Re: [PATCH 03/10] fast-export: store anonymized oids as hex strings

From: "SZEDER Gábor" <szeder.dev@gmail.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, Eric Sunshine <sunshine@sunshineco.com>,
	Junio C Hamano <gitster@pobox.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: Re: [PATCH 03/10] fast-export: store anonymized oids as hex strings
Date: Wed, 24 Jun 2020 13:43:13 +0200	[thread overview]
Message-ID: <20200624114313.GJ2898@szeder.dev> (raw)
In-Reply-To: <20200623152451.GC1435482@coredump.intra.peff.net>

On Tue, Jun 23, 2020 at 11:24:51AM -0400, Jeff King wrote:

> diff --git a/builtin/fast-export.c b/builtin/fast-export.c
> index 289395a131..4a3a4c933e 100644
> --- a/builtin/fast-export.c
> +++ b/builtin/fast-export.c
> @@ -387,16 +387,19 @@ static void *generate_fake_oid(const void *old, size_t *len)
>  {
>  	static uint32_t counter = 1; /* avoid null oid */
>  	const unsigned hashsz = the_hash_algo->rawsz;
> -	unsigned char *out = xcalloc(hashsz, 1);
> -	put_be32(out + hashsz - 4, counter++);
> -	return out;
> +	struct object_id oid;
> +	char *hex = xmallocz(GIT_MAX_HEXSZ);
> +
> +	oidclr(&oid);
> +	put_be32(oid.hash + hashsz - 4, counter++);
> +	return oid_to_hex_r(hex, &oid);
>  }

GCC 4.8 complains about this change in our CI job:

  $ make CC=gcc-4.8 builtin/fast-export.o
      CC builtin/fast-export.o
  builtin/fast-export.c: In function ‘generate_fake_oid’:
  builtin/fast-export.c:394:2: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
    put_be32(oid.hash + hashsz - 4, counter++);
    ^
  cc1: all warnings being treated as errors