Patchwork [03/24] qemu-common.h: comment about usage rules

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Submitter Eduardo Habkost
Date Oct. 24, 2012, 3:01 a.m.
Message ID <1351047728-20360-4-git-send-email-ehabkost@redhat.com>
Download mbox | patch
Permalink /patch/193625/
State New
Headers show

Comments

Eduardo Habkost - Oct. 24, 2012, 3:01 a.m.
Every time we make a tiny change on a header file, we often find
circular header dependency problems. To avoid this nightmare, we need to
stop including qemu-common.h on other headers, and we should gradually
move the declarations from the catchall qemu-common.h header to their
specific headers.

This simply adds a comment documenting the rules about qemu-common.h,
hoping that people will see it before including qemu-common.h from other
header files, and before adding more declarations to qemu-common.h.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qemu-common.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Patch

diff --git a/qemu-common.h b/qemu-common.h
index b54612b..630bfa0 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -1,5 +1,14 @@ 
 
-/* Common header file that is included by all of qemu.  */
+/* Common header file that is included by all of qemu.
+ *
+ * This file is supposed to be included only by .c files. No header file should
+ * depend on qemu-common.h, as this would easily lead to circular header
+ * dependencies.
+ *
+ * If a header files uses a definition from qemu-common.h, that definition
+ * must be moved to a separate header file, and the header that uses it
+ * must include that header.
+ */
 #ifndef QEMU_COMMON_H
 #define QEMU_COMMON_H