patch 8.2.1623: Vim9: using :call where it is not needed

Problem:    Vim9: using :call where it is not needed.
Solution:   Remove :call. (closes #6892)
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index fb1a0de..a277767 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -29,7 +29,7 @@
 def Test_return_something()
   assert_equal('string', ReturnString())
   assert_equal(123, ReturnNumber())
-  assert_fails('call ReturnGlobal()', 'E1029: Expected number but got string')
+  assert_fails('ReturnGlobal()', 'E1029: Expected number but got string')
 enddef
 
 def Test_missing_return()
@@ -111,7 +111,7 @@
 def Test_call_default_args()
   assert_equal('string', MyDefaultArgs())
   assert_equal('one', MyDefaultArgs('one'))
-  assert_fails('call MyDefaultArgs("one", "two")', 'E118:')
+  assert_fails('MyDefaultArgs("one", "two")', 'E118:')
 
   assert_equal('test', MyDefaultSecond('test'))
   assert_equal('test', MyDefaultSecond('test', true))
@@ -219,10 +219,10 @@
 endfunc
 
 def Test_call_wrong_args()
-  call CheckDefFailure(['TakesOneArg()'], 'E119:')
-  call CheckDefFailure(['TakesOneArg(11, 22)'], 'E118:')
-  call CheckDefFailure(['bufnr(xxx)'], 'E1001:')
-  call CheckScriptFailure(['def Func(Ref: func(s: string))'], 'E475:')
+  CheckDefFailure(['TakesOneArg()'], 'E119:')
+  CheckDefFailure(['TakesOneArg(11, 22)'], 'E118:')
+  CheckDefFailure(['bufnr(xxx)'], 'E1001:')
+  CheckScriptFailure(['def Func(Ref: func(s: string))'], 'E475:')
 
   let lines =<< trim END
     vim9script
@@ -244,7 +244,7 @@
 enddef
 
 def Test_call_def_varargs()
-  call assert_fails('call MyDefVarargs()', 'E119:')
+  assert_fails('MyDefVarargs()', 'E119:')
   assert_equal('one,foo', MyDefVarargs('one'))
   assert_equal('one,two', MyDefVarargs('one', 'two'))
   assert_equal('one,two,three', MyDefVarargs('one', 'two', 'three'))
@@ -333,8 +333,8 @@
   assert_equal('99text', RefDef2Arg(99))
   assert_equal('77some', RefDef2Arg(77, 'some'))
 
-  call CheckDefFailure(['let RefWrong: func(string?)'], 'E1010:')
-  call CheckDefFailure(['let RefWrong: func(?string, string)'], 'E1007:')
+  CheckDefFailure(['let RefWrong: func(string?)'], 'E1010:')
+  CheckDefFailure(['let RefWrong: func(?string, string)'], 'E1007:')
 
   let RefVarargs: func(...list<string>): string
   RefVarargs = FuncVarargs
@@ -342,8 +342,8 @@
   assert_equal('one', RefVarargs('one'))
   assert_equal('one,two', RefVarargs('one', 'two'))
 
-  call CheckDefFailure(['let RefWrong: func(...list<string>, string)'], 'E110:')
-  call CheckDefFailure(['let RefWrong: func(...list<string>, ?string)'], 'E110:')
+  CheckDefFailure(['let RefWrong: func(...list<string>, string)'], 'E110:')
+  CheckDefFailure(['let RefWrong: func(...list<string>, ?string)'], 'E110:')
 enddef
 
 " Only varargs
@@ -355,14 +355,14 @@
   assert_equal('', MyVarargsOnly())
   assert_equal('one', MyVarargsOnly('one'))
   assert_equal('one,two', MyVarargsOnly('one', 'two'))
-  call CheckDefFailure(['MyVarargsOnly(1)'], 'E1013: argument 1: type mismatch, expected string but got number')
-  call CheckDefFailure(['MyVarargsOnly("one", 2)'], 'E1013: argument 2: type mismatch, expected string but got number')
+  CheckDefFailure(['MyVarargsOnly(1)'], 'E1013: argument 1: type mismatch, expected string but got number')
+  CheckDefFailure(['MyVarargsOnly("one", 2)'], 'E1013: argument 2: type mismatch, expected string but got number')
 enddef
 
 def Test_using_var_as_arg()
-  call writefile(['def Func(x: number)',  'let x = 234', 'enddef', 'defcompile'], 'Xdef')
-  call assert_fails('so Xdef', 'E1006:')
-  call delete('Xdef')
+  writefile(['def Func(x: number)',  'let x = 234', 'enddef', 'defcompile'], 'Xdef')
+  assert_fails('so Xdef', 'E1006:')
+  delete('Xdef')
 enddef
 
 def DictArg(arg: dict<string>)
@@ -382,12 +382,12 @@
   ListArg(l)
   assert_equal('value', l[0])
 
