[pushed 1/2] c++: __has_trivial_destructor regression

[Jason Merrill]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

We don't want the new call to get_dtor to cause function instantiation.

        PR c++/107600

gcc/cp/ChangeLog:

        * semantics.cc (trait_expr_value) [CPTK_HAS_TRIVIAL_DESTRUCTOR]:
        Add cp_unevaluated.

gcc/testsuite/ChangeLog:

        * g++.dg/ext/has_trivial_destructor-3.C: New test.
---
 gcc/cp/semantics.cc                           |  1 +
 .../g++.dg/ext/has_trivial_destructor-3.C     | 21 +++++++++++++++++++
 2 files changed, 22 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ext/has_trivial_destructor-3.C

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 6551ca91928..7bc346b0f29 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -13419,6 +13419,7 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree 
type2)
       if (CLASS_TYPE_P (type1) && type_build_dtor_call (type1))
        {
          deferring_access_check_sentinel dacs (dk_no_check);
+         cp_unevaluated un;
          tree fn = get_dtor (type1, tf_none);
          if (!fn && !seen_error ())
            warning (0, "checking %qs for type %qT with a destructor that "
diff --git a/gcc/testsuite/g++.dg/ext/has_trivial_destructor-3.C 
b/gcc/testsuite/g++.dg/ext/has_trivial_destructor-3.C
new file mode 100644
index 00000000000..a179be52e93
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/has_trivial_destructor-3.C
@@ -0,0 +1,21 @@
+// { dg-do compile { target c++11 } }
+
+struct X;
+
+template<class T>
+struct default_delete
+{
+  void operator()(T*) { static_assert(sizeof(T), "type is not incomplete"); }
+};
+
+template<class T, class D = default_delete<T>>
+struct unique_ptr
+{
+  ~unique_ptr() { del(ptr); }
+
+  T* ptr;
+  D del;
+};
+
+
+constexpr bool b = __has_trivial_destructor(unique_ptr<X>);

base-commit: 08031b88e2a32cc334af540703c5332a6b716529
-- 
2.49.0