Add support for 'required-features'.

Discover 'required-features' in Cargo manifest and initialize value of
'rust-cargo-features'.

Author: little-arhat

flycheck-rust.el

@@ -119,10 +119,11 @@ FILE-NAME is the path of the file that is matched against the
 `src_path' value in the list of `targets' returned by `cargo
 read-manifest'.
 
-Return a cons cell (KIND . NAME) where KIND is the target
-kind (lib, bin, test, example or bench), and NAME the target
-name (usually, the crate name).  If FILE-NAME exactly matches a
-target `src-path', this target is returned.  Otherwise, return
+Return an alist ((KIND . k) (NAME . n) (REQUIRED-FEATURES . rf))
+where KIND is the target kind (lib, bin, test, example or bench),
+NAME the target name (usually, the crate name), and REQUIRED-FEATURES is the
+optional list of features required to build the selected target.  If FILE-NAME
+exactly matches a target `src-path', this target is returned.  Otherwise, return
 the closest matching target, or nil if no targets could be found.
 
 See http://doc.crates.io/manifest.html#the-project-layout for a
@@ -160,7 +161,10 @@ description of the conventional Cargo project layout."
                           (--find (not (equal target it))))))
       (when target
         (let-alist target
-          (cons (flycheck-rust-normalize-target-kind .kind) .name))))))
+          (seq-filter (lambda (kv) (cdr kv))
+                     (list (cons 'kind (flycheck-rust-normalize-target-kind .kind))
+                           (cons 'name .name)
+                           (cons 'required-features .required-features))))))))
 
 
 (defun flycheck-rust-normalize-target-kind (kinds)
@@ -194,9 +198,11 @@ Flycheck according to the Cargo project layout."
   ;; https://github.com/flycheck/flycheck-rust/issues/40#issuecomment-253760883).
   (with-demoted-errors "Error in flycheck-rust-setup: %S"
     (-when-let* ((file-name (buffer-file-name))
-                 ((kind . name) (flycheck-rust-find-cargo-target file-name)))
-      (setq-local flycheck-rust-crate-type kind)
-      (setq-local flycheck-rust-binary-name name))))
+                 (target (flycheck-rust-find-cargo-target file-name)))
+      (let-alist target
+        (setq-local flycheck-rust-features .required-features)
+        (setq-local flycheck-rust-crate-type .kind)
+        (setq-local flycheck-rust-binary-name .name)))))
 
 (provide 'flycheck-rust)
 

tests/crate-with-features/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "test-crate-with-features"
+version = "0.1.0"
+
+[features]
+fea1 = []
+fea2 = []
+
+[[bin]]
+name = "main"
+path = "src/main.rs"
+required-features = ["fea1"]
+
+[[example]]
+name = "example"
+path = "example/example.rs"
+required-features = ["fea1", "fea2"]

tests/crate-with-features/example/example.rs

@@ -0,0 +1 @@
+

tests/crate-with-features/src/main.rs

@@ -38,97 +38,122 @@
 (defun crate-file (file-name)
   (expand-file-name file-name "tests/test-crate"))
 
+(defun crate-with-features-file (file-name)
+  (expand-file-name file-name "tests/crate-with-features"))
+
 (defun lib-crate-file (file-name)
   (expand-file-name file-name "tests/custom-lib-target"))
 
 (defun build-script-crate-file (file-name)
   (expand-file-name file-name "tests/build-script-test"))
 
+(defun cdrassoc (sym alist) (cdr (assoc sym alist)))
+
 (describe
  "`flycheck-rust-find-cargo-target' associates"
 
  (it "'src/lib.rs' to the library target"
      (expect
-      (car (flycheck-rust-find-cargo-target (crate-file "src/lib.rs")))
+      (cdrassoc 'kind (flycheck-rust-find-cargo-target (crate-file "src/lib.rs")))
       :to-equal "lib"))
 
  (it "'src/a.rs' to the library target"
      (expect
-      (car (flycheck-rust-find-cargo-target (crate-file "src/a.rs")))
+      (cdrassoc 'kind (flycheck-rust-find-cargo-target (crate-file "src/a.rs")))
       :to-equal "lib"))
 
