From 525c617d3b92c10f79d1ffc786fb87dbf0958f0b Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Sun, 20 Feb 2011 18:18:01 -0500
Subject: [PATCH] re PR c++/46472 ([C++0X] constexpr is not constexpr)

	PR c++/46472
	* method.c (process_subob_fn): Instantiate constexpr templates.
	* optimize.c (maybe_clone_body): Propagate DECL_DECLARED_CONSTEXPR_P.

From-SVN: r170348
---
 gcc/cp/ChangeLog                              |  6 ++++++
 gcc/cp/method.c                               | 13 +++++++++++--
 gcc/cp/optimize.c                             |  1 +
 gcc/testsuite/ChangeLog                       |  4 ++++
 gcc/testsuite/g++.dg/cpp0x/constexpr-synth1.C | 14 ++++++++++++++
 5 files changed, 36 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-synth1.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a40fd02141b..b867ef327bc 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2011-02-20  Jason Merrill  <jason@redhat.com>
+
+	PR c++/46472
+	* method.c (process_subob_fn): Instantiate constexpr templates.
+	* optimize.c (maybe_clone_body): Propagate DECL_DECLARED_CONSTEXPR_P.
+
 2011-02-20  Dodji Seketeli  <dodji@redhat.com>
 
 	PR c++/46394
diff --git a/gcc/cp/method.c b/gcc/cp/method.c
index bfe8a067a8b..47f18081063 100644
--- a/gcc/cp/method.c
+++ b/gcc/cp/method.c
@@ -941,8 +941,17 @@ process_subob_fn (tree fn, bool move_p, tree *spec_p, bool *trivial_p,
       goto bad;
     }
 
-  if (constexpr_p && !DECL_DECLARED_CONSTEXPR_P (fn))
-    *constexpr_p = false;
+  if (constexpr_p)
+    {
+      /* If this is a specialization of a constexpr template, we need to
+	 force the instantiation now so that we know whether or not it's
+	 really constexpr.  */
+      if (DECL_DECLARED_CONSTEXPR_P (fn) && DECL_TEMPLATE_INSTANTIATION (fn)
+	  && !DECL_TEMPLATE_INSTANTIATED (fn))
+	instantiate_decl (fn, /*defer_ok*/false, /*expl_class*/false);
+      if (!DECL_DECLARED_CONSTEXPR_P (fn))
+	*constexpr_p = false;
+    }
 
   return;
 
diff --git a/gcc/cp/optimize.c b/gcc/cp/optimize.c
index b00bc28f030..ed59f91eff3 100644
--- a/gcc/cp/optimize.c
+++ b/gcc/cp/optimize.c
@@ -256,6 +256,7 @@ maybe_clone_body (tree fn)
       /* Update CLONE's source position information to match FN's.  */
       DECL_SOURCE_LOCATION (clone) = DECL_SOURCE_LOCATION (fn);
       DECL_DECLARED_INLINE_P (clone) = DECL_DECLARED_INLINE_P (fn);
+      DECL_DECLARED_CONSTEXPR_P (clone) = DECL_DECLARED_CONSTEXPR_P (fn);
       DECL_COMDAT (clone) = DECL_COMDAT (fn);
       DECL_WEAK (clone) = DECL_WEAK (fn);
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7078fdbb85f..9eff5ffcd2f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2011-02-20  Jason Merrill  <jason@redhat.com>
+
+	* g++.dg/cpp0x/constexpr-synth1.C: New.
+
 2011-02-20  Nicola Pero  <nicola.pero@meta-innovation.com>
 
 	* objc.dg/layout-2.m: New.
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-synth1.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-synth1.C
new file mode 100644
index 00000000000..9830939806b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-synth1.C
@@ -0,0 +1,14 @@
+// PR c++/46472
+// { dg-options -std=c++0x }
+
+template<class T> struct A {
+  T t;
+  constexpr A(){}
+};
+
+struct B
+{
+  A<int> a;
+};
+
+B b;
-- 
2.30.2