Merge pull request #1 from w0rp/master

update

13 files changed, 361 insertions, 219 deletions

diff --git a/autoload/ale.vim b/autoload/ale.vim
index 26c73547..6d1e8521 100644
--- a/autoload/ale.vim
+++ b/autoload/ale.vim
@@ -192,12 +192,7 @@ endfunction
 " Every variable name will be prefixed with 'ale_'.
 function! ale#Var(buffer, variable_name) abort
     let l:full_name = 'ale_' . a:variable_name
-    let l:vars = getbufvar(str2nr(a:buffer), '', 0)
-
-    if l:vars is 0
-        " Look for variables from deleted buffers, saved from :ALEFix
-        let l:vars = get(get(g:ale_fix_buffer_data, a:buffer, {}), 'vars', {})
-    endif
+    let l:vars = getbufvar(str2nr(a:buffer), '', {})
 
     return get(l:vars, l:full_name, g:[l:full_name])
 endfunction
diff --git a/autoload/ale/balloon.vim b/autoload/ale/balloon.vim
index 7a380da2..72f6b91c 100644
--- a/autoload/ale/balloon.vim
+++ b/autoload/ale/balloon.vim
@@ -34,26 +34,25 @@ function! ale#balloon#Expr() abort
 endfunction
 
 function! ale#balloon#Disable() abort
+    if has('balloon_eval')
+        set noballooneval
+        set balloonexpr=
+    endif
+
     if has('balloon_eval_term')
         set noballoonevalterm
+        set balloonexpr=
     endif
-
-    set noballooneval
-    set balloonexpr=
 endfunction
 
 function! ale#balloon#Enable() abort
-    if !has('balloon_eval') && !has('balloon_eval_term')
-        return
-    endif
-
     if has('balloon_eval')
         set ballooneval
+        set balloonexpr=ale#balloon#Expr()
     endif
 
     if has('balloon_eval_term')
         set balloonevalterm
+        set balloonexpr=ale#balloon#Expr()
     endif
-
-    set balloonexpr=ale#balloon#Expr()
 endfunction
diff --git a/autoload/ale/c.vim b/autoload/ale/c.vim
index 5ab10f00..fbfe9509 100644
--- a/autoload/ale/c.vim
+++ b/autoload/ale/c.vim
@@ -4,8 +4,11 @@
 call ale#Set('c_parse_makefile', 0)
 let s:sep = has('win32') ? '\' : '/'
 
+" Set just so tests can override it.
+let g:__ale_c_project_filenames = ['.git/HEAD', 'configure', 'Makefile', 'CMakeLists.txt']
+
 function! ale#c#FindProjectRoot(buffer) abort
-    for l:project_filename in ['.git/HEAD', 'configure', 'Makefile', 'CMakeLists.txt']
+    for l:project_filename in g:__ale_c_project_filenames
         let l:full_path = ale#path#FindNearestFile(a:buffer, l:project_filename)
 
         if !empty(l:full_path)
diff --git a/autoload/ale/completion.vim b/autoload/ale/completion.vim
index e7da4028..7440f8cd 100644
--- a/autoload/ale/completion.vim
+++ b/autoload/ale/completion.vim
@@ -336,7 +336,9 @@ function! ale#completion#ParseLSPCompletions(response) abort
         endif
 
         " See :help complete-items for Vim completion kinds
-        if l:item.kind is s:LSP_COMPLETION_METHOD_KIND
+        if !has_key(l:item, 'kind')
+            let l:kind = 'v'
+        elseif l:item.kind is s:LSP_COMPLETION_METHOD_KIND
             let l:kind = 'm'
         elseif l:item.kind is s:LSP_COMPLETION_CONSTRUCTOR_KIND
             let l:kind = 'm'
@@ -422,54 +424,65 @@ endfunction
 
 function! s:GetLSPCompletions(linter) abort
     let l:buffer = bufnr('')
-    let l:Callback = a:linter.lsp is# 'tsserver'
-    \   ? function('ale#completion#HandleTSServerResponse')
-    \   : function('ale#completion#HandleLSPResponse')
-
-    let l:lsp_details = ale#lsp_linter#StartLSP(l:buffer, a:linter, l:Callback)
+    let l:lsp_details = ale#lsp_linter#StartLSP(l:buffer, a:linter)
 
     if empty(l:lsp_details)
         return 0
     endif
 
     let l:id = l:lsp_details.connection_id
+    let l:root = l:lsp_details.project_root
 
-    if a:linter.lsp is# 'tsserver'
-        let l:message = ale#lsp#tsserver_message#Completions(
-        \   l:buffer,
-        \   b:ale_completion_info.line,
-        \   b:ale_completion_info.column,
-        \   b:ale_completion_info.prefix,
-        \)
-    else
-        " Send a message saying the buffer has changed first, otherwise
-        " completions won't know what text is nearby.
-        call ale#lsp#NotifyForChanges(l:lsp_details)
-
-        " For LSP completions, we need to clamp the column to the length of
-        " the line. python-language-server and perhaps others do not implement
-        " this correctly.
-        let l:message = ale#lsp#message#Completion(
-        \   l:buffer,
-        \   b:ale_completion_info.line,
-        \   min([
-        \       b:ale_completion_info.line_length,
-        \       b:ale_completion_info.column,
-        \   ]),
-        \   ale#completion#GetTriggerCharacter(&filetype, b:ale_completion_info.prefix),
-        \)
-    endif
+    function! OnReady(...) abort closure
+        " If we have sent a completion request already, don't send another.
+        if b:ale_completion_info.request_id
+            return
+        endif
 
