maint: Fix header includes once and for all

Previously #include statements were a bit of a mess across the codebase.
This commit is the result of a pass by the IWYU (Include What You Use)
tool, which suggests headers to add or remove based on what is in the
file, and can also suggest forward-declaring classes instead of
including their headers, if they are only used as a pointer in a
particular file. Cleaning this up should in general speed up compile
times.

IWYU isn't perfect, it produces a number of false positives, so we don't
try to automate this process and we don't accept all of its
recommendations. We do add a script and configuration file to the tools/
directory so that IWYU can be every so often in the future.

We also clean up all the includes according to a consistent style, which
is now described clearly in the C++ style guide.

1 files changed, 7 insertions, 4 deletions

diff --git a/modules/cairo-linear-gradient.cpp b/modules/cairo-linear-gradient.cpp
index 7892a1c4..2fca7e3f 100644
--- a/modules/cairo-linear-gradient.cpp
+++ b/modules/cairo-linear-gradient.cpp
@@ -20,13 +20,16 @@
  * IN THE SOFTWARE.
  */
 
-#include <config.h>
+#include <cairo.h>
+#include <glib.h>
+
+#include "gjs/jsapi-wrapper.h"
 
 #include "gjs/jsapi-class.h"
 #include "gjs/jsapi-util-args.h"
-#include "gjs/jsapi-wrapper.h"
-#include <cairo.h>
-#include "cairo-private.h"
+#include "gjs/jsapi-util.h"
+#include "gjs/macros.h"
+#include "modules/cairo-private.h"
 
 GJS_USE
 static JSObject *gjs_cairo_linear_gradient_get_proto(JSContext *);