Syntastic: allow to control what parts of the crate are checked

This allows to control the arguments to Cargo which determine what
targets in the crate will be checked. This is similar what is done in
the ALE Rust checker.

Author: da-x

doc/rust.txt

@@ -20,6 +20,9 @@ SETTINGS                                                       *rust-settings*
 This plugin has a few variables you can define in your vimrc that change the
 behavior of the plugin.
 
+Some variables can be set buffer local (`:b` prefix), and the buffer local
+will take precedence over the global `g:` counterpart.
+
                                                                 *g:rustc_path*
 g:rustc_path~
 	Set this option to the path to rustc for use in the |:RustRun| and
@@ -199,6 +202,38 @@ g:rust_cargo_avoid_whole_workspace~
 	workspace. >
             let g:rust_cargo_avoid_whole_workspace = 0
 <
+                                              *g:rust_cargo_check_all_targets*
+                                              *b:rust_cargo_check_all_targets*
+g:rust_cargo_check_all_targets~
+	When set to 1, the `--all-targets` option will be passed to cargo when
+	Syntastic executes it, allowing the linting of all targets under the
+	package.
+	The default is 0.
+
+                                                 *g:rust_cargo_check_examples*
+                                                 *b:rust_cargo_check_examples*
+g:rust_cargo_check_examples~
+	When set to 1, the `--examples` option will be passed to cargo when
+	Syntastic executes it, to prevent the exclusion of examples from
+	linting. The examples are normally under the `examples/` directory of
+	the crate.
+	The default is 0.
+
+                                                    *g:rust_cargo_check_tests*
+                                                    *b:rust_cargo_check_tests*
+g:rust_cargo_check_tests~
+	When set to 1, the `--tests` option will be passed to cargo when
+	Syntastic executes it, to prevent the exclusion of tests from linting.
+	The tests are normally under the `tests/` directory of the crate.
+	The default is 0.
+
+                                                  *g:rust_cargo_check_benches*
+                                                  *b:rust_cargo_check_benches*
+g:rust_cargo_check_benches~
+	When set to 1, the `--benches` option will be passed to cargo when
+	Syntastic executes it.  The benches are normally under the `benches/`
+	directory of the crate.
+	The default is 0.
 
 ==============================================================================
 COMMANDS                                                       *rust-commands*

syntax_checkers/rust/cargo.vim

@@ -45,6 +45,17 @@ function! SyntaxCheckers_rust_cargo_GetLocList() dict
 		    \ . " && " . makeprg
     endif
 
+    let l:check_all_targets = rust#GetConfigVar('rust_cargo_check_all_targets', 0)
+    let l:check_examples = rust#GetConfigVar('rust_cargo_check_examples', 0)
+    let l:check_tests = rust#GetConfigVar('rust_cargo_check_tests', 0)
+    let l:check_benches = rust#GetConfigVar('rust_cargo_check_benches', 0)
+
+    let makeprg = makeprg. ' '
+	\  . (l:check_all_targets ? ' --all-targets' : '')
+	\  . (l:check_benches ? ' --benches' : '')
+	\  . (l:check_examples ? ' --examples' : '')
+	\  . (l:check_tests ? ' --tests' : '')
+
     " Ignored patterns, and blank lines
     let errorformat  =
         \ '%-G,' .