Update runtime files

45 files changed, 4222 insertions, 378 deletions

diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 2baadcbf6f..b33c37bff5 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -57,6 +57,7 @@ runtime/compiler/gawk.vim		@dkearns
 runtime/compiler/gjs.vim		@dkearns
 runtime/compiler/go.vim			@dbarnett
 runtime/compiler/haml.vim		@tpope
+runtime/compiler/hare.vim		@rsaihe
 runtime/compiler/icon.vim		@dkearns
 runtime/compiler/javac.vim		@dkearns
 runtime/compiler/jest.vim		@dkearns
@@ -107,6 +108,7 @@ runtime/ftplugin/awk.vim		@dkearns
 runtime/ftplugin/basic.vim		@dkearns
 runtime/ftplugin/bst.vim		@tpope
 runtime/ftplugin/cfg.vim		@chrisbra
+runtime/ftplugin/chatito.vim		@ObserverOfTime
 runtime/ftplugin/clojure.vim		@axvr
 runtime/ftplugin/cs.vim			@nickspoons
 runtime/ftplugin/csh.vim		@dkearns
@@ -116,9 +118,9 @@ runtime/ftplugin/desktop.vim		@e-kwsm
 runtime/ftplugin/dosbatch.vim		@mrdubya
 runtime/ftplugin/eiffel.vim		@dkearns
 runtime/ftplugin/elixir.vim		@mhanberg
-runtime/ftplugin/expect.vim		@dkearns
 runtime/ftplugin/erlang.vim		@hcs42
 runtime/ftplugin/eruby.vim		@tpope @dkearns
+runtime/ftplugin/expect.vim		@dkearns
 runtime/ftplugin/fennel.vim		@gpanders
 runtime/ftplugin/fetchmail.vim		@dkearns
 runtime/ftplugin/fpcmake.vim		@dkearns
@@ -134,9 +136,11 @@ runtime/ftplugin/gitconfig.vim		@tpope
 runtime/ftplugin/gitignore.vim		@ObserverOfTime
 runtime/ftplugin/gitrebase.vim		@tpope
 runtime/ftplugin/gitsendemail.vim	@tpope
+runtime/ftplugin/gyp.vim		@ObserverOfTime
 runtime/ftplugin/go.vim			@dbarnett
 runtime/ftplugin/gprof.vim		@dpelle
 runtime/ftplugin/haml.vim		@tpope
+runtime/ftplugin/hare.vim		@rsaihe
 runtime/ftplugin/hgcommit.vim		@k-takata
 runtime/ftplugin/html.vim		@dkearns
 runtime/ftplugin/i3config.vim		@hiqua
@@ -208,6 +212,7 @@ runtime/ftplugin/zsh.vim		@chrisbra
 runtime/indent/basic.vim		@dkearns
 runtime/indent/bst.vim			@tpope
 runtime/indent/cdl.vim			@dkearns
+runtime/indent/chatito.vim		@ObserverOfTime
 runtime/indent/clojure.vim		@axvr
 runtime/indent/config.vim		@dkearns
 runtime/indent/cs.vim			@nickspoons
@@ -229,7 +234,9 @@ runtime/indent/gdscript.vim		@habamax
 runtime/indent/gitconfig.vim		@tpope
 runtime/indent/gitolite.vim		@sitaramc
 runtime/indent/go.vim			@dbarnett
+runtime/indent/gyp.vim			@ObserverOfTime
 runtime/indent/haml.vim			@tpope
+runtime/indent/hare.vim			@rsaihe
 runtime/indent/idlang.vim		@dkearns
 runtime/indent/j.vim			@glts
 runtime/indent/java.vim			@xuhdev
@@ -303,6 +310,7 @@ runtime/syntax/cabal.vim		@coot
 runtime/syntax/cabalconfig.vim		@coot
 runtime/syntax/cabalproject.vim		@coot
 runtime/syntax/cf.vim			@ernstvanderlinden
+runtime/syntax/chatito.vim		@ObserverOfTime
 runtime/syntax/clojure.vim		@axvr
 runtime/syntax/cs.vim			@nickspoons
 runtime/syntax/csh.vim			@cecamp
@@ -345,7 +353,9 @@ runtime/syntax/go.vim			@bhcleek
