Fix suggestion to add unneeded space in `manual_async`

4 files changed, 115 insertions, 10 deletions

diff --git a/clippy_lints/src/manual_async_fn.rs b/clippy_lints/src/manual_async_fn.rs
index 864d1ea87f5..e9d65abb443 100644
--- a/clippy_lints/src/manual_async_fn.rs
+++ b/clippy_lints/src/manual_async_fn.rs
@@ -69,7 +69,20 @@ impl<'tcx> LateLintPass<'tcx> for ManualAsyncFn {
                     |diag| {
                         if_chain! {
                             if let Some(header_snip) = snippet_opt(cx, header_span);
-                            if let Some(ret_pos) = header_snip.rfind("->");
+                            if let Some(ret_pos) = header_snip.rfind("->").map(|rpos| {
+                                let mut rpos = rpos;
+                                let chars: Vec<char> = header_snip.chars().collect();
+                                while rpos > 1 {
+                                    if let Some(c) = chars.get(rpos - 1) {
+                                        if c.is_whitespace() {
+                                            rpos -= 1;
+                                            continue;
+                                        }
+                                    }
+                                    break;
+                                }
+                                rpos
+                            });
                             if let Some((ret_sugg, ret_snip)) = suggested_ret(cx, output);
                             then {
                                 let help = format!("make the function `async` and {}", ret_sugg);
@@ -194,7 +207,7 @@ fn suggested_ret(cx: &LateContext<'_>, output: &Ty<'_>) -> Option<(&'static str,
         },
         _ => {
             let sugg = "return the output of the future directly";
-            snippet_opt(cx, output.span).map(|snip| (sugg, format!("-> {}", snip)))
+            snippet_opt(cx, output.span).map(|snip| (sugg, format!(" -> {}", snip)))
         },
     }
 }
diff --git a/tests/ui/manual_async_fn.fixed b/tests/ui/manual_async_fn.fixed
index 4f551690c43..5184f6fdb88 100644
--- a/tests/ui/manual_async_fn.fixed
+++ b/tests/ui/manual_async_fn.fixed
@@ -7,7 +7,19 @@ use std::future::Future;
 
 async fn fut() -> i32 { 42 }
 
-async fn empty_fut()  {}
+#[rustfmt::skip]
+async fn fut2() -> i32 { 42 }
+
+#[rustfmt::skip]
+async fn fut3() -> i32 { 42 }
+
+async fn empty_fut() {}
+
+#[rustfmt::skip]
+async fn empty_fut2() {}
+
+#[rustfmt::skip]
+async fn empty_fut3() {}
 
 async fn core_fut() -> i32 { 42 }
 
diff --git a/tests/ui/manual_async_fn.rs b/tests/ui/manual_async_fn.rs
index 6ed60309947..68c0e591f0b 100644
--- a/tests/ui/manual_async_fn.rs
+++ b/tests/ui/manual_async_fn.rs
@@ -9,10 +9,30 @@ fn fut() -> impl Future<Output = i32> {
     async { 42 }
 }
 
+#[rustfmt::skip]
+fn fut2() ->impl Future<Output = i32> {
+    async { 42 }
+}
+
+#[rustfmt::skip]
+fn fut3()-> impl Future<Output = i32> {
+    async { 42 }
+}
+
 fn empty_fut() -> impl Future<Output = ()> {
     async {}
 }
 
+#[rustfmt::skip]
+fn empty_fut2() ->impl Future<Output = ()> {
+    async {}
+}
+
+#[rustfmt::skip]
+fn empty_fut3()-> impl Future<Output = ()> {
+    async {}
+}
+
 fn core_fut() -> impl core::future::Future<Output = i32> {
     async move { 42 }
 }
diff --git a/tests/ui/manual_async_fn.stderr b/tests/ui/manual_async_fn.stderr
index ccd82867427..fdd43db3255 100644
--- a/tests/ui/manual_async_fn.stderr
+++ b/tests/ui/manual_async_fn.stderr
@@ -15,14 +15,44 @@ LL | fn fut() -> impl Future<Output = i32> { 42 }
    |                                       ^^^^^^
 
