Implement buffer-wide virtual text support (#4289)

* Remove virtual text via types-filter

This is more robust and has the additional sideeffect that it will make
it easier to implement showing virtual text for all warnings
simultaneously.

We definitely do not want to do a call to prop_remove() for every
virtual text as that will cause noticeable lag when many warnings are
present, thus we can use this to remove all virtual text lines with one
call in the future.

Fixes #4294

refs: https://github.com/vim/vim/pull/10945

* Allow virtual text to appear for all warnings of the buffer

This can be enabled with:

let g:ale_virtualtext_cursor = 2

It is implemented both for neovim and vim 9.0.0297.

Note that sometimes it may appear like some warnings are displayed
multiple times. This is not a bug in the virtual text implementation,
but a sideeffect of multiple linters returning similar results.

For example for Rust, the 'cargo' and 'rls' linters appear to be
activated at the same time, but they sometimes return identical errors.
This causes the virtual text to show the same warning twice.

In the future we can mitigate this problem by removing duplicate errors
from our internal location list.

However users can also achieve cleaner warnings simply by activating
only one linter for each language (or multiple unambiguous linters).

For example for Rust, the problem could be solved with:

let g:ale_linters = {'rust': ['analyzer']}

Fixes #2962
Fixes #3666

5 files changed, 68 insertions, 42 deletions

diff --git a/autoload/ale/engine.vim b/autoload/ale/engine.vim
index 00789a2d..97c46656 100644
--- a/autoload/ale/engine.vim
+++ b/autoload/ale/engine.vim
@@ -203,6 +203,10 @@ function! ale#engine#SetResults(buffer, loclist) abort
         call ale#highlight#SetHighlights(a:buffer, a:loclist)
     endif
 
+    if g:ale_virtualtext_cursor == 2
+        call ale#virtualtext#SetTexts(a:buffer, a:loclist)
+    endif
+
     if l:linting_is_done
         if g:ale_echo_cursor
             " Try and echo the warning now.
@@ -210,7 +214,7 @@ function! ale#engine#SetResults(buffer, loclist) abort
             call ale#cursor#EchoCursorWarning()
         endif
 
-        if g:ale_virtualtext_cursor
+        if g:ale_virtualtext_cursor == 1
             " Try and show the warning now.
             " This will only do something meaningful if we're in normal mode.
             call ale#virtualtext#ShowCursorWarning()
diff --git a/autoload/ale/events.vim b/autoload/ale/events.vim
index b8350c79..4efb8a3b 100644
--- a/autoload/ale/events.vim
+++ b/autoload/ale/events.vim
@@ -139,7 +139,7 @@ function! ale#events#Init() abort
                 autocmd InsertLeave * if exists('*ale#engine#Cleanup') | call ale#cursor#EchoCursorWarning() | endif
             endif
 
-            if g:ale_virtualtext_cursor
+            if g:ale_virtualtext_cursor == 1
                 autocmd CursorMoved,CursorHold * if exists('*ale#engine#Cleanup') | call ale#virtualtext#ShowCursorWarningWithDelay() | endif
                 " Look for a warning to echo as soon as we leave Insert mode.
                 " The script's position variable used when moving the cursor will
diff --git a/autoload/ale/toggle.vim b/autoload/ale/toggle.vim
index 122d6cc4..7f8957d4 100644
--- a/autoload/ale/toggle.vim
+++ b/autoload/ale/toggle.vim
@@ -14,8 +14,8 @@ function! s:DisablePostamble() abort
         call ale#highlight#UpdateHighlights()
     endif
 
-    if g:ale_virtualtext_cursor
-        call ale#virtualtext#Clear()
+    if g:ale_virtualtext_cursor == 1
+        call ale#virtualtext#Clear(bufnr(''))
     endif
 endfunction
 
diff --git a/autoload/ale/virtualtext.vim b/autoload/ale/virtualtext.vim
index e4bf5d25..5fade39b 100644
--- a/autoload/ale/virtualtext.vim
+++ b/autoload/ale/virtualtext.vim
@@ -15,52 +15,49 @@ if has('nvim-0.3.2')
     let s:has_virt_text = 1
 elseif has('textprop') && has('popupwin')
     let s:has_virt_text = 1
-    let s:emulate_virt = !has('patch-9.0.0214')
+    let s:emulate_virt = !has('patch-9.0.0297')
+    let s:hl_list = []
 
     if s:emulate_virt
         call prop_type_add('ale', {})
         let s:last_virt = -1
-    else
-        let s:last_virt = 1
     endif
 endif
 
-function! ale#virtualtext#Clear() abort
+function! ale#virtualtext#Clear(buf) abort
     if !s:has_virt_text
         return
     endif
 
-    let l:buffer = bufnr('')
-
     if has('nvim')
-        call nvim_buf_clear_highlight(l:buffer, s:ns_id, 0, -1)
+        call nvim_buf_clear_namespace(a:buf, s:ns_id, 0, -1)
     else
         if s:emulate_virt && s:last_virt != -1
             call prop_remove({'type': 'ale'})
             call popup_close(s:last_virt)
             let s:last_virt = -1
-        elseif !s:emulate_virt && s:last_virt != 1
-            call prop_remove({'id': s:last_virt})
-            let s:last_virt = 1
+        elseif !empty(s:hl_list)
+            call prop_remove({
+            \ 'types': s:hl_list,
+            \ 'all': 1,
+            \ 'bufnr': a:buf})
         endif
     endif
 endfunction
 
