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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 01:47:29 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 01:47:29 +0000
commit0ebf5bdf043a27fd3dfb7f92e0cb63d88954c44d (patch)
treea31f07c9bcca9d56ce61e9a1ffd30ef350d513aa /third_party/rust/futures-macro
parentInitial commit. (diff)
downloadfirefox-esr-0ebf5bdf043a27fd3dfb7f92e0cb63d88954c44d.tar.xz
firefox-esr-0ebf5bdf043a27fd3dfb7f92e0cb63d88954c44d.zip
Adding upstream version 115.8.0esr.upstream/115.8.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/futures-macro')
-rw-r--r--third_party/rust/futures-macro/.cargo-checksum.json1
-rw-r--r--third_party/rust/futures-macro/Cargo.toml37
-rw-r--r--third_party/rust/futures-macro/LICENSE-APACHE202
-rw-r--r--third_party/rust/futures-macro/LICENSE-MIT26
-rw-r--r--third_party/rust/futures-macro/src/executor.rs55
-rw-r--r--third_party/rust/futures-macro/src/join.rs144
-rw-r--r--third_party/rust/futures-macro/src/lib.rs61
-rw-r--r--third_party/rust/futures-macro/src/select.rs330
-rw-r--r--third_party/rust/futures-macro/src/stream_select.rs113
9 files changed, 969 insertions, 0 deletions
diff --git a/third_party/rust/futures-macro/.cargo-checksum.json b/third_party/rust/futures-macro/.cargo-checksum.json
new file mode 100644
index 0000000000..42b0cac5d1
--- /dev/null
+++ b/third_party/rust/futures-macro/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"Cargo.toml":"9f3770e94e9f029eec62dcc54159942eee17256c19b3e97d0c096cbcd6f12d32","LICENSE-APACHE":"275c491d6d1160553c32fd6127061d7f9606c3ea25abfad6ca3f6ed088785427","LICENSE-MIT":"6652c868f35dfe5e8ef636810a4e576b9d663f3a17fb0f5613ad73583e1b88fd","src/executor.rs":"2a6c40ebf1fb70ac5bd0dfb991c7b945210c731b558b546f2ecb6d7a8976f3f6","src/join.rs":"eb1b7beb09e877a88fb76ba195b87b657681234002386ab3519f33b0a6670098","src/lib.rs":"8324c4d5cc4e9e377b2f95afde751168d7e94196c1f2cb35802193c900ca0026","src/select.rs":"a7ed344932225fbe1b070d132a937184250c31385ac6764a8a6e6817413c7538","src/stream_select.rs":"5fb84834a40876ab1fd975c3af67594d0c5a4f8d724cb164db9bee71e70d14b1"},"package":"95a73af87da33b5acf53acfebdc339fe592ecf5357ac7c0a7734ab9d8c876a70"} \ No newline at end of file
diff --git a/third_party/rust/futures-macro/Cargo.toml b/third_party/rust/futures-macro/Cargo.toml
new file mode 100644
index 0000000000..356e092b5c
--- /dev/null
+++ b/third_party/rust/futures-macro/Cargo.toml
@@ -0,0 +1,37 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+rust-version = "1.45"
+name = "futures-macro"
+version = "0.3.26"
+description = """
+The futures-rs procedural macro implementations.
+"""
+homepage = "https://rust-lang.github.io/futures-rs"
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/rust-lang/futures-rs"
+
+[lib]
+proc-macro = true
+
+[dependencies.proc-macro2]
+version = "1.0"
+
+[dependencies.quote]
+version = "1.0"
+
+[dependencies.syn]
+version = "1.0.56"
+features = ["full"]
+
+[features]
diff --git a/third_party/rust/futures-macro/LICENSE-APACHE b/third_party/rust/futures-macro/LICENSE-APACHE
new file mode 100644
index 0000000000..9eb0b097f5
--- /dev/null
+++ b/third_party/rust/futures-macro/LICENSE-APACHE
@@ -0,0 +1,202 @@
+ Apache License
+ Version 2.0, January 2004
+ http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+1. Definitions.
