c++: preserve location through constexpr

While working on the patch for PR101460, I noticed that we were losing the
expression location when folding class prvalue expressions.  The final patch
doesn't fold class prvalues, but this still seems a worthwhile change.  I
don't add location wrappers for scalar prvalues because many callers are
trying to fold them away.

gcc/cp/ChangeLog:

	* constexpr.c (cxx_eval_outermost_constant_expr): Copy
	expr location to result.

diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 9606719..e78fdf0 100644 (file)
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -7445,6 +7445,11 @@ cxx_eval_outermost_constant_expr (tree t, bool allow_non_constant,
        }
     }
 
+  /* Remember the original location if that wouldn't need a wrapper.  */
+  if (location_t loc = EXPR_LOCATION (t))
+    if (CAN_HAVE_LOCATION_P (r))
+      SET_EXPR_LOCATION (r, loc);
+
   return r;
 }