-    let l:request_id = ale#lsp#Send(l:id, l:message, l:lsp_details.project_root)
+        let l:Callback = a:linter.lsp is# 'tsserver'
+        \   ? function('ale#completion#HandleTSServerResponse')
+        \   : function('ale#completion#HandleLSPResponse')
+        call ale#lsp#RegisterCallback(l:id, l:Callback)
+
+        if a:linter.lsp is# 'tsserver'
+            let l:message = ale#lsp#tsserver_message#Completions(
+            \   l:buffer,
+            \   b:ale_completion_info.line,
+            \   b:ale_completion_info.column,
+            \   b:ale_completion_info.prefix,
+            \)
+        else
+            " Send a message saying the buffer has changed first, otherwise
+            " completions won't know what text is nearby.
+            call ale#lsp#NotifyForChanges(l:id, l:root, l:buffer)
+
+            " For LSP completions, we need to clamp the column to the length of
+            " the line. python-language-server and perhaps others do not implement
+            " this correctly.
+            let l:message = ale#lsp#message#Completion(
+            \   l:buffer,
+            \   b:ale_completion_info.line,
+            \   min([
+            \       b:ale_completion_info.line_length,
+            \       b:ale_completion_info.column,
+            \   ]),
+            \   ale#completion#GetTriggerCharacter(&filetype, b:ale_completion_info.prefix),
+            \)
+        endif
 
-    if l:request_id
-        let b:ale_completion_info.conn_id = l:id
-        let b:ale_completion_info.request_id = l:request_id
+        let l:request_id = ale#lsp#Send(l:id, l:message, l:lsp_details.project_root)
 
-        if has_key(a:linter, 'completion_filter')
-            let b:ale_completion_info.completion_filter = a:linter.completion_filter
+        if l:request_id
+            let b:ale_completion_info.conn_id = l:id
+            let b:ale_completion_info.request_id = l:request_id
+
+            if has_key(a:linter, 'completion_filter')
+                let b:ale_completion_info.completion_filter = a:linter.completion_filter
+            endif
         endif
-    endif
+    endfunction
+
+    call ale#lsp#WaitForCapability(l:id, l:root, 'completion', function('OnReady'))
 endfunction
 
 function! ale#completion#GetCompletions() abort
diff --git a/autoload/ale/definition.vim b/autoload/ale/definition.vim
index 6c70b64c..6c7d7d32 100644
--- a/autoload/ale/definition.vim
+++ b/autoload/ale/definition.vim
@@ -60,43 +60,50 @@ endfunction
 function! s:GoToLSPDefinition(linter, options) abort
     let l:buffer = bufnr('')
     let [l:line, l:column] = getcurpos()[1:2]
+    let l:lsp_details = ale#lsp_linter#StartLSP(l:buffer, a:linter)
 
-    let l:Callback = a:linter.lsp is# 'tsserver'
-    \   ? function('ale#definition#HandleTSServerResponse')
-    \   : function('ale#definition#HandleLSPResponse')
-
-    let l:lsp_details = ale#lsp_linter#StartLSP(l:buffer, a:linter, l:Callback)
+    if a:linter.lsp isnot# 'tsserver'
+        let l:column = min([l:column, len(getline(l:line))])
+    endif
 
     if empty(l:lsp_details)
         return 0
     endif
 
     let l:id = l:lsp_details.connection_id
+    let l:root = l:lsp_details.project_root
+
+    function! OnReady(...) abort closure
+        let l:Callback = a:linter.lsp is# 'tsserver'
+        \   ? function('ale#definition#HandleTSServerResponse')
+        \   : function('ale#definition#HandleLSPResponse')
+        call ale#lsp#RegisterCallback(l:id, l:Callback)
+
+        if a:linter.lsp is# 'tsserver'
+            let l:message = ale#lsp#tsserver_message#Definition(
+            \   l:buffer,
+            \   l:line,
+            \   l:column
+            \)
+        else
+            " Send a message saying the buffer has changed first, or the
+            " definition position probably won't make sense.
+            call ale#lsp#NotifyForChanges(l:id, l:root, l:buffer)
+
+            " For LSP completions, we need to clamp the column to the length of
+            " the line. python-language-server and perhaps others do not implement
+            " this correctly.
+            let l:message = ale#lsp#message#Definition(l:buffer, l:line, l:column)
+        endif
 
-    if a:linter.lsp is# 'tsserver'
-        let l:message = ale#lsp#tsserver_message#Definition(
-        \   l:buffer,
-        \   l:line,
-        \   l:column
-        \)
-    else
-        " Send a message saying the buffer has changed first, or the
-        " definition position probably won't make sense.
-        call ale#lsp#NotifyForChanges(l:lsp_details)
-
-        let l:column = min([l:column, len(getline(l:line))])
-
-        " For LSP completions, we need to clamp the column to the length of
-        " the line. python-language-server and perhaps others do not implement
-        " this correctly.
-        let l:message = ale#lsp#message#Definition(l:buffer, l:line, l:column)
-    endif
+        let l:request_id = ale#lsp#Send(l:id, l:message, l:lsp_details.project_root)
 
