Reduce type errors in async fns

[birkenfeld]

I will admit that this specific async fn is a bit long, but I'd like the compiler to tell me in a different way. (Actual reason is addition of one line borrowing the wrong type across an .await boundary, of course)

Like this, we're coming out ahead of C++ 😄

    = help: the trait `std::marker::Sync` is not implemented for `dyn jobs::Job`
    = note: required because of the requirements on the impl of `std::marker::Send` for `&dyn jobs::Job`
    = note: required because it appears within the type `for<'r, 's, 't0, 't1, 't2, 't3, 
't4, 't5, 't6, 't7, 't8, 't9, 't10, 't11, 't12, 't13, 't14, 't15, 't16, 't17, 't18, 't19, 
't20, 't21, 't22, 't23, 't24, 't25, 't26, 't27, 't28, 't29, 't30, 't31, 't32, 't33, 't34, 
't35, 't36, 't37, 't38, 't39, 't40, 't41, 't42, 't43, 't44, 't45, 't46, 't47, 't48, 't49, 
't50, 't51, 't52, 't53, 't54, 't55, 't56, 't57, 't58, 't59, 't60, 't61, 't62, 't63, 
't64, 't65, 't66, 't67, 't68, 't69, 't70, 't71, 't72, 't73, 't74, 't75, 't76, 't77, 
't78, 't79, 't80, 't81, 't82, 't83, 't84, 't85, 't86, 't87, 't88, 't89, 't90, 't91, 
't92, 't93, 't94, 't95, 't96, 't97, 't98, 't99, 't100, 't101, 't102, 't103, 't104, 
't105, 't106, 't107, 't108, 't109, 't110, 't111, 't112, 't113, 't114, 't115, 't116, 
't117, 't118, 't119, 't120, 't121, 't122, 't123, 't124, 't125, 't126, 't127, 't128, 
't129, 't130, 't131, 't132, 't133, 't134, 't135, 't136, 't137, 't138, 't139, 't140, 
't141, 't142, 't143, 't144, 't145, 't146, 't147, 't148, 't149, 't150, 't151, 't152, 
't153, 't154, 't155, 't156, 't157, 't158, 't159, 't160, 't161, 't162, 't163, 't164, 
't165, 't166, 't167, 't168, 't169, 't170, 't171, 't172, 't173, 't174, 't175, 't176, 
't177, 't178, 't179, 't180, 't181, 't182, 't183, 't184, 't185, 't186, 't187, 't188, 
't189, 't190, 't191, 't192, 't193, 't194, 't195, 't196, 't197, 't198, 't199, 't200, 
't201, 't202, 't203, 't204, 't205, 't206, 't207, 't208, 't209, 't210, 't211, 't212, 
't213, 't214, 't215, 't216, 't217, 't218, 't219, 't220, 't221, 't222, 't223, 't224, 
't225, 't226, 't227, 't228, 't229, 't230, 't231, 't232, 't233, 't234, 't235, 't236, 
't237, 't238, 't239, 't240, 't241, 't242, 't243, 't244, 't245, 't246, 't247, 't248> 
{handler::Handler, handler::Handler, handler::Handler, &'r mut 
tokio_sync::mpsc::bounded::Receiver<handler::Action>, 
tokio_sync::mpsc::bounded::Receiver<handler::Action>, 
futures_util::stream::next::Next<'s, 
tokio_sync::mpsc::bounded::Receiver<handler::Action>>, 
futures_util::stream::next::Next<'t0, 
tokio_sync::mpsc::bounded::Receiver<handler::Action>>, (), 
std::option::Option<handler::Action>, handler::Action, handler::Action, 
handler::Request, auth::ClientInfo, tokio_sync::oneshot::Sender<handler::Response>, 
handler::Request, std::collections::HashMap<std::string::String, handler::ServiceInfo>, 
handler::Handler, &'t1 std::collections::HashMap<std::string::String, (jobs::Service, 
usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::hash_map::Values<'t2, std::string::String, (jobs::Service, usize)>, 
std::collections::hash_map::Values<'t3, std::string::String, (jobs::Service, usize)>, 
std::collections::hash_map::Values<'t4, std::string::String, (jobs::Service, usize)>, 
&'t5 (jobs::Service, usize), &'t6 jobs::Service, &'t7 usize, handler::Handler, &'t8 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't9)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't10)>>, std::boxed::Box<(dyn jobs::Job + 
't11)>, (dyn jobs::Job + 't12), &'t13 (dyn jobs::Job + 't14), bool, bool, &'t15 mut 
handler::ServiceInfo, &'t16 mut (dyn jobs::Job + 't17), &'t18 (dyn jobs::Job + 't19), 
&'t20 jobs::Service, &'t21 jobs::Service, std::pin::Pin<std::boxed::Box<(dyn 
core::future::future::Future<Output = jobs::ExtStatus> + std::marker::Send + 't22)>>, 
std::pin::Pin<std::boxed::Box<(dyn core::future::future::Future<Output = 
