[gcc r13-9304] c++: ICE with noexcept and local specialization, again [PR114349]

[Marek Polacek]

https://gcc.gnu.org/g:0430ec8881d657ddedff6c9d9fa4ea5db125f462

commit r13-9304-g0430ec8881d657ddedff6c9d9fa4ea5db125f462
Author: Marek Polacek <polacek@redhat.com>
Date:   Fri Jan 10 17:26:18 2025 -0500

    c++: ICE with noexcept and local specialization, again [PR114349]
    
    Patrick noticed that my r14-9339-gdc6c3bfb59baab patch is wrong;
    we're dealing with a noexcept-spec there, not a noexcept-expr, so
    setting cp_noexcept_operand et al is incorrect.  Back to the drawing
    board then.
    
    To fix noexcept84.C, we should probably avoid doing push_to_top_level
    in certain cases.  maybe_push_to_top_level didn't work here as-is, so
    I changed it to not push to top level if decl_function_context is
    non-null, when we are not dealing with a lambda.
    
    This also fixes c++/114349, introduced by r14-9339.
    
    This GCC 13 backport squashes r14-9659 and r14-9339.
    
            PR c++/114349
    
    gcc/cp/ChangeLog:
    
            * name-lookup.cc (maybe_push_to_top_level): For a non-lambda,
            don't push to top level if decl_function_context is non-null.
            * pt.cc (maybe_instantiate_noexcept): Use maybe_push_to_top_level.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp0x/noexcept84.C: New test.
            * g++.dg/cpp0x/noexcept85.C: New test.
            * g++.dg/cpp0x/noexcept86.C: New test.

Diff:
---
 gcc/cp/name-lookup.cc                   | 11 +++++++----
 gcc/cp/pt.cc                            |  4 ++--
 gcc/testsuite/g++.dg/cpp0x/noexcept84.C | 32 ++++++++++++++++++++++++++++++++
 gcc/testsuite/g++.dg/cpp0x/noexcept85.C | 33 +++++++++++++++++++++++++++++++++
 gcc/testsuite/g++.dg/cpp0x/noexcept86.C | 25 +++++++++++++++++++++++++
 5 files changed, 99 insertions(+), 6 deletions(-)

diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
index 7c61bc3bf611..1ea25f076b85 100644
--- a/gcc/cp/name-lookup.cc
+++ b/gcc/cp/name-lookup.cc
@@ -8244,10 +8244,13 @@ maybe_push_to_top_level (tree d)
 {
   /* Push if D isn't function-local, or is a lambda function, for which name
      resolution is already done.  */
-  bool push_to_top
-    = !(current_function_decl
-	&& !LAMBDA_FUNCTION_P (d)
-	&& decl_function_context (d) == current_function_decl);
+  const bool push_to_top
+    = (LAMBDA_FUNCTION_P (d)
+       || (TREE_CODE (d) == TYPE_DECL
+	   && TREE_TYPE (d)
+	   && LAMBDA_TYPE_P (TREE_TYPE (d)))
+       || !current_function_decl
+       || !decl_function_context (d));
 
   if (push_to_top)
     push_to_top_level ();
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 5a6bf80c3d42..ddfa3c25d10e 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -26772,7 +26772,7 @@ maybe_instantiate_noexcept (tree fn, tsubst_flags_t complain)
 	}
       else if (push_tinst_level (fn))
 	{
-	  push_to_top_level ();
+	  const bool push_to_top = maybe_push_to_top_level (fn);
 	  push_access_scope (fn);
 	  push_deferring_access_checks (dk_no_deferred);
 	  input_location = DECL_SOURCE_LOCATION (fn);
@@ -26809,7 +26809,7 @@ maybe_instantiate_noexcept (tree fn, tsubst_flags_t complain)
 	  pop_deferring_access_checks ();
 	  pop_access_scope (fn);
 	  pop_tinst_level ();
-	  pop_from_top_level ();
+	  maybe_pop_from_top_level (push_to_top);
 	}
       else
 	spec = noexcept_false_spec;
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept84.C b/gcc/testsuite/g++.dg/cpp0x/noexcept84.C
new file mode 100644
index 000000000000..06f33264f77c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept84.C
@@ -0,0 +1,32 @@
+// PR c++/114114
+// { dg-do compile { target c++11 } }
+
+template<bool B>
+constexpr void
+test ()
+{
+  constexpr bool is_yes = B;
+  struct S {
+    constexpr S() noexcept(is_yes) { }
+  };
+  S s;
+}
+
+constexpr bool foo() { return true; }
+
+template<typename T>
+constexpr void
+test2 ()
+{
+  constexpr T (*pfn)() = &foo;
+  struct S {
+    constexpr S() noexcept(pfn()) { }
+  };
+  S s;
+}
+
+int main()
+{
+  test<true>();
+  test2<bool>();
+}
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept85.C b/gcc/testsuite/g++.dg/cpp0x/noexcept85.C
new file mode 100644
index 000000000000..b415bb46bc94
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept85.C
@@ -0,0 +1,33 @@
+// PR c++/114349
+// { dg-do compile { target c++11 } }
+
+using A = struct {};
+template <template <typename> class, typename, typename>
+using B = A;
+template <typename T>
+using C = typename T::D;
+struct E {
+  using D = B<C, int, A>;
+};
+template <class> constexpr bool foo (A) { return false; }
+template <class T> struct F {
+  using G = T;
+  using H = E;
+  F(const F &);
+  void operator=(F) noexcept(foo <G> (H::D{}));
+};
+template <typename, typename, typename>
+using I = F<int>;
+template <typename K, typename V, typename H = K>
+using J = I<K, V, H>;
+struct K {
+  typedef J<long, char> L;
+  L k;
+  K();
+};
+struct M {
+  bool bar () const;
+  K::L m;
+};
+K n;
+bool M::bar () const { n.k = m; return true; }
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept86.C b/gcc/testsuite/g++.dg/cpp0x/noexcept86.C
new file mode 100644
index 000000000000..2d040c090f50
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept86.C
@@ -0,0 +1,25 @@
+// PR c++/114349
+// { dg-do compile { target c++14 } }
+
+struct B
+{
+  int i;
+};
+
+template <bool BA>
+void
+goo ()
+{
+  constexpr bool is_yes = BA;
+  struct C
+  {
+    static auto g(B b) noexcept(is_yes) { }
+  };
+  C::g({});
+}
+
+void
+x ()
+{
+  goo<false>();
+}