The paragraph about typedefs is very sparse and caused some trouble already: Is this mandatory coding style or just a recommendation? ... since this is the HACKING file and not in CODING_STYLE. And various versions of GCC and Clang disallow duplicated typedefs in certain language modes, so the "enforced" typedeffing repeatedly caused compile errors in the past. Thus let's reword this paragraph a little bit, so that it is clear that typedefs are welcome, but not a mandatory coding style. Also add some information about our include/qemu/typedefs.h file here since most newcomers are not aware of this file yet.
Signed-off-by: Thomas Huth <th...@redhat.com> --- HACKING | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/HACKING b/HACKING index 0fc3e0f..aa6fc3f 100644 --- a/HACKING +++ b/HACKING @@ -100,7 +100,13 @@ pointer, you're guaranteed that it is used to modify the storage it points to, or it is aliased to another pointer that is. 2.3. Typedefs -Typedefs are used to eliminate the redundant 'struct' keyword. +Typedefs can be used to eliminate the redundant 'struct' keyword. This is +especially helpful for common types that are used all over the place. Since +certain C compilers choke on duplicated typedefs, you should avoid them and +declare a typedef only in one header file. For common types, you can use +"include/qemu/typedefs.h" for example. Note that it is also perfectly fine to +use forward struct definitions without typedefs for references in headers +to avoid the problem with duplicated typedefs. 2.4. Reserved namespaces in C and POSIX Underscore capital, double underscore, and underscore 't' suffixes should be -- 1.8.3.1