jobs::ExtStatus> + std::marker::Send + 't23)>>, (), std::string::String, 
handler::Handler, &'t24 std::collections::HashMap<std::string::String, (jobs::Service, 
usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t25 std::string::String, &'t26 std::string::String, 
std::option::Option<&'t27 (jobs::Service, usize)>, &'t28 jobs::Service, &'t29 usize, 
handler::Handler, &'t30 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't31)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't32)>>, std::boxed::Box<(dyn jobs::Job + 
't33)>, (dyn jobs::Job + 't34), &'t35 mut (dyn jobs::Job + 't36), &'t37 mut (dyn 
jobs::Job + 't38), &'t39 mut (dyn jobs::Job + 't40), &'t41 jobs::Service, &'t42 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t49 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t50 std::string::String, &'t51 std::string::String, 
std::option::Option<&'t52 (jobs::Service, usize)>, &'t53 jobs::Service, &'t54 usize, 
handler::Handler, &'t55 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't56)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't57)>>, std::boxed::Box<(dyn jobs::Job + 
't58)>, (dyn jobs::Job + 't59), &'t60 mut (dyn jobs::Job + 't61), &'t62 mut (dyn 
jobs::Job + 't63), &'t64 mut (dyn jobs::Job + 't65), &'t66 jobs::Service, &'t67 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t74 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t75 std::string::String, &'t76 std::string::String, 
std::option::Option<&'t77 (jobs::Service, usize)>, &'t78 jobs::Service, &'t79 usize, 
handler::Handler, &'t80 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't81)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't82)>>, std::boxed::Box<(dyn jobs::Job + 
't83)>, (dyn jobs::Job + 't84), &'t85 mut (dyn jobs::Job + 't86), &'t87 mut (dyn 
jobs::Job + 't88), &'t89 mut (dyn jobs::Job + 't90), &'t91 jobs::Service, &'t92 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t99 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t100 std::string::String, &'t101 std::string::String, 
std::option::Option<&'t102 (jobs::Service, usize)>, &'t103 jobs::Service, &'t104 usize, 
handler::Handler, &'t105 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't106)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't107)>>, std::boxed::Box<(dyn jobs::Job 
+ 't108)>, (dyn jobs::Job + 't109), &'t110 mut (dyn jobs::Job + 't111), &'t112 mut (dyn 
jobs::Job + 't113), &'t114 mut (dyn jobs::Job + 't115), &'t116 jobs::Service, &'t117 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t124 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t125 std::string::String, &'t126 std::string::String, 
std::option::Option<&'t127 (jobs::Service, usize)>, &'t128 jobs::Service, &'t129 usize, 
handler::Handler, &'t130 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't131)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't132)>>, std::boxed::Box<(dyn jobs::Job 
+ 't133)>, (dyn jobs::Job + 't134), &'t135 mut (dyn jobs::Job + 't136), &'t137 mut (dyn 
jobs::Job + 't138), &'t139 mut (dyn jobs::Job + 't140), &'t141 jobs::Service, &'t142 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, std::string::String, std::string::String, handler::Handler, &'t149 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t150 std::string::String, &'t151 std::string::String, 
std::option::Option<&'t152 (jobs::Service, usize)>, &'t153 jobs::Service, &'t154 usize, 
handler::Handler, &'t155 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't156)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't157)>>, std::boxed::Box<(dyn jobs::Job 
+ 't158)>, (dyn jobs::Job + 't159), &'t160 mut (dyn jobs::Job + 't161), &'t162 mut (dyn 
jobs::Job + 't163), &'t164 mut (dyn jobs::Job + 't165), &'t166 jobs::Service, &'t167 