-function! ale#virtualtext#ShowMessage(message, hl_group) abort
-    if !s:has_virt_text
+function! ale#virtualtext#ShowMessage(message, hl_group, buf, line) abort
+    if !s:has_virt_text || !bufexists(str2nr(a:buf))
         return
     endif
 
-    let l:line = line('.')
-    let l:buffer = bufnr('')
     let l:prefix = get(g:, 'ale_virtualtext_prefix', '> ')
     let l:msg = l:prefix.trim(substitute(a:message, '\n', ' ', 'g'))
 
     if has('nvim')
-        call nvim_buf_set_virtual_text(l:buffer, s:ns_id, l:line-1, [[l:msg, a:hl_group]], {})
+        call nvim_buf_set_virtual_text(a:buf, s:ns_id, a:line-1, [[l:msg, a:hl_group]], {})
     elseif s:emulate_virt
         let l:left_pad = col('$')
-        call prop_add(l:line, l:left_pad, {
+        call prop_add(a:line, l:left_pad, {
         \ 'type': 'ale',
         \})
         let s:last_virt = popup_create(l:msg, {
@@ -77,12 +74,14 @@ function! ale#virtualtext#ShowMessage(message, hl_group) abort
         let type = prop_type_get(a:hl_group)
 
         if type == {}
+            call add(s:hl_list, a:hl_group)
             call prop_type_add(a:hl_group, {'highlight': a:hl_group})
         endif
 
-        let s:last_virt = prop_add(l:line, 0, {
+        call prop_add(a:line, 0, {
         \ 'type': a:hl_group,
-        \ 'text': ' ' . l:msg
+        \ 'text': ' ' . l:msg,
+        \ 'bufnr': a:buf
         \})
     endif
 endfunction
@@ -94,8 +93,26 @@ function! s:StopCursorTimer() abort
     endif
 endfunction
 
+function! ale#virtualtext#GetHlGroup(type, style) abort
+    if a:type is# 'E'
+        if a:style is# 'style'
+            return 'ALEVirtualTextStyleError'
+        else
+            return 'ALEVirtualTextError'
+        endif
+    elseif a:type is# 'W'
+        if a:style is# 'style'
+            return 'ALEVirtualTextStyleWarning'
+        else
+            return 'ALEVirtualTextWarning'
+        endif
+    else
+        return 'ALEVirtualTextInfo'
+    endif
+endfunction
+
 function! ale#virtualtext#ShowCursorWarning(...) abort
-    if !g:ale_virtualtext_cursor
+    if g:ale_virtualtext_cursor != 1
         return
     endif
 
@@ -111,35 +128,21 @@ function! ale#virtualtext#ShowCursorWarning(...) abort
 
     let [l:info, l:loc] = ale#util#FindItemAtCursor(l:buffer)
 
-    call ale#virtualtext#Clear()
+    call ale#virtualtext#Clear(l:buffer)
 
     if !empty(l:loc)
         let l:msg = l:loc.text
-        let l:hl_group = 'ALEVirtualTextInfo'
         let l:type = get(l:loc, 'type', 'E')
-
-        if l:type is# 'E'
-            if get(l:loc, 'sub_type', '') is# 'style'
-                let l:hl_group = 'ALEVirtualTextStyleError'
-            else
-                let l:hl_group = 'ALEVirtualTextError'
-            endif
-        elseif l:type is# 'W'
-            if get(l:loc, 'sub_type', '') is# 'style'
-                let l:hl_group = 'ALEVirtualTextStyleWarning'
-            else
-                let l:hl_group = 'ALEVirtualTextWarning'
-            endif
-        endif
-
-        call ale#virtualtext#ShowMessage(l:msg, l:hl_group)
+        let l:style = get(l:loc, 'sub_type', '')
+        let l:hl_group = ale#virtualtext#GetHlGroup(l:type, l:style)
+        call ale#virtualtext#ShowMessage(l:msg, l:hl_group, l:buffer, line('.'))
     endif
 endfunction
 
 function! ale#virtualtext#ShowCursorWarningWithDelay() abort
     let l:buffer = bufnr('')
 
-    if !g:ale_virtualtext_cursor
+    if g:ale_virtualtext_cursor != 1
         return
     endif
 
@@ -166,3 +169,19 @@ function! ale#virtualtext#ShowCursorWarningWithDelay() abort
     endif
 endfunction
 
+function! ale#virtualtext#SetTexts(buf, loclist) abort
+    if !has('nvim') && s:emulate_virt
+        return
+    endif
+
+    call ale#virtualtext#Clear(a:buf)
+
+    for l in a:loclist
+        if l['bufnr'] != a:buf
+            continue
+        endif
+
+        let hl = ale#virtualtext#GetHlGroup(l['type'], get(l, 'sub_type', ''))
+        call ale#virtualtext#ShowMessage(l['text'], hl, a:buf, l['lnum'])
+    endfor
+endfunction
diff --git a/doc/ale.txt b/doc/ale.txt
index c9cb8585..049f7159 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -2297,6 +2297,9 @@ g:ale_virtualtext_cursor                             *g:ale_virtualtext_cursor*
   column nearest to the cursor when the cursor is resting on a line which
   contains a warning or error. This option can be set to `0` to disable this
   behavior.
+  When this option is set to `2`, then all warnings will be shown for the
+  whole buffer, regardless of if the cursor is currently positioned in that
+  line.
 
   Messages are only displayed after a short delay. See |g:ale_virtualtext_delay|.