Could not compile protobuf due to errors

[nathanduchesne]

Hello all,
While trying to use this crate for a project, I encountered the following errors upon compiling:

Compiling protobuf v3.0.1
error[E0658]: use of unstable library feature 'vec_spare_capacity'
--> /root/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/protobuf-3.0.1/src/coded_input_stream/buf_read_iter.rs:334:45
|
334 | self.read_exact(&mut target.spare_capacity_mut()[..count])?;
| ^^^^^^^^^^^^^^^^^^
|
= note: see issue #75017 rust-lang/rust#75017 for more information

error[E0658]: use of unstable library feature 'vec_spare_capacity'
--> /root/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/protobuf-3.0.1/src/coded_output_stream/mod.rs:62:55
|
62 | let buffer = OutputBuffer::new(buffer_storage.spare_capacity_mut());
| ^^^^^^^^^^^^^^^^^^
|
= note: see issue #75017 rust-lang/rust#75017 for more information

error[E0658]: use of unstable library feature 'vec_spare_capacity'
--> /root/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/protobuf-3.0.1/src/coded_output_stream/mod.rs:88:44
|
88 | let buffer = OutputBuffer::new(vec.spare_capacity_mut());
| ^^^^^^^^^^^^^^^^^^
|
= note: see issue #75017 rust-lang/rust#75017 for more information

error[E0658]: use of unstable library feature 'vec_spare_capacity'
--> /root/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/protobuf-3.0.1/src/coded_output_stream/mod.rs:112:55
|
112 | self.buffer.replace_buffer_keep_pos(v.spare_capacity_mut());
| ^^^^^^^^^^^^^^^^^^
|
= note: see issue #75017 rust-lang/rust#75017 for more information

error[E0658]: use of unstable library feature 'vec_spare_capacity'
--> /root/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/protobuf-3.0.1/src/coded_output_stream/mod.rs:179:53
|
179 | self.buffer = OutputBuffer::new(vec.spare_capacity_mut());
| ^^^^^^^^^^^^^^^^^^
|
= note: see issue #75017 rust-lang/rust#75017 for more information

error[E0658]: use of unstable library feature 'vec_spare_capacity'
--> /root/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/protobuf-3.0.1/src/coded_output_stream/mod.rs:207:53
|
207 | self.buffer = OutputBuffer::new(vec.spare_capacity_mut());
| ^^^^^^^^^^^^^^^^^^
|
= note: see issue #75017 rust-lang/rust#75017 for more information

error[E0658]: use of unstable library feature 'vec_spare_capacity'
--> /root/.cargo/registry/src/git.luolix.top-1ecc6299db9ec823/protobuf-3.0.1/src/coded_output_stream/mod.rs:251:53
|
251 | self.buffer = OutputBuffer::new(vec.spare_capacity_mut());
| ^^^^^^^^^^^^^^^^^^
|
= note: see issue #75017 rust-lang/rust#75017 for more information

For more information about this error, try rustc --explain E0658.
error: could not compile protobuf due to 7 previous errors

In other words, this vec_spare_capacity method doesn't seem to be liked by my compiler and I was wondering if this was a known "problem" or if there are any ways of going around this.

To understand how to use the crate, I was greatly inspired by the snippets in https://github.com/stepancheg/rust-protobuf/tree/master/protobuf-examples/pure-vs-protoc. Please let me know if there is anything more you would like to know or anything I can do.
Cheers,
Nathan

[stepancheg]

Vec::spare_capacity_mut was stabilized in Rust 1.60.0 (2022-04-07).