[INFO] fetching crate mmreg 0.1.1...
[INFO] testing mmreg-0.1.1 against master#0d162b25edd5bf0dba9a22e83b614f1113e90474 for pr-150681
[INFO] extracting crate mmreg 0.1.1 into /workspace/builds/worker-2-tc1/source
[INFO] removed /workspace/builds/worker-2-tc1/source/.cargo/config.toml
[INFO] started tweaking crates.io crate mmreg 0.1.1
[INFO] finished tweaking crates.io crate mmreg 0.1.1
[INFO] tweaked toml for crates.io crate mmreg 0.1.1 written to /workspace/builds/worker-2-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate mmreg 0.1.1 on toolchain 0d162b25edd5bf0dba9a22e83b614f1113e90474
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0d162b25edd5bf0dba9a22e83b614f1113e90474" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate crates.io crate mmreg 0.1.1 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0d162b25edd5bf0dba9a22e83b614f1113e90474" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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@sha256:845e597a41426bbf2703be69acdb67d10b6de511142d05cba7bbe119c898b2c7" "/opt/rustwide/cargo-home/bin/cargo" "+0d162b25edd5bf0dba9a22e83b614f1113e90474" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] e2e71d2cc5f0ee45527f6a134b3e887d5526ca4163c89890aa3d891be982cd67
[INFO] running `Command { std: "docker" "start" "-a" "e2e71d2cc5f0ee45527f6a134b3e887d5526ca4163c89890aa3d891be982cd67", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e2e71d2cc5f0ee45527f6a134b3e887d5526ca4163c89890aa3d891be982cd67", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e2e71d2cc5f0ee45527f6a134b3e887d5526ca4163c89890aa3d891be982cd67", kill_on_drop: false }`
[INFO] [stdout] e2e71d2cc5f0ee45527f6a134b3e887d5526ca4163c89890aa3d891be982cd67
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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" "RUSTDOCFLAGS=--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@sha256:845e597a41426bbf2703be69acdb67d10b6de511142d05cba7bbe119c898b2c7" "/opt/rustwide/cargo-home/bin/cargo" "+0d162b25edd5bf0dba9a22e83b614f1113e90474" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ea36f8711abfa2d8a60ade52160324455b044f3df85af94c6985f36522032bcc
[INFO] running `Command { std: "docker" "start" "-a" "ea36f8711abfa2d8a60ade52160324455b044f3df85af94c6985f36522032bcc", kill_on_drop: false }`
[INFO] [stderr]    Compiling fs2 v0.4.3
[INFO] [stderr]    Compiling mmreg v0.1.1 (/opt/rustwide/workdir)
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.62s
[INFO] running `Command { std: "docker" "inspect" "ea36f8711abfa2d8a60ade52160324455b044f3df85af94c6985f36522032bcc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ea36f8711abfa2d8a60ade52160324455b044f3df85af94c6985f36522032bcc", kill_on_drop: false }`
[INFO] [stdout] ea36f8711abfa2d8a60ade52160324455b044f3df85af94c6985f36522032bcc
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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" "RUSTDOCFLAGS=--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@sha256:845e597a41426bbf2703be69acdb67d10b6de511142d05cba7bbe119c898b2c7" "/opt/rustwide/cargo-home/bin/cargo" "+0d162b25edd5bf0dba9a22e83b614f1113e90474" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] db5ad6ea16b9bf8c5fdb3263beb505c06b5cd3b98997493f9f6566a4921ae444
[INFO] running `Command { std: "docker" "start" "-a" "db5ad6ea16b9bf8c5fdb3263beb505c06b5cd3b98997493f9f6566a4921ae444", kill_on_drop: false }`
[INFO] [stderr]    Compiling mmreg v0.1.1 (/opt/rustwide/workdir)
[INFO] [stderr]     Finished `test` profile [unoptimized + debuginfo] target(s) in 0.33s
[INFO] running `Command { std: "docker" "inspect" "db5ad6ea16b9bf8c5fdb3263beb505c06b5cd3b98997493f9f6566a4921ae444", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "db5ad6ea16b9bf8c5fdb3263beb505c06b5cd3b98997493f9f6566a4921ae444", kill_on_drop: false }`
[INFO] [stdout] db5ad6ea16b9bf8c5fdb3263beb505c06b5cd3b98997493f9f6566a4921ae444
