Merge from origin/emacs-29

59365f9285 * lisp/progmodes/go-ts-mode.el: Use treesit-language-avai...
56cd810b9d Don’t signal warning when loading go-ts-mode.el without g...
b06d551966 Fix c-ts-mode empty line indentation (bug#61893)
6b2720778d Improve tree-sitter's prev-sibling indent anchor

lisp/progmodes/c-ts-mode.el

@@ -257,7 +257,7 @@ is actually the parent of point at the moment of indentation."
         0
       c-ts-mode-indent-offset)))
 
-(defun c-ts-mode--anchor-prev-sibling (node &rest _)
+(defun c-ts-mode--anchor-prev-sibling (node parent bol &rest _)
   "Return the start of the previous named sibling of NODE.
 
 This anchor handles the special case where the previous sibling
@@ -273,8 +273,14 @@ The anchor of \"int y = 2;\" should be \"int x = 1;\" rather than
 the labeled_statement.
 
 Return nil if a) there is no prev-sibling, or 2) prev-sibling
-doesn't have a child."
-  (when-let ((prev-sibling (treesit-node-prev-sibling node t)))
+doesn't have a child.
+
+PARENT and BOL are like other anchor functions."
+  (when-let ((prev-sibling
+              (or (treesit-node-prev-sibling node t)
+                  (treesit-node-prev-sibling
+                   (treesit-node-first-child-for-pos parent bol) t)
+                  (treesit-node-child parent -1 t))))
     (while (and prev-sibling
                 (equal "labeled_statement"
                        (treesit-node-type prev-sibling)))
@@ -350,17 +356,17 @@ MODE is either `c' or `cpp'."
 
            ;; int[5] a = { 0, 0, 0, 0 };
            ((match nil "initializer_list" nil 1 1) parent-bol c-ts-mode-indent-offset)
-           ((match nil "initializer_list" nil 2) c-ts-mode--anchor-prev-sibling 0)
+           ((parent-is "initializer_list") c-ts-mode--anchor-prev-sibling 0)
            ;; Statement in enum.
            ((match nil "enumerator_list" nil 1 1) standalone-parent c-ts-mode-indent-offset)
-           ((match nil "enumerator_list" nil 2) c-ts-mode--anchor-prev-sibling 0)
+           ((parent-is "enumerator_list") c-ts-mode--anchor-prev-sibling 0)
            ;; Statement in struct and union.
            ((match nil "field_declaration_list" nil 1 1) standalone-parent c-ts-mode-indent-offset)
-           ((match nil "field_declaration_list" nil 2) c-ts-mode--anchor-prev-sibling 0)
+           ((parent-is "field_declaration_list") c-ts-mode--anchor-prev-sibling 0)
 
            ;; Statement in {} blocks.
            ((match nil "compound_statement" nil 1 1) standalone-parent c-ts-mode-indent-offset)
-           ((match nil "compound_statement" nil 2) c-ts-mode--anchor-prev-sibling 0)
+           ((parent-is "compound_statement") c-ts-mode--anchor-prev-sibling 0)
            ;; Opening bracket.
            ((node-is "compound_statement") standalone-parent c-ts-mode-indent-offset)
            ;; Bug#61291.

lisp/progmodes/go-ts-mode.el

@@ -427,7 +427,7 @@ what the parent of the node would be if it were a node."
 
     (treesit-major-mode-setup)))
 
-(if (treesit-ready-p 'gomod)
+(if (treesit-language-available-p 'gomod)
     (add-to-list 'auto-mode-alist '("/go\\.mod\\'" . go-mod-ts-mode)))
 
 (provide 'go-ts-mode)

lisp/treesit.el

@@ -1237,9 +1237,17 @@ See `treesit-simple-indent-presets'.")
                                           (line-beginning-position))
                         (throw 'term (point)))
                       (setq parent (treesit-node-parent parent)))))))
-        (cons 'prev-sibling (lambda (node &rest _)
+        (cons 'prev-sibling (lambda (node parent bol &rest _)
                               (treesit-node-start
-                               (treesit-node-prev-sibling node))))
+                               (or (treesit-node-prev-sibling node t)
+                                   ;; If node is nil (indenting empty
+                                   ;; line), we still try to guess the
+                                   ;; previous sibling.
+                                   (treesit-node-prev-sibling
+                                    (treesit-node-first-child-for-pos
+                                     parent bol)
+                                    t)
+                                   (treesit-node-child parent -1 t)))))
         (cons 'no-indent (lambda (_n _p bol &rest _) bol))
         (cons 'prev-line (lambda (_n _p bol &rest _)
                            (save-excursion

test/lisp/progmodes/c-ts-mode-resources/indent.erts

@@ -84,14 +84,6 @@ int main()
 }
 =-=-=
 
-Name: Empty Line
-=-=
-int main()
-{
-  |
-}
-=-=-=
-
 Name: Concecutive blocks (GNU Style) (bug#60873)
 
 =-=
@@ -385,3 +377,28 @@ namespace test {
   };
 }
 =-=-=
+
+Code:
+  (lambda ()
+    (c-ts-mode)
+    (setq-local indent-tabs-mode nil)
+    (setq-local c-ts-mode-indent-offset 2)
+    (c-ts-mode-set-style 'gnu)
+    (indent-for-tab-command))
+
+Name: Empty Line
+=-=
+int main()
+{
+  |
+}
+=-=-=
+
+Name: Empty Line Previous Sibling
+=-=
+int main()
+{
+  int a = 1;
+  |
+}
+=-=-=