Re: [vim/vim] Vim9 script fails to parse multi-line dictionary inside a lambda (Issue #20693)

h-east left a comment (vim/vim#20693)

The lambda body is not parsed while it is read.  `get_function_body()` in
`src/userfunc.c` collects the lines one by one and ends the block at the first
line whose first non-blank character is `}`.  In your example that is the line
closing the dictionary, so the block that gets compiled is

```vim
  const d = {
    'foo': {'bar': 'baz'}
```

hence E723.

Doing better would mean tokenizing the contents while the lines are read, that
is a full command and expression parser at that point, since `{` and `}` also
occur in strings, comments, patterns and nested lambdas.  Bram rejected that in
#9352:

> The commands are not parsed, the block simply stops at the first line
> starting with a "}".  [...] Parsing the lines inside the block would require
> rewriting the whole command parsing code, that is infeasible.

Put the `}` of the dictionary after the last item instead:

```vim
timer_start(0, (_) => {
  const d = {
    'foo': {'bar': 'baz'} }
})
```

A lambda block and a command block are read by the same code, so this is not
specific to `:command`.  It is documented at `:help command-block`, and #20872
adds a note at `:help inline-function` as well.

Duplicate of #9352.

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