jobs::Service, auth::ClientInfo, std::string::String, std::string::String, impl 
core::future::future::Future, impl core::future::future::Future, impl 
core::future::future::Future, (), std::string::String, handler::Handler, &'t174 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t175 std::string::String, &'t176 std::string::String, 
std::option::Option<&'t177 (jobs::Service, usize)>, &'t178 jobs::Service, &'t179 usize, 
handler::Handler, &'t180 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't181)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't182)>>, std::boxed::Box<(dyn jobs::Job 
+ 't183)>, (dyn jobs::Job + 't184), &'t185 mut (dyn jobs::Job + 't186), &'t187 mut (dyn 
jobs::Job + 't188), &'t189 mut (dyn jobs::Job + 't190), &'t191 jobs::Service, &'t192 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t199 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t200 std::string::String, &'t201 std::string::String, 
std::option::Option<&'t202 (jobs::Service, usize)>, &'t203 jobs::Service, &'t204 usize, 
handler::Handler, &'t205 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't206)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't207)>>, std::boxed::Box<(dyn jobs::Job 
+ 't208)>, (dyn jobs::Job + 't209), &'t210 mut (dyn jobs::Job + 't211), &'t212 mut (dyn 
jobs::Job + 't213), &'t214 mut (dyn jobs::Job + 't215), &'t216 jobs::Service, &'t217 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t224 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t225 std::string::String, &'t226 std::string::String, 
std::option::Option<&'t227 (jobs::Service, usize)>, &'t228 jobs::Service, &'t229 usize, 
handler::Handler, &'t230 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't231)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't232)>>, std::boxed::Box<(dyn jobs::Job 
+ 't233)>, (dyn jobs::Job + 't234), &'t235 mut (dyn jobs::Job + 't236), &'t237 mut (dyn 
jobs::Job + 't238), &'t239 mut (dyn jobs::Job + 't240), &'t241 jobs::Service, &'t242 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, ()}`
    = note: required because it appears within the type `[static 
generator@src/handler.rs:137:32: 198:6 __arg0:handler::Handler for<'r, 's, 't0, 't1, 
't2, 't3, 't4, 't5, 't6, 't7, 't8, 't9, 't10, 't11, 't12, 't13, 't14, 't15, 't16, 't17, 
't18, 't19, 't20, 't21, 't22, 't23, 't24, 't25, 't26, 't27, 't28, 't29, 't30, 't31, 
't32, 't33, 't34, 't35, 't36, 't37, 't38, 't39, 't40, 't41, 't42, 't43, 't44, 't45, 
't46, 't47, 't48, 't49, 't50, 't51, 't52, 't53, 't54, 't55, 't56, 't57, 't58, 't59, 
't60, 't61, 't62, 't63, 't64, 't65, 't66, 't67, 't68, 't69, 't70, 't71, 't72, 't73, 
't74, 't75, 't76, 't77, 't78, 't79, 't80, 't81, 't82, 't83, 't84, 't85, 't86, 't87, 
't88, 't89, 't90, 't91, 't92, 't93, 't94, 't95, 't96, 't97, 't98, 't99, 't100, 't101, 
't102, 't103, 't104, 't105, 't106, 't107, 't108, 't109, 't110, 't111, 't112, 't113, 
't114, 't115, 't116, 't117, 't118, 't119, 't120, 't121, 't122, 't123, 't124, 't125, 
't126, 't127, 't128, 't129, 't130, 't131, 't132, 't133, 't134, 't135, 't136, 't137, 
't138, 't139, 't140, 't141, 't142, 't143, 't144, 't145, 't146, 't147, 't148, 't149, 
't150, 't151, 't152, 't153, 't154, 't155, 't156, 't157, 't158, 't159, 't160, 't161, 
't162, 't163, 't164, 't165, 't166, 't167, 't168, 't169, 't170, 't171, 't172, 't173, 
't174, 't175, 't176, 't177, 't178, 't179, 't180, 't181, 't182, 't183, 't184, 't185, 
't186, 't187, 't188, 't189, 't190, 't191, 't192, 't193, 't194, 't195, 't196, 't197, 
't198, 't199, 't200, 't201, 't202, 't203, 't204, 't205, 't206, 't207, 't208, 't209, 
't210, 't211, 't212, 't213, 't214, 't215, 't216, 't217, 't218, 't219, 't220, 't221, 
't222, 't223, 't224, 't225, 't226, 't227, 't228, 't229, 't230, 't231, 't232, 't233, 
't234, 't235, 't236, 't237, 't238, 't239, 't240, 't241, 't242, 't243, 't244, 't245, 
't246, 't247, 't248> {handler::Handler, handler::Handler, handler::Handler, &'r mut 
