backport fix(diagnostic): status() respects config.signs (#39601)

Problem:
`diagnostic.status` only follows the `config.status.format` setting to determine how to display diagnostic signs. However, `signs` can actually also be configured via `config.signs.text`.

Solution:
If the user has set symbols via `config.status.format`, let that determine the content of `signs`; otherwise, use `config.signs.text` for display.

TODO: drop support `type(config.status.format) == 'table'`; users should just configure `config.signs.text` directly.

Co-authored-by: Yi Ming <ofseed@foxmail.com>

.github/workflows/backport.yml

@@ -26,7 +26,7 @@ jobs:
 
       - name: Create backport PR
         id: backport
-        uses: korthout/backport-action@4aaf0e03a94ff0a619c9a511b61aeb42adea5b02 # v4.2.0
+        uses: korthout/backport-action@7c3f6cd5843cac11bc59a04a1b7699af93261670 # v4.5.0
         with:
           pull_title: "backport: ${pull_title}"
           label_pattern: "^ci:backport ([^ ]+)$"

.github/workflows/codeql.yml

@@ -31,11 +31,11 @@ jobs:
     - uses: ./.github/actions/setup
 
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@v4.35.1
+      uses: github/codeql-action/init@v4.35.2
       with:
         languages: cpp
 
     - run: make
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v4.35.1
+      uses: github/codeql-action/analyze@v4.35.2

.github/workflows/zizmor.yml

@@ -21,4 +21,4 @@ jobs:
           persist-credentials: false
 
       - name: Run zizmor
-        uses: zizmorcore/zizmor-action@71321a20a9ded102f6e9ce5718a2fcec2c4f70d8 # v0.5.2
+        uses: zizmorcore/zizmor-action@b1d7e1fb5de872772f31590499237e7cce841e8e # v0.5.3

runtime/doc/diagnostic.txt

@@ -661,9 +661,9 @@ Lua module: vim.diagnostic                                    *diagnostic-api*
                      |diagnostic-severity|
       • {text}?      (`table<vim.diagnostic.Severity,string>`) A table mapping
                      |diagnostic-severity| to the sign text to display in the
-                     sign column. The default is to use `"E"`, `"W"`, `"I"`,
-                     and `"H"` for errors, warnings, information, and hints,
-                     respectively. Example: >lua
+                     sign column and statusline. The default is to use `"E"`,
+                     `"W"`, `"I"`, and `"H"` for errors, warnings,
+                     information, and hints, respectively. Example: >lua
                          vim.diagnostic.config({
                            signs = { text = { [vim.diagnostic.severity.ERROR] = 'E', ... } }
                          })

runtime/doc/news.txt

@@ -158,6 +158,8 @@ DIAGNOSTICS
   enabled or disabled diagnostics.
 • |vim.diagnostic.status()| returns a status description of current buffer
   diagnostics.
+  • It uses the severity names defined by the `signs` field of
+    |vim.diagnostic.config()|, if any.
 • |vim.diagnostic.fromqflist()| accepts `opts.merge_lines` to merge multiline
   compiler messages.
 

runtime/lua/vim/diagnostic.lua

@@ -313,8 +313,8 @@ end
 --- @field priority? integer
 ---
 --- A table mapping |diagnostic-severity| to the sign text to display in the
---- sign column. The default is to use `"E"`, `"W"`, `"I"`, and `"H"` for errors,
---- warnings, information, and hints, respectively. Example:
+--- sign column and statusline. The default is to use `"E"`, `"W"`, `"I"`, and `"H"`
+--- for errors, warnings, information, and hints, respectively. Example:
 --- ```lua
 --- vim.diagnostic.config({
 ---   signs = { text = { [vim.diagnostic.severity.ERROR] = 'E', ... } }
@@ -3028,20 +3028,26 @@ function M.status(bufnr)
   bufnr = bufnr or 0
   local config = assert(M.config()).status or {}
   vim.validate('config.format', config.format, { 'table', 'function' }, true)
+
   local counts = M.count(bufnr)
-  local format = config.format or default_status_signs
-  --- @type string
-  local result_str
-  if type(format) == 'table' then
-    local signs = vim.tbl_extend('keep', format, default_status_signs)
+  local format = config.format
+  local result_str --- @type string
+  if type(format) == 'function' then
+    result_str = format(counts)
+  else
+    local signs ---@type table<vim.diagnostic.Severity, string>
+    if type(format) == 'table' then
+      signs = format
+    else
+      local signs_config = assert(vim.diagnostic.config()).signs
+      signs = type(signs_config) == 'table' and signs_config.text or default_status_signs
+    end
     result_str = vim
       .iter(pairs(counts))
       :map(function(severity, count)
         return ('%%#%s#%s:%s'):format(hl_map[severity], signs[severity], count)
       end)
       :join(' ')
-  elseif type(format) == 'function' then
-    result_str = format(counts)
   end
   if result_str:len() > 0 then
     result_str = result_str .. '%##'