 runtime/syntax/godoc.vim		@dbarnett
 runtime/syntax/gprof.vim		@dpelle
 runtime/syntax/groff.vim		@jmarshall
+runtime/syntax/gyp.vim			@ObserverOfTime
 runtime/syntax/haml.vim			@tpope
+runtime/syntax/hare.vim			@rsaihe
 runtime/syntax/haskell.vim		@coot
 runtime/syntax/hgcommit.vim		@k-takata
 runtime/syntax/html.vim			@dkearns
diff --git a/runtime/autoload/context.vim b/runtime/autoload/context.vim
index e42b99e2e9..fc59309768 100644
--- a/runtime/autoload/context.vim
+++ b/runtime/autoload/context.vim
@@ -3,13 +3,18 @@ vim9script
 # Language:           ConTeXt typesetting engine
 # Maintainer:         Nicola Vitacolonna <nvitacolonna@gmail.com>
 # Former Maintainers: Nikolai Weibull <now@bitwi.se>
-# Latest Revision:    2022 Aug 12
+# Latest Revision:    2022 Sep 19
 
 # Typesetting {{{
 import autoload './typeset.vim'
 
 export def ConTeXtCmd(path: string): list<string>
-  return ['mtxrun', '--script', 'context', '--nonstopmode', '--autogenerate', path]
+  var cmd = ['mtxrun', '--script', 'context', '--nonstopmode', '--autogenerate']
+  if !empty(get(g:, 'context_extra_options', ''))
+    cmd += g:context_extra_options
+  endif
+  cmd->add(path)
+  return cmd
 enddef
 
 export def Typeset(bufname: string, env = {}, Cmd = ConTeXtCmd): bool
diff --git a/runtime/autoload/dist/vimindent.vim b/runtime/autoload/dist/vimindent.vim
new file mode 100644
index 0000000000..572fc7c6cb
--- /dev/null
+++ b/runtime/autoload/dist/vimindent.vim
@@ -0,0 +1,1200 @@
+vim9script
+
+# Language:     Vim script
+# Maintainer:   github user lacygoill
+# Last Change:  2022 Sep 24
+
+# Config {{{1
+
+const TIMEOUT: number = get(g:, 'vim_indent', {})
+    ->get('searchpair_timeout', 100)
+
+def IndentMoreInBracketBlock(): number # {{{2
+    if get(g:, 'vim_indent', {})
+            ->get('more_in_bracket_block', false)
+        return shiftwidth()
+    else
+        return 0
+    endif
+enddef
+
+def IndentMoreLineContinuation(): number # {{{2
+    var n: any = get(g:, 'vim_indent', {})
+        # We inspect `g:vim_indent_cont` to stay backward compatible.
+        ->get('line_continuation', get(g:, 'vim_indent_cont', shiftwidth() * 3))
+
+    if n->typename() == 'string'
+        return n->eval()
+    else
+        return n
+    endif
+enddef
+# }}}2
+
+# Init {{{1
+var patterns: list<string>
+# Tokens {{{2
+# BAR_SEPARATION {{{3
+
+const BAR_SEPARATION: string = '[^|\\]\@1<=|'
+
+# OPENING_BRACKET {{{3
+
+const OPENING_BRACKET: string = '[[{(]'
+
+# CLOSING_BRACKET {{{3
+
+const CLOSING_BRACKET: string = '[]})]'
+
+# NON_BRACKET {{{3
+
+const NON_BRACKET: string = '[^[\]{}()]'
+
+# LIST_OR_DICT_CLOSING_BRACKET {{{3
+
+const LIST_OR_DICT_CLOSING_BRACKET: string = '[]}]'
+
+# LIST_OR_DICT_OPENING_BRACKET {{{3
+
+const LIST_OR_DICT_OPENING_BRACKET: string = '[[{]'
+
+# CHARACTER_UNDER_CURSOR {{{3
+
+const CHARACTER_UNDER_CURSOR: string = '\%.c.'
