feat(eval/method): partially port v8.1.1921

Adds method call support for all functions in the patch, but it cannot
be fully ported due to missing tests for:

- filereadable(): requires v8.1.1378 for Test_delete_rf(), but there
                  appears to have been some trouble porting it. (#12784)

- confirm(): requires v8.1.0832 for Test_confirm() and v8.1.0815 for
             feedkeys()'s "L" flag.

             (I did attempt to port the test using nvim_input() instead,
             but seems that input handling for confirm() doesn't work in
             --headless mode?)

             Note that confirm() was actually added as a method in
             v8.1.1915.

Uncomment use of method call syntax in Test_Executable() previously
included instead from v8.2.2259.

12 files changed, 100 insertions, 43 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index d9ecdb40de..832fc6bc1b 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -3831,6 +3831,9 @@ escape({string}, {chars})				*escape()*
 			c:\\program\ files\\vim
 <		Also see |shellescape()| and |fnameescape()|.
 
+		Can also be used as a |method|: >
+			GetText()->escape(' \')
+<
 							*eval()*
 eval({string})	Evaluate {string} and return the result.  Especially useful to
 		turn the result of |string()| back into the original value.
@@ -3870,6 +3873,9 @@ executable({expr})					*executable()*
 			-1	not implemented on this system
 		|exepath()| can be used to get the full path of an executable.
 
+		Can also be used as a |method|: >
+			GetCommand()->executable()
+
 execute({command} [, {silent}])				*execute()*
 		Execute {command} and capture its output.
 		If {command} is a |String|, returns {command} output.
@@ -3897,12 +3903,18 @@ execute({command} [, {silent}])				*execute()*
 		To execute a command in another window than the current one
 		use `win_execute()`.
 
+		Can also be used as a |method|: >
+			GetCommand()->execute()
+
 exepath({expr})						*exepath()*
 		Returns the full path of {expr} if it is an executable and
 		given as a (partial or full) path or is found in $PATH.
 		Returns empty string otherwise.
 		If {expr} starts with "./" the |current-directory| is used.
 
+		Can also be used as a |method|: >
+			GetCommand()->exepath()
+
 							*exists()*
 exists({expr})	The result is a Number, which is |TRUE| if {expr} is
 		defined, zero otherwise.
@@ -3988,6 +4000,9 @@ exists({expr})	The result is a Number, which is |TRUE| if {expr} is
 <		This doesn't check for existence of the "bufcount" variable,
 		but gets the value of "bufcount", and checks if that exists.
 
+		Can also be used as a |method|: >
+			Varname()->exists()
+
 exp({expr})						*exp()*
 		Return the exponential of {expr} as a |Float| in the range
 		[0, inf].
@@ -4094,6 +4109,9 @@ expand({string} [, {nosuf} [, {list}]])				*expand()*
 		See |glob()| for finding existing files.  See |system()| for
 		getting the raw output of an external command.
 
+		Can also be used as a |method|: >
+			Getpattern()->expand()
+
 expandcmd({expr})					*expandcmd()*
 		Expand special items in {expr} like what is done for an Ex
 		command such as `:edit`.  This expands special keywords, like
@@ -4101,6 +4119,9 @@ expandcmd({expr})					*expandcmd()*
 		{expr}.  "~user" and "~/path" are only expanded at the start.
 		Returns the expanded string.  Example: >
 			:echo expandcmd('make %<.o')
+
+<		Can also be used as a |method|: >
+			GetCommand()->expandcmd()
 <
 extend({expr1}, {expr2} [, {expr3}])			*extend()*
 		{expr1} and {expr2} must be both |Lists| or both
@@ -4186,6 +4207,9 @@ feedkeys({string} [, {mode}])				*feedkeys()*
 
 		Return value is always 0.
 
+		Can also be used as a |method|: >
+			GetInput()->feedkeys()
+
 filereadable({file})					*filereadable()*
 		The result is a Number, which is |TRUE| when a file with the
 		name {file} exists, and can be read.  If {file} doesn't exist,
@@ -4199,12 +4223,17 @@ filereadable({file})					*filereadable()*
 			echo filereadable(expand('~/.vimrc'))
 			1
 
+<		Can also be used as a |method|: >
+			GetName()->filereadable()
+
 filewritable({file})					*filewritable()*
 		The result is a Number, which is 1 when a file with the
 		name {file} exists, and can be written.  If {file} doesn't
 		exist, or is not writable, the result is 0.  If {file} is a
 		directory, and we can write to it, the result is 2.
 