 error: this function can be simplified using the `async fn` syntax
-  --> $DIR/manual_async_fn.rs:12:1
+  --> $DIR/manual_async_fn.rs:13:1
+   |
+LL | fn fut2() ->impl Future<Output = i32> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: make the function `async` and return the output of the future directly
+   |
+LL | async fn fut2() -> i32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^
+help: move the body of the async block to the enclosing function
+   |
+LL | fn fut2() ->impl Future<Output = i32> { 42 }
+   |                                       ^^^^^^
+
+error: this function can be simplified using the `async fn` syntax
+  --> $DIR/manual_async_fn.rs:18:1
+   |
+LL | fn fut3()-> impl Future<Output = i32> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: make the function `async` and return the output of the future directly
+   |
+LL | async fn fut3() -> i32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^
+help: move the body of the async block to the enclosing function
+   |
+LL | fn fut3()-> impl Future<Output = i32> { 42 }
+   |                                       ^^^^^^
+
+error: this function can be simplified using the `async fn` syntax
+  --> $DIR/manual_async_fn.rs:22:1
    |
 LL | fn empty_fut() -> impl Future<Output = ()> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: make the function `async` and remove the return type
    |
-LL | async fn empty_fut()  {
+LL | async fn empty_fut() {
    | ^^^^^^^^^^^^^^^^^^^^
 help: move the body of the async block to the enclosing function
    |
@@ -30,7 +60,37 @@ LL | fn empty_fut() -> impl Future<Output = ()> {}
    |                                            ^^
 
 error: this function can be simplified using the `async fn` syntax
-  --> $DIR/manual_async_fn.rs:16:1
+  --> $DIR/manual_async_fn.rs:27:1
+   |
+LL | fn empty_fut2() ->impl Future<Output = ()> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: make the function `async` and remove the return type
+   |
+LL | async fn empty_fut2() {
+   | ^^^^^^^^^^^^^^^^^^^^^
+help: move the body of the async block to the enclosing function
+   |
+LL | fn empty_fut2() ->impl Future<Output = ()> {}
+   |                                            ^^
+
+error: this function can be simplified using the `async fn` syntax
+  --> $DIR/manual_async_fn.rs:32:1
+   |
+LL | fn empty_fut3()-> impl Future<Output = ()> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: make the function `async` and remove the return type
+   |
+LL | async fn empty_fut3() {
+   | ^^^^^^^^^^^^^^^^^^^^^
+help: move the body of the async block to the enclosing function
+   |
+LL | fn empty_fut3()-> impl Future<Output = ()> {}
+   |                                            ^^
+
+error: this function can be simplified using the `async fn` syntax
+  --> $DIR/manual_async_fn.rs:36:1
    |
 LL | fn core_fut() -> impl core::future::Future<Output = i32> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -45,7 +105,7 @@ LL | fn core_fut() -> impl core::future::Future<Output = i32> { 42 }
    |                                                          ^^^^^^
 
 error: this function can be simplified using the `async fn` syntax
-  --> $DIR/manual_async_fn.rs:38:5
+  --> $DIR/manual_async_fn.rs:58:5
    |
 LL |     fn inh_fut() -> impl Future<Output = i32> {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -65,7 +125,7 @@ LL |             let c = 21;
  ...
 
 error: this function can be simplified using the `async fn` syntax
-  --> $DIR/manual_async_fn.rs:73:1
+  --> $DIR/manual_async_fn.rs:93:1
    |
 LL | fn elided(_: &i32) -> impl Future<Output = i32> + '_ {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -80,7 +140,7 @@ LL | fn elided(_: &i32) -> impl Future<Output = i32> + '_ { 42 }
    |                                                      ^^^^^^
 
 error: this function can be simplified using the `async fn` syntax
-  --> $DIR/manual_async_fn.rs:82:1
+  --> $DIR/manual_async_fn.rs:102:1
    |
 LL | fn explicit<'a, 'b>(_: &'a i32, _: &'b i32) -> impl Future<Output = i32> + 'a + 'b {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -94,5 +154,5 @@ help: move the body of the async block to the enclosing function
 LL | fn explicit<'a, 'b>(_: &'a i32, _: &'b i32) -> impl Future<Output = i32> + 'a + 'b { 42 }
    |                                                                                    ^^^^^^
 
-error: aborting due to 6 previous errors
+error: aborting due to 10 previous errors