Re: MSVC: Always dllimport the variable for MSVC in link-order.at

[Peter Rosin]

Hi Ralf,

Den 2010-07-16 05:36 skrev Ralf Wildenhues:
> OK.  The patch is fine with me then.

Good, thanks! I'm swapped "defined PIC" for "defined DLL_EXPORT", so this
is what I pushed:

diff --git a/ChangeLog b/ChangeLog
index a20add4..5c425b7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-07-17  Peter Rosin  <address@hidden>
+
+       dllimport the variable for MSVC in link-order.at
+       * tests/link-order.at [MSVC]: Makes the test pass by dllimporting
+       imported variables when working with shared libraries.
+
 2010-07-08  Peter Rosin  <address@hidden>
            Ralf Wildenhues  <address@hidden>

diff --git a/tests/link-order.at b/tests/link-order.at
index 0122a45..05ce776 100644
--- a/tests/link-order.at
+++ b/tests/link-order.at
@@ -48,13 +48,31 @@ for i in old new; do
   mkdir src

   cat >src/a_$i.c <<EOF
-extern int c;
+/* w32 fun, MSVC needs to dllimport when using a shared library, so use
+ * DLL_EXPORT to discriminate as that happens to coinside in this case.
+ * gnu has auto import.
+ */
+#if defined _MSC_VER && defined DLL_EXPORT
+#  define LIBCEE_SCOPE __declspec(dllimport)
+#else
+#  define LIBCEE_SCOPE extern
+#endif
+LIBCEE_SCOPE int c;
 extern int b_$i();
 int a_$i() { return c + b_$i(); }
 EOF

   cat >src/b_$i.c <<EOF
-extern int c;
+/* w32 fun, MSVC needs to dllimport when using a shared library, so use
+ * DLL_EXPORT to discriminate as that happens to coinside in this case.
+ * gnu has auto import.
+ */
+#if defined _MSC_VER && defined DLL_EXPORT
+#  define LIBCEE_SCOPE __declspec(dllimport)
+#else
+#  define LIBCEE_SCOPE extern
+#endif
+LIBCEE_SCOPE int c;
 int b_$i() { return 1 + c; }
 EOF



> OK.  Do we need to remember it somewhere (e.g., in TODO, exept that
> this is hopelessly outdated)?

I don't think *I* need a reminder. But documentation isn't written by
itself so I don't know when it will be done...

> > I didn't think the onus
> > was on me to write this as it has been a known issue on Windows for a
> > long time (I was just temporarily fooled that it was a non-issue with
> > MSVC when I misguidedly thought you could always dllimport with it).
>
> I didn't mean to imply that the onus is on you.  Just that it needs to
> be done.

Ok, it is just easy to read too much into your notes. Sorry about that.

> > The manual already says that it is not portable to export data items from
> > a libtool library. At least I think it does.
>
> The "Library tips" nodes has a bit.

Hmmm, my memory says that I have read something with the meaning that
exporting variables makes your life difficult on some platforms but I
now fail to find it in the libtool manual. Strange...

Cheers,
Peter