[PATCH 4/8] add helper: valid_type()

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

'bad_type' is used for ... bad types instead of NULL
in order to avoid later lots of null-checking.

Alas NULL is also often used and so we have to check
for NULL and 'bad_ctype' when checking a type's validity.

Add an helper: valid_type() to make the code a bit simpler.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 symbol.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/symbol.h b/symbol.h
index fd5746429..b4d1c2acc 100644
--- a/symbol.h
+++ b/symbol.h
@@ -309,6 +309,11 @@ extern void debug_symbol(struct symbol *);
 extern void merge_type(struct symbol *sym, struct symbol *base_type);
 extern void check_declaration(struct symbol *sym);
 
+static inline int valid_type(const struct symbol *ctype)
+{
+	return ctype && ctype != &bad_ctype;
+}
+
 static inline struct symbol *get_base_type(const struct symbol *sym)
 {
 	return examine_symbol_type(sym->ctype.base_type);
-- 
2.16.0