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+ for use, reproduction, or distribution of Your modifications, or
+ for any such Derivative Works as a whole, provided Your use,
+ reproduction, and distribution of the Work otherwise complies with
+ the conditions stated in this License.
+
+5. Submission of Contributions. Unless You explicitly state otherwise,
+ any Contribution intentionally submitted for inclusion in the Work
+ by You to the Licensor shall be under the terms and conditions of
+ this License, without any additional terms or conditions.
+ Notwithstanding the above, nothing herein shall supersede or modify
+ the terms of any separate license agreement you may have executed
+ with Licensor regarding such Contributions.
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+6. Trademarks. This License does not grant permission to use the trade
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+7. Disclaimer of Warranty. Unless required by applicable law or
+ agreed to in writing, Licensor provides the Work (and each
+ Contributor provides its Contributions) on an "AS IS" BASIS,
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+ risks associated with Your exercise of permissions under this License.
+
+8. Limitation of Liability. In no event and under no legal theory,
+ whether in tort (including negligence), contract, or otherwise,
+ unless required by applicable law (such as deliberate and grossly
+ negligent acts) or agreed to in writing, shall any Contributor be
+ liable to You for damages, including any direct, indirect, special,
+ incidental, or consequential damages of any character arising as a
+ result of this License or out of the use or inability to use the
+ Work (including but not limited to damages for loss of goodwill,
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+ other commercial damages or losses), even if such Contributor
+ has been advised of the possibility of such damages.
+
+9. Accepting Warranty or Additional Liability. While redistributing
+ the Work or Derivative Works thereof, You may choose to offer,
+ and charge a fee for, acceptance of support, warranty, indemnity,
+ or other liability obligations and/or rights consistent with this
+ License. However, in accepting such obligations, You may act only
+ on Your own behalf and on Your sole responsibility, not on behalf
+ of any other Contributor, and only if You agree to indemnify,
+ defend, and hold each Contributor harmless for any liability
+ incurred by, or claims asserted against, such Contributor by reason
+ of your accepting any such warranty or additional liability.
+
+END OF TERMS AND CONDITIONS
+
+APPENDIX: How to apply the Apache License to your work.
+
+ To apply the Apache License to your work, attach the following
+ boilerplate notice, with the fields enclosed by brackets "[]"
+ replaced with your own identifying information. (Don't include
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+
+Copyright (c) 2016 Alex Crichton
+Copyright (c) 2017 The Tokio Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
diff --git a/third_party/rust/futures-macro/LICENSE-MIT b/third_party/rust/futures-macro/LICENSE-MIT
new file mode 100644
index 0000000000..8ad082ec4f
--- /dev/null
+++ b/third_party/rust/futures-macro/LICENSE-MIT
@@ -0,0 +1,26 @@
+Copyright (c) 2016 Alex Crichton
+Copyright (c) 2017 The Tokio Authors
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
diff --git a/third_party/rust/futures-macro/src/executor.rs b/third_party/rust/futures-macro/src/executor.rs
new file mode 100644
index 0000000000..40a091f94c
--- /dev/null
+++ b/third_party/rust/futures-macro/src/executor.rs
@@ -0,0 +1,55 @@
+use proc_macro::TokenStream;
+use proc_macro2::Span;
+use quote::{quote, quote_spanned, ToTokens};
+
+pub(crate) fn test(args: TokenStream, item: TokenStream) -> TokenStream {
+ if !args.is_empty() {
+ return syn::Error::new_spanned(proc_macro2::TokenStream::from(args), "invalid argument")
+ .to_compile_error()
+ .into();
+ }
+
+ let mut input = syn::parse_macro_input!(item as syn::ItemFn);
+
+ if input.sig.asyncness.take().is_none() {
+ return syn::Error::new_spanned(input.sig.fn_token, "Only async functions are supported")
+ .to_compile_error()
+ .into();
+ }
+
+ // If type mismatch occurs, the current rustc points to the last statement.
