Re: [PATCH 1/1] sparse-checkout: use extern for global variables

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 2, 2020, 18:17 UTC
Message-ID: <xmqq36cxg1u5.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <c704cb554e1897278913520f266d95a4b04f9639.1577798268.git.gitgitgadget@gmail.com>

"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:

Show 12 quoted lines

> From: Derrick Stolee <dstolee@microsoft.com>
>
> When the core.sparseCheckoutCone config setting was added in
> 879321eb0b ("sparse-checkout: add 'cone' mode" 2019-11-21), the
> variables storing the config values for core.sparseCheckout and
> core.sparseCheckoutCone were rearranged in cache.h, but in doing
> so the "extern" keyword was dropped.
>
> While we are tending to drop the "extern" keyword for function
> declarations, it is still necessary for global variables used
> across multiple *.c files. The impact of not having the extern
> keyword may be unpredictable.

"May be unpredictable" might be a bit too strong, but I agree that it is better not to rely on the "common extension" these days, and instead make sure variable decls have "extern" in front.

Will queue.  Thanks.

Show 20 quoted lines

> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> ---
>  cache.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/cache.h b/cache.h
> index 1554488d66..cbfaead23a 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -958,8 +958,8 @@ extern int protect_hfs;
>  extern int protect_ntfs;
>  extern const char *core_fsmonitor;
>  
> -int core_apply_sparse_checkout;
> -int core_sparse_checkout_cone;
> +extern int core_apply_sparse_checkout;
> +extern int core_sparse_checkout_cone;
>  
>  /*
>   * Include broken refs in all ref iterations, which will