From 29edb15c5637738f3ac9c9d63003303127848204 Mon Sep 17 00:00:00 2001
From: Mark Mitchell <mark@codesourcery.com>
Date: Mon, 15 Sep 2003 00:27:16 +0000
Subject: [PATCH] class.c (layout_class_type): Make DECL_MODE match TYPE_MODE
 for an bit-field whose width exceeds that of its...

	* class.c (layout_class_type): Make DECL_MODE match TYPE_MODE for
	an bit-field whose width exceeds that of its type.

	* g++.dg/abi/bitfield11.C: New test.
	* g++.dg/abi/bitfield12.C: Likewise.

From-SVN: r71392
---
 gcc/cp/class.c                        | 10 +++++++++-
 gcc/testsuite/ChangeLog               |  5 +++++
 gcc/testsuite/g++.dg/abi/bitfield11.C | 14 ++++++++++++++
 gcc/testsuite/g++.dg/abi/bitfield12.C |  5 +++++
 4 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/abi/bitfield11.C
 create mode 100644 gcc/testsuite/g++.dg/abi/bitfield12.C

diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index 582caf4279ed..706ebbff6782 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -4759,7 +4759,15 @@ layout_class_type (tree t, tree *virtuals_p)
 	     field to the size of its declared type; the rest of the
 	     field is effectively invisible.  */
 	  DECL_SIZE (field) = TYPE_SIZE (type);
-	  DECL_MODE (field) = TYPE_MODE (type);
+	  /* We must also reset the DECL_MODE of the field.  */
+	  if (abi_version_at_least (2))
+	    DECL_MODE (field) = TYPE_MODE (type);
+	  else if (warn_abi
+		   && DECL_MODE (field) != TYPE_MODE (type))
+	    /* Versions of G++ before G++ 3.4 did not reset the
+	       DECL_MODE.  */
+	    warning ("the offset of `%D' may not be ABI-compliant and may "
+		     "change in a future version of GCC", field);
 	}
       else
 	layout_nonempty_base_or_field (rli, field, NULL_TREE,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 9d7c8e5547a7..802d53e4a3cd 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2003-09-14  Mark Mitchell  <mark@codesourcery.com>
+
+	* g++.dg/abi/bitfield11.C: New test.
+	* g++.dg/abi/bitfield12.C: Likewise.
+
 2003-09-14  Alexandre Oliva  <aoliva@redhat.com>
 
 	* gcc.dg/cpp/separate-1.c: Adjust line of error.  Test for correct
diff --git a/gcc/testsuite/g++.dg/abi/bitfield11.C b/gcc/testsuite/g++.dg/abi/bitfield11.C
new file mode 100644
index 000000000000..e78ea121d615
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/bitfield11.C
@@ -0,0 +1,14 @@
+// { dg-do run } 
+// { dg-options "-w -fabi-version=0" }
+
+struct S {
+  char c : 1024;
+};
+
+S s;
+
+int main () {
+  s.c = 1;
+  if (*(char *)&s != 1)
+    return 1;
+}
diff --git a/gcc/testsuite/g++.dg/abi/bitfield12.C b/gcc/testsuite/g++.dg/abi/bitfield12.C
new file mode 100644
index 000000000000..6cfda5d47df5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/bitfield12.C
@@ -0,0 +1,5 @@
+// { dg-options "-Wabi -fabi-version=1" }
+
+struct S { // { dg-warning "ABI" }
+  char c : 1024; // { dg-warning "width" }
+};