Add an eassert back to XSYMBOL

Problem reported by Alan Mackenzie in:
https://lists.gnu.org/r/emacs-devel/2024-01/msg00755.html
* src/lisp.h (XSYMBOL): If the arg is not a bare symbol, then
eassert (symbols_with_pos_enabled).  This shouldn’t affect code
generated for regular builds, and could catch caller errors in
debug builds.  For debug builds although this slows things down
XSYMBOL should still be faster than it was the day before
yesterday, as there’s still no need to eassert (SYMBOLP	(a)).

1 files changed, 6 insertions, 1 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 29d2a08785a..efdb3886141 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1161,7 +1161,12 @@ XBARE_SYMBOL (Lisp_Object a)
 INLINE struct Lisp_Symbol * ATTRIBUTE_NO_SANITIZE_UNDEFINED
 XSYMBOL (Lisp_Object a)
 {
-  return XBARE_SYMBOL (BARE_SYMBOL_P (a) ? a : XSYMBOL_WITH_POS (a)->sym);
+  if (!BARE_SYMBOL_P (a))
+    {
+      eassert (symbols_with_pos_enabled);
+      a = XSYMBOL_WITH_POS (a)->sym;
+    }
+  return XBARE_SYMBOL (a);
 }
 
 INLINE Lisp_Object