Make more of futures-util dependencies optional

Author: taiki-e

.travis.yml

@@ -119,6 +119,28 @@ matrix:
             --no-default-features
             --features nightly,alloc
 
+    - name: cargo check (futures-util)
+      rust: nightly
+      script:
+        - cargo run --manifest-path ci/remove-dev-dependencies/Cargo.toml */Cargo.toml
+
+        - cargo check --manifest-path futures-util/Cargo.toml
+        - cargo check --manifest-path futures-util/Cargo.toml --all-features
+
+        - cargo check --manifest-path futures-util/Cargo.toml --features sink
+        - cargo check --manifest-path futures-util/Cargo.toml --features io
+        - cargo check --manifest-path futures-util/Cargo.toml --features channel
+        - cargo check --manifest-path futures-util/Cargo.toml --features nightly,async-await
+        - cargo check --manifest-path futures-util/Cargo.toml --features nightly,select-macro
+        - cargo check --manifest-path futures-util/Cargo.toml --features compat
+        - cargo check --manifest-path futures-util/Cargo.toml --features io-compat
+        - cargo check --manifest-path futures-util/Cargo.toml --features sink,compat
+        - cargo check --manifest-path futures-util/Cargo.toml --features sink,channel
+
+        - cargo check --manifest-path futures-util/Cargo.toml --no-default-features
+        - cargo check --manifest-path futures-util/Cargo.toml --no-default-features --features sink
+        - cargo check --manifest-path futures-util/Cargo.toml --no-default-features --features alloc,sink
+
     - name: cargo doc
       rust: nightly
       script:

futures-sink/Cargo.toml

@@ -15,9 +15,8 @@ The asynchronous `Sink` trait for the futures-rs library.
 name = "futures_sink"
 
 [features]
-std = ["alloc", "futures-core-preview/std"]
 default = ["std"]
-nightly = ["futures-core-preview/nightly"]
+std = ["alloc", "futures-core-preview/std"]
 alloc = ["futures-core-preview/alloc"]
 
 [dependencies]

futures-test/Cargo.toml

@@ -26,4 +26,4 @@ futures-preview = { version = "=0.3.0-alpha.16", path = "../futures", default-fe
 
 [features]
 default = ["std"]
-std = ["futures-core-preview/std", "futures-io-preview/std", "futures-util-preview/std", "futures-executor-preview/std"]
+std = ["futures-core-preview/std", "futures-io-preview/std", "futures-util-preview/std", "futures-util-preview/io", "futures-executor-preview/std"]

futures-util/Cargo.toml

@@ -15,21 +15,25 @@ Common utilities and extension traits for the futures-rs library.
 name = "futures_util"
 
 [features]
-std = ["alloc", "futures-core-preview/std", "futures-io-preview/std", "futures-sink-preview/std", "slab", "memchr"]
 default = ["std"]
-async-await = ["std", "futures-select-macro-preview", "proc-macro-hack", "proc-macro-nested", "rand"]
+std = ["alloc", "futures-core-preview/std", "slab"]
+alloc = ["futures-core-preview/alloc"]
+async-await = ["std"]
 compat = ["std", "futures_01"]
-io-compat = ["compat", "tokio-io"]
+io-compat = ["io", "compat", "tokio-io"]
 bench = []
-nightly = ["futures-core-preview/nightly", "futures-sink-preview/nightly"]
+nightly = ["futures-core-preview/nightly"]
 cfg-target-has-atomic = ["futures-core-preview/cfg-target-has-atomic"]
-alloc = ["futures-core-preview/alloc", "futures-sink-preview/alloc"]
+sink = ["futures-sink-preview"]
+io = ["std", "futures-io-preview", "memchr"]
+channel = ["std", "futures-channel-preview"]
+select-macro = ["async-await", "futures-select-macro-preview", "proc-macro-hack", "proc-macro-nested", "rand"]
 
 [dependencies]
 futures-core-preview = { path = "../futures-core", version = "=0.3.0-alpha.16", default-features = false }
-futures-channel-preview = { path = "../futures-channel", version = "=0.3.0-alpha.16", default-features = false }
-futures-io-preview = { path = "../futures-io", version = "=0.3.0-alpha.16", default-features = false }
-futures-sink-preview = { path = "../futures-sink", version = "=0.3.0-alpha.16", default-features = false}
+futures-channel-preview = { path = "../futures-channel", version = "=0.3.0-alpha.16", default-features = false, features = ["std"], optional = true }
+futures-io-preview = { path = "../futures-io", version = "=0.3.0-alpha.16", default-features = false, features = ["std"], optional = true }
+futures-sink-preview = { path = "../futures-sink", version = "=0.3.0-alpha.16", default-features = false, optional = true }
 futures-select-macro-preview = { path = "../futures-select-macro", version = "=0.3.0-alpha.16", default-features = false, optional = true }
 proc-macro-hack = { version = "0.5", optional = true }
 proc-macro-nested = { version = "0.1.2", optional = true }
@@ -42,7 +46,6 @@ pin-utils = "0.1.0-alpha.4"
 