-    let l:request_id = ale#lsp#Send(l:id, l:message, l:lsp_details.project_root)
+        let s:go_to_definition_map[l:request_id] = {
+        \   'open_in_tab': get(a:options, 'open_in_tab', 0),
+        \}
+    endfunction
 
-    let s:go_to_definition_map[l:request_id] = {
-    \   'open_in_tab': get(a:options, 'open_in_tab', 0),
-    \}
+    call ale#lsp#WaitForCapability(l:id, l:root, 'definition', function('OnReady'))
 endfunction
 
 function! ale#definition#GoTo(options) abort
diff --git a/autoload/ale/fix.vim b/autoload/ale/fix.vim
index 62674b87..8dfdeca8 100644
--- a/autoload/ale/fix.vim
+++ b/autoload/ale/fix.vim
@@ -420,9 +420,7 @@ function! ale#fix#InitBufferData(buffer, fixing_flag) abort
     " The 'done' flag tells the function for applying changes when fixing
     " is complete.
     let g:ale_fix_buffer_data[a:buffer] = {
-    \   'vars': getbufvar(a:buffer, ''),
     \   'lines_before': getbufline(a:buffer, 1, '$'),
-    \   'filename': expand('#' . a:buffer . ':p'),
     \   'done': 0,
     \   'should_save': a:fixing_flag is# 'save_file',
     \   'temporary_directory_list': [],
diff --git a/autoload/ale/handlers/writegood.vim b/autoload/ale/handlers/writegood.vim
index aee7c4de..aff66d5f 100644
--- a/autoload/ale/handlers/writegood.vim
+++ b/autoload/ale/handlers/writegood.vim
@@ -59,3 +59,14 @@ function! ale#handlers#writegood#Handle(buffer, lines) abort
 
     return l:output
 endfunction
+
+" Define the writegood linter for a given filetype.
+function! ale#handlers#writegood#DefineLinter(filetype) abort
+    call ale#linter#Define(a:filetype, {
+    \   'name': 'writegood',
+    \   'aliases': ['write-good'],
+    \   'executable_callback': 'ale#handlers#writegood#GetExecutable',
+    \   'command_callback': 'ale#handlers#writegood#GetCommand',
+    \   'callback': 'ale#handlers#writegood#Handle',
+    \})
+endfunction
diff --git a/autoload/ale/hover.vim b/autoload/ale/hover.vim
index 6d131adc..5e97e16e 100644
--- a/autoload/ale/hover.vim
+++ b/autoload/ale/hover.vim
@@ -93,45 +93,51 @@ function! ale#hover#HandleLSPResponse(conn_id, response) abort
 endfunction
 
 function! s:ShowDetails(linter, buffer, line, column, opt) abort
-    let l:Callback = a:linter.lsp is# 'tsserver'
-    \   ? function('ale#hover#HandleTSServerResponse')
-    \   : function('ale#hover#HandleLSPResponse')
-
-    let l:lsp_details = ale#lsp_linter#StartLSP(a:buffer, a:linter, l:Callback)
+    let l:lsp_details = ale#lsp_linter#StartLSP(a:buffer, a:linter)
 
     if empty(l:lsp_details)
         return 0
     endif
 
     let l:id = l:lsp_details.connection_id
+    let l:root = l:lsp_details.project_root
     let l:language_id = l:lsp_details.language_id
 
-    if a:linter.lsp is# 'tsserver'
-        let l:column = a:column
+    function! OnReady(...) abort closure
+        let l:Callback = a:linter.lsp is# 'tsserver'
+        \   ? function('ale#hover#HandleTSServerResponse')
+        \   : function('ale#hover#HandleLSPResponse')
+        call ale#lsp#RegisterCallback(l:id, l:Callback)
 
-        let l:message = ale#lsp#tsserver_message#Quickinfo(
-        \   a:buffer,
-        \   a:line,
-        \   l:column
-        \)
-    else
-        " Send a message saying the buffer has changed first, or the
-        " hover position probably won't make sense.
-        call ale#lsp#NotifyForChanges(l:lsp_details)
+        if a:linter.lsp is# 'tsserver'
+            let l:column = a:column
 
-        let l:column = min([a:column, len(getbufline(a:buffer, a:line)[0])])
+            let l:message = ale#lsp#tsserver_message#Quickinfo(
+            \   a:buffer,
+            \   a:line,
+            \   l:column
+            \)
+        else
+            " Send a message saying the buffer has changed first, or the
+            " hover position probably won't make sense.
+            call ale#lsp#NotifyForChanges(l:id, l:root, a:buffer)
 
-        let l:message = ale#lsp#message#Hover(a:buffer, a:line, l:column)
-    endif
+            let l:column = min([a:column, len(getbufline(a:buffer, a:line)[0])])
+
+            let l:message = ale#lsp#message#Hover(a:buffer, a:line, l:column)
+        endif
+
+        let l:request_id = ale#lsp#Send(l:id, l:message, l:lsp_details.project_root)
 