+ let (last_stmt_start_span, last_stmt_end_span) = {
+ let mut last_stmt = input
+ .block
+ .stmts
+ .last()
+ .map(ToTokens::into_token_stream)
+ .unwrap_or_default()
+ .into_iter();
+ // `Span` on stable Rust has a limitation that only points to the first
+ // token, not the whole tokens. We can work around this limitation by
+ // using the first/last span of the tokens like
+ // `syn::Error::new_spanned` does.
+ let start = last_stmt.next().map_or_else(Span::call_site, |t| t.span());
+ let end = last_stmt.last().map_or(start, |t| t.span());
+ (start, end)
+ };
+
+ let path = quote_spanned! {last_stmt_start_span=>
+ ::futures_test::__private
+ };
+ let body = &input.block;
+ input.block.stmts = vec![syn::Stmt::Expr(
+ syn::parse2(quote_spanned! {last_stmt_end_span=>
+ #path::block_on(async #body)
+ })
+ .unwrap(),
+ )];
+
+ let gen = quote! {
+ #[::core::prelude::v1::test]
+ #input
+ };
+
+ gen.into()
+}
diff --git a/third_party/rust/futures-macro/src/join.rs b/third_party/rust/futures-macro/src/join.rs
new file mode 100644
index 0000000000..94e356f729
--- /dev/null
+++ b/third_party/rust/futures-macro/src/join.rs
@@ -0,0 +1,144 @@
+//! The futures-rs `join! macro implementation.
+
+use proc_macro::TokenStream;
+use proc_macro2::{Span, TokenStream as TokenStream2};
+use quote::{format_ident, quote};
+use syn::parse::{Parse, ParseStream};
+use syn::{Expr, Ident, Token};
+
+#[derive(Default)]
+struct Join {
+ fut_exprs: Vec<Expr>,
+}
+
+impl Parse for Join {
+ fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
+ let mut join = Self::default();
+
+ while !input.is_empty() {
+ join.fut_exprs.push(input.parse::<Expr>()?);
+
+ if !input.is_empty() {
+ input.parse::<Token![,]>()?;
+ }
+ }
+
+ Ok(join)
+ }
+}
+
+fn bind_futures(fut_exprs: Vec<Expr>, span: Span) -> (Vec<TokenStream2>, Vec<Ident>) {
+ let mut future_let_bindings = Vec::with_capacity(fut_exprs.len());
+ let future_names: Vec<_> = fut_exprs
+ .into_iter()
+ .enumerate()
+ .map(|(i, expr)| {
+ let name = format_ident!("_fut{}", i, span = span);
+ future_let_bindings.push(quote! {
+ // Move future into a local so that it is pinned in one place and
+ // is no longer accessible by the end user.
+ let mut #name = __futures_crate::future::maybe_done(#expr);
+ let mut #name = unsafe { __futures_crate::Pin::new_unchecked(&mut #name) };
+ });
+ name
+ })
+ .collect();
+
+ (future_let_bindings, future_names)
+}
+
+/// The `join!` macro.
+pub(crate) fn join(input: TokenStream) -> TokenStream {
+ let parsed = syn::parse_macro_input!(input as Join);
+
+ // should be def_site, but that's unstable
+ let span = Span::call_site();
+
+ let (future_let_bindings, future_names) = bind_futures(parsed.fut_exprs, span);
+
+ let poll_futures = future_names.iter().map(|fut| {
+ quote! {
+ __all_done &= __futures_crate::future::Future::poll(
+ #fut.as_mut(), __cx).is_ready();
+ }
+ });
+ let take_outputs = future_names.iter().map(|fut| {
+ quote! {
+ #fut.as_mut().take_output().unwrap(),
+ }
+ });
+
+ TokenStream::from(quote! { {
+ #( #future_let_bindings )*
+
+ __futures_crate::future::poll_fn(move |__cx: &mut __futures_crate::task::Context<'_>| {
+ let mut __all_done = true;
+ #( #poll_futures )*
+ if __all_done {
+ __futures_crate::task::Poll::Ready((
+ #( #take_outputs )*
+ ))
+ } else {
+ __futures_crate::task::Poll::Pending
+ }
+ }).await
+ } })
+}
+
+/// The `try_join!` macro.