+
+# INLINE_COMMENT {{{3
+
+# TODO: It is not required for an inline comment to be surrounded by whitespace.
+# But it might help against false positives.
+# To be more reliable, we should inspect the syntax, and only require whitespace
+# before  the `#`  comment leader.   But that  might be  too costly  (because of
+# `synstack()`).
+const INLINE_COMMENT: string = '\s[#"]\%(\s\|[{}]\{3}\)'
+
+# INLINE_VIM9_COMMENT {{{3
+
+const INLINE_VIM9_COMMENT: string = '\s#'
+
+# COMMENT {{{3
+
+# TODO: Technically, `"\s` is wrong.
+#
+# First, whitespace is not required.
+# Second, in Vim9, a string might appear at the start of the line.
+# To be sure, we should also inspect the syntax.
+# We can't use `INLINE_COMMENT` here. {{{
+#
+#     const COMMENT: string = $'^\s*{INLINE_COMMENT}'
+#                                    ^------------^
+#                                          ✘
+#
+# Because  `INLINE_COMMENT` asserts  the  presence of  a  whitespace before  the
+# comment leader.  This assertion is not satisfied for a comment starting at the
+# start of the line.
+#}}}
+const COMMENT: string = '^\s*\%(#\|"\\\=\s\).*$'
+
+# DICT_KEY {{{3
+
+const DICT_KEY: string = '^\s*\%('
+    .. '\%(\w\|-\)\+'
+    .. '\|'
+    .. '"[^"]*"'
+    .. '\|'
+    .. "'[^']*'"
+    .. '\|'
+    .. '\[[^]]\+\]'
+    .. '\)'
+    .. ':\%(\s\|$\)'
+
+# END_OF_COMMAND {{{3
+
+const END_OF_COMMAND: string = $'\s*\%($\|||\@!\|{INLINE_COMMENT}\)'
+
+# END_OF_LINE {{{3
+
+const END_OF_LINE: string = $'\s*\%($\|{INLINE_COMMENT}\)'
+
+# END_OF_VIM9_LINE {{{3
+
+const END_OF_VIM9_LINE: string = $'\s*\%($\|{INLINE_VIM9_COMMENT}\)'
+
+# OPERATOR {{{3
+
+const OPERATOR: string = '\%(^\|\s\)\%([-+*/%]\|\.\.\|||\|&&\|??\|?\|<<\|>>\|\%([=!]=\|[<>]=\=\|[=!]\~\|is\|isnot\)[?#]\=\)\%(\s\|$\)\@=\%(\s*[|<]\)\@!'
+    # assignment operators
+    .. '\|' .. '\s\%([-+*/%]\|\.\.\)\==\%(\s\|$\)\@='
+    # support `:` when used inside conditional operator `?:`
+    .. '\|' .. '\%(\s\|^\):\%(\s\|$\)'
+
+# HEREDOC_OPERATOR {{{3
+
+const HEREDOC_OPERATOR: string = '\s=<<\s\@=\%(\s\+\%(trim\|eval\)\)\{,2}'
+
+# PATTERN_DELIMITER {{{3
+
+# A better regex would be:
+#
+#     [^-+*/%.:# \t[:alnum:]\"|]\@=.\|->\@!\%(=\s\)\@!\|[+*/%]\%(=\s\)\@!
+#
+# But sometimes, it can be too costly and cause `E363` to be given.
+const PATTERN_DELIMITER: string = '[-+*/%]\%(=\s\)\@!'