+		Can also be used as a |method|: >
+			GetName()->filewriteable()
 
 filter({expr1}, {expr2})					*filter()*
 		{expr1} must be a |List|, |Blob|, or a |Dictionary|.
@@ -4275,6 +4304,9 @@ finddir({name} [, {path} [, {count}]])				*finddir()*
 
 		This is quite similar to the ex-command `:find`.
 
+		Can also be used as a |method|: >
+			GetName()->finddir()
+
 findfile({name} [, {path} [, {count}]])				*findfile()*
 		Just like |finddir()|, but find a file instead of a directory.
 		Uses 'suffixesadd'.
@@ -4283,6 +4315,9 @@ findfile({name} [, {path} [, {count}]])				*findfile()*
 <		Searches from the directory of the current file upwards until
 		it finds the file "tags.vim".
 
+		Can also be used as a |method|: >
+			GetName()->findfile()
+
 flatten({list} [, {maxdepth}])					*flatten()*
 		Flatten {list} up to {maxdepth} levels.  Without {maxdepth}
 		the result is a |List| without nesting, as if {maxdepth} is
@@ -4372,6 +4407,9 @@ fnameescape({string})					*fnameescape()*
 			:exe "edit " . fnameescape(fname)
 <		results in executing: >
 			edit \+some\ str\%nge\|name
+<
+		Can also be used as a |method|: >
+			GetName()->fnameescape()
 
 fnamemodify({fname}, {mods})				*fnamemodify()*
 		Modify file name {fname} according to {mods}.  {mods} is a
@@ -4385,6 +4423,9 @@ fnamemodify({fname}, {mods})				*fnamemodify()*
 		Note: Environment variables don't work in {fname}, use
 		|expand()| first then.
 
+		Can also be used as a |method|: >
+			GetName()->fnamemodify(':p:h')
+
 foldclosed({lnum})					*foldclosed()*
 		The result is a Number.  If the line {lnum} is in a closed
 		fold, the result is the number of the first line in that fold.
@@ -4392,6 +4433,9 @@ foldclosed({lnum})					*foldclosed()*
 		{lnum} is used like with |getline()|.  Thus "." is the current
 		line, "'m" mark m, etc.
 
+		Can also be used as a |method|: >
+			GetLnum()->foldclosed()
+
 foldclosedend({lnum})					*foldclosedend()*
 		The result is a Number.  If the line {lnum} is in a closed
 		fold, the result is the number of the last line in that fold.
@@ -4399,6 +4443,9 @@ foldclosedend({lnum})					*foldclosedend()*
 		{lnum} is used like with |getline()|.  Thus "." is the current
 		line, "'m" mark m, etc.
 
+		Can also be used as a |method|: >
+			GetLnum()->foldclosedend()
+
 foldlevel({lnum})					*foldlevel()*
 		The result is a Number, which is the foldlevel of line {lnum}
 		in the current buffer.  For nested folds the deepest level is
@@ -4411,6 +4458,9 @@ foldlevel({lnum})					*foldlevel()*
 		{lnum} is used like with |getline()|.  Thus "." is the current
 		line, "'m" mark m, etc.
 
+		Can also be used as a |method|: >
+			GetLnum()->foldlevel()
+
 							*foldtext()*
 foldtext()	Returns a String, to be displayed for a closed fold.  This is
 		the default function used for the 'foldtext' option and should
@@ -4436,6 +4486,9 @@ foldtextresult({lnum})					*foldtextresult()*
 		line, "'m" mark m, etc.
 		Useful when exporting folded text, e.g., to HTML.
 
+		Can also be used as a |method|: >
+			GetLnum()->foldtextresult()
+<
 							*foreground()*
 foreground()	Move the Vim window to the foreground.  Useful when sent from
 		a client to a Vim server. |remote_send()|
@@ -4454,6 +4507,9 @@ funcref({name} [, {arglist}] [, {dict}])
 		Also for autoloaded functions. {name} cannot be a builtin
 		function.
 
