Fix for deprecated vim.lsp.diagnostic.get_all (#840)

lua/nvim-tree/diagnostics.lua

@@ -1,7 +1,6 @@
 local a = vim.api
 local utils = require'nvim-tree.utils'
 local view = require'nvim-tree.view'
-local get_diagnostics = vim.lsp.diagnostic.get_all
 
 local M = {}
 
@@ -35,7 +34,23 @@ end
 local function from_nvim_lsp()
   local buffer_severity = {}
 
-  for buf, diagnostics in pairs(get_diagnostics()) do
+  -- vim.lsp.diagnostic.get_all was deprecated in nvim 0.7 and replaced with vim.diagnostic.get
+  -- This conditional can be removed when the minimum required version of nvim is changed to 0.7.
+  if vim.diagnostic then
+    -- nvim version >= 0.7
+    for _, diagnostic in ipairs(vim.diagnostic.get()) do
+      local buf = diagnostic.bufnr
+      if a.nvim_buf_is_valid(buf) then
+        local bufname = a.nvim_buf_get_name(buf)
+        local lowest_severity = buffer_severity[bufname]
+        if not lowest_severity or diagnostic.severity < lowest_severity then
+          buffer_severity[bufname] = diagnostic.severity
+        end
+      end
+    end
+  else
+    -- nvim version < 0.7
+    for buf, diagnostics in pairs(vim.lsp.diagnostic.get_all()) do
       if a.nvim_buf_is_valid(buf) then
         local bufname = a.nvim_buf_get_name(buf)
         if not buffer_severity[bufname] then
@@ -44,6 +59,7 @@ local function from_nvim_lsp()
         end
       end
     end
+  end
 
   return buffer_severity
 end