-  call CheckScriptFailure(['def Func(arg: number)', 'arg = 3', 'enddef', 'defcompile'], 'E1090:')
+  CheckScriptFailure(['def Func(arg: number)', 'arg = 3', 'enddef', 'defcompile'], 'E1090:')
 enddef
 
 def Test_call_func_defined_later()
-  call assert_equal('one', g:DefinedLater('one'))
-  call assert_fails('call NotDefined("one")', 'E117:')
+  assert_equal('one', g:DefinedLater('one'))
+  assert_fails('NotDefined("one")', 'E117:')
 enddef
 
 func DefinedLater(arg)
@@ -523,7 +523,7 @@
 
 def Test_error_in_nested_function()
   # Error in called function requires unwinding the call stack.
-  assert_fails('call FuncWithForwardCall()', 'E1096:')
+  assert_fails('FuncWithForwardCall()', 'E1096:')
 enddef
 
 def Test_return_type_wrong()
@@ -742,19 +742,19 @@
 enddef
 
 def Test_redef_failure()
-  call writefile(['def Func0(): string',  'return "Func0"', 'enddef'], 'Xdef')
+  writefile(['def Func0(): string',  'return "Func0"', 'enddef'], 'Xdef')
   so Xdef
-  call writefile(['def Func1(): string',  'return "Func1"', 'enddef'], 'Xdef')
+  writefile(['def Func1(): string',  'return "Func1"', 'enddef'], 'Xdef')
   so Xdef
-  call writefile(['def! Func0(): string', 'enddef', 'defcompile'], 'Xdef')
-  call assert_fails('so Xdef', 'E1027:')
-  call writefile(['def Func2(): string',  'return "Func2"', 'enddef'], 'Xdef')
+  writefile(['def! Func0(): string', 'enddef', 'defcompile'], 'Xdef')
+  assert_fails('so Xdef', 'E1027:')
+  writefile(['def Func2(): string',  'return "Func2"', 'enddef'], 'Xdef')
   so Xdef
-  call delete('Xdef')
+  delete('Xdef')
 
-  call assert_equal(0, g:Func0())
-  call assert_equal('Func1', g:Func1())
-  call assert_equal('Func2', g:Func2())
+  assert_equal(0, g:Func0())
+  assert_equal('Func1', g:Func1())
+  assert_equal('Func2', g:Func2())
 
   delfunc! Func0
   delfunc! Func1
@@ -960,10 +960,10 @@
   CheckDefFailure(['let Ref1: func(?bool)', 'Ref1 = FuncTwoArgNoRet'], 'E1012: type mismatch, expected func(?bool) but got func(bool, number)')
   CheckDefFailure(['let Ref1: func(...bool)', 'Ref1 = FuncTwoArgNoRet'], 'E1012: type mismatch, expected func(...bool) but got func(bool, number)')
 
-  call CheckDefFailure(['let RefWrong: func(string ,number)'], 'E1068:')
-  call CheckDefFailure(['let RefWrong: func(string,number)'], 'E1069:')
-  call CheckDefFailure(['let RefWrong: func(bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool)'], 'E1005:')
-  call CheckDefFailure(['let RefWrong: func(bool):string'], 'E1069:')
+  CheckDefFailure(['let RefWrong: func(string ,number)'], 'E1068:')
+  CheckDefFailure(['let RefWrong: func(string,number)'], 'E1069:')
+  CheckDefFailure(['let RefWrong: func(bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool)'], 'E1005:')
+  CheckDefFailure(['let RefWrong: func(bool):string'], 'E1069:')
 enddef
 
 def Test_func_return_type()
@@ -1702,7 +1702,7 @@
 
 def Test_cmd_modifier()
   tab echo '0'
-  call CheckDefFailure(['5tab echo 3'], 'E16:')
+  CheckDefFailure(['5tab echo 3'], 'E16:')
 enddef
 
 def Test_restore_modifiers()