+		Can also be used as a |method|: >
+			GetFuncname()->funcref([arg])
+<
 				       *function()* *E700* *E922* *E923*
 function({name} [, {arglist}] [, {dict}])
 		Return a |Funcref| variable that refers to function {name}.
@@ -4503,7 +4559,9 @@ function({name} [, {arglist}] [, {dict}])
 			call Func(500)
 <		Invokes the function as with: >
 			call context.Callback('one', 500)
-
+<
+		Can also be used as a |method|: >
+			GetFuncname()->function([arg])
 
 garbagecollect([{atexit}])				*garbagecollect()*
 		Cleanup unused |Lists| and |Dictionaries| that have circular
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index c6ac27b269..f9f6af3bfd 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -102,38 +102,38 @@ return {
     diff_hlID={args=2, base=1},
     empty={args=1, base=1},
     environ={},
-    escape={args=2},
+    escape={args=2, base=1},
     eval={args=1, base=1},
     eventhandler={},
-    executable={args=1},
-    execute={args={1, 2}},
-    exepath={args=1},
-    exists={args=1},
+    executable={args=1, base=1},
+    execute={args={1, 2}, base=1},
+    exepath={args=1, base=1},
+    exists={args=1, base=1},
     exp={args=1, base=1, func="float_op_wrapper", data="&exp"},
-    expand={args={1, 3}},
-    expandcmd={args=1},
+    expand={args={1, 3}, base=1},
+    expandcmd={args=1, base=1},
     extend={args={2, 3}, base=1},
-    feedkeys={args={1, 2}},
-    file_readable={args=1, func='f_filereadable'},  -- obsolete
-    filereadable={args=1},
-    filewritable={args=1},
+    feedkeys={args={1, 2}, base=1},
+    file_readable={args=1, base=1, func='f_filereadable'},  -- obsolete
+    filereadable={args=1, base=1},
+    filewritable={args=1, base=1},
     filter={args=2, base=1},
-    finddir={args={1, 3}},
-    findfile={args={1, 3}},
+    finddir={args={1, 3}, base=1},
+    findfile={args={1, 3}, base=1},
     flatten={args={1, 2}},
     float2nr={args=1, base=1},
     floor={args=1, base=1, func="float_op_wrapper", data="&floor"},
     fmod={args=2, base=1},
-    fnameescape={args=1},
-    fnamemodify={args=2},
-    foldclosed={args=1},
-    foldclosedend={args=1},
-    foldlevel={args=1},
+    fnameescape={args=1, base=1},
+    fnamemodify={args=2, base=1},
+    foldclosed={args=1, base=1},
+    foldclosedend={args=1, base=1},
+    foldlevel={args=1, base=1},
     foldtext={},
-    foldtextresult={args=1},
+    foldtextresult={args=1, base=1},
     foreground={},
-    funcref={args={1, 3}},
-    ['function']={args={1, 3}},
+    funcref={args={1, 3}, base=1},
+    ['function']={args={1, 3}, base=1},
     garbagecollect={args={0, 1}},
     get={args={2, 3}, base=1},
     getbufinfo={args={0, 1}},
diff --git a/src/nvim/testdir/test_expand_func.vim b/src/nvim/testdir/test_expand_func.vim
index 4d9e89fe3e..44d2c156d5 100644
--- a/src/nvim/testdir/test_expand_func.vim
+++ b/src/nvim/testdir/test_expand_func.vim
@@ -40,7 +40,7 @@ endfunc
 func Test_expand()
   new
   call assert_equal("",  expand('%:S'))
-  call assert_equal('3', expand('<slnum>'))
+  call assert_equal('3', '<slnum>'->expand())
   call assert_equal(['4'], expand('<slnum>', v:false, v:true))
   " Don't add any line above this, otherwise <slnum> will change.
   quit
diff --git a/src/nvim/testdir/test_expr.vim b/src/nvim/testdir/test_expr.vim
index c49285621a..6343c47fde 100644
--- a/src/nvim/testdir/test_expr.vim
+++ b/src/nvim/testdir/test_expr.vim
@@ -147,7 +147,7 @@ function Test_printf_spec_s()
   call assert_equal(string(value), printf('%s', value))
 
   " funcref
-  call assert_equal('printf', printf('%s', function('printf')))
+  call assert_equal('printf', printf('%s', 'printf'->function()))
 
   " partial
   call assert_equal(string(function('printf', ['%s'])), printf('%s', function('printf', ['%s'])))
@@ -477,7 +477,7 @@ func Test_funcref()
   endfunc
   call assert_equal(2, OneByName())
   call assert_equal(1, OneByRef())
-  let OneByRef = funcref('One')
+  let OneByRef = 'One'->funcref()
   call assert_equal(2, OneByRef())
   call assert_fails('echo funcref("{")', 'E475:')
   let OneByRef = funcref("One", repeat(["foo"], 20))
diff --git a/src/nvim/testdir/test_findfile.vim b/src/nvim/testdir/test_findfile.vim
index 2195bf527e..d92706dbe5 100644
--- a/src/nvim/testdir/test_findfile.vim
+++ b/src/nvim/testdir/test_findfile.vim
@@ -50,7 +50,7 @@ func Test_findfile()
   set path=.
   call assert_equal('Xdir2/foo',    findfile('foo'))
   call assert_equal('',             findfile('bar'))
-  call assert_equal('Xdir2/foobar', findfile('foobar'))
+  call assert_equal('Xdir2/foobar', 'foobar'->findfile())
 
