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Re: [PR c++/84497] ref to undefined tls init
On 03/02/2018 01:43 PM, Jason Merrill wrote:
On Fri, Mar 2, 2018 at 11:07 AM, Nathan Sidwell <nathan@acm.org> wrote:
NEEDS_CONSTRUCTING && !HAS_CONSTEXPR_CTOR && !HAS_DEFAULT_CONSTRUCTOR seems
like it would be sufficient. and indeed that works in this case.
Do you mean !HAS_TRIVIAL_DFLT rather than !HAS_DEFAULT_CONSTRUCTOR?
That makes sense to me.
Even better!
nathan
--
Nathan Sidwell
2018-03-05 Pádraig Brady <P@draigBrady.com>
Jason Merrill <jason@redhat.com>
Nathan Sidwell <nathan@acm.org>
PR c++/84497
* decl2.c (get_tls_init_fn): Check TYPE_HAS_TRIVIAL_DFLT too.
PR c++/84497
* g++.dg/cpp0x/pr84497.C: New.
Index: cp/decl2.c
===================================================================
--- cp/decl2.c (revision 258114)
+++ cp/decl2.c (working copy)
@@ -3337,7 +3337,8 @@ get_tls_init_fn (tree var)
/* If the variable is defined somewhere else and might have static
initialization, make the init function a weak reference. */
if ((!TYPE_NEEDS_CONSTRUCTING (obtype)
- || TYPE_HAS_CONSTEXPR_CTOR (obtype))
+ || TYPE_HAS_CONSTEXPR_CTOR (obtype)
+ || TYPE_HAS_TRIVIAL_DFLT (obtype))
&& TYPE_HAS_TRIVIAL_DESTRUCTOR (obtype)
&& DECL_EXTERNAL (var))
declare_weak (fn);
Index: testsuite/g++.dg/cpp0x/pr84497.C
===================================================================
--- testsuite/g++.dg/cpp0x/pr84497.C (revision 0)
+++ testsuite/g++.dg/cpp0x/pr84497.C (working copy)
@@ -0,0 +1,37 @@
+// PR 84497 mismatch with thread constructor fn weakness
+// { dg-do compile { target c++11 } }
+// { dg-require-weak "" }
+
+struct Base
+{
+ int m;
+
+ Base() noexcept = default; // trivial but not constexpr
+ ~Base() noexcept = default;
+};
+
+struct Derived : Base {};
+struct Container {
+ Base m;
+};
+
+#ifdef DEF
+// This bit for exposition only.
+// All items placed in .tbss
+// __tls_init simply sets __tls_guard
+// no aliases to __tls_init generated
+thread_local Base base_obj;
+thread_local Derived derived_obj;
+thread_local Container container_obj;
+#else
+// Erroneously created strong undef refs to
+// _ZTH11derived_obj, _ZTH13container_obj, _ZTH8base_obj
+extern thread_local Base base_obj;
+extern thread_local Derived derived_obj;
+extern thread_local Container container_obj;
+int main() { return !(&base_obj && &derived_obj && &container_obj);}
+#endif
+
+// { dg-final { scan-assembler ".weak\[ \t\]*_ZTH8base_obj" } }
+// { dg-final { scan-assembler ".weak\[ \t\]*_ZTH11derived_obj" } }
+// { dg-final { scan-assembler ".weak\[ \t\]*_ZTH13container_obj" } }