Merge pull request #2432 from superobertking/master

Let rust rls linter find the default rust toolchain automatically

ale_linters/rust/rls.vim

@@ -2,7 +2,7 @@
 " Description: A language server for Rust
 
 call ale#Set('rust_rls_executable', 'rls')
-call ale#Set('rust_rls_toolchain', 'nightly')
+call ale#Set('rust_rls_toolchain', '')
 call ale#Set('rust_rls_config', {})
 
 function! ale_linters#rust#rls#GetCommand(buffer) abort

doc/ale-rust.txt

@@ -164,10 +164,14 @@ g:ale_rust_rls_executable                           *g:ale_rust_rls_executable*
 g:ale_rust_rls_toolchain                             *g:ale_rust_rls_toolchain*
                                                      *b:ale_rust_rls_toolchain*
   Type: |String|
-  Default: `'nightly'`
+  Default: `''`
 
   This option can be set to change the toolchain used for `rls`. Possible
-  values include `'nightly'`, `'beta'`, and `'stable'`.
+  values include `'nightly'`, `'beta'`, `'stable'`, and `''`. When using
+  option `''`, rls will automatically find the default toolchain set by
+  rustup. If you want to use `rls` from a specific toolchain version, you may
+  also use values like `'channel-yyyy-mm-dd-arch-target'` as long as
+  `'rls +{toolchain_name} -V'` runs correctly in your command line.
 
   The `rls` server will only be started once per executable.
 

test/command_callback/test_rust_rls_callbacks.vader

@@ -5,7 +5,7 @@ After:
   call ale#assert#TearDownLinterTest()
 
 Execute(The default executable path should be correct):
-  AssertLinter 'rls', ale#Escape('rls') . ' +' . ale#Escape('nightly')
+  AssertLinter 'rls', ale#Escape('rls')
 
 Execute(The toolchain should be configurable):
   let g:ale_rust_rls_toolchain = 'stable'