Re: [PATCH] ci: do not die on deprecated-declarations warning

[Ramsay Jones <ramsay@ramsayjones.plus.com>]

Hi Junio,

On 14/01/2023 03:47, Junio C Hamano wrote:
> Like a recent GitHub CI run on linux-musl [1] shows, we seem to be
> getting a bunch of errors of the form:
> 
>   Error: http.c:1002:9: 'CURLOPT_REDIR_PROTOCOLS' is deprecated:
>   since 7.85.0. Use CURLOPT_REDIR_PROTOCOLS_STR
>   [-Werror=deprecated-declarations]

Yes, on 30-Dec-2022 I updated my cygwin installation, which updated
the curl package(s) from v7.86.0 to v7.87.0, and caused my build
to fail. I had a quick look at the new 'curl.h' header file and
disabled the deprecation warnings to fix my build. I used vim to
add the following to my config.mak:

    CFLAGS += -DCURL_DISABLE_DEPRECATION

.. and then promptly forgot about it for a couple of weeks! :)

As it happens, just last night I started to look at fixing the code
to avoid the deprecated 'options'. However, if you are not interested
in doing that, I can stop looking into that. ;)

[I was probably doing it wrong anyway - I was just #ifdef-ing code
based on the curl version number, rather than setting something up
in the git-curl-compat.h header file; I haven't grokked that yet.]

> 
> For some of them, it may be reasonable to follow the deprecation
> notice and update the code, but some symbols like the above is not.
> 
> According to the release table [2], 7.85.0 that deprecates
> CURLOPT_REDIR_PROTOCOLS was released on 2022-08-31, less than a year
> ago, and according to the symbols-in-versions table [3],
> CURLOPT_REDIR_PROTOCOLS_STR was introduced in 7.85.0, so it will
> make us incompatible with anything older than a year if we rewrote
> the call as the message suggests.
> 
> Make sure that we won't break the build when -Wdeprecated-declarations
> triggers.
> 
> [1] https://github.com/git/git/actions/runs/3915509922/jobs/6693756050
> [2] https://curl.se/docs/releases.html
> [3] https://github.com/curl/curl/blob/master/docs/libcurl/symbols-in-versions
> 
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  config.mak.dev | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/config.mak.dev b/config.mak.dev
> index 981304727c..afcffa6a04 100644
> --- a/config.mak.dev
> +++ b/config.mak.dev
> @@ -69,6 +69,15 @@ DEVELOPER_CFLAGS += -Wno-missing-braces
>  endif
>  endif
>  
> +# Libraries deprecate symbols while retaining them for a long time to
> +# keep software working with both older and newer versions of them.
> +# Getting warnings does help the developers' awareness, but we cannot
> +# afford to update too aggressively.  E.g. CURLOPT_REDIR_PROTOCOLS_STR
> +# is only available in 7.85.0 that deprecates CURLOPT_REDIR_PROTOCOLS
> +# but we cannot rewrite the uses of the latter with the former until
> +# 7.85.0, which was released in August 2022, becomes ubiquitous.
> +DEVELOPER_CFLAGS += -Wno-error=deprecated-declarations
> +
>  # Old versions of clang complain about initializaing a
>  # struct-within-a-struct using just "{0}" rather than "{{0}}".  This
>  # error is considered a false-positive and not worth fixing, because

Rather than suppressing 'deprecated-declarations' globally, we could
just add '-DCURL_DISABLE_DEPRECATION' to the compilation of http.c,
http-push.c and remote-curl.c; similar to how we use target specific
rules to pass '-DCURL_DISABLE_TYPECHECK' to sparse (only) to a similar
set of files.

I haven't tried that yet (so famous last words...).

Sorry for not looking into this (and notifying the list) sooner.

ATB,
Ramsay Jones