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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" "RUSTDOCFLAGS=--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@sha256:845e597a41426bbf2703be69acdb67d10b6de511142d05cba7bbe119c898b2c7" "/opt/rustwide/cargo-home/bin/cargo" "+0d162b25edd5bf0dba9a22e83b614f1113e90474" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 7b638048be45530406384ec8a6fb075f046d4737a780cb6223a6ccd9a4ef3682
[INFO] running `Command { std: "docker" "start" "-a" "7b638048be45530406384ec8a6fb075f046d4737a780cb6223a6ccd9a4ef3682", kill_on_drop: false }`
[INFO] [stderr]     Finished `test` profile [unoptimized + debuginfo] target(s) in 0.01s
[INFO] [stderr]      Running unittests src/lib.rs (/opt/rustwide/target/debug/deps/mmreg-2d0df0ba0d33eeb8)
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] [stderr]      Running unittests src/main.rs (/opt/rustwide/target/debug/deps/mmreg-57b9bfabef08b0ee)
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] [stderr]    Doc-tests mmreg
[INFO] [stdout] 
[INFO] [stdout] running 16 tests
[INFO] [stdout] test src/lib.rs - write_register_at (line 67) ... FAILED
[INFO] [stdout] test src/interface.rs - interface::Interface::read_subregister (line 201) ... FAILED
[INFO] [stdout] test src/register.rs - register::SubRegister::new (line 144) ... FAILED
[INFO] [stdout] test src/interface.rs - interface::Interface::write_subregister (line 244) ... FAILED
[INFO] [stdout] test src/interface.rs - interface::Interface::write_register (line 134) ... FAILED
[INFO] [stdout] test src/interface.rs - interface::Interface::unmap (line 104) ... FAILED
[INFO] [stdout] test src/interface.rs - interface::Interface::map (line 63) ... FAILED
[INFO] [stdout] test src/lib.rs - (line 8) ... FAILED
[INFO] [stdout] test src/interface.rs - interface::Interface::parse_subregister (line 294) ... FAILED
[INFO] [stdout] test src/interface.rs - interface::Interface::read_register (line 167) ... FAILED
[INFO] [stdout] test src/register.rs - register::Register::new (line 51) ... FAILED
[INFO] [stdout] test src/lib.rs - read_register_at (line 42) ... FAILED
[INFO] [stdout] test src/interface.rs - interface::Interface::is_mapped (line 49) ... FAILED
[INFO] [stdout] test src/register.rs - register::Register (line 8) ... ok
[INFO] [stdout] test src/interface.rs - interface::Interface::new (line 30) ... ok
[INFO] [stdout] test src/register.rs - register::SubRegister (line 28) ... ok
[INFO] [stdout] 
[INFO] [stdout] failures:
[INFO] [stdout] 
[INFO] [stdout] ---- src/lib.rs - write_register_at (line 67) stdout ----
[INFO] [stdout] error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
[INFO] [stdout]   --> src/lib.rs:69:50
[INFO] [stdout]    |
[INFO] [stdout] 68 | fn main() { #[allow(non_snake_case)] fn _doctest_main_src_lib_rs_67_0() {
[INFO] [stdout]    |                                      ---------------------------------- this function should return `Result` or `Option` to accept `?`
[INFO] [stdout] 69 | mmreg::write_register_at(0x4000_0000, 0xDEADBEEF)?;
[INFO] [stdout]    |                                                  ^ cannot use the `?` operator in a function that returns `()`
[INFO] [stdout]    |
[INFO] [stdout] help: consider adding return type
[INFO] [stdout]    |
[INFO] [stdout] 68 ~ fn main() { #[allow(non_snake_case)] fn _doctest_main_src_lib_rs_67_0() -> Result<(), Box<dyn std::error::Error>> {
[INFO] [stdout] 69 | mmreg::write_register_at(0x4000_0000, 0xDEADBEEF)?;
[INFO] [stdout] 70 | println!("Wrote value.");
[INFO] [stdout] 71 +     Ok(())
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0277`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/interface.rs - interface::Interface::read_subregister (line 201) stdout ----
[INFO] [stdout] error[E0425]: cannot find value `iface` in this scope
[INFO] [stdout]    --> src/interface.rs:202:12
[INFO] [stdout]     |
[INFO] [stdout] 202 | let bits = iface.read_subregister("reg", "status")?;
[INFO] [stdout]     |            ^^^^^ not found in this scope
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/register.rs - register::SubRegister::new (line 144) stdout ----
