fix: simplify root handling during tex parser

Did not see exactly what was wrong, but it seems I was passing the root
as part of an option dict and somehow did not control the dict properly.
But we did not need the dict and could just simply pass the root value
directly. That seems to fix things.

refer: #3208

Author: lervag

autoload/vimtex/parser/tex.vim

@@ -16,7 +16,7 @@ function! vimtex#parser#tex#parse(file, opts) abort " {{{1
         \ 'default': {'ftime': -2},
         \})
 
-  let l:parsed = s:parse(a:file, l:opts, l:cache)
+  let l:parsed = s:parse(a:file, l:opts.root, l:cache)
 
   if !l:opts.detailed
     call map(l:parsed, 'v:val[2]')
@@ -37,7 +37,7 @@ function! vimtex#parser#tex#parse_files(file, opts) abort " {{{1
         \ 'default': {'ftime': -2},
         \})
 
-  return vimtex#util#uniq_unsorted(s:parse_files(a:file, l:opts, l:cache))
+  return vimtex#util#uniq_unsorted(s:parse_files(a:file, l:opts.root, l:cache))
 endfunction
 
 " }}}1
@@ -55,7 +55,7 @@ function! vimtex#parser#tex#parse_preamble(file, opts) abort " {{{1
   let l:time = min([localtime() - 60, getftime(a:file)])
   if l:time > l:current.time
     let l:current.time = l:time
-    let l:current.lines = s:parse_preamble(a:file, l:opts, [])
+    let l:current.lines = s:parse_preamble(a:file, l:opts.root, [])
   endif
 
   return deepcopy(l:current.lines)
@@ -179,12 +179,12 @@ endfunction
 " }}}1
 
 
-function! s:parse(file, opts, cache) abort " {{{1
+function! s:parse(file, root, cache) abort " {{{1
   let l:current = a:cache.get(a:file)
   let l:ftime = getftime(a:file)
   if l:ftime > l:current.ftime
     let l:current.ftime = l:ftime
-    call s:parse_current(a:file, a:opts, l:current)
+    call s:parse_current(a:file, a:root, l:current)
   endif
 
   let l:parsed = []
@@ -193,37 +193,35 @@ function! s:parse(file, opts, cache) abort " {{{1
     if type(l:val) == v:t_list
       call add(l:parsed, l:val)
     else
-      call extend(l:parsed, s:parse(l:val, a:opts, a:cache))
+      let l:parsed += s:parse(l:val.file, l:val.new_root, a:cache)
     endif
   endfor
 
   return l:parsed
 endfunction
 
 " }}}1
-function! s:parse_files(file, opts, cache) abort " {{{1
+function! s:parse_files(file, root, cache) abort " {{{1
   let l:current = a:cache.get(a:file)
   let l:ftime = getftime(a:file)
   if l:ftime > l:current.ftime
     let l:current.ftime = l:ftime
-    call s:parse_current(a:file, a:opts, l:current)
+    call s:parse_current(a:file, a:root, l:current)
   endif
 
   " Only include existing files
   if !filereadable(a:file) | return [] | endif
 
   let l:files = [a:file]
   for l:included in l:current.includes
-    let l:opts = deepcopy(a:opts)
-    let l:opts.root = l:included.new_root
-    let l:files += s:parse_files(l:included.file, l:opts, a:cache)
+    let l:files += s:parse_files(l:included.file, l:included.new_root, a:cache)
   endfor
 
   return l:files
 endfunction
 
 " }}}1
-function! s:parse_current(file, opts, current) abort " {{{1
+function! s:parse_current(file, root, current) abort " {{{1
   let a:current.lines = []
   let a:current.includes = []
 
@@ -243,8 +241,8 @@ function! s:parse_current(file, opts, current) abort " {{{1
         continue
       endif
 
-      let l:result = vimtex#parser#tex#input_parser(l:line, a:file, a:opts.root)
-      call add(a:current.lines, l:result.file)
+      let l:result = vimtex#parser#tex#input_parser(l:line, a:file, a:root)
+      call add(a:current.lines, l:result)
 
       if a:file ==# l:result.file
         call vimtex#log#error([
@@ -261,7 +259,7 @@ function! s:parse_current(file, opts, current) abort " {{{1
 endfunction
 
 " }}}1
-function! s:parse_preamble(file, opts, parsed_files) abort " {{{1
+function! s:parse_preamble(file, root, parsed_files) abort " {{{1
   if !filereadable(a:file) || index(a:parsed_files, a:file) >= 0
     return []
   endif
@@ -270,11 +268,9 @@ function! s:parse_preamble(file, opts, parsed_files) abort " {{{1
   let l:lines = []
   for l:line in readfile(a:file)
     if l:line =~# g:vimtex#re#tex_input
-      let l:result = vimtex#parser#tex#input_parser(l:line, a:file, a:opts.root)
-
-      let l:opts = deepcopy(a:opts)
-      let l:opts.root = l:result.new_root
-      call extend(l:lines, s:parse_preamble(l:result.file, l:opts, a:parsed_files))
+      let l:result = vimtex#parser#tex#input_parser(l:line, a:file, a:root)
+      let l:lines += s:parse_preamble(
+            \ l:result.file, l:result.new_root, a:parsed_files)
     else
       call add(l:lines, l:line)
     endif