Add rust_docs rule

Additional updates to Rust rules:
* Consolidate BUILD files for Rust distribution.
* Prevent rust_binary from depending directly on cc_library.
* Update Rust version to 1.3.0

RELNOTES: [rust] Add rust_docs rule for generating rustdoc.

--
MOS_MIGRATED_REVID=103827592

3 files changed, 43 insertions, 2 deletions

diff --git a/examples/rust/hello_lib/BUILD b/examples/rust/hello_lib/BUILD
index 64cc935b27..a075f8b168 100644
--- a/examples/rust/hello_lib/BUILD
+++ b/examples/rust/hello_lib/BUILD
@@ -1,6 +1,6 @@
 package(default_visibility = ["//visibility:public"])
 
-load("/tools/build_rules/rust/rust", "rust_library", "rust_test")
+load("/tools/build_rules/rust/rust", "rust_library", "rust_docs", "rust_test")
 
 rust_library(
     name = "hello_lib",
@@ -10,6 +10,11 @@ rust_library(
     ],
 )
 
+rust_docs(
+    name = "hello_lib_docs",
+    dep = ":hello_lib",
+)
+
 rust_test(
     name = "greeting",
     srcs = ["tests/greeting.rs"],
diff --git a/examples/rust/hello_lib/src/greeter.rs b/examples/rust/hello_lib/src/greeter.rs
index be59ff888d..2a4a2f1d3f 100644
--- a/examples/rust/hello_lib/src/greeter.rs
+++ b/examples/rust/hello_lib/src/greeter.rs
@@ -12,19 +12,50 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+/// Object that displays a greeting.
 pub struct Greeter {
     greeting: String,
 }
 
+/// Implementation of Greeter.
 impl Greeter {
+    /// Constructs a new `Greeter`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hello_lib::greeter;
+    ///
+    /// let greeter = Greeter::new("Hello");
+    /// ```
     pub fn new(greeting: &str) -> Greeter {
         Greeter { greeting: greeting.to_string(), }
     }
 
+    /// Returns the greeting as a string.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hello_lib::greeter;
+    ///
+    /// let greeter = Greeter::new("Hello");
+    /// let greeting = greeter.greeting("World");
+    /// ```
     pub fn greeting(&self, thing: &str) -> String {
         format!("{} {}", &self.greeting, thing)
     }
 
+    /// Prints the greeting.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hello_lib::greeter;
+    ///
+    /// let greeter = Greeter::new("Hello");
+    /// greeter.greet("World");
+    /// ```
     pub fn greet(&self, thing: &str) {
         println!("{} {}", &self.greeting, thing);
     }
diff --git a/examples/rust/hello_world/BUILD b/examples/rust/hello_world/BUILD
index e774dcc835..ccd87f1b93 100644
--- a/examples/rust/hello_world/BUILD
+++ b/examples/rust/hello_world/BUILD
@@ -1,9 +1,14 @@
 package(default_visibility = ["//visibility:public"])
 
-load("/tools/build_rules/rust/rust", "rust_binary")
+load("/tools/build_rules/rust/rust", "rust_binary", "rust_docs")
 
 rust_binary(
     name = "hello_world",
     srcs = ["src/main.rs"],
     deps = ["//examples/rust/hello_lib"],
 )
+
+rust_docs(
+    name = "hello_world_docs",
+    dep = ":hello_world",
+)