PR c/70297

	* c-decl.c (merge_decls): Also set TYPE_ALIGN and TYPE_USER_ALIGN.

	* decl.c (duplicate_decls): Also set TYPE_ALIGN and TYPE_USER_ALIGN.

	* c-c++-common/pr70297.c: New test.
	* g++.dg/cpp0x/typedef-redecl.C: New test.
	* gcc.dg/typedef-redecl2.c: New test.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@234626 138bc75d-0d04-0410-961f-82ee72b054a4

8 files changed, 89 insertions, 0 deletions

diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index c8cb0227e2a..b52b414478f 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,8 @@
+2016-03-31  Marek Polacek  <polacek@redhat.com>
+
+	PR c/70297
+	* c-decl.c (merge_decls): Also set TYPE_ALIGN and TYPE_USER_ALIGN.
+
 2016-03-18  David Malcolm  <dmalcolm@redhat.com>
 
 	PR c/70281
diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index bab47153235..0dd2121b868 100644
--- a/gcc/c/c-decl.c
+++ b/gcc/c/c-decl.c
@@ -2358,6 +2358,35 @@ merge_decls (tree newdecl, tree olddecl, tree newtype, tree oldtype)
   DECL_ATTRIBUTES (newdecl)
     = targetm.merge_decl_attributes (olddecl, newdecl);
 
+  /* For typedefs use the old type, as the new type's DECL_NAME points
+     at newdecl, which will be ggc_freed.  */
+  if (TREE_CODE (newdecl) == TYPE_DECL)
+    {
+      /* But NEWTYPE might have an attribute, honor that.  */
+      tree tem = newtype;
+      newtype = oldtype;
+
+      if (TYPE_USER_ALIGN (tem))
+	{
+	  if (TYPE_ALIGN (tem) > TYPE_ALIGN (newtype))
+	    TYPE_ALIGN (newtype) = TYPE_ALIGN (tem);
+	  TYPE_USER_ALIGN (newtype) = true;
+	}
+
+      /* And remove the new type from the variants list.  */
+      if (TYPE_NAME (TREE_TYPE (newdecl)) == newdecl)
+	{
+	  tree remove = TREE_TYPE (newdecl);
+	  for (tree t = TYPE_MAIN_VARIANT (remove); ;
+	       t = TYPE_NEXT_VARIANT (t))
+	    if (TYPE_NEXT_VARIANT (t) == remove)
+	      {
+		TYPE_NEXT_VARIANT (t) = TYPE_NEXT_VARIANT (remove);
+		break;
+	      }
+	}
+    }
+
   /* Merge the data types specified in the two decls.  */
   TREE_TYPE (newdecl)
     = TREE_TYPE (olddecl)
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 96f02210aa9..8aad906fc12 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2016-03-31  Marek Polacek  <polacek@redhat.com>
+
+	PR c/70297
+	* decl.c (duplicate_decls): Also set TYPE_ALIGN and TYPE_USER_ALIGN.
+
 2016-03-31  Richard Biener  <rguenther@suse.de>
 
 	PR c++/70430
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index cfae210da55..4730093da99 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -2028,8 +2028,17 @@ duplicate_decls (tree newdecl, tree olddecl, bool newdecl_is_friend)
 	 at newdecl, which will be ggc_freed.  */
       if (TREE_CODE (newdecl) == TYPE_DECL)
 	{
+	  /* But NEWTYPE might have an attribute, honor that.  */
+	  tree tem = TREE_TYPE (newdecl);
 	  newtype = oldtype;
 
+	  if (TYPE_USER_ALIGN (tem))
+	    {
+	      if (TYPE_ALIGN (tem) > TYPE_ALIGN (newtype))
+		TYPE_ALIGN (newtype) = TYPE_ALIGN (tem);
+	      TYPE_USER_ALIGN (newtype) = true;
+	    }
+
 	  /* And remove the new type from the variants list.  */
 	  if (TYPE_NAME (TREE_TYPE (newdecl)) == newdecl)
 	    {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index aa0e17e1519..d1dd5ea7680 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2016-03-31  Marek Polacek  <polacek@redhat.com>
+
+	PR c/70297
+	* c-c++-common/pr70297.c: New test.
+	* g++.dg/cpp0x/typedef-redecl.C: New test.
+	* gcc.dg/typedef-redecl2.c: New test.
+
 2016-03-31  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/70460
diff --git a/gcc/testsuite/c-c++-common/pr70297.c b/gcc/testsuite/c-c++-common/pr70297.c
new file mode 100644
index 00000000000..70a4f15cd22
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr70297.c
@@ -0,0 +1,9 @@
+/* PR c/70297 */
+/* { dg-do compile } */
+/* { dg-options "-g" } */
+
+typedef int T;
+typedef int T __attribute__((aligned (4)));
+struct S {
+  T *t;
+};
diff --git a/gcc/testsuite/g++.dg/cpp0x/typedef-redecl.C b/gcc/testsuite/g++.dg/cpp0x/typedef-redecl.C
new file mode 100644
index 00000000000..576c7ce0332
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/typedef-redecl.C
@@ -0,0 +1,12 @@
+// PR c/70297
+// { dg-do compile { target c++11 } }
+
+#define N 64
+
+typedef int T;
+typedef int T __attribute__((aligned (N)));
+typedef int T __attribute__((aligned (N * 2)));
+typedef int T __attribute__((aligned (N)));
+typedef int T;
+
+static_assert (alignof (T) == N * 2, "N * 2");
diff --git a/gcc/testsuite/gcc.dg/typedef-redecl2.c b/gcc/testsuite/gcc.dg/typedef-redecl2.c
new file mode 100644
index 00000000000..c2314c78eaa
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/typedef-redecl2.c
@@ -0,0 +1,13 @@
+/* PR c/70297 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+#define N 64
+
+typedef int T;
+typedef int T __attribute__((aligned (N)));
+typedef int T __attribute__((aligned (N * 2)));
+typedef int T __attribute__((aligned (N)));
+typedef int T;
+
+_Static_assert (_Alignof (T) == N * 2, "N * 2");