+
+# QUOTE {{{3
+
+const QUOTE: string = '["'']'
+# }}}2
+# Syntaxes {{{2
+# ASSIGNS_HEREDOC {{{3
+
+const ASSIGNS_HEREDOC: string = $'^\%({COMMENT}\)\@!.*\%({HEREDOC_OPERATOR}\)\s\+\zs[A-Z]\+{END_OF_LINE}'
+
+# CD_COMMAND {{{3
+
+const CD_COMMAND: string = $'[lt]\=cd!\=\s\+-{END_OF_COMMAND}'
+
+# HIGHER_ORDER_COMMAND {{{3
+
+patterns =<< trim eval END
+    argdo\>!\=
+    bufdo\>!\=
+    cdo\>!\=
+    folddoc\%[losed]\>
+    foldd\%[oopen]\>
+    ldo\=\>!\=
+    tabdo\=\>
+    windo\>
+    au\%[tocmd]\>.*
+    com\%[mand]\>.*
+    g\%[lobal]!\={PATTERN_DELIMITER}.*
+    v\%[global]!\={PATTERN_DELIMITER}.*
+END
+const HIGHER_ORDER_COMMAND: string = $'\%(^\|{BAR_SEPARATION}\)\s*\<\%(' .. patterns->join('\|') .. '\):\@!'
+
+# MAPPING_COMMAND {{{3
+
+const MAPPING_COMMAND: string = '\%(\<sil\%[ent]!\=\s\+\)\=[nvxsoilct]\=\%(nore\|un\)map!\=\s'
+
+# NORMAL_COMMAND {{{3
+
+const NORMAL_COMMAND: string = '\<norm\%[al]!\=\s*\S\+$'
+
+# PLUS_MINUS_COMMAND {{{3
+
+# In legacy, the `:+` and `:-` commands are not required to be preceded by a colon.
+# As a result, when `+` or `-` is alone on a line, there is ambiguity.
+# It might be an operator or a command.
+# To not break the indentation in legacy scripts, we might need to consider such
+# lines as commands.
+const PLUS_MINUS_COMMAND: string = '^\s*[+-]\s*$'
+
+# ENDS_BLOCK {{{3
+
+const ENDS_BLOCK: string = '^\s*\%('
+    .. 'en\%[dif]'
+    .. '\|' .. 'endfor\='
+    .. '\|' .. 'endw\%[hile]'
+    .. '\|' .. 'endt\%[ry]'
+    .. '\|' .. 'enddef'
+    .. '\|' .. 'endf\%[unction]'
+    .. '\|' .. 'aug\%[roup]\s\+[eE][nN][dD]'
+    .. '\|' .. CLOSING_BRACKET
+    .. $'\){END_OF_COMMAND}'
+
+# ENDS_BLOCK_OR_CLAUSE {{{3
+
+patterns =<< trim END
+    en\%[dif]
+    el\%[se]
+    endfor\=
+    endw\%[hile]
+    endt\%[ry]
+    fina\|finally\=
+    enddef
+    endf\%[unction]
+    aug\%[roup]\s\+[eE][nN][dD]
+END
+
+const ENDS_BLOCK_OR_CLAUSE: string = '^\s*\%(' .. patterns->join('\|') .. $'\){END_OF_COMMAND}'
+    .. $'\|^\s*cat\%[ch]\%(\s\+\({PATTERN_DELIMITER}\).*\1\)\={END_OF_COMMAND}'
+    .. $'\|^\s*elseif\=\s\+\%({OPERATOR}\)\@!'
+
+# STARTS_CURLY_BLOCK {{{3
+
+# TODO: `{` alone on a line is not necessarily the start of a block.
+# It  could be  a dictionary  if the  previous line  ends with  a binary/ternary
+# operator.  This  can cause  an issue whenever  we use  `STARTS_CURLY_BLOCK` or
+# `LINE_CONTINUATION_AT_EOL`.
+const STARTS_CURLY_BLOCK: string = '\%('
+    .. '^\s*{'
+    .. '\|' .. '^.*\zs\s=>\s\+{'
+    .. '\|' ..  $'^\%(\s*\|.*{BAR_SEPARATION}\s*\)\%(com\%[mand]\|au\%[tocmd]\).*\zs\s{{'
+    .. '\)' .. END_OF_COMMAND
+
+# STARTS_NAMED_BLOCK {{{3
+
+# All of these will be used at the start of a line (or after a bar).
