Add tests and improve checks.

clippy_lints/src/doc.rs

@@ -1,4 +1,4 @@
-use crate::utils::{is_entrypoint_fn, match_type, paths, return_ty, span_lint};
+use crate::utils::{get_trait_def_id, implements_trait, is_entrypoint_fn, match_type, paths, return_ty, span_lint};
 use itertools::Itertools;
 use rustc::lint::in_external_macro;
 use rustc::ty::TyKind;
@@ -223,19 +223,24 @@ fn lint_for_missing_headers<'a, 'tcx>(
                 "docs for function returning `Result` missing `# Errors` section",
             );
         } else {
-            use TyKind::*;
             let def_id = cx.tcx.hir().local_def_id(hir_id);
             let mir = cx.tcx.optimized_mir(def_id);
-            if let Opaque(_, subs) = mir.return_ty().kind {
-                if let Some(ty) = subs.types().next() {
-                    if let Generator(_, subs, _) = ty.kind {
-                        if match_type(cx, subs.as_generator().return_ty(def_id, cx.tcx), &paths::RESULT) {
-                            span_lint(
-                                cx,
-                                MISSING_ERRORS_DOC,
-                                span,
-                                "docs for function returning `Result` missing `# Errors` section",
-                            );
+            if let Some(future) = get_trait_def_id(cx, &paths::FUTURE) {
+                if implements_trait(cx, mir.return_ty(), future, &[]) {
+                    use TyKind::*;
+
+                    if let Opaque(_, subs) = mir.return_ty().kind {
+                        if let Some(ty) = subs.types().next() {
+                            if let Generator(_, subs, _) = ty.kind {
+                                if match_type(cx, subs.as_generator().return_ty(def_id, cx.tcx), &paths::RESULT) {
+                                    span_lint(
+                                        cx,
+                                        MISSING_ERRORS_DOC,
+                                        span,
+                                        "docs for function returning `Result` missing `# Errors` section",
+                                    );
+                                }
+                            }
                         }
                     }
                 }

clippy_lints/src/utils/paths.rs

@@ -36,6 +36,7 @@ pub const FMT_ARGUMENTS_NEW_V1_FORMATTED: [&str; 4] = ["core", "fmt", "Arguments
 pub const FMT_ARGUMENTV1_NEW: [&str; 4] = ["core", "fmt", "ArgumentV1", "new"];
 pub const FROM_FROM: [&str; 4] = ["core", "convert", "From", "from"];
 pub const FROM_TRAIT: [&str; 3] = ["core", "convert", "From"];
+pub const FUTURE: [&str; 3] = ["std", "future", "Future"];
 pub const HASH: [&str; 2] = ["hash", "Hash"];
 pub const HASHMAP: [&str; 5] = ["std", "collections", "hash", "map", "HashMap"];
 pub const HASHMAP_ENTRY: [&str; 5] = ["std", "collections", "hash", "map", "Entry"];

tests/ui/doc_errors.rs

@@ -1,3 +1,4 @@
+// compile-flags: --edition 2018
 #![warn(clippy::missing_errors_doc)]
 
 use std::io;
@@ -6,22 +7,42 @@ pub fn pub_fn_missing_errors_header() -> Result<(), ()> {
     unimplemented!();
 }
 
+pub async fn async_pub_fn_missing_errors_header() -> Result<(), ()> {
+    unimplemented!();
+}
+
 /// This is not sufficiently documented.
 pub fn pub_fn_returning_io_result() -> io::Result<()> {
     unimplemented!();
 }
 
+/// This is not sufficiently documented.
+pub async fn async_pub_fn_returning_io_result() -> io::Result<()> {
+    unimplemented!();
+}
+
 /// # Errors
 /// A description of the errors goes here.
 pub fn pub_fn_with_errors_header() -> Result<(), ()> {
     unimplemented!();
 }
 
+/// # Errors
+/// A description of the errors goes here.
+pub async fn async_pub_fn_with_errors_header() -> Result<(), ()> {
+    unimplemented!();
+}
+
 /// This function doesn't require the documentation because it is private
 fn priv_fn_missing_errors_header() -> Result<(), ()> {
     unimplemented!();
 }
 
+/// This function doesn't require the documentation because it is private
+async fn async_priv_fn_missing_errors_header() -> Result<(), ()> {
+    unimplemented!();
+}
+
 pub struct Struct1;
 
 impl Struct1 {
@@ -30,16 +51,32 @@ impl Struct1 {
         unimplemented!();
     }
 
+    /// This is not sufficiently documented.
+    pub async fn async_pub_method_missing_errors_header() -> Result<(), ()> {
+        unimplemented!();
+    }
+
     /// # Errors
     /// A description of the errors goes here.
     pub fn pub_method_with_errors_header() -> Result<(), ()> {
         unimplemented!();
     }
 
+    /// # Errors
+    /// A description of the errors goes here.
+    pub async fn async_pub_method_with_errors_header() -> Result<(), ()> {
+        unimplemented!();
+    }
+
     /// This function doesn't require the documentation because it is private.
     fn priv_method_missing_errors_header() -> Result<(), ()> {
         unimplemented!();
     }
+
+    /// This function doesn't require the documentation because it is private.
+    async fn async_priv_method_missing_errors_header() -> Result<(), ()> {
+        unimplemented!();
+    }
 }
 
 pub trait Trait1 {

tests/ui/doc_errors.stderr

@@ -1,5 +1,5 @@
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:5:1
+  --> $DIR/doc_errors.rs:6:1
    |
 LL | / pub fn pub_fn_missing_errors_header() -> Result<(), ()> {
 LL | |     unimplemented!();
@@ -11,13 +11,29 @@ LL | | }
 error: docs for function returning `Result` missing `# Errors` section
   --> $DIR/doc_errors.rs:10:1
    |
+LL | / pub async fn async_pub_fn_missing_errors_header() -> Result<(), ()> {
+LL | |     unimplemented!();
+LL | | }
+   | |_^
+
+error: docs for function returning `Result` missing `# Errors` section
+  --> $DIR/doc_errors.rs:15:1
+   |
 LL | / pub fn pub_fn_returning_io_result() -> io::Result<()> {
 LL | |     unimplemented!();
 LL | | }
    | |_^
 
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:29:5
+  --> $DIR/doc_errors.rs:20:1
+   |
+LL | / pub async fn async_pub_fn_returning_io_result() -> io::Result<()> {
+LL | |     unimplemented!();
+LL | | }
+   | |_^
+
+error: docs for function returning `Result` missing `# Errors` section
+  --> $DIR/doc_errors.rs:50:5
    |
 LL | /     pub fn pub_method_missing_errors_header() -> Result<(), ()> {
 LL | |         unimplemented!();
@@ -25,10 +41,18 @@ LL | |     }
    | |_____^
 
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:47:5
+  --> $DIR/doc_errors.rs:55:5
+   |
+LL | /     pub async fn async_pub_method_missing_errors_header() -> Result<(), ()> {
+LL | |         unimplemented!();
+LL | |     }
+   | |_____^
+
+error: docs for function returning `Result` missing `# Errors` section
+  --> $DIR/doc_errors.rs:84:5
    |
 LL |     fn trait_method_missing_errors_header() -> Result<(), ()>;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 4 previous errors
+error: aborting due to 7 previous errors