Close #1559 - Report errors from LSP servers in :ALEInfo

autoload/ale/debugging.vim

@@ -168,6 +168,30 @@ function! s:EchoLinterAliases(all_linters) abort
     endfor
 endfunction
 
+function! s:EchoLSPErrorMessages(all_linter_names) abort
+    let l:lsp_error_messages = get(g:, 'ale_lsp_error_messages', {})
+    let l:header_echoed = 0
+
+    for l:linter_name in a:all_linter_names
+        let l:error_list = get(l:lsp_error_messages, l:linter_name, [])
+
+        if !empty(l:error_list)
+            if !l:header_echoed
+                call s:Echo(' LSP Error Messages:')
+                call s:Echo('')
+            endif
+
+            call s:Echo('(Errors for ' . l:linter_name . ')')
+
+            for l:message in l:error_list
+                for l:line in split(l:message, "\n")
+                    call s:Echo(l:line)
+                endfor
+            endfor
+        endif
+    endfor
+endfunction
+
 function! ale#debugging#Info() abort
     let l:filetype = &filetype
 
@@ -200,6 +224,7 @@ function! ale#debugging#Info() abort
     call s:Echo(' Global Variables:')
     call s:Echo('')
     call s:EchoGlobalVariables()
+    call s:EchoLSPErrorMessages(l:all_names)
     call s:Echo('  Command History:')
     call s:Echo('')
     call s:EchoCommandHistory()

autoload/ale/engine.vim

@@ -81,6 +81,11 @@ function! ale#engine#ClearLSPData() abort
     let s:lsp_linter_map = {}
 endfunction
 
+" Just for tests.
+function! ale#engine#SetLSPLinterMap(replacement_map) abort
+    let s:lsp_linter_map = a:replacement_map
+endfunction
+
 " This function is documented and part of the public API.
 "
 " Return 1 if ALE is busy checking a given buffer
@@ -270,20 +275,38 @@ function! s:HandleTSServerDiagnostics(response, error_type) abort
     call ale#engine#HandleLoclist('tsserver', l:buffer, l:loclist)
 endfunction
 
-function! s:HandleLSPErrorMessage(error_message) abort
-    execute 'echoerr ''Error from LSP:'''
+function! s:HandleLSPErrorMessage(linter_name, response) abort
+    if !g:ale_history_enabled || !g:ale_history_log_output
+        return
+    endif
 
-    for l:line in split(a:error_message, "\n")
-        execute 'echoerr l:line'
-    endfor
+    if empty(a:linter_name)
+        return
+    endif
+
+    let l:message = ale#lsp#response#GetErrorMessage(a:response)
+
+    if empty(l:message)
+        return
+    endif
+
+    " This global variable is set here so we don't load the debugging.vim file
+    " until someone uses :ALEInfo.
+    let g:ale_lsp_error_messages = get(g:, 'ale_lsp_error_messages', {})
+
+    if !has_key(g:ale_lsp_error_messages, a:linter_name)
+        let g:ale_lsp_error_messages[a:linter_name] = []
+    endif
+
+    call add(g:ale_lsp_error_messages[a:linter_name], l:message)
 endfunction
 
 function! ale#engine#HandleLSPResponse(conn_id, response) abort
     let l:method = get(a:response, 'method', '')
+    let l:linter_name = get(s:lsp_linter_map, a:conn_id, '')
 
     if get(a:response, 'jsonrpc', '') is# '2.0' && has_key(a:response, 'error')
-        " Uncomment this line to print LSP error messages.
-        " call s:HandleLSPErrorMessage(a:response.error.message)
+        call s:HandleLSPErrorMessage(l:linter_name, a:response)
     elseif l:method is# 'textDocument/publishDiagnostics'
         call s:HandleLSPDiagnostics(a:conn_id, a:response)
     elseif get(a:response, 'type', '') is# 'event'

autoload/ale/lsp/response.vim

@@ -1,6 +1,20 @@
 " Author: w0rp <devw0rp@gmail.com>
 " Description: Parsing and transforming of LSP server responses.
 
+" Constants for error codes.
+" Defined by JSON RPC
+let s:PARSE_ERROR = -32700
+let s:INVALID_REQUEST = -32600
+let s:METHOD_NOT_FOUND = -32601
+let s:INVALID_PARAMS = -32602
+let s:INTERNAL_ERROR = -32603
+let s:SERVER_ERROR_START = -32099
+let s:SERVER_ERROR_END = -32000
+let s:SERVER_NOT_INITIALIZED = -32002
+let s:UNKNOWN_ERROR_CODE = -32001
+" Defined by the protocol.
+let s:REQUEST_CANCELLED = -32800
+
 " Constants for message severity codes.
 let s:SEVERITY_ERROR = 1
 let s:SEVERITY_WARNING = 2
@@ -72,3 +86,31 @@ function! ale#lsp#response#ReadTSServerDiagnostics(response) abort
 
     return l:loclist
 endfunction
+
+function! ale#lsp#response#GetErrorMessage(response) abort
+    if type(get(a:response, 'error', 0)) isnot type({})
+        return ''
+    endif
+
+    let l:code = get(a:response.error, 'code')
+
+    " Only report things for these error codes.
+    if l:code isnot s:INVALID_PARAMS && l:code isnot s:INTERNAL_ERROR
+        return ''
+    endif
+
+    let l:message = get(a:response.error, 'message', '')
+
+    if empty(l:message)
+        return ''
+    endif
+
+    " Include the traceback as details, if it's there.
+    let l:traceback = get(get(a:response.error, 'data', {}), 'traceback', [])
+
+    if type(l:traceback) is type([]) && !empty(l:traceback)
+        let l:message .= "\n" . join(l:traceback, "\n")
+    endif
+
+    return l:message
+endfunction