On 03/19/2018 08:54 PM, Michael S. Tsirkin wrote:
QEMU coding style at the moment asks for all non-system include files to be used with #include "foo.h".
[I'm replying without having read the rest of the thread, so bear with me if I repeat some of the other comments that have already been made]
And Markus even just did a cleanup along those lines.
However this rule actually does not make sense and creates issues for when the included file is generated. In C, include "file" means look in current directory, then on include search path. Current directory here means the source file directory. By comparison include <file> means look on include search path.
It's also nice when "file" means file belonging to our project, and <file> means 3rd-party file. So we have to choose which semantics are easier; perhaps better Makefile rules that prevent us from seeing stale files is a better solution than figuring out which files are generated.
As generated files are not in the search directory (unless the build directory happens to match the source directory),
Why can't we fix Makefile to include BOTH the build and the source directories (to pick up generated files first, and then version-controlled files), and possibly include logic to simplify to a single -I instead of two when doing in-tree builds?
it does not make sense to include them with "" - doing so is merely more work for preprocessor and a source or errors if a stale file happens to exist in the source directory. This changes include directives for all generated files, across the tree. The idea is to avoid sending a huge amount of email. But when merging, the changes will be split with one commit per file, e.g. for ease of bisect in case of build failures, and to ease merging. Note that should some generated files be missed by this tree-wide refactoring, it isn't a big deal - this merely maintains the status quo, and this can be addressed by a separate patch on top.
I'm not sure I'm a fan of this patch yet, if there may be other alternatives that solve the real issue of stale generated files breaking incremental builds.
-- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