-    let l:request_id = ale#lsp#Send(l:id, l:message, l:lsp_details.project_root)
+        let s:hover_map[l:request_id] = {
+        \   'buffer': a:buffer,
+        \   'line': a:line,
+        \   'column': l:column,
+        \   'hover_from_balloonexpr': get(a:opt, 'called_from_balloonexpr', 0),
+        \}
+    endfunction
 
-    let s:hover_map[l:request_id] = {
-    \   'buffer': a:buffer,
-    \   'line': a:line,
-    \   'column': l:column,
-    \   'hover_from_balloonexpr': get(a:opt, 'called_from_balloonexpr', 0),
-    \}
+    call ale#lsp#WaitForCapability(l:id, l:root, 'hover', function('OnReady'))
 endfunction
 
 " Obtain Hover information for the specified position
diff --git a/autoload/ale/lsp.vim b/autoload/ale/lsp.vim
index e44b5bc3..312319ab 100644
--- a/autoload/ale/lsp.vim
+++ b/autoload/ale/lsp.vim
@@ -15,13 +15,23 @@ function! ale#lsp#NewConnection(initialization_options) abort
     " open_documents: A Dictionary mapping buffers to b:changedtick, keeping
     "   track of when documents were opened, and when we last changed them.
     " callback_list: A list of callbacks for handling LSP responses.
+    " initialization_options: Options to send to the server.
+    " capabilities: Features the server supports.
     let l:conn = {
+    \   'is_tsserver': 0,
     \   'id': '',
     \   'data': '',
     \   'projects': {},
     \   'open_documents': {},
     \   'callback_list': [],
     \   'initialization_options': a:initialization_options,
+    \   'capabilities': {
+    \       'hover': 0,
+    \       'references': 0,
+    \       'completion': 0,
+    \       'completion_trigger_characters': [],
+    \       'definition': 0,
+    \   },
     \}
 
     call add(s:connections, l:conn)
@@ -44,6 +54,11 @@ function! s:FindConnection(key, value) abort
     return {}
 endfunction
 
+" Get the capabilities for a connection, or an empty Dictionary.
+function! ale#lsp#GetConnectionCapabilities(id) abort
+    return get(s:FindConnection('id', a:id), 'capabilities', {})
+endfunction
+
 function! ale#lsp#GetNextMessageID() abort
     " Use the current ID
     let l:id = g:ale_lsp_next_message_id
@@ -174,6 +189,16 @@ function! s:MarkProjectAsInitialized(conn, project) abort
 
     " Remove the messages now.
     let a:conn.message_queue = []
+
+    " Call capabilities callbacks queued for the project.
+    for [l:capability, l:Callback] in a:project.capabilities_queue
+        if a:conn.is_tsserver || a:conn.capabilities[l:capability]
+            call call(l:Callback, [a:conn.id, a:project.root])
+        endif
+    endfor
+
+    " Clear the queued callbacks now.
+    let a:project.capabilities_queue = []
 endfunction
 
 function! s:HandleInitializeResponse(conn, response) abort
@@ -185,6 +210,38 @@ function! s:HandleInitializeResponse(conn, response) abort
     endif
 endfunction
 
+" Update capabilities from the server, so we know which features the server
+" supports.
+function! s:UpdateCapabilities(conn, capabilities) abort
+    if type(a:capabilities) != type({})
+        return
+    endif
+
+    if get(a:capabilities, 'hoverProvider') is v:true
+        let a:conn.capabilities.hover = 1
+    endif
+
+    if get(a:capabilities, 'referencesProvider') is v:true
+        let a:conn.capabilities.references = 1
+    endif
+
+    if !empty(get(a:capabilities, 'completionProvider'))
+        let a:conn.capabilities.completion = 1
+    endif
+
+    if type(get(a:capabilities, 'completionProvider')) is type({})
+        let l:chars = get(a:capabilities.completionProvider, 'triggerCharacters')
+
+        if type(l:chars) is type([])
+            let a:conn.capabilities.completion_trigger_characters = l:chars
+        endif
+    endif
+
+    if get(a:capabilities, 'definitionProvider') is v:true
+        let a:conn.capabilities.definition = 1
+    endif
+endfunction
+
 function! ale#lsp#HandleOtherInitializeResponses(conn, response) abort
     let l:uninitialized_projects = []
 
@@ -200,6 +257,8 @@ function! ale#lsp#HandleOtherInitializeResponses(conn, response) abort
 
     if get(a:response, 'method', '') is# ''
         if has_key(get(a:response, 'result', {}), 'capabilities')
+            call s:UpdateCapabilities(a:conn, a:response.result.capabilities)
+
             for [l:dir, l:project] in l:uninitialized_projects
                 call s:MarkProjectAsInitialized(a:conn, l:project)
             endfor
@@ -254,22 +313,43 @@ function! s:HandleCommandMessage(job_id, message) abort
     call ale#lsp#HandleMessage(l:conn, a:message)
 endfunction
 