+# NOTE: Don't replace `\%x28` with `(`.{{{
+#
+# Otherwise, the paren would be unbalanced which might cause syntax highlighting
+# issues much  later in the  code of the  current script (sometimes,  the syntax
+# highlighting plugin fails  to correctly recognize a heredoc which  is far away
+# and/or not displayed because inside a fold).
+# }}}
+patterns =<< trim END
+    if
+    el\%[se]
+    elseif\=
+    for
+    wh\%[ile]
+    try
+    cat\%[ch]
+    fina\|finally\=
+    fu\%[nction]\%x28\@!
+    \%(export\s\+\)\=def
+    aug\%[roup]\%(\s\+[eE][nN][dD]\)\@!\s\+\S\+
+END
+const STARTS_NAMED_BLOCK: string = '^\s*\%(sil\%[ent]\s\+\)\=\%(' .. patterns->join('\|') .. '\)\>:\@!'
+
+# STARTS_FUNCTION {{{3
+
+const STARTS_FUNCTION: string = '^\s*\%(export\s\+\)\=def\>:\@!'
+
+# ENDS_FUNCTION {{{3
+
+const ENDS_FUNCTION: string = $'^\s*enddef\>:\@!{END_OF_COMMAND}'
+
+# START_MIDDLE_END {{{3
+
+const START_MIDDLE_END: dict<list<string>> = {
+    if: ['if', 'el\%[se]\|elseif\=', 'en\%[dif]'],
+    else: ['if', 'el\%[se]\|elseif\=', 'en\%[dif]'],
+    elseif: ['if', 'el\%[se]\|elseif\=', 'en\%[dif]'],
+    endif: ['if', 'el\%[se]\|elseif\=', 'en\%[dif]'],
+    for: ['for', '', 'endfor\='],
+    endfor: ['for', '', 'endfor\='],
+    while: ['wh\%[ile]', '', 'endw\%[hile]'],
+    endwhile: ['wh\%[ile]', '', 'endw\%[hile]'],
+    try: ['try', 'cat\%[ch]\|fina\|finally\=', 'endt\%[ry]'],
+    catch: ['try', 'cat\%[ch]\|fina\|finally\=', 'endt\%[ry]'],
+    finally: ['try', 'cat\%[ch]\|fina\|finally\=', 'endt\%[ry]'],
+    endtry: ['try', 'cat\%[ch]\|fina\|finally\=', 'endt\%[ry]'],
+    def: ['\%(export\s\+\)\=def', '', 'enddef'],
+    enddef: ['\%(export\s\+\)\=def', '', 'enddef'],
+    function: ['fu\%[nction]', '', 'endf\%[unction]'],
+    endfunction: ['fu\%[nction]', '', 'endf\%[unction]'],
+    augroup: ['aug\%[roup]\%(\s\+[eE][nN][dD]\)\@!\s\+\S\+', '', 'aug\%[roup]\s\+[eE][nN][dD]'],
+}->map((_, kwds: list<string>) =>
+    kwds->map((_, kwd: string) => kwd == ''
+    ? ''
+    : $'\%(^\|{BAR_SEPARATION}\|\<sil\%[ent]\|{HIGHER_ORDER_COMMAND}\)\s*'
+    .. $'\%({printf('\C\<\%%(%s\)\>:\@!\%%(\s*%s\)\@!', kwd, OPERATOR)}\)'))
+# }}}2
+# EOL {{{2
+# OPENING_BRACKET_AT_EOL {{{3
+
+const OPENING_BRACKET_AT_EOL: string = $'{OPENING_BRACKET}{END_OF_VIM9_LINE}'
+
+# COMMA_AT_EOL {{{3
+
+const COMMA_AT_EOL: string = $',{END_OF_VIM9_LINE}'
+
+# COMMA_OR_DICT_KEY_AT_EOL {{{3
+
+const COMMA_OR_DICT_KEY_AT_EOL: string = $'\%(,\|{DICT_KEY}\){END_OF_VIM9_LINE}'
+
+# LAMBDA_ARROW_AT_EOL {{{3
+
+const LAMBDA_ARROW_AT_EOL: string = $'\s=>{END_OF_VIM9_LINE}'
+
+# LINE_CONTINUATION_AT_EOL {{{3
+
+const LINE_CONTINUATION_AT_EOL: string = '\%('
+    .. ','
+    .. '\|' .. OPERATOR
+    .. '\|' .. '\s=>'
+    .. '\|' .. '[^=]\zs[[(]'
+    .. '\|' .. DICT_KEY
+    # `{` is ambiguous.