+pub(crate) fn try_join(input: TokenStream) -> TokenStream {
+ let parsed = syn::parse_macro_input!(input as Join);
+
+ // should be def_site, but that's unstable
+ let span = Span::call_site();
+
+ let (future_let_bindings, future_names) = bind_futures(parsed.fut_exprs, span);
+
+ let poll_futures = future_names.iter().map(|fut| {
+ quote! {
+ if __futures_crate::future::Future::poll(
+ #fut.as_mut(), __cx).is_pending()
+ {
+ __all_done = false;
+ } else if #fut.as_mut().output_mut().unwrap().is_err() {
+ // `.err().unwrap()` rather than `.unwrap_err()` so that we don't introduce
+ // a `T: Debug` bound.
+ // Also, for an error type of ! any code after `err().unwrap()` is unreachable.
+ #[allow(unreachable_code)]
+ return __futures_crate::task::Poll::Ready(
+ __futures_crate::Err(
+ #fut.as_mut().take_output().unwrap().err().unwrap()
+ )
+ );
+ }
+ }
+ });
+ let take_outputs = future_names.iter().map(|fut| {
+ quote! {
+ // `.ok().unwrap()` rather than `.unwrap()` so that we don't introduce
+ // an `E: Debug` bound.
+ // Also, for an ok type of ! any code after `ok().unwrap()` is unreachable.
+ #[allow(unreachable_code)]
+ #fut.as_mut().take_output().unwrap().ok().unwrap(),
+ }
+ });
+
+ TokenStream::from(quote! { {
+ #( #future_let_bindings )*
+
+ #[allow(clippy::diverging_sub_expression)]
+ __futures_crate::future::poll_fn(move |__cx: &mut __futures_crate::task::Context<'_>| {
+ let mut __all_done = true;
+ #( #poll_futures )*
+ if __all_done {
+ __futures_crate::task::Poll::Ready(
+ __futures_crate::Ok((
+ #( #take_outputs )*
+ ))
+ )
+ } else {
+ __futures_crate::task::Poll::Pending
+ }
+ }).await
+ } })
+}
diff --git a/third_party/rust/futures-macro/src/lib.rs b/third_party/rust/futures-macro/src/lib.rs
new file mode 100644
index 0000000000..0afe34b83b
--- /dev/null
+++ b/third_party/rust/futures-macro/src/lib.rs
@@ -0,0 +1,61 @@
+//! The futures-rs procedural macro implementations.
+
+#![warn(rust_2018_idioms, single_use_lifetimes, unreachable_pub)]
+#![doc(test(
+ no_crate_inject,
+ attr(
+ deny(warnings, rust_2018_idioms, single_use_lifetimes),
+ allow(dead_code, unused_assignments, unused_variables)
+ )
+))]
+
+// Since https://github.com/rust-lang/cargo/pull/7700 `proc_macro` is part of the prelude for
+// proc-macro crates, but to support older compilers we still need this explicit `extern crate`.
+#[allow(unused_extern_crates)]
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+mod executor;
+mod join;
+mod select;
+mod stream_select;
+
+/// The `join!` macro.
+#[proc_macro]
+pub fn join_internal(input: TokenStream) -> TokenStream {
+ crate::join::join(input)
+}
+
+/// The `try_join!` macro.
+#[proc_macro]
+pub fn try_join_internal(input: TokenStream) -> TokenStream {
+ crate::join::try_join(input)
+}
+
+/// The `select!` macro.
+#[proc_macro]
+pub fn select_internal(input: TokenStream) -> TokenStream {
+ crate::select::select(input)
+}
+
+/// The `select_biased!` macro.
+#[proc_macro]
+pub fn select_biased_internal(input: TokenStream) -> TokenStream {
+ crate::select::select_biased(input)
+}
+
+// TODO: Change this to doc comment once rustdoc bug fixed: https://github.com/rust-lang/futures-rs/pull/2435
+// The `test` attribute.
+#[proc_macro_attribute]
+pub fn test_internal(input: TokenStream, item: TokenStream) -> TokenStream {
+ crate::executor::test(input, item)
+}
+
+/// The `stream_select!` macro.
