For cleanliness the prelude module only needs to reexport preludes from
direct, "top-most" crates, which themselves take care of reexporting
preludes from its dependencies again. This shaves off some code while
maintaining the same set of exports.
This was temporarily allowed by Value trait refactoring, but the root
cause of the unused imports has been found (`glib::ToValue` for property
getters) and fixed in https://github.com/gtk-rs/gir/pull/1117.
In gir it was brought up [1] that some traits (in particular
`*ExtManual`) are exported from the crate root in addition to the
prelude, cluttering the environment unnecessarily. This commit removes
all these reexports, leaving those in prelude (that were already there)
only.
After this commit everything matching `Ext(Manual)?\b` in `lib.rs` sits
within `pub mod prelude {};`.
[1]: https://github.com/gtk-rs/gir/pull/1111
This includes mut overrides to prevent the caller from borrowing memory
as mutable. That enforces all kinds of ownership restrictions inside
the miniobject logic when only the underlying data for this memory needs
to be mutable.
Copy functions have been marked unsafe because tex_id might not be valid
and result in UB.
GLMemory input/output objects cannot be passed as mutable:
to_glib_none_mut checks if the miniobject is writable, even though the
underlying implementation should really only care about whether the
_data_ owned by this miniobject is.
(This temporary GLMemory object references its parent buffer object
that is also referenced externally, resulting in two references making
the object itself immutable)
Furthermore take care of automatically calling `add_rgba_pad_templates`
in `class_init` if `ADD_RGBA_PAD_TEMPLATES` is set to `true` (the
default).
Also enable all dependencies used by this type. Copying
AllocationParams is possible without borrowing the source mutable.
The offset and size parameters of `memcpy` are unchecked and may result
in out-of-bounds reads/writes, which is why this function is marked as
`unsafe`.
The next version of gir is going to generate doc(cfg()) attributes on
many symbols to show feature-dependence hints. While autogenerated sys
crates get this attribute in their own (generated) lib.rs file the safe
wrapper crates do not have such an autogenerated lib.rs file.