tokio_sync::mpsc::bounded::Receiver<handler::Action>, 
tokio_sync::mpsc::bounded::Receiver<handler::Action>, 
futures_util::stream::next::Next<'s, 
tokio_sync::mpsc::bounded::Receiver<handler::Action>>, 
futures_util::stream::next::Next<'t0, 
tokio_sync::mpsc::bounded::Receiver<handler::Action>>, (), 
std::option::Option<handler::Action>, handler::Action, handler::Action, 
handler::Request, auth::ClientInfo, tokio_sync::oneshot::Sender<handler::Response>, 
handler::Request, std::collections::HashMap<std::string::String, handler::ServiceInfo>, 
handler::Handler, &'t1 std::collections::HashMap<std::string::String, (jobs::Service, 
usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::hash_map::Values<'t2, std::string::String, (jobs::Service, usize)>, 
std::collections::hash_map::Values<'t3, std::string::String, (jobs::Service, usize)>, 
std::collections::hash_map::Values<'t4, std::string::String, (jobs::Service, usize)>, 
&'t5 (jobs::Service, usize), &'t6 jobs::Service, &'t7 usize, handler::Handler, &'t8 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't9)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't10)>>, std::boxed::Box<(dyn jobs::Job + 
't11)>, (dyn jobs::Job + 't12), &'t13 (dyn jobs::Job + 't14), bool, bool, &'t15 mut 
handler::ServiceInfo, &'t16 mut (dyn jobs::Job + 't17), &'t18 (dyn jobs::Job + 't19), 
&'t20 jobs::Service, &'t21 jobs::Service, std::pin::Pin<std::boxed::Box<(dyn 
core::future::future::Future<Output = jobs::ExtStatus> + std::marker::Send + 't22)>>, 
std::pin::Pin<std::boxed::Box<(dyn core::future::future::Future<Output = 
jobs::ExtStatus> + std::marker::Send + 't23)>>, (), std::string::String, 
handler::Handler, &'t24 std::collections::HashMap<std::string::String, (jobs::Service, 
usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t25 std::string::String, &'t26 std::string::String, 
std::option::Option<&'t27 (jobs::Service, usize)>, &'t28 jobs::Service, &'t29 usize, 
handler::Handler, &'t30 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't31)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't32)>>, std::boxed::Box<(dyn jobs::Job + 
't33)>, (dyn jobs::Job + 't34), &'t35 mut (dyn jobs::Job + 't36), &'t37 mut (dyn 
jobs::Job + 't38), &'t39 mut (dyn jobs::Job + 't40), &'t41 jobs::Service, &'t42 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t49 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t50 std::string::String, &'t51 std::string::String, 
std::option::Option<&'t52 (jobs::Service, usize)>, &'t53 jobs::Service, &'t54 usize, 
handler::Handler, &'t55 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't56)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't57)>>, std::boxed::Box<(dyn jobs::Job + 
't58)>, (dyn jobs::Job + 't59), &'t60 mut (dyn jobs::Job + 't61), &'t62 mut (dyn 
jobs::Job + 't63), &'t64 mut (dyn jobs::Job + 't65), &'t66 jobs::Service, &'t67 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t74 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t75 std::string::String, &'t76 std::string::String, 
std::option::Option<&'t77 (jobs::Service, usize)>, &'t78 jobs::Service, &'t79 usize, 
handler::Handler, &'t80 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't81)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't82)>>, std::boxed::Box<(dyn jobs::Job + 
't83)>, (dyn jobs::Job + 't84), &'t85 mut (dyn jobs::Job + 't86), &'t87 mut (dyn 
jobs::Job + 't88), &'t89 mut (dyn jobs::Job + 't90), &'t91 jobs::Service, &'t92 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t99 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t100 std::string::String, &'t101 std::string::String, 
std::option::Option<&'t102 (jobs::Service, usize)>, &'t103 jobs::Service, &'t104 usize, 