   " Empty {path} 2nd argument is the same as no 2nd argument.
   call assert_equal('Xdir2/foo', findfile('foo', ''))
@@ -138,7 +138,7 @@ func Test_finddir()
   cd Xdir1
 
   call assert_equal('Xdir2', finddir('Xdir2'))
-  call assert_equal('',      finddir('Xdir3'))
+  call assert_equal('',      'Xdir3'->finddir())
 
   " Files should not be found (findfile() finds them).
   call assert_equal('', finddir('foo'))
diff --git a/src/nvim/testdir/test_fnameescape.vim b/src/nvim/testdir/test_fnameescape.vim
index 0bafdc29fb..cdb96ba5ff 100644
--- a/src/nvim/testdir/test_fnameescape.vim
+++ b/src/nvim/testdir/test_fnameescape.vim
@@ -13,7 +13,7 @@ func Test_fnameescape()
   let fname = 'Xemark!'
   let status = v:false
   try
-    exe "w! " . fnameescape(fname)
+    exe "w! " . fname->fnameescape()
     let status = v:true
   endtry
   call assert_true(status, "ExclamationMark")
diff --git a/src/nvim/testdir/test_fnamemodify.vim b/src/nvim/testdir/test_fnamemodify.vim
index fe1df8fd4a..411f7ebbb3 100644
--- a/src/nvim/testdir/test_fnamemodify.vim
+++ b/src/nvim/testdir/test_fnamemodify.vim
@@ -13,7 +13,7 @@ func Test_fnamemodify()
   call assert_equal('a', fnamemodify('../testdir/a', ':.'))
   call assert_equal('~/testdir/test.out', fnamemodify('test.out', ':~'))
   call assert_equal('~/testdir/a', fnamemodify('../testdir/a', ':~'))
-  call assert_equal('a', fnamemodify('../testdir/a', ':t'))
+  call assert_equal('a', '../testdir/a'->fnamemodify(':t'))
   call assert_equal('', fnamemodify('.', ':p:t'))
   call assert_equal('test.out', fnamemodify('test.out', ':p:t'))
   call assert_equal('out', fnamemodify('test.out', ':p:e'))
diff --git a/src/nvim/testdir/test_fold.vim b/src/nvim/testdir/test_fold.vim
index 2cc5b47cb0..5586fe2151 100644
--- a/src/nvim/testdir/test_fold.vim
+++ b/src/nvim/testdir/test_fold.vim
@@ -88,7 +88,7 @@ func Test_indent_fold2()
     setl fen fdm=marker
     2
     norm! >>
-    let a=map(range(1,5), 'foldclosed(v:val)')
+    let a=map(range(1,5), 'v:val->foldclosed()')
     call assert_equal([-1,-1,-1,4,4], a)
     bw!
 endfunc
@@ -132,7 +132,7 @@ func Test_indent_fold_with_read()
   call assert_equal(0, foldlevel(3))
   call assert_equal(0, foldlevel(4))
   call assert_equal(1, foldlevel(5))
-  call assert_equal(7, foldclosedend(5))
+  call assert_equal(7, 5->foldclosedend())
 
   bwipe!
   set foldmethod&
@@ -207,7 +207,7 @@ func Test_update_folds_expr_read()
   %foldclose
   call assert_equal(2, foldclosedend(1))
   call assert_equal(0, foldlevel(3))
-  call assert_equal(0, foldlevel(4))
+  call assert_equal(0, 4->foldlevel())
   call assert_equal(6, foldclosedend(5))
   call assert_equal(10, foldclosedend(7))
   call assert_equal(14, foldclosedend(11))
@@ -663,7 +663,7 @@ func Test_fold_move()
   call assert_equal(10, foldclosed(10))
   call assert_equal(11, foldclosedend(10))
   call assert_equal('+--  2 lines: Line2', foldtextresult(2))
-  call assert_equal('+--  2 lines: Line8', foldtextresult(10))
+  call assert_equal('+--  2 lines: Line8', 10->foldtextresult())
 
   set fdm& sw& fdl&
   enew!
diff --git a/src/nvim/testdir/test_functions.vim b/src/nvim/testdir/test_functions.vim
index 9268a13d4e..e3a80be6d5 100644
--- a/src/nvim/testdir/test_functions.vim
+++ b/src/nvim/testdir/test_functions.vim
@@ -1057,7 +1057,7 @@ func Test_filewritable()
   call assert_equal(0, filewritable('Xfilewritable'))
 
   call assert_notequal(0, setfperm('Xfilewritable', 'rw-r-----'))
-  call assert_equal(1, filewritable('Xfilewritable'))
+  call assert_equal(1, 'Xfilewritable'->filewritable())
 
   call assert_equal(0, filewritable('doesnotexist'))
 
