C++ Mode: Handle "if constexpr (...)" with a simple statement correctly

* lisp/progmodes/cc-engine.el (c-beginning-of-statement-1): Add a check and
handling for c-block-stmt-hangon-key in the main loop.

1 files changed, 9 insertions, 0 deletions

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 079985a6bc5..5a8b2f4f906 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -1184,6 +1184,15 @@ comment at the start of cc-engine.el for more info."
                            ;; suitable error.
                            (setq pre-stmt-found t)
                            (throw 'loop nil))
+                         ;; Handle C++'s `constexpr', etc.
+                         (if (save-excursion
+                               (and (looking-at c-block-stmt-hangon-key)
+                                    (progn
+                                      (c-backward-syntactic-ws lim)
+                                      (c-safe (c-backward-sexp) t))
+                                    (looking-at c-block-stmt-2-key)
+                                    (setq pos (point))))
+                             (goto-char pos))
                          (cond
                           ;; Have we moved into a macro?
                           ((and (not macro-start)