-function! ale#lsp#RegisterProject(conn, project_root) abort
+" Given a connection ID, mark it as a tsserver connection, so it will be
+" handled that way.
+function! ale#lsp#MarkConnectionAsTsserver(conn_id) abort
+    let l:conn = s:FindConnection('id', a:conn_id)
+
+    if !empty(l:conn)
+        let l:conn.is_tsserver = 1
+    endif
+endfunction
+
+" Register a project for an LSP connection.
+"
+" This function will throw if the connection doesn't exist.
+function! ale#lsp#RegisterProject(conn_id, project_root) abort
+    let l:conn = s:FindConnection('id', a:conn_id)
+
     " Empty strings can't be used for Dictionary keys in NeoVim, due to E713.
     " This appears to be a nonsensical bug in NeoVim.
     let l:key = empty(a:project_root) ? '<<EMPTY>>' : a:project_root
 
-    if !has_key(a:conn.projects, l:key)
+    if !has_key(l:conn.projects, l:key)
         " Tools without project roots are ready right away, like tsserver.
-        let a:conn.projects[l:key] = {
+        let l:conn.projects[l:key] = {
+        \   'root': a:project_root,
         \   'initialized': empty(a:project_root),
         \   'init_request_id': 0,
         \   'message_queue': [],
+        \   'capabilities_queue': [],
         \}
     endif
 endfunction
 
 function! ale#lsp#GetProject(conn, project_root) abort
+    if empty(a:conn)
+        return {}
+    endif
+
     let l:key = empty(a:project_root) ? '<<EMPTY>>' : a:project_root
 
     return get(a:conn.projects, l:key, {})
@@ -279,7 +359,7 @@ endfunction
 "
 " The job ID will be returned for for the program if it ran, otherwise
 " 0 will be returned.
-function! ale#lsp#StartProgram(executable, command, project_root, callback, initialization_options) abort
+function! ale#lsp#StartProgram(executable, command, init_options) abort
     if !executable(a:executable)
         return 0
     endif
@@ -287,7 +367,7 @@ function! ale#lsp#StartProgram(executable, command, project_root, callback, init
     let l:conn = s:FindConnection('executable', a:executable)
 
     " Get the current connection or a new one.
-    let l:conn = !empty(l:conn) ? l:conn : ale#lsp#NewConnection(a:initialization_options)
+    let l:conn = !empty(l:conn) ? l:conn : ale#lsp#NewConnection(a:init_options)
     let l:conn.executable = a:executable
 
     if !has_key(l:conn, 'id') || !ale#job#IsRunning(l:conn.id)
@@ -305,18 +385,15 @@ function! ale#lsp#StartProgram(executable, command, project_root, callback, init
     endif
 
     let l:conn.id = l:job_id
-    " Add the callback to the List if it's not there already.
-    call uniq(sort(add(l:conn.callback_list, a:callback)))
-    call ale#lsp#RegisterProject(l:conn, a:project_root)
 
     return l:job_id
 endfunction
 
 " Connect to an address and set up a callback for handling responses.
-function! ale#lsp#ConnectToAddress(address, project_root, callback, initialization_options) abort
+function! ale#lsp#ConnectToAddress(address, init_options) abort
     let l:conn = s:FindConnection('id', a:address)
     " Get the current connection or a new one.
-    let l:conn = !empty(l:conn) ? l:conn : ale#lsp#NewConnection(a:initialization_options)
+    let l:conn = !empty(l:conn) ? l:conn : ale#lsp#NewConnection(a:init_options)
 
     if !has_key(l:conn, 'channel_id') || !ale#socket#IsOpen(l:conn.channel_id)
         let l:conn.channel_id = ale#socket#Open(a:address, {
@@ -329,13 +406,21 @@ function! ale#lsp#ConnectToAddress(address, project_root, callback, initializati
     endif
 
     let l:conn.id = a:address
-    " Add the callback to the List if it's not there already.
-    call uniq(sort(add(l:conn.callback_list, a:callback)))
-    call ale#lsp#RegisterProject(l:conn, a:project_root)
 
     return a:address
 endfunction
 
+" Given a connection ID and a callback, register that callback for handling
+" messages if the connection exists.
+function! ale#lsp#RegisterCallback(conn_id, callback) abort
+    let l:conn = s:FindConnection('id', a:conn_id)
+
+    if !empty(l:conn)
+        " Add the callback to the List if it's not there already.
+        call uniq(sort(add(l:conn.callback_list, a:callback)))
+    endif
+endfunction
+
 " Stop all LSP connections, closing all jobs and channels, and removing any
 " queued messages.
 function! ale#lsp#StopAll() abort
@@ -373,11 +458,6 @@ function! ale#lsp#Send(conn_id, message, ...) abort
     let l:project_root = get(a:000, 0, '')
 
     let l:conn = s:FindConnection('id', a:conn_id)
-
-    if empty(l:conn)
-        return 0
-    endif
-
     let l:project = ale#lsp#GetProject(l:conn, l:project_root)
 
     if empty(l:project)
@@ -411,45 +491,22 @@ function! ale#lsp#Send(conn_id, message, ...) abort
     return l:id == 0 ? -1 : l:id
 endfunction
 