  (it "'src/main.rs' to the main binary target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "src/main.rs"))
-      :to-equal '("bin" . "test-crate")))
+      :to-equal '((kind . "bin") (name . "test-crate"))))
 
  (it "'src/bin/a.rs' to the 'a' binary target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "src/bin/a.rs"))
-      :to-equal '("bin" . "a")))
+      :to-equal '((kind . "bin") (name . "a"))))
 
  (it "'src/bin/b.rs' to the 'b' binary target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "src/bin/b.rs"))
-      :to-equal '("bin" . "b")))
+      :to-equal '((kind . "bin") (name . "b"))))
 
  (it "'src/bin/support/mod.rs' to any binary target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "src/bin/support/mod.rs"))
-      :to-equal-one-of '("bin". "a") '("bin". "b")))
+      :to-equal-one-of
+      '((kind . "bin") (name . "a"))
+      '((kind . "bin") (name . "b"))))
 
  (it "'tests/a.rs' to the 'a' test target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "tests/a.rs"))
-      :to-equal '("test" . "a")))
+      :to-equal '((kind . "test") (name . "a"))))
 
  (it "'tests/support/mod.rs' to any test target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "tests/support/mod.rs"))
-      :to-equal-one-of '("test". "a") '("test". "b")))
+      :to-equal-one-of
+      '((kind . "test") (name . "a"))
+      '((kind . "test") (name . "b"))))
 
  (it "'examples/a.rs' to the 'a' example target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "examples/a.rs"))
-      :to-equal '("example" . "a")))
+      :to-equal '((kind . "example") (name . "a"))))
 
  (it "'examples/b.rs' to the 'b' example target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "examples/b.rs"))
-      :to-equal '("example" . "b")))
+      :to-equal '((kind . "example") (name . "b"))))
 
  (it "'examples/support/mod.rs' to any example target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "examples/support/mod.rs"))
-      :to-equal-one-of '("example" . "a") '("example" . "b")))
+      :to-equal-one-of
+      '((kind . "example") (name . "a"))
+      '((kind . "example") (name . "b"))))
 
  (it "'benches/a.rs' to the 'a' bench target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "benches/a.rs"))
-      :to-equal '("bench" . "a")))
+      :to-equal '((kind . "bench") (name . "a"))))
 
  (it "'benches/b.rs' to the 'b' bench target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "benches/b.rs"))
-      :to-equal '("bench" . "b")))
+      :to-equal '((kind . "bench") (name . "b"))))
 
  (it "'benches/support/mod.rs' to any bench target"
      (expect
       (flycheck-rust-find-cargo-target (crate-file "benches/support/mod.rs"))
-      :to-equal-one-of '("bench" . "a") '("bench" . "b")))
+      :to-equal-one-of
+      '((kind . "bench") (name . "a"))
+      '((kind . "bench") (name . "b"))))
 
  (it "'src/lib.rs' to the library target (custom-lib-target)"
      (expect
       (car (flycheck-rust-find-cargo-target (lib-crate-file "src/lib.rs")))
-      :to-equal "lib"))
+      :to-equal '(kind . "lib")))
 
  (it "'build.rs' to any target in the same workspace member (parent)"
      (expect
       (flycheck-rust-find-cargo-target (build-script-crate-file "build.rs"))
-      :to-equal (cons "bin" "build-script-test")))
+      :to-equal '((kind . "bin") (name . "build-script-test"))))
 
  (it "'build.rs' to any target in the same workspace member (child)"
      (expect
       (flycheck-rust-find-cargo-target (build-script-crate-file "lib-test/build.rs"))
-      :to-equal (cons "lib" "lib-test")))
+      :to-equal '((kind . "lib") (name . "lib-test"))))
+
+ (it "'src/main.rs' to the bin target with required-features (fea1)"
+     (expect
+      (flycheck-rust-find-cargo-target (crate-with-features-file "src/main.rs"))
+      :to-equal '((kind . "bin") (name . "main") (required-features . ("fea1")))))
+
+ (it "'example/example.rs' to the example target with required-features (fea1 fea2)"
+     (expect
+      (flycheck-rust-find-cargo-target (crate-with-features-file "example/example.rs"))
+      :to-equal '((kind . "example")
+                  (name . "example")
+                  (required-features . ("fea1" "fea2")))))
  )