+    # It can be the start of a dictionary or a block.
+    # We only want to match the former.
+    .. '\|' .. $'^\%({STARTS_CURLY_BLOCK}\)\@!.*\zs{{'
+    .. '\)\s*\%(\s#.*\)\=$'
+# }}}2
+# SOL {{{2
+# BACKSLASH_AT_SOL {{{3
+
+const BACKSLASH_AT_SOL: string = '^\s*\%(\\\|[#"]\\ \)'
+
+# CLOSING_BRACKET_AT_SOL {{{3
+
+const CLOSING_BRACKET_AT_SOL: string = $'^\s*{CLOSING_BRACKET}'
+
+# LINE_CONTINUATION_AT_SOL {{{3
+
+const LINE_CONTINUATION_AT_SOL: string = '^\s*\%('
+    .. '\\'
+    .. '\|' .. '[#"]\\ '
+    .. '\|' .. OPERATOR
+    .. '\|' .. '->\s*\h'
+    .. '\|' .. '\.\h'  # dict member
+    .. '\|' .. '|'
+    # TODO: `}` at the start of a line is not necessarily a line continuation.
+    # Could be the end of a block.
+    .. '\|' .. CLOSING_BRACKET
+    .. '\)'
+
+# RANGE_AT_SOL {{{3
+
+const RANGE_AT_SOL: string = '^\s*:\S'
+# }}}1
+# Interface {{{1
+export def Expr(lnum: number): number # {{{2
+    # line which is indented
+    var line_A: dict<any> = {text: getline(lnum), lnum: lnum}
+    # line above, on which we'll base the indent of line A
+    var line_B: dict<any>
+
+    if line_A->AtStartOf('HereDoc')
+        line_A->CacheHeredoc()
+    elseif line_A.lnum->IsInside('HereDoc')
+        return line_A.text->HereDocIndent()
+    elseif line_A.lnum->IsRightBelow('HereDoc')
+        var ind: number = b:vimindent.startindent
+        unlet! b:vimindent
+        return ind
+    endif
+
+    # Don't move this block after the function header one.
+    # Otherwise, we  might clear the cache  too early if the  line following the
+    # header is a comment.
+    if line_A.text =~ COMMENT
+        return CommentIndent()
+    endif
+
+    line_B = PrevCodeLine(line_A.lnum)
+    if line_A.text =~ BACKSLASH_AT_SOL
+        if line_B.text =~ BACKSLASH_AT_SOL
+            return Indent(line_B.lnum)
+        else
+            return Indent(line_B.lnum) + IndentMoreLineContinuation()
+        endif
+    endif
+
+    if line_A->AtStartOf('FuncHeader')
+        line_A.lnum->CacheFuncHeader()
+    elseif line_A.lnum->IsInside('FuncHeader')
+        return b:vimindent.startindent + 2 * shiftwidth()
+    elseif line_A.lnum->IsRightBelow('FuncHeader')
+        var startindent: number = b:vimindent.startindent
+        unlet! b:vimindent
+        if line_A.text =~ ENDS_FUNCTION
+            return startindent
+        else
+            return startindent + shiftwidth()
+        endif
+    endif
+
+    var past_bracket_block: dict<any>
+    if exists('b:vimindent')
+            && b:vimindent->has_key('is_BracketBlock')
+        past_bracket_block = RemovePastBracketBlock(line_A)
+    endif
+    if line_A->AtStartOf('BracketBlock')
+        line_A->CacheBracketBlock()
+    endif
+    if line_A.lnum->IsInside('BracketBlock')
+            && !b:vimindent.block_stack[0].is_curly_block
+        for block: dict<any> in b:vimindent.block_stack
+            # Can't call `BracketBlockIndent()` before we're indenting a line *after* the start of the block.{{{
+            #
+            # That's because it might need  the correct indentation of the start
+            # of the block.   But if we're still *on* the  start, we haven't yet
+            # computed that indentation.
