[PATCH] Don't require class to be constructed (PR c++/58408)

[David Bartley]

2013-09-24  David Bartley  <d...@google.com>

        PR c++/58408
        * gcc/cp/class.c: Don't require class to be constructed if it
        has a trivial default constructor.
        * gcc/testsuite/g++.dg/tls/init-1.C: New testcase.
---
 gcc/cp/class.c                    | 14 +++++++++-----
 gcc/testsuite/g++.dg/tls/init-1.C | 11 +++++++++++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index 9e0229f..7523fac 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -5383,6 +5383,7 @@ check_bases_and_members (tree t)
   tree access_decls;
   bool saved_complex_asn_ref;
   bool saved_nontrivial_dtor;
+  bool trivial_default_ctor;
   tree fn;
 
   /* By default, we use const reference arguments and generate default
@@ -5426,12 +5427,15 @@ check_bases_and_members (tree t)
   TYPE_HAS_COMPLEX_COPY_CTOR (t) |= TYPE_CONTAINS_VPTR_P (t);
   TYPE_HAS_COMPLEX_MOVE_CTOR (t) |= TYPE_CONTAINS_VPTR_P (t);
   /* We need to call a constructor for this class if it has a
-     user-provided constructor, or if the default constructor is going
-     to initialize the vptr.  (This is not an if-and-only-if;
-     TYPE_NEEDS_CONSTRUCTING is set elsewhere if bases or members
-     themselves need constructing.)  */
+     user-provided constructor and no trivial default constructor
+     or if the default constructor is going to initialize the vptr.
+     (This is not an if-and-only-if; TYPE_NEEDS_CONSTRUCTING is set
+     elsewhere if bases or members themselves need constructing.)  */
+  trivial_default_ctor =
+      TYPE_HAS_DEFAULT_CONSTRUCTOR (t) && !TYPE_HAS_COMPLEX_DFLT (t);
   TYPE_NEEDS_CONSTRUCTING (t)
-    |= (type_has_user_provided_constructor (t) || TYPE_CONTAINS_VPTR_P (t));
+    |= ((type_has_user_provided_constructor (t) && !trivial_default_ctor)
+        || TYPE_CONTAINS_VPTR_P (t));
   /* [dcl.init.aggr]
 
      An aggregate is an array or a class with no user-provided
diff --git a/gcc/testsuite/g++.dg/tls/init-1.C 
b/gcc/testsuite/g++.dg/tls/init-1.C
index 9786712..c24d874 100644
--- a/gcc/testsuite/g++.dg/tls/init-1.C
+++ b/gcc/testsuite/g++.dg/tls/init-1.C
@@ -1,5 +1,6 @@
 /* Valid initializations.  */
 /* { dg-require-effective-target tls } */
+/* { dg-options "-std=c++11" } */
 
 __thread int i = 42;
 
@@ -12,3 +13,13 @@ int *q = &i;
 /* Valid because "const int k" is an integral constant expression in C++.  */
 __thread const int k = 42;
 __thread const int l = k;
+
+/* Defined copy constructor with explicitly-default constructor.*/
+class Test {
+ public:
+  Test() = default;
+  Test(int) {
+  }
+  int t;
+};
+__thread Test t;
-- 
1.8.4