[INFO] [stdout] error[E0433]: failed to resolve: use of undeclared type `SubRegister`
[INFO] [stdout]    --> src/register.rs:145:11
[INFO] [stdout]     |
[INFO] [stdout] 145 | let sub = SubRegister::new("flag", 7, 0);
[INFO] [stdout]     |           ^^^^^^^^^^^ use of undeclared type `SubRegister`
[INFO] [stdout]     |
[INFO] [stdout] help: consider importing this struct
[INFO] [stdout]     |
[INFO] [stdout] 144 + use mmreg::SubRegister;
[INFO] [stdout]     |
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0433`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/interface.rs - interface::Interface::write_subregister (line 244) stdout ----
[INFO] [stdout] error[E0425]: cannot find value `iface` in this scope
[INFO] [stdout]    --> src/interface.rs:245:1
[INFO] [stdout]     |
[INFO] [stdout] 245 | iface.write_subregister("reg", "status", 0x1)?;
[INFO] [stdout]     | ^^^^^ not found in this scope
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/interface.rs - interface::Interface::write_register (line 134) stdout ----
[INFO] [stdout] error[E0425]: cannot find value `iface` in this scope
[INFO] [stdout]    --> src/interface.rs:135:1
[INFO] [stdout]     |
[INFO] [stdout] 135 | iface.write_register("reg", 0xDEADBEEF)?;
[INFO] [stdout]     | ^^^^^ not found in this scope
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/interface.rs - interface::Interface::unmap (line 104) stdout ----
[INFO] [stdout] error[E0425]: cannot find value `iface` in this scope
[INFO] [stdout]    --> src/interface.rs:105:1
[INFO] [stdout]     |
[INFO] [stdout] 105 | iface.unmap();
[INFO] [stdout]     | ^^^^^ not found in this scope
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/interface.rs - interface::Interface::map (line 63) stdout ----
[INFO] [stdout] error[E0425]: cannot find value `iface` in this scope
[INFO] [stdout]   --> src/interface.rs:64:1
[INFO] [stdout]    |
[INFO] [stdout] 64 | iface.map()?;
[INFO] [stdout]    | ^^^^^ not found in this scope
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/lib.rs - (line 8) stdout ----
[INFO] [stdout] error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
[INFO] [stdout]   --> src/lib.rs:13:42
[INFO] [stdout]    |
[INFO] [stdout]  9 | fn main() { #[allow(non_snake_case)] fn _doctest_main_src_lib_rs_8_0() {
[INFO] [stdout]    |                                      --------------------------------- this function should return `Result` or `Option` to accept `?`
[INFO] [stdout] ...
[INFO] [stdout] 13 | let value = read_register_at(0x4000_0000)?;
[INFO] [stdout]    |                                          ^ cannot use the `?` operator in a function that returns `()`
[INFO] [stdout]    |
[INFO] [stdout] help: consider adding return type
[INFO] [stdout]    |
[INFO] [stdout]  9 ~ fn main() { #[allow(non_snake_case)] fn _doctest_main_src_lib_rs_8_0() -> Result<(), Box<dyn std::error::Error>> {
[INFO] [stdout] 10 | use mmreg::{read_register_at, write_register_at};
[INFO] [stdout] ...
[INFO] [stdout] 16 | write_register_at(0x4000_0000, 0xDEADBEEF)?;
[INFO] [stdout] 17 +     Ok(())
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
[INFO] [stdout]   --> src/lib.rs:16:43
[INFO] [stdout]    |
[INFO] [stdout]  9 | fn main() { #[allow(non_snake_case)] fn _doctest_main_src_lib_rs_8_0() {
[INFO] [stdout]    |                                      --------------------------------- this function should return `Result` or `Option` to accept `?`
[INFO] [stdout] ...
[INFO] [stdout] 16 | write_register_at(0x4000_0000, 0xDEADBEEF)?;
[INFO] [stdout]    |                                           ^ cannot use the `?` operator in a function that returns `()`
[INFO] [stdout]    |
[INFO] [stdout] help: consider adding return type
[INFO] [stdout]    |
[INFO] [stdout]  9 ~ fn main() { #[allow(non_snake_case)] fn _doctest_main_src_lib_rs_8_0() -> Result<(), Box<dyn std::error::Error>> {
[INFO] [stdout] 10 | use mmreg::{read_register_at, write_register_at};
[INFO] [stdout] ...