+            #}}}
+            if line_A.lnum > block.startlnum
+                    && !block.is_curly_block
+                return BracketBlockIndent(line_A, block)
+            endif
+        endfor
+    endif
+    if line_A.text->ContinuesBelowBracketBlock(line_B, past_bracket_block)
+            && line_A.text !~ CLOSING_BRACKET_AT_SOL
+        return past_bracket_block.startindent
+    endif
+
+    # Problem: If we press `==` on the line right below the start of a multiline
+    # lambda (split after its arrow `=>`), the indent is not correct.
+    # Solution: Indent relative to the line above.
+    if line_B->EndsWithLambdaArrow()
+        return Indent(line_B.lnum) + shiftwidth() + IndentMoreInBracketBlock()
+    endif
+
+    # Don't move this block before the heredoc one.{{{
+    #
+    # A heredoc might be assigned on the very first line.
+    # And if it is, we need to cache some info.
+    #}}}
+    # Don't move it before the function header and bracket block ones either.{{{
+    #
+    # You could, because these blocks of code deal with construct which can only
+    # appear  in a  Vim9  script.  And  in  a  Vim9 script,  the  first line  is
+    # `vim9script`.  Or  maybe some legacy code/comment  (see `:help vim9-mix`).
+    # But you  can't find a  Vim9 function header or  Vim9 bracket block  on the
+    # first line.
+    #
+    # Anyway, even if you could, don't.  First, it would be inconsistent.
+    # Second, it  could give unexpected results  while we're trying to  fix some
+    # failing test.
+    #}}}
+    if line_A.lnum == 1
+        return 0
+    endif
+
+    # Don't do that:
+    #     if line_A.text !~ '\S'
+    #         return -1
+    #     endif
+    # It would prevent  a line from being automatically indented  when using the
+    # normal command `o`.
+    # TODO: Can we write a test for this?
+
+    if line_B.text =~ STARTS_CURLY_BLOCK
+        return Indent(line_B.lnum) + shiftwidth() + IndentMoreInBracketBlock()
+
+    elseif line_A.text =~ CLOSING_BRACKET_AT_SOL
+        var start: number = MatchingOpenBracket(line_A)
+        if start <= 0
+            return -1
+        endif
+        return Indent(start) + IndentMoreInBracketBlock()
+
+    elseif line_A.text =~ ENDS_BLOCK_OR_CLAUSE
+            && !line_B->EndsWithLineContinuation()
+        var kwd: string = BlockStartKeyword(line_A.text)
+        if !START_MIDDLE_END->has_key(kwd)
+            return -1
+        endif
+
+        # If the cursor  is after the match  for the end pattern,  we won't find
+        # the start of the block.  Let's make sure that doesn't happen.
+        cursor(line_A.lnum, 1)
+
+        var [start: string, middle: string, end: string] = START_MIDDLE_END[kwd]
+        var block_start = SearchPairStart(start, middle, end)
+        if block_start > 0
+            return Indent(block_start)
+        else
+            return -1
+        endif
+    endif
+
+    var base_ind: number
+    if line_A->IsFirstLineOfCommand(line_B)
+        line_A.isfirst = true
+        line_B = line_B->FirstLinePreviousCommand()
+        base_ind = Indent(line_B.lnum)
+
+        if line_B->EndsWithCurlyBlock()
+                && !line_A->IsInThisBlock(line_B.lnum)
+            return base_ind
+        endif
+
+    else
+        line_A.isfirst = false
+        base_ind = Indent(line_B.lnum)
+
+        var line_C: dict<any> = PrevCodeLine(line_B.lnum)
+        if !line_B->IsFirstLineOfCommand(line_C) || line_C.lnum <= 0
+            return base_ind
+        endif
+    endif
+
+    var ind: number = base_ind + Offset(line_A, line_B)
+    return [ind, 0]->max()
+enddef
+
+def g:GetVimIndent(): number # {{{2
+    # for backward compatibility
+    return Expr(v:lnum)
+enddef
+# }}}1
+# Core {{{1
+def Offset( # {{{2
+        # we indent this line ...
