refactor(diagnostic): remove get_virt_text_chunks()

This function isn't compatible with including diagnostic sources when
"source" is "if_many" since it only has access to diagnostics for a
single line. Rather than having an inconsistent or incomplete interface,
make this function private. It is still exported as part of the module
for backward compatibility with vim.lsp.diagnostics, but it can
eventually be made into a local function.

runtime/doc/deprecated.txt

@@ -75,7 +75,9 @@ For each of the functions below, use the corresponding function in
 *vim.lsp.diagnostic.get_prev()*
 *vim.lsp.diagnostic.get_prev_pos()*
 *vim.lsp.diagnostic.get_virtual_text_chunks_for_line()*
-			Use |vim.diagnostic.get_virt_text_chunks()| instead.
+				No replacement. Use options provided by
+				|vim.diagnostic.config()| to customize
+				virtual text.
 *vim.lsp.diagnostic.goto_next()*
 *vim.lsp.diagnostic.goto_prev()*
 *vim.lsp.diagnostic.redraw()*		Use |vim.diagnostic.show()| instead.

runtime/doc/diagnostic.txt

@@ -333,26 +333,6 @@ get_prev_pos({opts})                           *vim.diagnostic.get_prev_pos()*
                 Return: ~
                     table Previous diagnostic position as a (row, col) tuple.
 
-                                       *vim.diagnostic.get_virt_text_chunks()*
-get_virt_text_chunks({line_diags}, {opts})
-                Get virtual text chunks to display using
-                |nvim_buf_set_extmark()|.
-
-                Parameters: ~
-                    {line_diags}  table The diagnostics associated with the
-                                  line.
-                    {opts}        table|nil Configuration table with the
-                                  following keys:
-                                  • prefix: (string) Prefix to display before
-                                    virtual text on line.
-                                  • spacing: (number) Number of spaces to
-                                    insert before virtual text.
-
-                Return: ~
-                    array of ({text}, {hl_group}) tuples. This can be passed
-                    directly to the {virt_text} option of
-                    |nvim_buf_set_extmark()|.
-
 goto_next({opts})                                 *vim.diagnostic.goto_next()*
                 Move to the next diagnostic.
 

runtime/lua/vim/diagnostic.lua

@@ -851,6 +851,8 @@ end
 ---@param opts table|nil Configuration table with the following keys:
 ---            - prefix: (string) Prefix to display before virtual text on line.
 ---            - spacing: (number) Number of spaces to insert before virtual text.
+---            - source: (string) Include the diagnostic source in virtual text. One of "always" or
+---                      "if_many".
 ---@private
 function M._set_virtual_text(namespace, bufnr, diagnostics, opts)
   vim.validate {
@@ -872,7 +874,7 @@ function M._set_virtual_text(namespace, bufnr, diagnostics, opts)
     if opts and opts.severity then
       line_diagnostics = filter_by_severity(opts.severity, line_diagnostics)
     end
-    local virt_texts = M.get_virt_text_chunks(line_diagnostics, opts)
+    local virt_texts = M._get_virt_text_chunks(line_diagnostics, opts)
 
     if virt_texts then
       vim.api.nvim_buf_set_extmark(bufnr, namespace, line, 0, {
@@ -885,13 +887,11 @@ end
 
 --- Get virtual text chunks to display using |nvim_buf_set_extmark()|.
 ---
----@param line_diags table The diagnostics associated with the line.
+--- Exported for backward compatibility with
----@param opts table|nil Configuration table with the following keys:
+--- vim.lsp.diagnostic.get_virtual_text_chunks_for_line(). When that function is eventually removed,
----            - prefix: (string) Prefix to display before virtual text on line.
+--- this can be made local.
----            - spacing: (number) Number of spaces to insert before virtual text.
+---@private
----@return array of ({text}, {hl_group}) tuples. This can be passed directly to
+function M._get_virt_text_chunks(line_diags, opts)
----        the {virt_text} option of |nvim_buf_set_extmark()|.
-function M.get_virt_text_chunks(line_diags, opts)
   if #line_diags == 0 then
     return nil
   end

runtime/lua/vim/lsp/diagnostic.lua

@@ -529,7 +529,7 @@ end
 ---@return an array of [text, hl_group] arrays. This can be passed directly to
 ---        the {virt_text} option of |nvim_buf_set_extmark()|.
 function M.get_virtual_text_chunks_for_line(bufnr, _, line_diags, opts)
-  return vim.diagnostic.get_virt_text_chunks(diagnostic_lsp_to_vim(line_diags, bufnr), opts)
+  return vim.diagnostic._get_virt_text_chunks(diagnostic_lsp_to_vim(line_diags, bufnr), opts)
 end
 
 --- Open a floating window with the diagnostics from {position}