Subject: Re: [PATCH 2/3] treewide: switch to khashl for memory savings

From: Junio C Hamano <[email-masked]>
Date: Wed, 27 Mar 2024 14:54:18 -0700

Jeff King <[email-masked]> writes:

> On Tue, Mar 26, 2024 at 10:48:40AM -0700, Junio C Hamano wrote:
>
>> $ make builtin/fast-import.sp ;# part of make sparse
>>     SP builtin/fast-import.c
>> builtin/fast-import.c: note: in included file (through oidset.h, packfile.h):
>> khashl.h:516:1: error: Using plain integer as NULL pointer
>> khashl.h:516:1: error: Using plain integer as NULL pointer
>> make: *** [Makefile:3237: builtin/fast-import.sp] Error 1
>> 
>> I found IMPL_GET and IMPL_DEL's use of (h->keys == 0) were giving
>> one of these two, and managed to reduce the error to just one with
>> the attached patch, but I don't know what the other error is coming
>> from.
>
> Probably:
>
> diff --git a/khashl.h b/khashl.h
> index 8fcebed237..1e724bbf88 100644
> --- a/khashl.h
> +++ b/khashl.h
> @@ -116,7 +116,7 @@ static kh_inline khint_t __kh_h2b(khint_t hash, khint_t bits) { return hash * 26
>  
>  #define __KHASHL_IMPL_RESIZE(SCOPE, HType, prefix, khkey_t, __hash_fn, __hash_eq) \
>  	SCOPE void prefix##_resize(HType *h, khint_t new_n_buckets) { \
> -		khint32_t *new_used = 0; \
> +		khint32_t *new_used = NULL; \
>  		khint_t j = 0, x = new_n_buckets, n_buckets, new_bits, new_mask; \
>  		while ((x >>= 1) != 0) ++j; \
>  		if (new_n_buckets & (new_n_buckets - 1)) ++j; \
>
> -Peff

Spot on.  With this (and the other two 0 -> NULL fixes), and with
the SWAP() thing in brian's credential series fixed, the tip of
'seen' passes the static-analysis and sparse CI jobs again.

Thanks.