-" The Document details Dictionary should contain the following keys.
-"
-"  buffer - The buffer number for the document.
-"  connection_id - The connection ID for the LSP server.
-"  command - The command to run to start the LSP connection.
-"  project_root - The project root for the LSP project.
-"  language_id - The language ID for the project, like 'python', 'rust', etc.
-
-" Create a new Dictionary containing more connection details, with the
-" following information added:
-"
-"   conn - An existing LSP connection for the document.
-"   document_open - 1 if the document is currently open, 0 otherwise.
-function! s:ExtendDocumentDetails(details) abort
-    let l:extended = copy(a:details)
-    let l:conn = s:FindConnection('id', a:details.connection_id)
-
-    let l:extended.conn = l:conn
-    let l:extended.document_open = !empty(l:conn)
-    \   && has_key(l:conn.open_documents, a:details.buffer)
-
-    return l:extended
-endfunction
-
 " Notify LSP servers or tsserver if a document is opened, if needed.
 " If a document is opened, 1 will be returned, otherwise 0 will be returned.
-function! ale#lsp#OpenDocument(basic_details) abort
-    let l:d = s:ExtendDocumentDetails(a:basic_details)
+function! ale#lsp#OpenDocument(conn_id, project_root, buffer, language_id) abort
+    let l:conn = s:FindConnection('id', a:conn_id)
     let l:opened = 0
 
-    if !empty(l:d.conn) && !l:d.document_open
-        if empty(l:d.language_id)
-            let l:message = ale#lsp#tsserver_message#Open(l:d.buffer)
+    " FIXME: Return 1 if the document is already open?
+    if !empty(l:conn) && !has_key(l:conn.open_documents, a:buffer)
+        if l:conn.is_tsserver
+            let l:message = ale#lsp#tsserver_message#Open(a:buffer)
         else
-            let l:message = ale#lsp#message#DidOpen(l:d.buffer, l:d.language_id)
+            let l:message = ale#lsp#message#DidOpen(a:buffer, a:language_id)
         endif
 
-        call ale#lsp#Send(l:d.connection_id, l:message, l:d.project_root)
-        let l:d.conn.open_documents[l:d.buffer] = getbufvar(l:d.buffer, 'changedtick')
+        call ale#lsp#Send(a:conn_id, l:message, a:project_root)
+        let l:conn.open_documents[a:buffer] = getbufvar(a:buffer, 'changedtick')
         let l:opened = 1
     endif
 
@@ -458,25 +515,50 @@ endfunction
 
 " Notify LSP servers or tsserver that a document has changed, if needed.
 " If a notification is sent, 1 will be returned, otherwise 0 will be returned.
-function! ale#lsp#NotifyForChanges(basic_details) abort
-    let l:d = s:ExtendDocumentDetails(a:basic_details)
+function! ale#lsp#NotifyForChanges(conn_id, project_root, buffer) abort
+    let l:conn = s:FindConnection('id', a:conn_id)
     let l:notified = 0
 
-    if l:d.document_open
-        let l:new_tick = getbufvar(l:d.buffer, 'changedtick')
+    if !empty(l:conn) && has_key(l:conn.open_documents, a:buffer)
+        let l:new_tick = getbufvar(a:buffer, 'changedtick')
 
-        if l:d.conn.open_documents[l:d.buffer] < l:new_tick
-            if empty(l:d.language_id)
-                let l:message = ale#lsp#tsserver_message#Change(l:d.buffer)
+        if l:conn.open_documents[a:buffer] < l:new_tick
+            if l:conn.is_tsserver
+                let l:message = ale#lsp#tsserver_message#Change(a:buffer)
             else
-                let l:message = ale#lsp#message#DidChange(l:d.buffer)
+                let l:message = ale#lsp#message#DidChange(a:buffer)
             endif
 
-            call ale#lsp#Send(l:d.connection_id, l:message, l:d.project_root)
-            let l:d.conn.open_documents[l:d.buffer] = l:new_tick
+            call ale#lsp#Send(a:conn_id, l:message, a:project_root)
+            let l:conn.open_documents[a:buffer] = l:new_tick
             let l:notified = 1
         endif
     endif
 
     return l:notified
 endfunction
+
+" Given some LSP details that must contain at least `connection_id` and
+" `project_root` keys,
+function! ale#lsp#WaitForCapability(conn_id, project_root, capability, callback) abort
+    let l:conn = s:FindConnection('id', a:conn_id)
+    let l:project = ale#lsp#GetProject(l:conn, a:project_root)
+
+    if empty(l:project)
+        return 0
+    endif
+
+    if type(get(l:conn.capabilities, a:capability, v:null)) isnot type(0)
+        throw 'Invalid capability ' . a:capability
+    endif
+
+    if l:project.initialized
+        if l:conn.is_tsserver || l:conn.capabilities[a:capability]
+            " The project has been initialized, so call the callback now.
+            call call(a:callback, [a:conn_id, a:project_root])
+        endif
+    else
+        " Call the callback later, once we have the information we need.
+        call add(l:project.capabilities_queue, [a:capability, a:callback])
+    endif
+endfunction
diff --git a/autoload/ale/lsp_linter.vim b/autoload/ale/lsp_linter.vim
index 6dc78e4c..87aee759 100644
--- a/autoload/ale/lsp_linter.vim
+++ b/autoload/ale/lsp_linter.vim
@@ -126,10 +126,9 @@ function! ale#lsp_linter#GetOptions(buffer, linter) abort
     return l:initialization_options
 endfunction
 
