cfg.mk: variable initialization when declared with cleanup macro

A variable, which is never assigned a value in the function, might get
passed into the cleanup function which may or may not raise any errors.

To maintain the correct usage, the variable must be initialized, either
with a value or with NULL. This syntax-check rule takes care of that.
Signed-off-by: NSukrit Bhatnagar <skrtbhtngr@gmail.com>
Reviewed-by: NErik Skultety <eskultet@redhat.com>

cfg.mk

@@ -1057,6 +1057,17 @@ sc_prohibit_backslash_alignment:
 	halt='Do not attempt to right-align backslashes' \
 	  $(_sc_search_regexp)
 
+# Some syntax rules pertaining to the usage of cleanup macros
+# implementing GNU C's cleanup attribute
+
+# Rule to ensure that varibales declared using a cleanup macro are
+# always initialized.
+sc_require_attribute_cleanup_initialization:
+	@prohibit='VIR_AUTO(FREE|PTR)\(.+\) *[^=]+;' \
+	in_vc_files='\.[chx]$$' \
+	halt='variable declared with a cleanup macro must be initialized' \
+	  $(_sc_search_regexp)
+
 # We don't use this feature of maint.mk.
 prev_version_file = /dev/null