return environ()
-    enddef
-  END
-  call writefile(lines, 'Xscript')
-  source Xscript
-
-  call assert_equal(2.0, RetFloat())
-  call assert_equal([['k', 'v']], RetListAny())
-  call assert_equal(['a', 'b', 'c'], RetListString())
-  call assert_notequal([], RetListDictAny())
-  call assert_notequal({}, RetDictNumber())
-  call assert_notequal({}, RetDictString())
-  call delete('Xscript')
-endfunc
-
-" Test for passing too many or too few arguments to internal functions
-func Test_internalfunc_arg_error()
-  let l =<< trim END
-    def! FArgErr(): float
-      return ceil(1.1, 2)
-    enddef
-  END
-  call writefile(l, 'Xinvalidarg')
-  call assert_fails('so Xinvalidarg', 'E118:')
-  let l =<< trim END
-    def! FArgErr(): float
-      return ceil()
-    enddef
-  END
-  call writefile(l, 'Xinvalidarg')
-  call assert_fails('so Xinvalidarg', 'E119:')
-  call delete('Xinvalidarg')
-endfunc
 
 " Keep this last, it messes up highlighting.
 def Test_substitute_cmd()
diff --git a/src/userfunc.c b/src/userfunc.c
index 71591eb5e9..cff86da6fd 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -951,6 +951,9 @@ func_clear_items(ufunc_T *fp)
     VIM_CLEAR(fp->uf_arg_types);
     VIM_CLEAR(fp->uf_def_