[INFO] fetching crate mail-core 0.6.2...
[INFO] building mail-core-0.6.2 against master#881c1ac408d93bb7adaa3a51dabab9266e82eee8 for issue-85264
[INFO] extracting crate mail-core 0.6.2 into /workspace/builds/worker-15/source
[INFO] validating manifest of crates.io crate mail-core 0.6.2 on toolchain 881c1ac408d93bb7adaa3a51dabab9266e82eee8
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+881c1ac408d93bb7adaa3a51dabab9266e82eee8" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate mail-core 0.6.2
[INFO] finished tweaking crates.io crate mail-core 0.6.2
[INFO] tweaked toml for crates.io crate mail-core 0.6.2 written to /workspace/builds/worker-15/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+881c1ac408d93bb7adaa3a51dabab9266e82eee8" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+881c1ac408d93bb7adaa3a51dabab9266e82eee8" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+881c1ac408d93bb7adaa3a51dabab9266e82eee8" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 45576ca77638013d804a9bc43a14443e5fc1edd6e5cd2336fc9639e99ceda2eb
[INFO] running `Command { std: "docker" "start" "-a" "45576ca77638013d804a9bc43a14443e5fc1edd6e5cd2336fc9639e99ceda2eb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "45576ca77638013d804a9bc43a14443e5fc1edd6e5cd2336fc9639e99ceda2eb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "45576ca77638013d804a9bc43a14443e5fc1edd6e5cd2336fc9639e99ceda2eb", kill_on_drop: false }`
[INFO] [stdout] 45576ca77638013d804a9bc43a14443e5fc1edd6e5cd2336fc9639e99ceda2eb
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+881c1ac408d93bb7adaa3a51dabab9266e82eee8" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] fde231b0811280b1b3cd19d9b1dbff672d90dfbae7bf1096f6ed163d93d72cbc
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "fde231b0811280b1b3cd19d9b1dbff672d90dfbae7bf1096f6ed163d93d72cbc", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling libc v0.2.95
[INFO] [stderr]    Compiling lazy_static v0.2.11
[INFO] [stderr]    Compiling gimli v0.24.0
[INFO] [stderr]    Compiling adler v1.0.2
[INFO] [stderr]    Compiling quoted-string v0.6.1
[INFO] [stderr]    Compiling rustc-demangle v0.1.19
[INFO] [stderr]    Compiling percent-encoding v1.0.1
[INFO] [stderr]    Compiling object v0.24.0
[INFO] [stderr]    Compiling log v0.4.14
[INFO] [stderr]    Compiling soft-ascii-string v1.1.0
[INFO] [stderr]    Compiling vec1 v1.8.0
[INFO] [stderr]    Compiling checked_command v0.2.4
[INFO] [stderr]    Compiling vec-drain-where v1.0.1
[INFO] [stderr]    Compiling quick-error v1.2.3
[INFO] [stderr]    Compiling miniz_oxide v0.4.4
[INFO] [stderr]    Compiling base64 v0.6.0
[INFO] [stderr]    Compiling owning_ref v0.4.1
[INFO] [stderr]    Compiling idna v0.1.5
[INFO] [stderr]    Compiling syn v1.0.72
[INFO] [stderr]    Compiling total-order-multi-map v0.4.6
[INFO] [stderr]    Compiling lut v0.1.0-unstable
[INFO] [stderr]    Compiling media-type-impl-utils v0.3.0-unstable
[INFO] [stderr]    Compiling log v0.3.9
[INFO] [stderr]    Compiling media-type v0.4.0-unstable
[INFO] [stderr]    Compiling memchr v1.0.2
[INFO] [stderr]    Compiling time v0.1.44
[INFO] [stderr]    Compiling rand v0.4.6
[INFO] [stderr]    Compiling num_cpus v1.13.0
[INFO] [stderr]    Compiling nom v3.2.1
[INFO] [stderr]    Compiling futures-cpupool v0.1.8
[INFO] [stderr]    Compiling chrono v0.4.19
[INFO] [stderr]    Compiling rand v0.3.23
[INFO] [stderr]    Compiling synstructure v0.12.4
[INFO] [stderr]    Compiling addr2line v0.15.1
[INFO] [stderr]    Compiling backtrace v0.3.59
[INFO] [stderr]    Compiling failure_derive v0.1.8
[INFO] [stderr]    Compiling failure v0.1.8
[INFO] [stderr]    Compiling mail-internals v0.2.3
[INFO] [stderr]    Compiling mail-headers v0.6.6
[INFO] [stderr]    Compiling mail-core v0.6.2 (/opt/rustwide/workdir)
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/error.rs:78:32
[INFO] [stdout]    |
[INFO] [stdout] 78 |     fn cause(&self) -> Option<&Fail> {
[INFO] [stdout]    |                                ^^^^ help: use `dyn`: `dyn Fail`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout]    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
[INFO] [stdout]    = note: for more information, see issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:13:36