@@ -1068,12 +1068,12 @@ endfunc
 func Test_Executable()
   if has('win32')
     call assert_equal(1, executable('notepad'))
-    call assert_equal(1, executable('notepad.exe'))
+    call assert_equal(1, 'notepad.exe'->executable())
     call assert_equal(0, executable('notepad.exe.exe'))
     call assert_equal(0, executable('shell32.dll'))
     call assert_equal(0, executable('win.ini'))
   elseif has('unix')
-    call assert_equal(1, executable('cat'))
+    call assert_equal(1, 'cat'->executable())
     call assert_equal(0, executable('nodogshere'))
 
     " get "cat" path and remove the leading /
@@ -1082,8 +1082,7 @@ func Test_Executable()
     " check that the relative path works in /
     lcd /
     call assert_equal(1, executable(catcmd))
-    " let result = catcmd->exepath()
-    let result = exepath(catcmd)
+    let result = catcmd->exepath()
     " when using chroot looking for sbin/cat can return bin/cat, that is OK
     if catcmd =~ '\<sbin\>' && result =~ '\<bin\>'
       call assert_equal('/' .. substitute(catcmd, '\<sbin\>', 'bin', ''), result)
@@ -1320,7 +1319,7 @@ func Test_func_exists_on_reload()
   call writefile(['func ExistingFunction()', 'echo "yes"', 'endfunc'], 'Xfuncexists')
   call assert_equal(0, exists('*ExistingFunction'))
   source Xfuncexists
-  call assert_equal(1, exists('*ExistingFunction'))
+  call assert_equal(1, '*ExistingFunction'->exists())
   " Redefining a function when reloading a script is OK.
   source Xfuncexists
   call assert_equal(1, exists('*ExistingFunction'))
@@ -1351,7 +1350,7 @@ func Test_func_sandbox()
   sandbox let F = {-> 'hello'}
   call assert_equal('hello', F())
 
-  sandbox let F = {-> execute("normal ix\<Esc>")}
+  sandbox let F = {-> "normal ix\<Esc>"->execute()}
   call assert_fails('call F()', 'E48:')
   unlet F
 
diff --git a/src/nvim/testdir/test_search.vim b/src/nvim/testdir/test_search.vim
index 5ba24d047c..7570049e7c 100644
--- a/src/nvim/testdir/test_search.vim
+++ b/src/nvim/testdir/test_search.vim
@@ -1338,7 +1338,7 @@ func Test_search_display_pattern()
 
   call cursor(1, 1)
   let @/ = 'foo'
-  let pat = escape(@/, '()*?'. '\s\+')
+  let pat = @/->escape('()*?'. '\s\+')
   let g:a = execute(':unsilent :norm! n')
   call assert_match(pat, g:a)
 
diff --git a/src/nvim/testdir/test_vimscript.vim b/src/nvim/testdir/test_vimscript.vim
index b18ce563d3..34733f127f 100644
--- a/src/nvim/testdir/test_vimscript.vim
+++ b/src/nvim/testdir/test_vimscript.vim
@@ -635,7 +635,7 @@ function! MSG(enr, emsg)
 	if v:errmsg == ""
 	    Xout "Message missing."
 	else
-	    let v:errmsg = escape(v:errmsg, '"')
+	    let v:errmsg = v:errmsg->escape('"')
 	    Xout "Unexpected message:" v:errmsg
 	endif
     endif
diff --git a/test/functional/legacy/expand_spec.lua b/test/functional/legacy/expand_spec.lua
index f238128b31..cd3713eabe 100644
--- a/test/functional/legacy/expand_spec.lua
+++ b/test/functional/legacy/expand_spec.lua
@@ -81,7 +81,7 @@ describe('expand file name', function()
         call assert_equal('e Xfile1', expandcmd('e %'))
         edit Xfile2
         edit Xfile1
-        call assert_equal('e Xfile2', expandcmd('e #'))
+        call assert_equal('e Xfile2', 'e #'->expandcmd())
         edit Xfile2
         edit Xfile3
         edit Xfile4