[PATCH 1/2] c++: Use seen_error instead of errorcount [PR118388]

[Simon Martin]

noexcept28.C fails with a checking ICE when run with -fpermissive,
because of a checking assert that uses errorcount instead of seen_error.

        PR c++/118388

gcc/cp/ChangeLog:

        * typeck2.cc (merge_exception_specifiers): Use seen_error
        instead of errorcount.

gcc/testsuite/ChangeLog:

        * g++.dg/cpp0x/noexcept128-fpermissive.C: New test.

---
This part was approved by Jason in May 2025 but I'm resending it given
how long it took me to follow-up.

 gcc/cp/typeck2.cc                             |  2 +-
 .../g++.dg/cpp0x/noexcept128-fpermissive.C    | 21 +++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept128-fpermissive.C

diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc
index c7ebd080edc6..2d263e085099 100644
--- a/gcc/cp/typeck2.cc
+++ b/gcc/cp/typeck2.cc
@@ -2981,7 +2981,7 @@ merge_exception_specifiers (tree list, tree add)
     return add;
   noex = TREE_PURPOSE (list);
   gcc_checking_assert (!TREE_PURPOSE (add)
-                      || errorcount || !flag_exceptions
+                      || seen_error () || !flag_exceptions
                       || cp_tree_equal (noex, TREE_PURPOSE (add)));
 
   /* Combine the dynamic-exception-specifiers, if any.  */
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept128-fpermissive.C 
b/gcc/testsuite/g++.dg/cpp0x/noexcept128-fpermissive.C
new file mode 100644
index 000000000000..dfc9629cb063
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept128-fpermissive.C
@@ -0,0 +1,21 @@
+// PR c++/118388
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-fpermissive" }
+
+template<typename T>
+struct traits
+{
+  static constexpr bool foo() { return sizeof(T) > 1; }
+  static constexpr bool bar() { return sizeof(T) > 1; }
+};
+
+template<typename T>
+struct X
+{
+  X& operator=(X&&) noexcept(traits<T>::foo());
+};
+
+template<typename T>
+  X<T>&
+  X<T>::operator=(X&&) noexcept(traits<T>::foo() && traits<T>::bar()) // { 
dg-warning "different exception" }
+  { return *this; }
-- 
2.56.0