+#[proc_macro]
+pub fn stream_select_internal(input: TokenStream) -> TokenStream {
+ crate::stream_select::stream_select(input.into())
+ .unwrap_or_else(syn::Error::into_compile_error)
+ .into()
+}
diff --git a/third_party/rust/futures-macro/src/select.rs b/third_party/rust/futures-macro/src/select.rs
new file mode 100644
index 0000000000..0c8e5f1ca0
--- /dev/null
+++ b/third_party/rust/futures-macro/src/select.rs
@@ -0,0 +1,330 @@
+//! The futures-rs `select! macro implementation.
+
+use proc_macro::TokenStream;
+use proc_macro2::Span;
+use quote::{format_ident, quote};
+use syn::parse::{Parse, ParseStream};
+use syn::{parse_quote, Expr, Ident, Pat, Token};
+
+mod kw {
+ syn::custom_keyword!(complete);
+}
+
+struct Select {
+ // span of `complete`, then expression after `=> ...`
+ complete: Option<Expr>,
+ default: Option<Expr>,
+ normal_fut_exprs: Vec<Expr>,
+ normal_fut_handlers: Vec<(Pat, Expr)>,
+}
+
+#[allow(clippy::large_enum_variant)]
+enum CaseKind {
+ Complete,
+ Default,
+ Normal(Pat, Expr),
+}
+
+impl Parse for Select {
+ fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
+ let mut select = Self {
+ complete: None,
+ default: None,
+ normal_fut_exprs: vec![],
+ normal_fut_handlers: vec![],
+ };
+
+ while !input.is_empty() {
+ let case_kind = if input.peek(kw::complete) {
+ // `complete`
+ if select.complete.is_some() {
+ return Err(input.error("multiple `complete` cases found, only one allowed"));
+ }
+ input.parse::<kw::complete>()?;
+ CaseKind::Complete
+ } else if input.peek(Token![default]) {
+ // `default`
+ if select.default.is_some() {
+ return Err(input.error("multiple `default` cases found, only one allowed"));
+ }
+ input.parse::<Ident>()?;
+ CaseKind::Default
+ } else {
+ // `<pat> = <expr>`
+ let pat = input.parse()?;
+ input.parse::<Token![=]>()?;
+ let expr = input.parse()?;
+ CaseKind::Normal(pat, expr)
+ };
+
+ // `=> <expr>`
+ input.parse::<Token![=>]>()?;
+ let expr = input.parse::<Expr>()?;
+
+ // Commas after the expression are only optional if it's a `Block`
+ // or it is the last branch in the `match`.
+ let is_block = match expr {
+ Expr::Block(_) => true,
+ _ => false,
+ };
+ if is_block || input.is_empty() {
+ input.parse::<Option<Token![,]>>()?;
+ } else {
+ input.parse::<Token![,]>()?;
+ }
+
+ match case_kind {
+ CaseKind::Complete => select.complete = Some(expr),
+ CaseKind::Default => select.default = Some(expr),
+ CaseKind::Normal(pat, fut_expr) => {
+ select.normal_fut_exprs.push(fut_expr);
+ select.normal_fut_handlers.push((pat, expr));
+ }
+ }
+ }
+
+ Ok(select)
+ }
+}
+
+// Enum over all the cases in which the `select!` waiting has completed and the result
+// can be processed.
+//
+// `enum __PrivResult<_1, _2, ...> { _1(_1), _2(_2), ..., Complete }`
+fn declare_result_enum(
+ result_ident: Ident,
+ variants: usize,
+ complete: bool,
+ span: Span,
+) -> (Vec<Ident>, syn::ItemEnum) {
+ // "_0", "_1", "_2"
+ let variant_names: Vec<Ident> =
+ (0..variants).map(|num| format_ident!("_{}", num, span = span)).collect();
+
+ let type_parameters = &variant_names;
+ let variants = &variant_names;
+
+ let complete_variant = if complete { Some(quote!(Complete)) } else { None };
+
+ let enum_item = parse_quote! {
+ enum #result_ident<#(#type_parameters,)*> {
+ #(
+ #variants(#type_parameters),
+ )*
+ #complete_variant
+ }
+ };
+
+ (variant_names, enum_item)
+}
+
+/// The `select!` macro.