[INFO] [stdout] 16 | write_register_at(0x4000_0000, 0xDEADBEEF)?;
[INFO] [stdout] 17 +     Ok(())
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0277`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/interface.rs - interface::Interface::parse_subregister (line 294) stdout ----
[INFO] [stdout] error[E0425]: cannot find value `iface` in this scope
[INFO] [stdout]    --> src/interface.rs:295:12
[INFO] [stdout]     |
[INFO] [stdout] 295 | let bits = iface.parse_subregister("reg", "status")?;
[INFO] [stdout]     |            ^^^^^ not found in this scope
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/interface.rs - interface::Interface::read_register (line 167) stdout ----
[INFO] [stdout] error[E0425]: cannot find value `iface` in this scope
[INFO] [stdout]    --> src/interface.rs:168:11
[INFO] [stdout]     |
[INFO] [stdout] 168 | let val = iface.read_register("reg")?;
[INFO] [stdout]     |           ^^^^^ not found in this scope
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/register.rs - register::Register::new (line 51) stdout ----
[INFO] [stdout] error[E0433]: failed to resolve: use of undeclared type `Register`
[INFO] [stdout]   --> src/register.rs:52:11
[INFO] [stdout]    |
[INFO] [stdout] 52 | let reg = Register::new("status", 0x0, vec![]);
[INFO] [stdout]    |           ^^^^^^^^ use of undeclared type `Register`
[INFO] [stdout]    |
[INFO] [stdout] help: consider importing this struct
[INFO] [stdout]    |
[INFO] [stdout] 51 + use mmreg::Register;
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0433`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/lib.rs - read_register_at (line 42) stdout ----
[INFO] [stdout] error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
[INFO] [stdout]   --> src/lib.rs:44:49
[INFO] [stdout]    |
[INFO] [stdout] 43 | fn main() { #[allow(non_snake_case)] fn _doctest_main_src_lib_rs_42_0() {
[INFO] [stdout]    |                                      ---------------------------------- this function should return `Result` or `Option` to accept `?`
[INFO] [stdout] 44 | let value = mmreg::read_register_at(0x4000_0000)?;
[INFO] [stdout]    |                                                 ^ cannot use the `?` operator in a function that returns `()`
[INFO] [stdout]    |
[INFO] [stdout] help: consider adding return type
[INFO] [stdout]    |
[INFO] [stdout] 43 ~ fn main() { #[allow(non_snake_case)] fn _doctest_main_src_lib_rs_42_0() -> Result<(), Box<dyn std::error::Error>> {
[INFO] [stdout] 44 | let value = mmreg::read_register_at(0x4000_0000)?;
[INFO] [stdout] 45 | println!("Value: 0x{:08X}", value);
[INFO] [stdout] 46 +     Ok(())
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0277`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/interface.rs - interface::Interface::is_mapped (line 49) stdout ----
[INFO] [stdout] error[E0425]: cannot find value `iface` in this scope
[INFO] [stdout]   --> src/interface.rs:50:4
[INFO] [stdout]    |
[INFO] [stdout] 50 | if iface.is_mapped() { /* ... */ }
[INFO] [stdout]    |    ^^^^^ not found in this scope
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] 
[INFO] [stdout] failures:
[INFO] [stdout]     src/interface.rs - interface::Interface::is_mapped (line 49)
[INFO] [stdout]     src/interface.rs - interface::Interface::map (line 63)
[INFO] [stdout]     src/interface.rs - interface::Interface::parse_subregister (line 294)
[INFO] [stdout]     src/interface.rs - interface::Interface::read_register (line 167)
[INFO] [stdout]     src/interface.rs - interface::Interface::read_subregister (line 201)
[INFO] [stdout]     src/interface.rs - interface::Interface::unmap (line 104)
[INFO] [stdout]     src/interface.rs - interface::Interface::write_register (line 134)
[INFO] [stdout]     src/interface.rs - interface::Interface::write_subregister (line 244)
[INFO] [stdout]     src/lib.rs - (line 8)
[INFO] [stdout]     src/lib.rs - read_register_at (line 42)
[INFO] [stdout]     src/lib.rs - write_register_at (line 67)
[INFO] [stdout]     src/register.rs - register::Register::new (line 51)
[INFO] [stdout]     src/register.rs - register::SubRegister::new (line 144)
[INFO] [stdout] 
[INFO] [stdout] test result: FAILED. 3 passed; 13 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.17s
[INFO] [stdout] 
[INFO] [stdout] all doctests ran in 0.29s; merged doctests compilation took 0.12s
[INFO] [stderr] error: doctest failed, to rerun pass `--doc`
[INFO] running `Command { std: "docker" "inspect" "7b638048be45530406384ec8a6fb075f046d4737a780cb6223a6ccd9a4ef3682", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7b638048be45530406384ec8a6fb075f046d4737a780cb6223a6ccd9a4ef3682", kill_on_drop: false }`
[INFO] [stdout] 7b638048be45530406384ec8a6fb075f046d4737a780cb6223a6ccd9a4ef3682