handler::Handler, &'t105 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't106)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't107)>>, std::boxed::Box<(dyn jobs::Job 
+ 't108)>, (dyn jobs::Job + 't109), &'t110 mut (dyn jobs::Job + 't111), &'t112 mut (dyn 
jobs::Job + 't113), &'t114 mut (dyn jobs::Job + 't115), &'t116 jobs::Service, &'t117 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t124 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t125 std::string::String, &'t126 std::string::String, 
std::option::Option<&'t127 (jobs::Service, usize)>, &'t128 jobs::Service, &'t129 usize, 
handler::Handler, &'t130 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't131)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't132)>>, std::boxed::Box<(dyn jobs::Job 
+ 't133)>, (dyn jobs::Job + 't134), &'t135 mut (dyn jobs::Job + 't136), &'t137 mut (dyn 
jobs::Job + 't138), &'t139 mut (dyn jobs::Job + 't140), &'t141 jobs::Service, &'t142 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, std::string::String, std::string::String, handler::Handler, &'t149 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t150 std::string::String, &'t151 std::string::String, 
std::option::Option<&'t152 (jobs::Service, usize)>, &'t153 jobs::Service, &'t154 usize, 
handler::Handler, &'t155 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't156)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't157)>>, std::boxed::Box<(dyn jobs::Job 
+ 't158)>, (dyn jobs::Job + 't159), &'t160 mut (dyn jobs::Job + 't161), &'t162 mut (dyn 
jobs::Job + 't163), &'t164 mut (dyn jobs::Job + 't165), &'t166 jobs::Service, &'t167 
jobs::Service, auth::ClientInfo, std::string::String, std::string::String, impl 
core::future::future::Future, impl core::future::future::Future, impl 
core::future::future::Future, (), std::string::String, handler::Handler, &'t174 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t175 std::string::String, &'t176 std::string::String, 
std::option::Option<&'t177 (jobs::Service, usize)>, &'t178 jobs::Service, &'t179 usize, 
handler::Handler, &'t180 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't181)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't182)>>, std::boxed::Box<(dyn jobs::Job 
+ 't183)>, (dyn jobs::Job + 't184), &'t185 mut (dyn jobs::Job + 't186), &'t187 mut (dyn 
jobs::Job + 't188), &'t189 mut (dyn jobs::Job + 't190), &'t191 jobs::Service, &'t192 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t199 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t200 std::string::String, &'t201 std::string::String, 
std::option::Option<&'t202 (jobs::Service, usize)>, &'t203 jobs::Service, &'t204 usize, 
handler::Handler, &'t205 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't206)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't207)>>, std::boxed::Box<(dyn jobs::Job 
+ 't208)>, (dyn jobs::Job + 't209), &'t210 mut (dyn jobs::Job + 't211), &'t212 mut (dyn 
jobs::Job + 't213), &'t214 mut (dyn jobs::Job + 't215), &'t216 jobs::Service, &'t217 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, (), 
std::string::String, handler::Handler, &'t224 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::collections::HashMap<std::string::String, (jobs::Service, usize)>, 
std::string::String, &'t225 std::string::String, &'t226 std::string::String, 
std::option::Option<&'t227 (jobs::Service, usize)>, &'t228 jobs::Service, &'t229 usize, 
handler::Handler, &'t230 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't231)>>, 
std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't232)>>, std::boxed::Box<(dyn jobs::Job 
+ 't233)>, (dyn jobs::Job + 't234), &'t235 mut (dyn jobs::Job + 't236), &'t237 mut (dyn 
jobs::Job + 't238), &'t239 mut (dyn jobs::Job + 't240), &'t241 jobs::Service, &'t242 
jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl 
core::future::future::Future, impl core::future::future::Future, ()}]`

