diagnostics: convert columns to bytes

lua/null-ls/diagnostics.lua

@@ -89,8 +89,29 @@ local postprocess = function(diagnostic, _, generator)
     diagnostic.message = formatted
 end
 
+local function column_to_byte(line, col, offset_encoding)
+    local ok, result = pcall(vim.str_byteindex, line, col, offset_encoding == "utf-16")
+    if ok then
+        return result
+    end
+
+    return col
+end
+
+local function columns_to_bytes(bufnr, diagnostics)
+    local offset_encoding = "utf-16"
+    return vim.tbl_map(function(diagnostic)
+        local start_line = vim.api.nvim_buf_get_lines(bufnr, diagnostic.lnum, diagnostic.lnum + 1, false)[1]
+        local end_line = vim.api.nvim_buf_get_lines(bufnr, diagnostic.end_lnum, diagnostic.end_lnum + 1, false)[1]
+        return vim.tbl_deep_extend("force", diagnostic, {
+            col = column_to_byte(start_line, diagnostic.col, offset_encoding),
+            end_col = column_to_byte(end_line, diagnostic.end_col, offset_encoding),
+        })
+    end, diagnostics)
+end
+
 local handle_single_file_diagnostics = function(namespace, diagnostics, bufnr)
-    vim.diagnostic.set(namespace, bufnr, diagnostics)
+    vim.diagnostic.set(namespace, bufnr, columns_to_bytes(bufnr, diagnostics))
 end
 
 local handle_multiple_file_diagnostics = function(namespace, diagnostics)
@@ -110,7 +131,7 @@ local handle_multiple_file_diagnostics = function(namespace, diagnostics)
     end
 
     for bufnr, bufnr_diagnostics in pairs(by_bufnr) do
-        vim.diagnostic.set(namespace, bufnr, bufnr_diagnostics)
+        vim.diagnostic.set(namespace, bufnr, columns_to_bytes(bufnr, bufnr_diagnostics))
     end
 end