[INFO] [stdout]    |
[INFO] [stdout] 13 | pub type SendBoxFuture<I, E> = Box<Future<Item=I, Error=E> + Send + 'static>;
[INFO] [stdout]    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn Future<Item=I, Error=E> + Send + 'static`
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
[INFO] [stdout]    = note: for more information, see issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/mail.rs:600:17
[INFO] [stdout]     |
[INFO] [stdout] 600 |             let mut headers: &mut HeaderMap = headers;
[INFO] [stdout]     |                 ----^^^^^^^
[INFO] [stdout]     |                 |
[INFO] [stdout]     |                 help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/resource/loading.rs:184:21
[INFO] [stdout]     |
[INFO] [stdout] 184 |                     mem::replace(resource_ref, new_resource.to_resource());
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/mail.rs:466:21
[INFO] [stdout]     |
[INFO] [stdout] 466 | /                     mem::replace(
[INFO] [stdout] 467 | |                         &mut self.inner,
[INFO] [stdout] 468 | |                         InnerMailFuture::Loading {
[INFO] [stdout] 469 | |                             mail, ctx,
[INFO] [stdout] 470 | |                             pending: future::join_all(futures)
[INFO] [stdout] 471 | |                         }
[INFO] [stdout] 472 | |                     );
[INFO] [stdout]     | |______________________^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/mail.rs:478:29
[INFO] [stdout]     |
[INFO] [stdout] 478 | / ...                   mem::replace(
[INFO] [stdout] 479 | | ...                       &mut self.inner,
[INFO] [stdout] 480 | | ...                       InnerMailFuture::Loading { mail, pending, ctx }
[INFO] [stdout] 481 | | ...                   );
[INFO] [stdout]     | |________________________^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/mail.rs:554:9
[INFO] [stdout]     |
[INFO] [stdout] 554 |         mem::replace(resource, Resource::EncData(enc_data));
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 13.20s
[INFO] running `Command { std: "docker" "inspect" "fde231b0811280b1b3cd19d9b1dbff672d90dfbae7bf1096f6ed163d93d72cbc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fde231b0811280b1b3cd19d9b1dbff672d90dfbae7bf1096f6ed163d93d72cbc", kill_on_drop: false }`
[INFO] [stdout] fde231b0811280b1b3cd19d9b1dbff672d90dfbae7bf1096f6ed163d93d72cbc
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+881c1ac408d93bb7adaa3a51dabab9266e82eee8" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 0686e66796139b9800c6ee5a3e71152038f13bf331098fe0a1e9c07f055ed43d
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "0686e66796139b9800c6ee5a3e71152038f13bf331098fe0a1e9c07f055ed43d", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling itoa v0.4.7
[INFO] [stderr]    Compiling serde_test v1.0.126
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/error.rs:78:32
[INFO] [stdout]    |
[INFO] [stdout] 78 |     fn cause(&self) -> Option<&Fail> {
[INFO] [stdout]    |                                ^^^^ help: use `dyn`: `dyn Fail`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout]    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
[INFO] [stdout]    = note: for more information, see issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:13:36
[INFO] [stdout]    |
[INFO] [stdout] 13 | pub type SendBoxFuture<I, E> = Box<Future<Item=I, Error=E> + Send + 'static>;
[INFO] [stdout]    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn Future<Item=I, Error=E> + Send + 'static`
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
[INFO] [stdout]    = note: for more information, see issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/mail.rs:600:17
[INFO] [stdout]     |
[INFO] [stdout] 600 |             let mut headers: &mut HeaderMap = headers;
[INFO] [stdout]     |                 ----^^^^^^^
[INFO] [stdout]     |                 |
[INFO] [stdout]     |                 help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/resource/loading.rs:184:21
[INFO] [stdout]     |
[INFO] [stdout] 184 |                     mem::replace(resource_ref, new_resource.to_resource());
