[PATCH 2/2 v2] compat: add compatibility definitions for old MM_MODEM_BAND_EUTRAN_* values

[Aleksander Morgado]

On Wed, Jun 28, 2017 at 9:36 AM, Ben Chan <benchan at chromium.org> wrote:
> When adding this compat header, I noticed that __attribute__((deprecated)),
> which G_DEPRECATED_FOR is based on, can't be associated with macros.  Both
> gcc and clang associated the attribute to the next identifier found after
> the macro definition, not the macro itself:
>
> #1
>     G_DEPRECATED_FOR(NEW_ENUM)
>     #define OLD_ENUM NEW_NUM
>     void foo() {}   // __attribute__((deprecated)) is applied to foo()
> instead of OLD_ENUM
>     foo();  // this triggers a deprecation warning
>
> #2
>     G_DEPRECATED_FOR(NEW_ENUM)
>     #define OLD_ENUM NEW_NUM
>     struct bar;   // clang fails to apply __attribute__((deprecated)) here
> and throws an ignored-attribute warning
>
> It seems like only MSVC supports deprecation attribute on macro definitions
> via #pragma deprecated.  Enumerator attribute would be the solution, but
> only gcc 6 or above (clang 3 or above) supports that. For example, we can
> use unnamed enum to define deprecated enumerators like this:
>
>     enum {
>         OLD_ENUM G_DEPRECATED_FOR(NEW_ENUM) = NEW_ENUM
>     };
>
> Instead of relying on compiler support of enumerator attribute, I use a
> `static const int` in this patch as a workaround:
>
>     G_DEPRECATED_FOR(NEW_ENUM)
>     static const int OLD_ENUM = NEW_ENUM;
>
> We can eventually migrate to use enumerator attribute when that is widely
> supported by the default toolchain.  I also posted patches to fix the
> G_DEPRECATED_FOR annotations in libqmi and libmbim.

I just realized we lost documentation for the compat symbols when this
new logic is introduced... See e.g. how the symbols were documented
for libqmi:
https://www.freedesktop.org/software/libqmi/libqmi-glib/latest/libqmi-glib-API-break-replacements.html

If you rebuild with gtk-doc enabled, the new documentation doesn't
show those any more. Maybe we need to add them explicitly in the
sections file?

-- 
Aleksander
https://aleksander.es