c++: constexpr, array, private ctor [PR120800]

Here cxx_eval_vec_init_1 wants to recreate the default constructor call that
we previously built and threw away in build_vec_init_elt, but we aren't in
the same access context at this point.  Since we already checked access,
let's just suppress access control here.

Redoing overload resolution at constant evaluation time is sketchy, but
should usually be fine for a default/copy constructor.

	PR c++/120800

gcc/cp/ChangeLog:

	* constexpr.cc (cxx_eval_vec_init_1): Suppress access control.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/constexpr-array30.C: New test.

(cherry picked from commit f6462f664725844faa97ae7e8690e4fedee65788)

diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 6d368b2ae6f3fcb3a08d681eb1c2879ef678f777..1855e27103319e3307b9283a249cdc3e836d01e8 100644 (file)
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -5507,6 +5507,9 @@ cxx_eval_vec_init_1 (const constexpr_ctx *ctx, tree atype, tree init,
     return cxx_eval_bare_aggregate (ctx, init, lval,
                                    non_constant_p, overflow_p);
 
+  /* We already checked access when building the VEC_INIT_EXPR.  */
+  deferring_access_check_sentinel acs (dk_deferred);
+
   /* For the default constructor, build up a call to the default
      constructor of the element type.  We only need to handle class types
      here, as for a constructor to be constexpr, all members must be

diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-array30.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-array30.C
new file mode 100644 (file)
index 0000000..3f72407
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-array30.C
@@ -0,0 +1,22 @@
+// PR c++/120800
+// { dg-do compile { target c++11 } }
+
+template<typename T>
+struct Container
+{
+ T m_data[1] {};
+};
+
+class Element
+{
+private:
+ Element() = default;
+
+private:
+ bool m_bool1 { false };
+ bool m_bool2;
+
+ friend struct Container<Element>;
+};
+
+Container<Element> element;