+pub(crate) fn select(input: TokenStream) -> TokenStream {
+ select_inner(input, true)
+}
+
+/// The `select_biased!` macro.
+pub(crate) fn select_biased(input: TokenStream) -> TokenStream {
+ select_inner(input, false)
+}
+
+fn select_inner(input: TokenStream, random: bool) -> TokenStream {
+ let parsed = syn::parse_macro_input!(input as Select);
+
+ // should be def_site, but that's unstable
+ let span = Span::call_site();
+
+ let enum_ident = Ident::new("__PrivResult", span);
+
+ let (variant_names, enum_item) = declare_result_enum(
+ enum_ident.clone(),
+ parsed.normal_fut_exprs.len(),
+ parsed.complete.is_some(),
+ span,
+ );
+
+ // bind non-`Ident` future exprs w/ `let`
+ let mut future_let_bindings = Vec::with_capacity(parsed.normal_fut_exprs.len());
+ let bound_future_names: Vec<_> = parsed
+ .normal_fut_exprs
+ .into_iter()
+ .zip(variant_names.iter())
+ .map(|(expr, variant_name)| {
+ match expr {
+ syn::Expr::Path(path) => {
+ // Don't bind futures that are already a path.
+ // This prevents creating redundant stack space
+ // for them.
+ // Passing Futures by path requires those Futures to implement Unpin.
+ // We check for this condition here in order to be able to
+ // safely use Pin::new_unchecked(&mut #path) later on.
+ future_let_bindings.push(quote! {
+ __futures_crate::async_await::assert_fused_future(&#path);
+ __futures_crate::async_await::assert_unpin(&#path);
+ });
+ path
+ }
+ _ => {
+ // Bind and pin the resulting Future on the stack. This is
+ // necessary to support direct select! calls on !Unpin
+ // Futures. The Future is not explicitly pinned here with
+ // a Pin call, but assumed as pinned. The actual Pin is
+ // created inside the poll() function below to defer the
+ // creation of the temporary pointer, which would otherwise
+ // increase the size of the generated Future.
+ // Safety: This is safe since the lifetime of the Future
+ // is totally constraint to the lifetime of the select!
+ // expression, and the Future can't get moved inside it
+ // (it is shadowed).
+ future_let_bindings.push(quote! {
+ let mut #variant_name = #expr;
+ });
+ parse_quote! { #variant_name }
+ }
+ }
+ })
+ .collect();
+
+ // For each future, make an `&mut dyn FnMut(&mut Context<'_>) -> Option<Poll<__PrivResult<...>>`
+ // to use for polling that individual future. These will then be put in an array.
+ let poll_functions = bound_future_names.iter().zip(variant_names.iter()).map(
+ |(bound_future_name, variant_name)| {
+ // Below we lazily create the Pin on the Future below.
+ // This is done in order to avoid allocating memory in the generator
+ // for the Pin variable.
+ // Safety: This is safe because one of the following condition applies:
+ // 1. The Future is passed by the caller by name, and we assert that
+ // it implements Unpin.