    = note: required because it appears within the type `std::future::GenFuture<[static generator@src/handler.rs:137:32: 198:6 __arg0:handler::Handler for<'r, 's, 't0, 't1, 't2, 't3, 't4, 't5, 't6, 't7, 't8, 't9, 't10, 't11, 't12, 't13, 't14, 't15, 't16, 't17, 't18, 't19, 't20, 't21, 't22, 't23, 't24, 't25, 't26, 't27, 't28, 't29, 't30, 't31, 't32, 't33, 't34, 't35, 't36, 't37, 't38, 't39, 't40, 't41, 't42, 't43, 't44, 't45, 't46, 't47, 't48, 't49, 't50, 't51, 't52, 't53, 't54, 't55, 't56, 't57, 't58, 't59, 't60, 't61, 't62, 't63, 't64, 't65, 't66, 't67, 't68, 't69, 't70, 't71, 't72, 't73, 't74, 't75, 't76, 't77, 't78, 't79, 't80, 't81, 't82, 't83, 't84, 't85, 't86, 't87, 't88, 't89, 't90, 't91, 't92, 't93, 't94, 't95, 't96, 't97, 't98, 't99, 't100, 't101, 't102, 't103, 't104, 't105, 't106, 't107, 't108, 't109, 't110, 't111, 't112, 't113, 't114, 't115, 't116, 't117, 't118, 't119, 't120, 't121, 't122, 't123, 't124, 't125, 't126, 't127, 't128, 't129, 't130, 't131, 't132, 't133, 't134, 't135, 't136, 't137, 't138, 't139, 't140, 't141, 't142, 't143, 't144, 't145, 't146, 't147, 't148, 't149, 't150, 't151, 't152, 't153, 't154, 't155, 't156, 't157, 't158, 't159, 't160, 't161, 't162, 't163, 't164, 't165, 't166, 't167, 't168, 't169, 't170, 't171, 't172, 't173, 't174, 't175, 't176, 't177, 't178, 't179, 't180, 't181, 't182, 't183, 't184, 't185, 't186, 't187, 't188, 't189, 't190, 't191, 't192, 't193, 't194, 't195, 't196, 't197, 't198, 't199, 't200, 't201, 't202, 't203, 't204, 't205, 't206, 't207, 't208, 't209, 't210, 't211, 't212, 't213, 't214, 't215, 't216, 't217, 't218, 't219, 't220, 't221, 't222, 't223, 't224, 't225, 't226, 't227, 't228, 't229, 't230, 't231, 't232, 't233, 't234, 't235, 't236, 't237, 't238, 't239, 't240, 't241, 't242, 't243, 't244, 't245, 't246, 't247, 't248> {handler::Handler, handler::Handler, handler::Handler, &'r mut tokio_sync::mpsc::bounded::Receiver<handler::Action>, tokio_sync::mpsc::bounded::Receiver<handler::Action>, futures_util::stream::next::Next<'s, tokio_sync::mpsc::bounded::Receiver<handler::Action>>, futures_util::stream::next::Next<'t0, tokio_sync::mpsc::bounded::Receiver<handler::Action>>, (), std::option::Option<handler::Action>, handler::Action, handler::Action, handler::Request, auth::ClientInfo, tokio_sync::oneshot::Sender<handler::Response>, handler::Request, std::collections::HashMap<std::string::String, handler::ServiceInfo>, handler::Handler, &'t1 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::hash_map::Values<'t2, std::string::String, (jobs::Service, usize)>, std::collections::hash_map::Values<'t3, std::string::String, (jobs::Service, usize)>, std::collections::hash_map::Values<'t4, std::string::String, (jobs::Service, usize)>, &'t5 (jobs::Service, usize), &'t6 jobs::Service, &'t7 usize, handler::Handler, &'t8 std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't9)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't10)>>, std::boxed::Box<(dyn jobs::Job + 't11)>, (dyn jobs::Job + 't12), &'t13 (dyn jobs::Job + 't14), bool, bool, &'t15 mut handler::ServiceInfo, &'t16 mut (dyn jobs::Job + 't17), &'t18 (dyn jobs::Job + 't19), &'t20 jobs::Service, &'t21 jobs::Service, std::pin::Pin<std::boxed::Box<(dyn core::future::future::Future<Output = jobs::ExtStatus> + std::marker::Send + 't22)>>, std::pin::Pin<std::boxed::Box<(dyn core::future::future::Future<Output = jobs::ExtStatus> + std::marker::Send + 't23)>>, (), std::string::String, handler::Handler, &'t24 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::string::String, &'t25 std::string::String, &'t26 std::string::String, std::option::Option<&'t27 (jobs::Service, usize)>, &'t28 jobs::Service, &'t29 usize, handler::Handler, &'t30 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't31)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't32)>>, std::boxed::Box<(dyn jobs::Job + 't33)>, (dyn jobs::Job + 't34), &'t35 mut (dyn jobs::Job + 't36), &'t37 mut (dyn jobs::Job + 't38), &'t39 mut (dyn jobs::Job + 't40), &'t41 jobs::Service, &'t42 jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl core::future::future::Future, impl core::future::future::Future, (), std::string::String, handler::Handler, &'t49 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::string::String, &'t50 std::string::String, &'t51 std::string::String, std::option::Option<&'t52 (jobs::Service, usize)>, &'t53 jobs::Service, &'t54 usize, handler::Handler, &'t55 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't56)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't57)>>, std::boxed::Box<(dyn jobs::Job + 't58)>, (dyn jobs::Job + 't59), &'t60 mut (dyn jobs::Job + 't61), &'t62 mut (dyn jobs::Job + 't63), &'t64 mut (dyn jobs::Job + 't65), &'t66 jobs::Service, &'t67 jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl core::future::future::Future, impl core::future::future::Future, (), std::string::String, handler::Handler, &'t74 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::string::String, &'t75 std::string::String, &'t76 std::string::String, std::option::Option<&'t77 (jobs::Service, usize)>, &'t78 jobs::Service, &'t79 