[gcc r14-9039] c++: wrong looser exception spec with deleted fn

[Marek Polacek <mpolacek@gcc.gnu.org>]

https://gcc.gnu.org/g:40b8d7b73ad2ce498758c1d9bd38ebdbc26b918b

commit r14-9039-g40b8d7b73ad2ce498758c1d9bd38ebdbc26b918b
Author: Marek Polacek <polacek@redhat.com>
Date:   Thu Feb 15 14:58:31 2024 -0500

    c++: wrong looser exception spec with deleted fn
    
    I noticed we don't implement the "unless the overriding function is
    defined as deleted" wording added to [except.spec] via CWG 1351.
    
            DR 1351
    
    gcc/cp/ChangeLog:
    
            * search.cc (maybe_check_overriding_exception_spec): Don't error about
            a looser exception specification if the overrider is deleted.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp0x/noexcept82.C: New test.

Diff:
---
 gcc/cp/search.cc                        | 11 +++++++++--
 gcc/testsuite/g++.dg/cpp0x/noexcept82.C | 14 ++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
index 2b4ed5d024ea..c948839dc533 100644
--- a/gcc/cp/search.cc
+++ b/gcc/cp/search.cc
@@ -1949,7 +1949,11 @@ locate_field_accessor (tree basetype_path, tree field_decl, bool const_p)
 }
 
 /* Check throw specifier of OVERRIDER is at least as strict as
-   the one of BASEFN.  */
+   the one of BASEFN.  This is due to [except.spec]: "If a virtual function
+   has a non-throwing exception specification, all declarations, including
+   the definition, of any function that overrides that virtual function in
+   any derived class shall have a non-throwing exception specification,
+   unless the overriding function is defined as deleted."  */
 
 bool
 maybe_check_overriding_exception_spec (tree overrider, tree basefn)
@@ -1959,7 +1963,10 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
   tree base_throw = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (basefn));
   tree over_throw = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (overrider));
 
-  if (DECL_INVALID_OVERRIDER_P (overrider))
+  if (DECL_INVALID_OVERRIDER_P (overrider)
+      /* CWG 1351 added the "unless the overriding function is defined as
+	 deleted" wording.  */
+      || DECL_DELETED_FN (overrider))
     return true;
 
   /* Can't check this yet.  Pretend this is fine and let
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept82.C b/gcc/testsuite/g++.dg/cpp0x/noexcept82.C
new file mode 100644
index 000000000000..c996613139b5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept82.C
@@ -0,0 +1,14 @@
+// DR 1351, Problems with implicitly-declared exception-specifications
+// { dg-do compile { target c++11 } }
+
+struct B {
+  virtual void f() noexcept;
+  virtual void g();
+  virtual void h() noexcept = delete;
+};
+
+struct D: B {
+  void f();                     // { dg-error "looser" }
+  void g() noexcept;            // OK
+  void h() = delete;            // OK
+};