+        line_A: dict<any>,
+        # ... relatively to this line
+        line_B: dict<any>,
+        ): number
+
+    # increase indentation inside a block
+    if line_B.text =~ STARTS_NAMED_BLOCK || line_B->EndsWithCurlyBlock()
+        # But don't indent if the line starting the block also closes it.
+        if line_B->AlsoClosesBlock()
+            return 0
+        # Indent twice for  a line continuation in the block  header itself, so that
+        # we can easily  distinguish the end of  the block header from  the start of
+        # the block body.
+        elseif line_B->EndsWithLineContinuation()
+                && !line_A.isfirst
+                || line_A.text =~ LINE_CONTINUATION_AT_SOL
+                && line_A.text !~ PLUS_MINUS_COMMAND
+                || line_A.text->Is_IN_KeywordForLoop(line_B.text)
+            return 2 * shiftwidth()
+        else
+            return shiftwidth()
+        endif
+
+    # increase indentation of  a line if it's the continuation  of a command which
+    # started on a previous line
+    elseif !line_A.isfirst
+            && (line_B->EndsWithLineContinuation()
+            || line_A.text =~ LINE_CONTINUATION_AT_SOL)
+        return shiftwidth()
+    endif
+
+    return 0
+enddef
+
+def HereDocIndent(line_A: string): number # {{{2
+    # at the end of a heredoc
+    if line_A =~ $'^\s*{b:vimindent.endmarker}$'
+        # `END` must be at the very start of the line if the heredoc is not trimmed
+        if !b:vimindent.is_trimmed
+            # We can't invalidate the cache just yet.
+            # The indent of `END` is meaningless;  it's always 0.  The next line
+            # will need to be indented relative to the start of the heredoc.  It
+            # must know where it starts; it needs the cache.
+            return 0
+        else
+            var ind: number = b:vimindent.startindent
+            # invalidate the cache so that it's not used for the next heredoc
+            unlet! b:vimindent
+            return ind
+        endif
+    endif
+
+    # In a non-trimmed heredoc, all of leading whitespace is semantic.
+    # Leave it alone.
+    if !b:vimindent.is_trimmed
+        # But do save the indent of the assignment line.
+        if !b:vimindent->has_key('startindent')
+            b:vimindent.startindent = b:vimindent.startlnum->Indent()
+        endif
+        return -1
+    endif
+
+    # In a trimmed heredoc, *some* of the leading whitespace is semantic.
+    # We want to preserve  it, so we can't just indent  relative to the assignment
+    # line.  That's because we're dealing with data, not with code.
+    # Instead, we need  to compute by how  much the indent of  the assignment line
+    # was increased  or decreased.   Then, we  need to apply  that same  change to
+    # every line inside the body.
+    var offset: number
+    if !b:vimindent->has_key('offset')
+        var old_startindent: number = b:vimindent.startindent
+        var new_startindent: number = b:vimindent.startlnum->Indent()
+        offset = new_startindent - old_startindent
+
+        # If all the non-empty lines in  the body have a higher indentation relative
+        # to the assignment, there is no need to indent them more.
+        # But if  at least one of  them does have  the same indentation level  (or a
+        # lower one), then we want to indent it further (and the whole block with it).
+        # This way,  we can clearly distinguish  the heredoc block from  the rest of
+        # the code.
+        var end: number = search($'^\s*{b:vimindent.endmarker}$', 'nW')
+        var should_indent_more: bool = range(v:lnum, end - 1)
+            ->indexof((_, lnum: number): bool => Indent(lnum) <= old_startindent && getline(lnum) != '') >= 0
+        if should_indent_more
+            offset += shiftwidth()
+        endif