Installation on OpenBSD fails

[andinus]

Seems to be caused by usage of is_some_and in ide-assists. Installing rust-analyzer from 2023-06-26 tag works fine, it's just this method usage (in 2 files) that causes this breakage.

   Compiling ide-assists v0.0.0 (/home/andinus/dev/other/rust-analyzer/crates/ide-assists)            
error[E0658]: use of unstable library feature 'is_some_and'                                           
    --> crates/ide-assists/src/handlers/extract_function.rs:1364:50               
     |                              
1364 |     let insert_comma = parent_match_arm.as_ref().is_some_and(|it| it.comma_token().is_none()); 
     |                                                  ^^^^^^^^^^^                                   
     |                        
     = note: see issue #93050 <https://github.com/rust-lang/rust/issues/93050> for more information   
                                                   
For more information about this error, try `rustc --explain E0658`.                                                                                                                                         
error: could not compile `ide-assists` due to previous error                    
warning: build failed, waiting for other jobs to finish...                                            
error: failed to compile `rust-analyzer v0.0.0 (/home/andinus/dev/other/rust-analyzer/crates/rust-analyzer)`, intermediate artifacts can be found at `/home/andinus/dev/other/rust-analyzer/target`         
Error: install server                                                                                 
                                                                                                      
Caused by:                                                                                            
    command exited with non-zero code `cargo install --path crates/rust-analyzer --locked --force --features force-always-assert`: 101   

rustc version: rustc 1.68.0 (2c8cc3432 2023-03-06) (built from a source tarball)

[lnicola]

We don't support building with old compilers, that function was added in 1.70.