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/mail.rs:466:21
[INFO] [stdout]     |
[INFO] [stdout] 466 | /                     mem::replace(
[INFO] [stdout] 467 | |                         &mut self.inner,
[INFO] [stdout] 468 | |                         InnerMailFuture::Loading {
[INFO] [stdout] 469 | |                             mail, ctx,
[INFO] [stdout] 470 | |                             pending: future::join_all(futures)
[INFO] [stdout] 471 | |                         }
[INFO] [stdout] 472 | |                     );
[INFO] [stdout]     | |______________________^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/mail.rs:478:29
[INFO] [stdout]     |
[INFO] [stdout] 478 | / ...                   mem::replace(
[INFO] [stdout] 479 | | ...                       &mut self.inner,
[INFO] [stdout] 480 | | ...                       InnerMailFuture::Loading { mail, pending, ctx }
[INFO] [stdout] 481 | | ...                   );
[INFO] [stdout]     | |________________________^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/mail.rs:554:9
[INFO] [stdout]     |
[INFO] [stdout] 554 |         mem::replace(resource, Resource::EncData(enc_data));
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling serde_json v1.0.64
[INFO] [stderr]    Compiling mail-core v0.6.2 (/opt/rustwide/workdir)
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/error.rs:78:32
[INFO] [stdout]    |
[INFO] [stdout] 78 |     fn cause(&self) -> Option<&Fail> {
[INFO] [stdout]    |                                ^^^^ help: use `dyn`: `dyn Fail`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout]    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
[INFO] [stdout]    = note: for more information, see issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:13:36
[INFO] [stdout]    |
[INFO] [stdout] 13 | pub type SendBoxFuture<I, E> = Box<Future<Item=I, Error=E> + Send + 'static>;
[INFO] [stdout]    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn Future<Item=I, Error=E> + Send + 'static`
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
[INFO] [stdout]    = note: for more information, see issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/mail.rs:600:17
[INFO] [stdout]     |
[INFO] [stdout] 600 |             let mut headers: &mut HeaderMap = headers;
[INFO] [stdout]     |                 ----^^^^^^^
[INFO] [stdout]     |                 |
[INFO] [stdout]     |                 help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/resource/loading.rs:184:21
[INFO] [stdout]     |
[INFO] [stdout] 184 |                     mem::replace(resource_ref, new_resource.to_resource());
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/mail.rs:466:21
[INFO] [stdout]     |
[INFO] [stdout] 466 | /                     mem::replace(
[INFO] [stdout] 467 | |                         &mut self.inner,
[INFO] [stdout] 468 | |                         InnerMailFuture::Loading {
[INFO] [stdout] 469 | |                             mail, ctx,
[INFO] [stdout] 470 | |                             pending: future::join_all(futures)
[INFO] [stdout] 471 | |                         }
[INFO] [stdout] 472 | |                     );
[INFO] [stdout]     | |______________________^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/mail.rs:478:29
[INFO] [stdout]     |
[INFO] [stdout] 478 | / ...                   mem::replace(
[INFO] [stdout] 479 | | ...                       &mut self.inner,
[INFO] [stdout] 480 | | ...                       InnerMailFuture::Loading { mail, pending, ctx }
[INFO] [stdout] 481 | | ...                   );
[INFO] [stdout]     | |________________________^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/mail.rs:554:9
[INFO] [stdout]     |
[INFO] [stdout] 554 |         mem::replace(resource, Resource::EncData(enc_data));
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 9.08s
[INFO] running `Command { std: "docker" "inspect" "0686e66796139b9800c6ee5a3e71152038f13bf331098fe0a1e9c07f055ed43d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0686e66796139b9800c6ee5a3e71152038f13bf331098fe0a1e9c07f055ed43d", kill_on_drop: false }`
[INFO] [stdout] 0686e66796139b9800c6ee5a3e71152038f13bf331098fe0a1e9c07f055ed43d
