[vim/vim] Vim9: no error when declaring too many arguments in lambda passed to "searchpair()" (#8329)

[lacygoill]

Describe the bug

In Vim9 script, no error is given when we declare too many arguments in a lambda passed to searchpair(), or searchpairpos().

To Reproduce

Run this shell command:

vim -Nu NONE -S <(cat <<'EOF'
    vim9script
    searchpair('(', '', ')', 'W', (a, b, c) => true)
    echo 'no error'
EOF
)

"no error" is printed.

Expected behavior

searchpair() gives an error because we've declared too many arguments in the lambda passed to searchpair():

searchpair('(', '', ')', 'W', (a, b, c) => true)
                               ^-----^

"no error" is not printed because Vim aborts sourcing the script.

Environment

• Vim version: 8.2 Included patches: 1-2943
• OS: Ubuntu 20.04.2 LTS
• Terminal: XTerm(353)

Additional context

Same issue with searchpairpos():

vim9script
searchpairpos('(', '', ')', 'W', (a, b, c) => true)
echo 'no error'

no error

---

AFAIK, the lambda doesn't receive any argument. Shouldn't Vim complain that the lambda didn't receive enough arguments? Like when we pass a lambda to timer_start():

vim9script
timer_start(0, (a, b, c) => true)

E119: Not enough arguments for function: <lambda>1

Or to map():

vim9script
echo range(3)->map((a, b, c) => a + b)

E1190: One argument too few

Or to filter():

vim9script
echo range(3)->filter((a, b, c) => true)

E1190: One argument too few

Unrelated: To be consistent, maybe timer_start() should complain with E1190 rather than with E119.

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[lacygoill]

It seems that the issue is really specific to searchpair() and searchpairpos(), because in addition to timer_start(), map() and filter(), we have substitute(), sort() and setqflist() which also complain when we declare too many arguments in their lambda:

vim9script
echo 'some text'->substitute('.*', (a, b, c) => 'replacement', '')

E119: Not enough arguments for function: <lambda>1

vim9script
echo [4, 1, 3, 2]->sort((a, b, c) => a == b ? 0 : a > b ? 1 : -1)

E119: Not enough arguments for function: <lambda>1

vim9script
def MyQftf(_, _): any
    return repeat(['test'], 100)
enddef
def Func()
    setqflist([], 'r', {lines: v:oldfiles, efm: '%f', quickfixtextfunc: MyQftf})
    cw
enddef
Func()

E119: Not enough arguments for function: <SNR>1_MyQftf

[Bram Moolenaar]

Make sure to put the cursor on a "(", then the skip expression will be evaluated and I get:
E1190: 3 arguments too few

[Bram Moolenaar]

Closed #8329.

[lacygoill]

Ah yes:

vim9script
' ('->setline(1)

searchpair('(', '', ')', 'W', (a, b, c) => true)

E1190: 3 arguments too few

But it's only when the lambda is used while the cursor is somewhere before a paren that Vim gives the error. There is no error at compile time:

vim9script
def Func()
    ' ('->setline(1)
    

searchpair('(', '', ')', 'W', (a, b, c) => true)

enddef
defcompile

I guess it could, because Vim should know that whatever lambda we pass to searchpair(), it's not supposed to receive any argument. It might not be important here, but in general I think the sooner the errors are found (i.e. the more errors we get at compile time), the better.

[Bram Moolenaar]

> Ah yes:
> ```vim
> vim9script
> ' ('->setline(1)

> searchpair('(', '', ')', 'W', (a, b, c) => true)

> ```

> E1190: 3 arguments too few
>
> But it's only when the lambda is used while the cursor is somewhere before a paren that Vim gives the error. There is no error at compile time:

> ```vim

> vim9script
> def Func()
> ' ('->setline(1)

> searchpair('(', '', ')', 'W', (a, b, c) => true)

> enddef
> defcompile
> ```
> I guess it could, because Vim should know that whatever lambda we pass

> to `searchpair()`, it's not supposed to receive any argument. It

> might not be important here, but in general I think the sooner the
> errors are found (i.e. the more errors we get at compile time), the
> better.

Yes, this is very similar to issue #8092.

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