 [dev-dependencies]
 futures-preview = { path = "../futures", version = "=0.3.0-alpha.16", features = ["async-await", "nightly"] }
-futures-executor-preview = { path = "../futures-executor", version = "=0.3.0-alpha.16" }
 futures-test-preview = { path = "../futures-test", version = "=0.3.0-alpha.16" }
 tokio = "0.1.11"
 

futures-util/src/async_await/mod.rs

@@ -24,7 +24,9 @@ pub use self::pending::*;
 mod join;
 
 // Primary export is a macro
+#[cfg(feature = "select-macro")]
 mod select_mod;
+#[cfg(feature = "select-macro")]
 pub use self::select_mod::*;
 
 #[doc(hidden)]

futures-util/src/compat/compat01as03.rs

@@ -3,12 +3,15 @@ use futures_01::executor::{
     Spawn as Spawn01, UnsafeNotify as UnsafeNotify01,
 };
 use futures_01::{
-    Async as Async01, AsyncSink as AsyncSink01, Future as Future01,
-    Sink as Sink01, Stream as Stream01,
+    Async as Async01, Future as Future01,
+    Stream as Stream01,
 };
+#[cfg(feature = "sink")]
+use futures_01::{AsyncSink as AsyncSink01, Sink as Sink01};
 use futures_core::{task as task03, Future as Future03, Stream as Stream03};
 use std::pin::Pin;
 use std::task::Context;
+#[cfg(feature = "sink")]
 use futures_sink::Sink as Sink03;
 
 #[cfg(feature = "io-compat")]
@@ -101,6 +104,7 @@ pub trait Stream01CompatExt: Stream01 {
 impl<St: Stream01> Stream01CompatExt for St {}
 
 /// Extension trait for futures 0.1 [`Sink`](futures_01::sink::Sink)
+#[cfg(feature = "sink")]
 pub trait Sink01CompatExt: Sink01 {
     /// Converts a futures 0.1
     /// [`Sink<SinkItem = T, SinkError = E>`](futures_01::sink::Sink)
@@ -129,6 +133,7 @@ pub trait Sink01CompatExt: Sink01 {
         Compat01As03Sink::new(self)
     }
 }
+#[cfg(feature = "sink")]
 impl<Si: Sink01> Sink01CompatExt for Si {}
 
 fn poll_01_to_03<T, E>(x: Result<Async01<T>, E>) -> task03::Poll<Result<T, E>> {
@@ -165,6 +170,7 @@ impl<St: Stream01> Stream03 for Compat01As03<St> {
 }
 
 /// Converts a futures 0.1 Sink object to a futures 0.3-compatible version
+#[cfg(feature = "sink")]
 #[derive(Debug)]
 #[must_use = "sinks do nothing unless polled"]
 pub struct Compat01As03Sink<S, SinkItem> {
@@ -173,8 +179,10 @@ pub struct Compat01As03Sink<S, SinkItem> {
     pub(crate) close_started: bool,
 }
 
+#[cfg(feature = "sink")]
 impl<S, SinkItem> Unpin for Compat01As03Sink<S, SinkItem> {}
 
+#[cfg(feature = "sink")]
 impl<S, SinkItem> Compat01As03Sink<S, SinkItem> {
     /// Wraps a futures 0.1 Sink object in a futures 0.3-compatible wrapper.
     pub fn new(inner: S) -> Compat01As03Sink<S, SinkItem> {
@@ -200,6 +208,7 @@ impl<S, SinkItem> Compat01As03Sink<S, SinkItem> {
     }
 }
 
+#[cfg(feature = "sink")]
 impl<S, SinkItem> Stream03 for Compat01As03Sink<S, SinkItem>
 where
     S: Stream01,
@@ -218,6 +227,7 @@ where
     }
 }
 
