[libvirt] [PATCH 15/15] build: syntax check to avoid 'const fooPtr'

[Eric Blake]

'const fooPtr' is the same as 'foo * const' (the pointer won't
change, but it's contents can).  But in general, if an interface
is trying to be const-correct, it should be using 'const foo *'
(the pointer is to data that can't be changed).

Now that the code base has been cleaned, enforce it with a syntax
checker.

* cfg.mk (sc_forbid_const_pointer_typedef): New rule.
---
 cfg.mk | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/cfg.mk b/cfg.mk
index dad8a90..82ecc95 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -468,6 +468,14 @@ sc_correct_id_types:
 	halt="use pid_t for pid, uid_t for uid, gid_t for gid"		\
 	  $(_sc_search_regexp)

+# "const fooPtr a" is the same as "foo * const a", even though it is
+# usually desired to have 'foo const *a'.  It's easier to just prevent
+# the confusing mix of typedef vs. const placement.
+sc_forbid_const_pointer_typedef:
+	@prohibit='(^|[^"])const \w*Ptr'				\
+	halt='"const fooPtr var" does not declare what you meant'	\
+	  $(_sc_search_regexp)
+
 # Forbid sizeof foo or sizeof (foo), require sizeof(foo)
 sc_size_of_brackets:
 	@prohibit='sizeof\s'						\
-- 
1.8.3.1