+ // 2. The Future is created in scope of the select! function and will
+ // not be moved for the duration of it. It is thereby stack-pinned
+ quote! {
+ let mut #variant_name = |__cx: &mut __futures_crate::task::Context<'_>| {
+ let mut #bound_future_name = unsafe {
+ __futures_crate::Pin::new_unchecked(&mut #bound_future_name)
+ };
+ if __futures_crate::future::FusedFuture::is_terminated(&#bound_future_name) {
+ __futures_crate::None
+ } else {
+ __futures_crate::Some(__futures_crate::future::FutureExt::poll_unpin(
+ &mut #bound_future_name,
+ __cx,
+ ).map(#enum_ident::#variant_name))
+ }
+ };
+ let #variant_name: &mut dyn FnMut(
+ &mut __futures_crate::task::Context<'_>
+ ) -> __futures_crate::Option<__futures_crate::task::Poll<_>> = &mut #variant_name;
+ }
+ },
+ );
+
+ let none_polled = if parsed.complete.is_some() {
+ quote! {
+ __futures_crate::task::Poll::Ready(#enum_ident::Complete)
+ }
+ } else {
+ quote! {
+ panic!("all futures in select! were completed,\
+ but no `complete =>` handler was provided")
+ }
+ };
+
+ let branches = parsed.normal_fut_handlers.into_iter().zip(variant_names.iter()).map(
+ |((pat, expr), variant_name)| {
+ quote! {
+ #enum_ident::#variant_name(#pat) => { #expr },
+ }
+ },
+ );
+ let branches = quote! { #( #branches )* };
+
+ let complete_branch = parsed.complete.map(|complete_expr| {
+ quote! {
+ #enum_ident::Complete => { #complete_expr },
+ }
+ });
+
+ let branches = quote! {
+ #branches
+ #complete_branch
+ };
+
+ let await_select_fut = if parsed.default.is_some() {
+ // For select! with default this returns the Poll result
+ quote! {
+ __poll_fn(&mut __futures_crate::task::Context::from_waker(
+ __futures_crate::task::noop_waker_ref()
+ ))
+ }
+ } else {
+ quote! {
+ __futures_crate::future::poll_fn(__poll_fn).await
+ }
+ };
+
+ let execute_result_expr = if let Some(default_expr) = &parsed.default {
+ // For select! with default __select_result is a Poll, otherwise not
+ quote! {
+ match __select_result {
+ __futures_crate::task::Poll::Ready(result) => match result {
+ #branches
+ },
+ _ => #default_expr
+ }
+ }
+ } else {
+ quote! {
+ match __select_result {
+ #branches
+ }
+ }
+ };
+
+ let shuffle = if random {
+ quote! {
+ __futures_crate::async_await::shuffle(&mut __select_arr);
+ }
+ } else {
+ quote!()
+ };
+
+ TokenStream::from(quote! { {
+ #enum_item
+
+ let __select_result = {
+ #( #future_let_bindings )*
+
+ let mut __poll_fn = |__cx: &mut __futures_crate::task::Context<'_>| {
+ let mut __any_polled = false;
+
+ #( #poll_functions )*
+
+ let mut __select_arr = [#( #variant_names ),*];
+ #shuffle
+ for poller in &mut __select_arr {
+ let poller: &mut &mut dyn FnMut(
+ &mut __futures_crate::task::Context<'_>
+ ) -> __futures_crate::Option<__futures_crate::task::Poll<_>> = poller;
+ match poller(__cx) {
+ __futures_crate::Some(x @ __futures_crate::task::Poll::Ready(_)) =>
+ return x,
+ __futures_crate::Some(__futures_crate::task::Poll::Pending) => {
+ __any_polled = true;
+ }
+ __futures_crate::None => {}
+ }
+ }
+
+ if !__any_polled {
+ #none_polled
+ } else {
+ __futures_crate::task::Poll::Pending
+ }
+ };
+
+ #await_select_fut
+ };
+
+ #execute_result_expr
+ } })
+}
diff --git a/third_party/rust/futures-macro/src/stream_select.rs b/third_party/rust/futures-macro/src/stream_select.rs
new file mode 100644
index 0000000000..9927b53073
--- /dev/null
+++ b/third_party/rust/futures-macro/src/stream_select.rs
@@ -0,0 +1,113 @@
+use proc_macro2::TokenStream;
+use quote::{format_ident, quote, ToTokens};
+use syn::{parse::Parser, punctuated::Punctuated, Expr, Index, Token};
+
+/// The `stream_select!` macro.
+pub(crate) fn stream_select(input: TokenStream) -> Result<TokenStream, syn::Error> {
+ let args = Punctuated::<Expr, Token![,]>::parse_terminated.parse2(input)?;
+ if args.len() < 2 {
+ return Ok(quote! {
+ compile_error!("stream select macro needs at least two arguments.")
