add large future lint

tests/ui-toml/large_futures/clippy.toml

@@ -0,0 +1 @@
+future-size-threshold = 1024

tests/ui-toml/large_futures/large_futures.fixed

@@ -0,0 +1,29 @@
+// run-rustfix
+
+#![warn(clippy::large_futures)]
+
+fn main() {}
+
+pub async fn should_warn() {
+    let x = [0u8; 1024];
+    async {}.await;
+    dbg!(x);
+}
+
+pub async fn should_not_warn() {
+    let x = [0u8; 1020];
+    async {}.await;
+    dbg!(x);
+}
+
+pub async fn bar() {
+    Box::pin(should_warn()).await;
+
+    async {
+        let x = [0u8; 1024];
+        dbg!(x);
+    }
+    .await;
+
+    should_not_warn().await;
+}

tests/ui-toml/large_futures/large_futures.rs

@@ -0,0 +1,29 @@
+// run-rustfix
+
+#![warn(clippy::large_futures)]
+
+fn main() {}
+
+pub async fn should_warn() {
+    let x = [0u8; 1024];
+    async {}.await;
+    dbg!(x);
+}
+
+pub async fn should_not_warn() {
+    let x = [0u8; 1020];
+    async {}.await;
+    dbg!(x);
+}
+
+pub async fn bar() {
+    should_warn().await;
+
+    async {
+        let x = [0u8; 1024];
+        dbg!(x);
+    }
+    .await;
+
+    should_not_warn().await;
+}

tests/ui-toml/large_futures/large_futures.stderr

@@ -0,0 +1,10 @@
+error: large future with a size of 1026 bytes
+  --> $DIR/large_futures.rs:20:5
+   |
+LL |     should_warn().await;
+   |     ^^^^^^^^^^^^^ help: consider `Box::pin` on it: `Box::pin(should_warn())`
+   |
+   = note: `-D clippy::large-futures` implied by `-D warnings`
+
+error: aborting due to previous error
+

tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr

@@ -24,6 +24,7 @@ error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown fie
            enforced-import-renames
            enum-variant-name-threshold
            enum-variant-size-threshold
+           future-size-threshold
            ignore-interior-mutability
            large-error-threshold
            literal-representation-threshold

tests/ui/large_futures.fixed

@@ -0,0 +1,41 @@
+// run-rustfix
+
+#![feature(generators)]
+#![warn(clippy::large_futures)]
+#![allow(clippy::future_not_send)]
+#![allow(clippy::manual_async_fn)]
+
+async fn big_fut(_arg: [u8; 1024 * 16]) {}
+
+async fn wait() {
+    let f = async {
+        Box::pin(big_fut([0u8; 1024 * 16])).await;
+    };
+    Box::pin(f).await
+}
+async fn calls_fut(fut: impl std::future::Future<Output = ()>) {
+    loop {
+        Box::pin(wait()).await;
+        if true {
+            return fut.await;
+        } else {
+            Box::pin(wait()).await;
+        }
+    }
+}
+
+pub async fn test() {
+    let fut = big_fut([0u8; 1024 * 16]);
+    Box::pin(foo()).await;
+    Box::pin(calls_fut(fut)).await;
+}
+
+pub fn foo() -> impl std::future::Future<Output = ()> {
+    async {
+        let x = [0i32; 1024 * 16];
+        async {}.await;
+        dbg!(x);
+    }
+}
+
+fn main() {}

tests/ui/large_futures.rs

@@ -0,0 +1,41 @@
+// run-rustfix
+
+#![feature(generators)]
+#![warn(clippy::large_futures)]
+#![allow(clippy::future_not_send)]
+#![allow(clippy::manual_async_fn)]
+
+async fn big_fut(_arg: [u8; 1024 * 16]) {}
+
+async fn wait() {
+    let f = async {
+        big_fut([0u8; 1024 * 16]).await;
+    };
+    f.await
+}
+async fn calls_fut(fut: impl std::future::Future<Output = ()>) {
+    loop {
+        wait().await;
+        if true {
+            return fut.await;
+        } else {
+            wait().await;
+        }
+    }
+}
+
+pub async fn test() {
+    let fut = big_fut([0u8; 1024 * 16]);
+    foo().await;
+    calls_fut(fut).await;
+}
+
+pub fn foo() -> impl std::future::Future<Output = ()> {
+    async {
+        let x = [0i32; 1024 * 16];
+        async {}.await;
+        dbg!(x);
+    }
+}
+
+fn main() {}

tests/ui/large_futures.stderr

@@ -0,0 +1,40 @@
+error: large future with a size of 16385 bytes
+  --> $DIR/large_futures.rs:12:9
+   |
+LL |         big_fut([0u8; 1024 * 16]).await;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider `Box::pin` on it: `Box::pin(big_fut([0u8; 1024 * 16]))`
+   |
+   = note: `-D clippy::large-futures` implied by `-D warnings`
+
+error: large future with a size of 16386 bytes
+  --> $DIR/large_futures.rs:14:5
+   |
+LL |     f.await
+   |     ^ help: consider `Box::pin` on it: `Box::pin(f)`
+
+error: large future with a size of 16387 bytes
+  --> $DIR/large_futures.rs:18:9
+   |
+LL |         wait().await;
+   |         ^^^^^^ help: consider `Box::pin` on it: `Box::pin(wait())`
+
+error: large future with a size of 16387 bytes
+  --> $DIR/large_futures.rs:22:13
+   |
+LL |             wait().await;
+   |             ^^^^^^ help: consider `Box::pin` on it: `Box::pin(wait())`
+
+error: large future with a size of 65540 bytes
+  --> $DIR/large_futures.rs:29:5
+   |
+LL |     foo().await;
+   |     ^^^^^ help: consider `Box::pin` on it: `Box::pin(foo())`
+
+error: large future with a size of 49159 bytes
+  --> $DIR/large_futures.rs:30:5
+   |
+LL |     calls_fut(fut).await;
+   |     ^^^^^^^^^^^^^^ help: consider `Box::pin` on it: `Box::pin(calls_fut(fut))`
+
+error: aborting due to 6 previous errors
+