Re: [PATCH 2/7] c++: Adjust location of is_*_base_of diagnostics

[Jason Merrill]

On 10/26/25 7:32 AM, Nathaniel Shead wrote:

OK for trunk?

OK.

-- >8 --

It makes more sense to point at the derived type (that didn't specify
the base class).

gcc/cp/ChangeLog:

        * constraint.cc (diagnose_trait_expr): Use t2's location for
        is_base_of, is_pointer_interconvertible_base_of, and
        is_virtual_base_of.

gcc/testsuite/ChangeLog:

        * g++.dg/ext/is_virtual_base_of_diagnostic2.C: Adjust
        diagnostic.

Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
---
  gcc/cp/constraint.cc                                     | 9 ++++-----
  .../g++.dg/ext/is_virtual_base_of_diagnostic2.C          | 4 ++--
  2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index 60095d3c4f7..90c35023953 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -3135,7 +3135,7 @@ diagnose_trait_expr (location_t loc, tree expr, tree args)
        is_xible (MODIFY_EXPR, t1, t2, /*explain=*/true);
        break;
      case CPTK_IS_BASE_OF:
-      inform (decl_loc, "%qT is not a base of %qT", t1, t2);
+      inform (location_of (t2), "%qT is not a base of %qT", t1, t2);
        break;
      case CPTK_IS_BOUNDED_ARRAY:
        inform (loc, "%qT is not a bounded array", t1);
@@ -3236,7 +3236,8 @@ diagnose_trait_expr (location_t loc, tree expr, tree args)
        inform (loc, "%qT is not an object type", t1);
        break;
      case CPTK_IS_POINTER_INTERCONVERTIBLE_BASE_OF:
-      inform (decl_loc, "%qT is not a pointer-interconvertible base of %qT",
+      inform (location_of (t2),
+             "%qT is not a pointer-interconvertible base of %qT",
              t1, t2);
        break;
      case CPTK_IS_POD:
@@ -3295,9 +3296,7 @@ diagnose_trait_expr (location_t loc, tree expr, tree args)
        inform (decl_loc, "%qT is not a union", t1);
        break;
      case CPTK_IS_VIRTUAL_BASE_OF:
-      inform (decl_loc, "%qT is not a virtual base of %qT", t1, t2);
-      if (CLASS_TYPE_P (t2))
-       inform (location_of (t2), "%qT declared here", t2);
+      inform (location_of (t2), "%qT is not a virtual base of %qT", t1, t2);
        break;
      case CPTK_IS_VOLATILE:
        inform (loc, "%qT is not a volatile type", t1);
diff --git a/gcc/testsuite/g++.dg/ext/is_virtual_base_of_diagnostic2.C 
b/gcc/testsuite/g++.dg/ext/is_virtual_base_of_diagnostic2.C
index ac28121d49f..20d268570df 100644
--- a/gcc/testsuite/g++.dg/ext/is_virtual_base_of_diagnostic2.C
+++ b/gcc/testsuite/g++.dg/ext/is_virtual_base_of_diagnostic2.C
@@ -8,6 +8,6 @@ struct is_virtual_base_of {
  static_assert(is_virtual_base_of<int, int>::value, "");  // { dg-error 
"assert" }
  // { dg-message "'int' is not a virtual base of 'int'" "" { target *-*-* } 
.-1 }

-struct A {}; // { dg-message "'A' is not a virtual base of 'B'" }

-struct B : A {};  // { dg-message "declared here" }
+struct A {};
+struct B : A {};  // { dg-message "'A' is not a virtual base of 'B'" }
  static_assert(is_virtual_base_of<A, B>::value, "");  // { dg-error "assert" }