Re: [PATCH 1/2] pkt-line: fix declaration of `set_packet_header()`

[Junio C Hamano <gitster@pobox.com>]

"Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
writes:

> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>
> When this function was changed in a97d00799a19 (remote-curl: use
> post_rpc() for protocol v2 also, 2019-02-21) from file-local to global,
> the declaration was incorrectly missing the `const` qualifier.

I do not quite get it.  Back when the function was file-scope
static, it did not even have a separate declaration, and the
definition the said commit added looks correct to me.

Having "const int size" parameter in the definition of a function
does help the compilers and the developers by making sure any
earlier reference to the parameter in the function would not modify
it and cause later reference to obtain a different value.

But the parameter treated as a constant without getting modified
during the invocation of the function is an implementation detail of
the function; there is no point exposing that implementation detail
to its callers.  It does not even help the compilers handling the
caller's compilation unit---the parameter is passed by value, so the
caller knows that the callee would not modify it without "const"
there.

Does the language even allow flagging "const int in the definition,
int in the declaration" as a warning-worthy discrepancy?

> -void set_packet_header(char *buf, int size);
> +void set_packet_header(char *buf, const int size);