-" Given a buffer, an LSP linter, and a callback to register for handling
-" messages, start up an LSP linter and get ready to receive errors or
-" completions.
-function! ale#lsp_linter#StartLSP(buffer, linter, callback) abort
+" Given a buffer, an LSP linter, start up an LSP linter and get ready to
+" receive messages for the document.
+function! ale#lsp_linter#StartLSP(buffer, linter) abort
     let l:command = ''
     let l:address = ''
     let l:root = ale#util#GetFunction(a:linter.project_root_callback)(a:buffer)
@@ -140,16 +139,11 @@ function! ale#lsp_linter#StartLSP(buffer, linter, callback) abort
         return {}
     endif
 
-    let l:initialization_options = ale#lsp_linter#GetOptions(a:buffer, a:linter)
+    let l:init_options = ale#lsp_linter#GetOptions(a:buffer, a:linter)
 
     if a:linter.lsp is# 'socket'
         let l:address = ale#linter#GetAddress(a:buffer, a:linter)
-        let l:conn_id = ale#lsp#ConnectToAddress(
-        \   l:address,
-        \   l:root,
-        \   a:callback,
-        \   l:initialization_options,
-        \)
+        let l:conn_id = ale#lsp#ConnectToAddress(l:address, l:init_options)
     else
         let l:executable = ale#linter#GetExecutable(a:buffer, a:linter)
 
@@ -164,14 +158,10 @@ function! ale#lsp_linter#StartLSP(buffer, linter, callback) abort
         let l:conn_id = ale#lsp#StartProgram(
         \   l:executable,
         \   l:command,
-        \   l:root,
-        \   a:callback,
-        \   l:initialization_options,
+        \   l:init_options,
         \)
     endif
 
-    let l:language_id = ale#util#GetFunction(a:linter.language_callback)(a:buffer)
-
     if empty(l:conn_id)
         if g:ale_history_enabled && !empty(l:command)
             call ale#history#Add(a:buffer, 'failed', l:conn_id, l:command)
@@ -180,6 +170,16 @@ function! ale#lsp_linter#StartLSP(buffer, linter, callback) abort
         return {}
     endif
 
+    " tsserver behaves differently, so tell the LSP API that it is tsserver.
+    if a:linter.lsp is# 'tsserver'
+        call ale#lsp#MarkConnectionAsTsserver(l:conn_id)
+    endif
+
+    " Register the project now the connection is ready.
+    call ale#lsp#RegisterProject(l:conn_id, l:root)
+
+    let l:language_id = ale#util#GetFunction(a:linter.language_callback)(a:buffer)
+
     let l:details = {
     \   'buffer': a:buffer,
     \   'connection_id': l:conn_id,
@@ -188,7 +188,7 @@ function! ale#lsp_linter#StartLSP(buffer, linter, callback) abort
     \   'language_id': l:language_id,
     \}
 
-    if ale#lsp#OpenDocument(l:details)
+    if ale#lsp#OpenDocument(l:conn_id, l:root, a:buffer, l:language_id)
         if g:ale_history_enabled && !empty(l:command)
             call ale#history#Add(a:buffer, 'started', l:conn_id, l:command)
         endif
@@ -196,7 +196,7 @@ function! ale#lsp_linter#StartLSP(buffer, linter, callback) abort
 
     " The change message needs to be sent for tsserver before doing anything.
     if a:linter.lsp is# 'tsserver'
-        call ale#lsp#NotifyForChanges(l:details)
+        call ale#lsp#NotifyForChanges(l:conn_id, l:root, a:buffer)
     endif
 
     return l:details
@@ -204,11 +204,7 @@ endfunction
 
 function! ale#lsp_linter#CheckWithLSP(buffer, linter) abort
     let l:info = g:ale_buffer_info[a:buffer]
-    let l:lsp_details = ale#lsp_linter#StartLSP(
-    \   a:buffer,
-    \   a:linter,
-    \   function('ale#lsp_linter#HandleLSPResponse'),
-    \)
+    let l:lsp_details = ale#lsp_linter#StartLSP(a:buffer, a:linter)
 
     if empty(l:lsp_details)
         return 0
@@ -217,25 +213,25 @@ function! ale#lsp_linter#CheckWithLSP(buffer, linter) abort
     let l:id = l:lsp_details.connection_id
     let l:root = l:lsp_details.project_root
 
+    " Register a callback now for handling errors now.
+    let l:Callback = function('ale#lsp_linter#HandleLSPResponse')
+    call ale#lsp#RegisterCallback(l:id, l:Callback)
+
     " Remember the linter this connection is for.
     let s:lsp_linter_map[l:id] = a:linter.name
 
     if a:linter.lsp is# 'tsserver'
         let l:message = ale#lsp#tsserver_message#Geterr(a:buffer)
-        let l:request_id = ale#lsp#Send(l:id, l:message, l:root)
-
-        let l:notified = l:request_id != 0
+        let l:notified = ale#lsp#Send(l:id, l:message, l:root) != 0
     else
-        let l:notified = ale#lsp#NotifyForChanges(l:lsp_details)
+        let l:notified = ale#lsp#NotifyForChanges(l:id, l:root, a:buffer)
     endif
 
