symbol: do not inherit storage modifiers from base types at examination

Consider the following code snippet:
static inline foo(int dummy, ...) {}
static int a = 0;
static void bar(void)
{
foo(0, a);
}

Sparse moans:
test.c:5:9: warning: initializer for static storage duration object
is not a constant expression

The cause can be tracked down as follows:
The anonymous node created by inline_function() for the variadic argument will get assigned to its base_type whatever the passed expression's ctype is. For the special case of a primary expression referencing a symbol, this ctype is the referenced symbol itself. Furthermore, inline_function() sets that symbol node's initializer to this expression.

Now, when the anonymous symbol node is evaluated, its base_type is handled in examine_base_type(). This applies the base_type's modifiers, i.e. the referenced symbol's MOD_STATIC in this case, to the inheriting ctype, that of the anonymous node, itself.
This in turn instructs the evaluation of the symbol's initializer to allow constant expressions only.

Do not inherit a base_type's storage related modifiers in examine_base_type().

---
 symbol.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index cbc846b..605ec1c 100644
@@ -214,7 +214,8 @@ static struct symbol *examine_base_type(struct symbol *sym)
 	if (!base_type || base_type->type == SYM_PTR)
 		return base_type;
 	sym->ctype.as |= base_type->ctype.as;
-	sym->ctype.modifiers |= base_type->ctype.modifiers & MOD_PTRINHERIT;
+	sym->ctype.modifiers |= base_type->ctype.modifiers & MOD_PTRINHERIT &
+		~MOD_STORAGE;
 	concat_ptr_list((struct ptr_list *)base_type->ctype.contexts,
 			(struct ptr_list **)&sym->ctype.contexts);
 	if (base_type->type == SYM_NODE) {

2.4.5