+ });
+ }
+ let generic_idents = (0..args.len()).map(|i| format_ident!("_{}", i)).collect::<Vec<_>>();
+ let field_idents = (0..args.len()).map(|i| format_ident!("__{}", i)).collect::<Vec<_>>();
+ let field_idents_2 = (0..args.len()).map(|i| format_ident!("___{}", i)).collect::<Vec<_>>();
+ let field_indices = (0..args.len()).map(Index::from).collect::<Vec<_>>();
+ let args = args.iter().map(|e| e.to_token_stream());
+
+ Ok(quote! {
+ {
+ #[derive(Debug)]
+ struct StreamSelect<#(#generic_idents),*> (#(Option<#generic_idents>),*);
+
+ enum StreamEnum<#(#generic_idents),*> {
+ #(
+ #generic_idents(#generic_idents)
+ ),*,
+ None,
+ }
+
+ impl<ITEM, #(#generic_idents),*> __futures_crate::stream::Stream for StreamEnum<#(#generic_idents),*>
+ where #(#generic_idents: __futures_crate::stream::Stream<Item=ITEM> + ::std::marker::Unpin,)*
+ {
+ type Item = ITEM;
+
+ fn poll_next(mut self: ::std::pin::Pin<&mut Self>, cx: &mut __futures_crate::task::Context<'_>) -> __futures_crate::task::Poll<Option<Self::Item>> {
+ match self.get_mut() {
+ #(
+ Self::#generic_idents(#generic_idents) => ::std::pin::Pin::new(#generic_idents).poll_next(cx)
+ ),*,
+ Self::None => panic!("StreamEnum::None should never be polled!"),
+ }
+ }
+ }
+
+ impl<ITEM, #(#generic_idents),*> __futures_crate::stream::Stream for StreamSelect<#(#generic_idents),*>
+ where #(#generic_idents: __futures_crate::stream::Stream<Item=ITEM> + ::std::marker::Unpin,)*
+ {
+ type Item = ITEM;
+
+ fn poll_next(mut self: ::std::pin::Pin<&mut Self>, cx: &mut __futures_crate::task::Context<'_>) -> __futures_crate::task::Poll<Option<Self::Item>> {
+ let Self(#(ref mut #field_idents),*) = self.get_mut();
+ #(
+ let mut #field_idents_2 = false;
+ )*
+ let mut any_pending = false;
+ {
+ let mut stream_array = [#(#field_idents.as_mut().map(|f| StreamEnum::#generic_idents(f)).unwrap_or(StreamEnum::None)),*];
+ __futures_crate::async_await::shuffle(&mut stream_array);
+
+ for mut s in stream_array {
+ if let StreamEnum::None = s {
+ continue;
+ } else {
+ match __futures_crate::stream::Stream::poll_next(::std::pin::Pin::new(&mut s), cx) {
+ r @ __futures_crate::task::Poll::Ready(Some(_)) => {
+ return r;
+ },
+ __futures_crate::task::Poll::Pending => {
+ any_pending = true;
+ },
+ __futures_crate::task::Poll::Ready(None) => {
+ match s {
+ #(
+ StreamEnum::#generic_idents(_) => { #field_idents_2 = true; }
+ ),*,
+ StreamEnum::None => panic!("StreamEnum::None should never be polled!"),
+ }
+ },
+ }
+ }
+ }
+ }
+ #(
+ if #field_idents_2 {
+ *#field_idents = None;
+ }
+ )*
+ if any_pending {
+ __futures_crate::task::Poll::Pending
+ } else {
+ __futures_crate::task::Poll::Ready(None)
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let mut s = (0, Some(0));
+ #(
+ if let Some(new_hint) = self.#field_indices.as_ref().map(|s| s.size_hint()) {
+ s.0 += new_hint.0;
+ // We can change this out for `.zip` when the MSRV is 1.46.0 or higher.
+ s.1 = s.1.and_then(|a| new_hint.1.map(|b| a + b));
+ }
+ )*
+ s
+ }
+ }
+
+ StreamSelect(#(Some(#args)),*)
+
+ }
+ })
+}