+#[cfg(feature = "sink")]
 impl<S, SinkItem> Sink03<SinkItem> for Compat01As03Sink<S, SinkItem>
 where
     S: Sink01<SinkItem = SinkItem>,

futures-util/src/compat/compat03as01.rs

@@ -1,7 +1,10 @@
 use futures_01::{
-    task as task01, Async as Async01, AsyncSink as AsyncSink01,
-    Future as Future01, Poll as Poll01, Sink as Sink01,
-    StartSend as StartSend01, Stream as Stream01,
+    task as task01, Async as Async01, Future as Future01, Poll as Poll01,
+    Stream as Stream01,
+};
+#[cfg(feature = "sink")]
+use futures_01::{
+    AsyncSink as AsyncSink01, Sink as Sink01, StartSend as StartSend01,
 };
 use futures_core::{
     task::{
@@ -12,10 +15,12 @@ use futures_core::{
     TryFuture as TryFuture03,
     TryStream as TryStream03,
 };
+#[cfg(feature = "sink")]
 use futures_sink::Sink as Sink03;
 use crate::task::{ArcWake as ArcWake03, WakerRef};
+#[cfg(feature = "sink")]
+use std::marker::PhantomData;
 use std::{
-    marker::PhantomData,
     mem,
     pin::Pin,
     sync::Arc,
@@ -35,6 +40,7 @@ pub struct Compat<T> {
 }
 
 /// Converts a futures 0.3 Sink object to a futures 0.1-compatible version
+#[cfg(feature = "sink")]
 #[derive(Debug)]
 #[must_use = "sinks do nothing unless polled"]
 pub struct CompatSink<T, Item> {
@@ -64,6 +70,7 @@ impl<T> Compat<T> {
     }
 }
 
+#[cfg(feature = "sink")]
 impl<T, Item> CompatSink<T, Item> {
     /// Returns the inner item.
     pub fn into_inner(self) -> T {
@@ -116,6 +123,7 @@ where
     }
 }
 
+#[cfg(feature = "sink")]
 impl<T, Item> Sink01 for CompatSink<T, Item>
 where
     T: Sink03<Item> + Unpin,
@@ -201,6 +209,7 @@ where
     f(Pin::new(&mut compat.inner), &mut cx)
 }
 
+#[cfg(feature = "sink")]
 fn with_sink_context<T, Item, R, F>(compat: &mut CompatSink<T, Item>, f: F) -> R
 where
     T: Unpin,

futures-util/src/compat/mod.rs

@@ -7,10 +7,13 @@ mod executor;
 pub use self::executor::{Executor01CompatExt, Executor01Future, Executor01As03};
 
 mod compat01as03;
-pub use self::compat01as03::{Compat01As03, Compat01As03Sink, Future01CompatExt, Stream01CompatExt, Sink01CompatExt};
-
+pub use self::compat01as03::{Compat01As03, Future01CompatExt, Stream01CompatExt};
+#[cfg(feature = "sink")]
+pub use self::compat01as03::{Compat01As03Sink, Sink01CompatExt};
 #[cfg(feature = "io-compat")]
 pub use self::compat01as03::{AsyncRead01CompatExt, AsyncWrite01CompatExt};
 
 mod compat03as01;
-pub use self::compat03as01::{Compat, CompatSink};
+pub use self::compat03as01::Compat;
+#[cfg(feature = "sink")]
+pub use self::compat03as01::CompatSink;

futures-util/src/future/either.rs

@@ -2,6 +2,7 @@ use core::pin::Pin;
 use core::task::{Context, Poll};
 use futures_core::future::{FusedFuture, Future};
 use futures_core::stream::{FusedStream, Stream};
+#[cfg(feature = "sink")]
 use futures_sink::Sink;
 
 /// Combines two different futures, streams, or sinks having the same associated types into a single
@@ -108,6 +109,7 @@ where
     }
 }
 
+#[cfg(feature = "sink")]
 impl<A, B, Item> Sink<Item> for Either<A, B>
 where
     A: Sink<Item>,
@@ -152,6 +154,7 @@ where
     }
 }
 
+#[cfg(feature = "io")]
 #[cfg(feature = "std")]
 mod if_std {
     use super::Either;

futures-util/src/future/mod.rs

@@ -98,8 +98,10 @@ mod catch_unwind;
 #[cfg(feature = "std")]
 pub use self::catch_unwind::CatchUnwind;
 
+#[cfg(feature = "channel")]
 #[cfg(feature = "std")]
 mod remote_handle;
+#[cfg(feature = "channel")]
 #[cfg(feature = "std")]
 pub use self::remote_handle::{Remote, RemoteHandle};
 
@@ -480,6 +482,7 @@ pub trait FutureExt: Future {
     ///
     /// This method is only available when the `std` feature of this
     /// library is activated, and it is activated by default.
+    #[cfg(feature = "channel")]
     #[cfg(feature = "std")]
     fn remote_handle(self) -> (Remote<Self>, RemoteHandle<Self::Output>)
     where