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From: Aurelien Aptel <aaptel@nvidia.com>
To: "linux-sparse@vger.kernel.org" <linux-sparse@vger.kernel.org>
Subject: how to figure if a struct symbol is incomplete
Date: Thu, 17 Oct 2024 09:09:04 +0000	[thread overview]
Message-ID: <SJ2PR12MB8943C1A7AF702D739C892D8DA5472@SJ2PR12MB8943.namprd12.prod.outlook.com> (raw)

Hi,

I’m toying around with a new sparse-based program, trying to check for certain things in C structs definitions.

I’ve looked around at examples and ctags was the most useful as it’s using ‘file_scope’ as the symbol entry point instead of the sparse() return value, which allowed me to see the AST of the types.
After some trial and error, I've figured that I had to call examine_symbol_type() on each symbol before I dive into them to fully compute the bit_size & offset of all the struct members.

While doing that, I've noticed that I cannot tell an empty structure from an incompletely defined one.
I'd like to err out instead of silently using a size=0 struct when I see an undefined type.

struct empty {};
struct foo {
    int a;
    struct unknown b;
};

The symbol for 'struct empty' and the member 'b' both have a sym->size == 0, an empty sym->symbol_list and a sym->ctype.base_type == NULL.
How can you tell those 2 cases apart?

Thanks

                 reply	other threads:[~2024-10-17  9:09 UTC|newest]

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