[PATCH] teach sparse about __alignof__

This teaches sparse what __alignof__ really means, instead of just using
the same code as "__sizeof__"

It gets rid of the warnings in ebtables that does:
	struct ebt_entries {
...
	char data[0] __attribute__ ((aligned (__alignof__(struct ebt_replace)));
	};
Which caused warning because sparse was evaluating __alignof__ as the same as sizeof,
and sizeof was 57 (ie non-power of 2).

This is just based on the existing code and a peek at the data
structures in expression and symbol.

1 files changed, 22 insertions, 11 deletions

diff --git a/expression.c b/expression.c
index 5b817bb..6a705f9 100644
--- a/expression.c
+++ b/expression.c
@@ -370,17 +370,28 @@ static struct token *postfix_expression(struct token *token, struct expression *
 static struct token *cast_expression(struct token *token, struct expression **tree);
 static struct token *unary_expression(struct token *token, struct expression **tree)
 {
-	if (token_type(token) == TOKEN_IDENT &&
-	    (token->ident == &sizeof_ident ||
-	     token->ident == &__alignof___ident)) {
-		struct expression *sizeof_ex = alloc_expression(token->pos, EXPR_SIZEOF);
-		*tree = sizeof_ex;
-		tree = &sizeof_ex->unop;
-		token = token->next;
-		if (!match_op(token, '(') || !lookup_type(token->next))
-			return unary_expression(token, &sizeof_ex->cast_expression);
-		token = typename(token->next, &sizeof_ex->cast_type);
-		return expect(token, ')', "at end of sizeof type-name");
+	if (token_type(token) == TOKEN_IDENT) {
+		if (token->ident == &sizeof_ident) {
+			struct expression *sizeof_ex 
+				= alloc_expression(token->pos, EXPR_SIZEOF);
+			*tree = sizeof_ex;
+			tree = &sizeof_ex->unop;
+			token = token->next;
+			if (!match_op(token, '(') || !lookup_type(token->next))
+				return unary_expression(token, &sizeof_ex->cast_expression);
+			token = typename(token->next, &sizeof_ex->cast_type);
+			return expect(token, ')', "at end of sizeof type-name");
+		} else if (token->ident == &__alignof___ident) {
+			struct expression *alignof_ex 
+				= alloc_expression(token->pos, EXPR_ALIGNOF);
+			*tree = alignof_ex;
+			tree = &alignof_ex->unop;
+			token = token->next;
+			if (!match_op(token, '(') || !lookup_type(token->next))
+				return unary_expression(token, &alignof_ex->cast_expression);
+			token = typename(token->next, &alignof_ex->cast_type);
+			return expect(token, ')', "at end of alignof type-name");
+		}
 	}
 
 	if (token_type(token) == TOKEN_SPECIAL) {