Re: PING^1: [PATCH] Add TYPE_EMPTY_RECORD for C++ empty class

["H.J. Lu" <hjl.tools@gmail.com>]

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On Tue, Mar 15, 2016 at 5:25 PM, Joseph Myers <joseph@codesourcery.com> wrote:
> On Tue, 15 Mar 2016, H.J. Lu wrote:
>
>> On Tue, Mar 15, 2016 at 3:34 PM, Joseph Myers <joseph@codesourcery.com> wrote:
>> > On Tue, 15 Mar 2016, H.J. Lu wrote:
>> >
>> >> On Tue, Mar 15, 2016 at 2:39 PM, Joseph Myers <joseph@codesourcery.com> wrote:
>> >> > I'm not sure if the zero-size arrays (a GNU extension) are considered to
>> >> > make a struct non-empty, but in any case I think the tests should cover
>> >> > such arrays as elements of structs.
>> >>
>> >> There are couple tests for structs with members of array
>> >> of empty types.  testsuite/g++.dg/abi/empty14.h has
>> >
>> > My concern is the other way round - structs with elements such as
>> > "int a[0];", an array [0] of a nonempty type.  My reading of the subobject
>> > definition is that such an array should not cause the struct to be
>> > considered nonempty (it doesn't result in any int subobjects).
>>
>> This is a test for struct with zero-size array, which isn't treated
>> as empty type.  C++ and C are compatible in its passing.
>
> Where is the current definition of empty types you're proposing for use in
> GCC?  Is the behavior of this case clear from that definition?

https://gcc.gnu.org/ml/gcc/2016-03/msg00071.html

Jason's patch follows it.  Here is a test for struct with zero-size
array of empty type, which is treated as empty type.


-- 
H.J.

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From 222c8fcf6518b8689ead18516ce49ba71a1c0a49 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 15 Mar 2016 19:14:30 -0700
Subject: [PATCH] Add a test for struct with zero-size array of empty type

---
 gcc/testsuite/g++.dg/abi/empty19.C  | 17 +++++++++++++++++
 gcc/testsuite/g++.dg/abi/empty19.h  | 10 ++++++++++
 gcc/testsuite/g++.dg/abi/empty19a.c |  6 ++++++
 3 files changed, 33 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/abi/empty19.C
 create mode 100644 gcc/testsuite/g++.dg/abi/empty19.h
 create mode 100644 gcc/testsuite/g++.dg/abi/empty19a.c

diff --git a/gcc/testsuite/g++.dg/abi/empty19.C b/gcc/testsuite/g++.dg/abi/empty19.C
new file mode 100644
index 0000000..489eb3a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/empty19.C
@@ -0,0 +1,17 @@
+// PR c++/60336
+// { dg-do run }
+// { dg-options "-Wabi=9 -x c" }
+// { dg-additional-sources "empty14a.c" }
+// { dg-prune-output "command line option" }
+
+#include "empty19.h"
+extern "C" void fun(struct dummy, struct foo);
+
+int main()
+{
+  struct dummy d;
+  struct foo f = { -1, -2, -3, -4, -5 };
+
+  fun(d, f); // { dg-warning "empty" }
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/abi/empty19.h b/gcc/testsuite/g++.dg/abi/empty19.h
new file mode 100644
index 0000000..616b87b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/empty19.h
@@ -0,0 +1,10 @@
+struct dummy0 { };
+struct dummy { struct dummy0 d[0]; };
+struct foo
+{
+  int i1;
+  int i2;
+  int i3;
+  int i4;
+  int i5;
+};
diff --git a/gcc/testsuite/g++.dg/abi/empty19a.c b/gcc/testsuite/g++.dg/abi/empty19a.c
new file mode 100644
index 0000000..767b1eb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/empty19a.c
@@ -0,0 +1,6 @@
+#include "empty19.h"
+void fun(struct dummy d, struct foo f)
+{
+  if (f.i1 != -1)
+    __builtin_abort();
+}
-- 
2.5.0