usize, handler::Handler, &'t80 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't81)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't82)>>, std::boxed::Box<(dyn jobs::Job + 't83)>, (dyn jobs::Job + 't84), &'t85 mut (dyn jobs::Job + 't86), &'t87 mut (dyn jobs::Job + 't88), &'t89 mut (dyn jobs::Job + 't90), &'t91 jobs::Service, &'t92 jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl core::future::future::Future, impl core::future::future::Future, (), std::string::String, handler::Handler, &'t99 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::string::String, &'t100 std::string::String, &'t101 std::string::String, std::option::Option<&'t102 (jobs::Service, usize)>, &'t103 jobs::Service, &'t104 usize, handler::Handler, &'t105 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't106)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't107)>>, std::boxed::Box<(dyn jobs::Job + 't108)>, (dyn jobs::Job + 't109), &'t110 mut (dyn jobs::Job + 't111), &'t112 mut (dyn jobs::Job + 't113), &'t114 mut (dyn jobs::Job + 't115), &'t116 jobs::Service, &'t117 jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl core::future::future::Future, impl core::future::future::Future, (), std::string::String, handler::Handler, &'t124 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::string::String, &'t125 std::string::String, &'t126 std::string::String, std::option::Option<&'t127 (jobs::Service, usize)>, &'t128 jobs::Service, &'t129 usize, handler::Handler, &'t130 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't131)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't132)>>, std::boxed::Box<(dyn jobs::Job + 't133)>, (dyn jobs::Job + 't134), &'t135 mut (dyn jobs::Job + 't136), &'t137 mut (dyn jobs::Job + 't138), &'t139 mut (dyn jobs::Job + 't140), &'t141 jobs::Service, &'t142 jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl core::future::future::Future, impl core::future::future::Future, (), std::string::String, std::string::String, std::string::String, handler::Handler, &'t149 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::string::String, &'t150 std::string::String, &'t151 std::string::String, std::option::Option<&'t152 (jobs::Service, usize)>, &'t153 jobs::Service, &'t154 usize, handler::Handler, &'t155 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't156)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't157)>>, std::boxed::Box<(dyn jobs::Job + 't158)>, (dyn jobs::Job + 't159), &'t160 mut (dyn jobs::Job + 't161), &'t162 mut (dyn jobs::Job + 't163), &'t164 mut (dyn jobs::Job + 't165), &'t166 jobs::Service, &'t167 jobs::Service, auth::ClientInfo, std::string::String, std::string::String, impl core::future::future::Future, impl core::future::future::Future, impl core::future::future::Future, (), std::string::String, handler::Handler, &'t174 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::string::String, &'t175 std::string::String, &'t176 std::string::String, std::option::Option<&'t177 (jobs::Service, usize)>, &'t178 jobs::Service, &'t179 usize, handler::Handler, &'t180 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't181)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't182)>>, std::boxed::Box<(dyn jobs::Job + 't183)>, (dyn jobs::Job + 't184), &'t185 mut (dyn jobs::Job + 't186), &'t187 mut (dyn jobs::Job + 't188), &'t189 mut (dyn jobs::Job + 't190), &'t191 jobs::Service, &'t192 jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl core::future::future::Future, impl core::future::future::Future, (), std::string::String, handler::Handler, &'t199 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::string::String, &'t200 std::string::String, &'t201 std::string::String, std::option::Option<&'t202 (jobs::Service, usize)>, &'t203 jobs::Service, &'t204 usize, handler::Handler, &'t205 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't206)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't207)>>, std::boxed::Box<(dyn jobs::Job + 't208)>, (dyn jobs::Job + 't209), &'t210 mut (dyn jobs::Job + 't211), &'t212 mut (dyn jobs::Job + 't213), &'t214 mut (dyn jobs::Job + 't215), &'t216 jobs::Service, &'t217 jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl core::future::future::Future, impl core::future::future::Future, (), std::string::String, handler::Handler, &'t224 std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::collections::HashMap<std::string::String, (jobs::Service, usize)>, std::string::String, &'t225 std::string::String, &'t226 std::string::String, std::option::Option<&'t227 (jobs::Service, usize)>, &'t228 jobs::Service, &'t229 usize, handler::Handler, &'t230 mut std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't231)>>, std::vec::Vec<std::boxed::Box<(dyn jobs::Job + 't232)>>, std::boxed::Box<(dyn jobs::Job + 't233)>, (dyn jobs::Job + 't234), &'t235 mut (dyn jobs::Job + 't236), &'t237 mut (dyn jobs::Job + 't238), &'t239 mut (dyn jobs::Job + 't240), &'t241 jobs::Service, &'t242 jobs::Service, auth::ClientInfo, impl core::future::future::Future, impl core::future::future::Future, impl core::future::future::Future, ()}]>`

