ExecutorExt, spawn! and spawn_with_handle!

[MajorBreakfast]

• Adds ExecutorExt::spawn and ExecutorExt::spawn_with_handle
• Adds spawn! and spawn_with_handle! macros
• Removes ContextExt
• Removes spawn and spawn_with_handle free functions

[MajorBreakfast]

@cramertj I'd like to do:

spawn!(async {
    assert_eq!(thread::current().name(), Some("my-pool-0"));
    # tx.send("ran").unwrap();
}).unwrap();

But I get this error:

error: no rules expected the token `async`
  --> src/future/mod.rs:658:13
   |
20 |      spawn!(async {
   |             ^^^^^

[Nemo157]

Did you try spawn!((async { ... }))? Extra parentheses might get it into expression parsing. Probably should be a rust bug ticket as well.

[MajorBreakfast]

Yes. Then I get this. I think it's an ICE:

---- src/future/mod.rs - future::FutureExt::with_executor (line 640) stdout ----
thread 'src/future/mod.rs - future::FutureExt::with_executor (line 640)' panicked at 'called `Option::unwrap()` on a `None` value', libcore/option.rs:345:21
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: rustc::util::common::panic_hook
   5: std::panicking::rust_panic_with_hook
   6: std::panicking::continue_panic_fmt
   7: rust_begin_unwind
   8: core::panicking::panic_fmt
   9: core::panicking::panic
  10: syntax::print::pprust::State::print_expr_outer_attr_style
  11: syntax::print::pprust::State::print_expr_outer_attr_style
  12: syntax::print::pprust::to_string
  13: syntax::print::pprust::expr_to_string
  14: rustc_lint::unused::UnusedParens::check_unused_parens_core
  15: <rustc_lint::unused::UnusedParens as rustc::lint::EarlyLintPass>::check_expr
  16: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  17: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_block
  18: syntax::visit::walk_expr
  19: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  20: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_fn
  21: syntax::visit::walk_expr
  22: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  23: syntax::visit::walk_expr
  24: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  25: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_local
  26: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_block
  27: syntax::visit::walk_expr
  28: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  29: syntax::visit::walk_expr
  30: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  31: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_block
  32: syntax::visit::walk_expr
  33: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  34: syntax::visit::walk_expr
  35: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  36: syntax::visit::walk_expr
  37: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  38: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_local
  39: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_block
  40: syntax::visit::walk_expr
  41: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  42: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_local
  43: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_block
  44: syntax::visit::walk_expr
  45: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  46: syntax::visit::walk_expr
  47: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_expr
  48: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_block
  49: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_fn
  50: syntax::visit::walk_item
  51: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_item
  52: <rustc::lint::context::EarlyContext<'a> as syntax::visit::Visitor<'a>>::visit_mod
  53: rustc::lint::context::check_ast_crate
  54: rustc::util::common::time
  55: rustc_driver::driver::phase_2_configure_and_expand
  56: rustc_driver::driver::compile_input
  57: std::panicking::try::do_call
  58: __rust_maybe_catch_panic
  59: <scoped_tls::ScopedKey<T>>::set
  60: rustdoc::test::Collector::add_test::{{closure}}::{{closure}}::{{closure}}
  61: <scoped_tls::ScopedKey<T>>::set
  62: syntax::with_globals
  63: std::panicking::try::do_call
  64: __rust_maybe_catch_panic
  65: rustc_driver::in_named_rustc_thread
  66: <F as alloc::boxed::FnBox<A>>::call_box
  67: <F as alloc::boxed::FnBox<A>>::call_box
  68: __rust_maybe_catch_panic
query stack during panic:
end of query stack
thread 'src/future/mod.rs - future::FutureExt::with_executor (line 640)' panicked at 'couldn't compile the test', librustdoc/test.rs:332:13
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: rustc::util::common::panic_hook
   5: std::panicking::rust_panic_with_hook
   6: std::panicking::begin_panic
   7: rustdoc::test::Collector::add_test::{{closure}}::{{closure}}::{{closure}}
   8: <scoped_tls::ScopedKey<T>>::set
   9: syntax::with_globals
  10: std::panicking::try::do_call
  11: __rust_maybe_catch_panic
  12: rustc_driver::in_named_rustc_thread
  13: <F as alloc::boxed::FnBox<A>>::call_box
  14: <F as alloc::boxed::FnBox<A>>::call_box
  15: __rust_maybe_catch_panic
query stack during panic:
end of query stack


failures:
    src/future/mod.rs - future::FutureExt::with_executor (line 640)

[cramertj]

Hm, it looks like the macro matcher for expr isn't currently catching async. I'll file an issue and check the parser to see about a fix. Thanks for finding this! playground

[cramertj]

Filed rust-lang/rust#52951

[MajorBreakfast]

Wonderful! I've subscribed to your PR, so that I can make the change once a new nightly with the fix is released. IMO it's not a blocking issue for this PR, though

[Nemo157]

$crate::core_reexport::await! maybe? (probably not, can just rely on await being in scope).

[Nemo157]

In fact, it's probably a builtin macro rather than a core defined macro anyway

[MajorBreakfast]

The other macros (poll!, pending!) do it this way as well.

I don't know where await! comes from, but I don't think it's from libcore.

[cramertj]

It's in libstd right now, but it'll probably be moved into the compiler itself as a builtin and referenced from libcore at some point. I wouldn't worry about scoping it.