     " If this was a file save event, also notify the server of that.
     if a:linter.lsp isnot# 'tsserver'
     \&& getbufvar(a:buffer, 'ale_save_event_fired', 0)
         let l:save_message = ale#lsp#message#DidSave(a:buffer)
-        let l:request_id = ale#lsp#Send(l:id, l:save_message, l:root)
-
-        let l:notified = l:request_id != 0
+        let l:notified = ale#lsp#Send(l:id, l:save_message, l:root) != 0
     endif
 
     if l:notified
diff --git a/autoload/ale/references.vim b/autoload/ale/references.vim
index 89df69eb..3a710b7b 100644
--- a/autoload/ale/references.vim
+++ b/autoload/ale/references.vim
@@ -68,37 +68,46 @@ function! s:FindReferences(linter) abort
     let l:buffer = bufnr('')
     let [l:line, l:column] = getcurpos()[1:2]
 
-    let l:Callback = a:linter.lsp is# 'tsserver'
-    \   ? function('ale#references#HandleTSServerResponse')
-    \   : function('ale#references#HandleLSPResponse')
+    if a:linter.lsp isnot# 'tsserver'
+        let l:column = min([l:column, len(getline(l:line))])
+    endif
 
-    let l:lsp_details = ale#lsp_linter#StartLSP(l:buffer, a:linter, l:Callback)
+    let l:lsp_details = ale#lsp_linter#StartLSP(l:buffer, a:linter)
 
     if empty(l:lsp_details)
         return 0
     endif
 
     let l:id = l:lsp_details.connection_id
+    let l:root = l:lsp_details.project_root
 
-    if a:linter.lsp is# 'tsserver'
-        let l:message = ale#lsp#tsserver_message#References(
-        \   l:buffer,
-        \   l:line,
-        \   l:column
-        \)
-    else
-        " Send a message saying the buffer has changed first, or the
-        " references position probably won't make sense.
-        call ale#lsp#NotifyForChanges(l:lsp_details)
+    function! OnReady(...) abort closure
+        let l:Callback = a:linter.lsp is# 'tsserver'
+        \   ? function('ale#references#HandleTSServerResponse')
+        \   : function('ale#references#HandleLSPResponse')
 
-        let l:column = min([l:column, len(getline(l:line))])
+        call ale#lsp#RegisterCallback(l:id, l:Callback)
 
-        let l:message = ale#lsp#message#References(l:buffer, l:line, l:column)
-    endif
+        if a:linter.lsp is# 'tsserver'
+            let l:message = ale#lsp#tsserver_message#References(
+            \   l:buffer,
+            \   l:line,
+            \   l:column
+            \)
+        else
+            " Send a message saying the buffer has changed first, or the
+            " references position probably won't make sense.
+            call ale#lsp#NotifyForChanges(l:id, l:root, l:buffer)
+
+            let l:message = ale#lsp#message#References(l:buffer, l:line, l:column)
+        endif
+
+        let l:request_id = ale#lsp#Send(l:id, l:message, l:lsp_details.project_root)
 
-    let l:request_id = ale#lsp#Send(l:id, l:message, l:lsp_details.project_root)
+        let s:references_map[l:request_id] = {}
+    endfunction
 
-    let s:references_map[l:request_id] = {}
+    call ale#lsp#WaitForCapability(l:id, l:root, 'references', function('OnReady'))
 endfunction
 
 function! ale#references#Find() abort
diff --git a/autoload/ale/test.vim b/autoload/ale/test.vim
index bea10c53..083b546f 100644
--- a/autoload/ale/test.vim
+++ b/autoload/ale/test.vim
@@ -52,3 +52,26 @@ function! ale#test#SetFilename(path) abort
 
     silent! noautocmd execute 'file ' . fnameescape(ale#path#Simplify(l:full_path))
 endfunction
+
+function! s:RemoveModule(results) abort
+    for l:item in a:results
+      if has_key(l:item, 'module')
+        call remove(l:item, 'module')
+      endif
+    endfor
+endfunction
+
+" Return loclist data without the module string, only in newer Vim versions.
+function! ale#test#GetLoclistWithoutModule() abort
+    let l:results = getloclist(0)
+    call s:RemoveModule(l:results)
+
+    return l:results
+endfunction
+
+function! ale#test#GetQflistWithoutModule() abort
+    let l:results = getqflist()
+    call s:RemoveModule(l:results)
+
+    return l:results
+endfunction
diff --git a/autoload/ale/toggle.vim b/autoload/ale/toggle.vim
index 6b1affc4..da108782 100644
--- a/autoload/ale/toggle.vim
+++ b/autoload/ale/toggle.vim
@@ -43,7 +43,7 @@ function! ale#toggle#Toggle() abort
         call s:CleanupEveryBuffer()
         call s:DisablePostamble()
 
-        if has('balloon_eval')
+        if exists('*ale#balloon#Disable')
             call ale#balloon#Disable()
         endif
     endif