[Aaron1011]

@birkenfeld: Can you link to your repository, and re-fry on the latest nightly? I think more recent builds of rustc have improved errors inside async fns

[birkenfeld]

Didn't see a change with latest nightly (7afe6d9 2019-12-03).

Unfortunately I can't link to the repo, but if needed I can try to extract a minimal example which produces similar results.

[TannerRogalsky]

This looks very similar to an error that I'm getting around async code using mpsc. I can provide a minimal example:

use futures::executor::ThreadPool;
use std::sync::mpsc;
use std::time::Duration;

async fn wait(d: Duration) -> f32 {
    d.as_secs_f32()
}

async fn add_task(sender: mpsc::Sender<f32>, i: u64) {
//    let v = wait(Duration::from_millis(i)).await;
//    sender.send(v).unwrap();
    sender.send(wait(Duration::from_millis(i)).await).unwrap();
}

fn main() {
    let (sender, receiver) = mpsc::channel();
    let thread_pool = ThreadPool::new().unwrap();
    for i in (0..10).rev() {
        thread_pool.spawn_ok(add_task(sender.clone(), i * 100));
    }
    drop(sender);
    for v in receiver {
        println!("{}", v);
    }
}

While using these dependencies:

[dependencies]
futures = { version = "0.3", features = [ "thread-pool" ] }

results in this error:

error[E0277]: `std::sync::mpsc::Sender<f32>` cannot be shared between threads safely
  --> src/bin/thead_pool_mpsc.rs:19:21
   |
19 |         thread_pool.spawn_ok(add_task(sender.clone(), i * 100));
   |                     ^^^^^^^^ `std::sync::mpsc::Sender<f32>` cannot be shared between threads safely
   |
   = help: the trait `std::marker::Sync` is not implemented for `std::sync::mpsc::Sender<f32>`
   = note: required because of the requirements on the impl of `std::marker::Send` for `&std::sync::mpsc::Sender<f32>`
   = note: required because it appears within the type `for<'r> {std::sync::mpsc::Sender<f32>, u64, &'r std::sync::mpsc::Sender<f32>, std::sync::mpsc::Sender<f32>, u64, std::time::Duration, impl core::future::future::Future, impl core::future::future::Future, ()}`
   = note: required because it appears within the type `[static generator@src/bin/thead_pool_mpsc.rs:9:54: 13:2 sender:std::sync::mpsc::Sender<f32>, i:u64 for<'r> {std::sync::mpsc::Sender<f32>, u64, &'r std::sync::mpsc::Sender<f32>, std::sync::mpsc::Sender<f32>, u64, std::time::Duration, impl core::future::future::Future, impl core::future::future::Future, ()}]`
   = note: required because it appears within the type `std::future::GenFuture<[static generator@src/bin/thead_pool_mpsc.rs:9:54: 13:2 sender:std::sync::mpsc::Sender<f32>, i:u64 for<'r> {std::sync::mpsc::Sender<f32>, u64, &'r std::sync::mpsc::Sender<f32>, std::sync::mpsc::Sender<f32>, u64, std::time::Duration, impl core::future::future::Future, impl core::future::future::Future, ()}]>`
   = note: required because it appears within the type `impl core::future::future::Future`
   = note: required because it appears within the type `impl core::future::future::Future`

It's worth noting the the commented version works. Using await inline as an expression is the only failure case I've encountered. This is using nightly-x86_64-apple-darwin - rustc 1.41.0-nightly (710a362dc 2019-12-05).

[Aaron1011]

Minimized:

struct NotSync(*const ());

async fn async_not_sync() {
    let a = NotSync(0 as *const ());
    // Uncomment this line to see a better error
    //let b: *const ();
    
    // Force 'a' to be live across a yield point
    async fn dummy() {}
    dummy().await;
}

fn require_sync<T: Sync>(val: T) {}

fn main() {
    require_sync(async_not_sync());
}

It seems that the better error message is only being triggered by certain !Send/!Sync type, and falling back to the old behavior for others.

[nikomatsakis]

Possibly helped by #65345 as well

[nikomatsakis]

Marking as "triaged". Not promoting to "on deck" for now -- it seems likely though that existing PRs cover it. We should land those already!

[davidtwco]

#65345 produces the following error for @Aaron1011's minimized example:

error: future cannot be shared between threads safely
  --> /home/david/projects/rust/rust4/src/test/ui/async-await/issue-64130-foo.rs:18:5
   |
LL | fn require_sync<T: Sync>(val: T) {}
   |    ------------    ---- required by this bound in `require_sync`
...
LL |     require_sync(async_not_sync());
   |     ^^^^^^^^^^^^ future returned by `async_not_sync` is not `Sync`
   |
   = help: within `impl std::future::Future`, the trait `std::marker::Sync` is not implemented for `*const ()`
note: future is not `Sync` as this value is used across an await
  --> /home/david/projects/rust/rust4/src/test/ui/async-await/issue-64130-foo.rs:12:5
   |
LL |     let a = NotSync(0 as *const ());
   |         - has type `NotSync`
...
LL |     dummy().await;
   |     ^^^^^^^^^^^^^ await occurs here, with `a` maybe used later
LL | }
   | - `a` is later dropped here

error: aborting due to previous error

[csmoe]

Close as errors reduced.