[INFO] cloning repository https://github.com/qzj-123/rustlings
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/qzj-123/rustlings" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fqzj-123%2Frustlings", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fqzj-123%2Frustlings'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 5b8b35cab6d80dfa01e7bcf8f3e40c214643fc79
[INFO] building qzj-123/rustlings against master#ad85bc524b1ad696e42061ad8338d382dffbdbe5 for pr-146237-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fqzj-123%2Frustlings" "/workspace/builds/worker-4-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc1/source'...
[INFO] [stderr] done.
[INFO] [stderr] Updating files:  39% (760/1927)
Updating files:  40% (771/1927)
Updating files:  41% (791/1927)
Updating files:  42% (810/1927)
Updating files:  43% (829/1927)
Updating files:  44% (848/1927)
Updating files:  45% (868/1927)
Updating files:  46% (887/1927)
Updating files:  47% (906/1927)
Updating files:  48% (925/1927)
Updating files:  49% (945/1927)
Updating files:  50% (964/1927)
Updating files:  51% (983/1927)
Updating files:  52% (1003/1927)
Updating files:  53% (1022/1927)
Updating files:  54% (1041/1927)
Updating files:  55% (1060/1927)
Updating files:  56% (1080/1927)
Updating files:  57% (1099/1927)
Updating files:  58% (1118/1927)
Updating files:  59% (1137/1927)
Updating files:  60% (1157/1927)
Updating files:  61% (1176/1927)
Updating files:  62% (1195/1927)
Updating files:  63% (1215/1927)
Updating files:  64% (1234/1927)
Updating files:  65% (1253/1927)
Updating files:  66% (1272/1927)
Updating files:  67% (1292/1927)
Updating files:  68% (1311/1927)
Updating files:  69% (1330/1927)
Updating files:  70% (1349/1927)
Updating files:  71% (1369/1927)
Updating files:  72% (1388/1927)
Updating files:  73% (1407/1927)
Updating files:  74% (1426/1927)
Updating files:  75% (1446/1927)
Updating files:  76% (1465/1927)
Updating files:  77% (1484/1927)
Updating files:  78% (1504/1927)
Updating files:  79% (1523/1927)
Updating files:  80% (1542/1927)
Updating files:  81% (1561/1927)
Updating files:  82% (1581/1927)
Updating files:  83% (1600/1927)
Updating files:  84% (1619/1927)
Updating files:  85% (1638/1927)
Updating files:  86% (1658/1927)
Updating files:  87% (1677/1927)
Updating files:  88% (1696/1927)
Updating files:  89% (1716/1927)
Updating files:  90% (1735/1927)
Updating files:  91% (1754/1927)
Updating files:  92% (1773/1927)
Updating files:  93% (1793/1927)
Updating files:  94% (1812/1927)
Updating files:  95% (1831/1927)
Updating files:  96% (1850/1927)
Updating files:  97% (1870/1927)
Updating files:  98% (1889/1927)
Updating files:  99% (1908/1927)
Updating files: 100% (1927/1927)
Updating files: 100% (1927/1927), done.
[INFO] started tweaking git repo https://github.com/qzj-123/rustlings
[INFO] finished tweaking git repo https://github.com/qzj-123/rustlings
[INFO] tweaked toml for git repo https://github.com/qzj-123/rustlings written to /workspace/builds/worker-4-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/qzj-123/rustlings on toolchain ad85bc524b1ad696e42061ad8338d382dffbdbe5
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+ad85bc524b1ad696e42061ad8338d382dffbdbe5" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/qzj-123/rustlings 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" "+ad85bc524b1ad696e42061ad8338d382dffbdbe5" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+ad85bc524b1ad696e42061ad8338d382dffbdbe5" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] c6dacdfbf4a041e4efda8a4f12bf1575eec0ba047cbcaf279b1630e0b81000b0
[INFO] running `Command { std: "docker" "start" "-a" "c6dacdfbf4a041e4efda8a4f12bf1575eec0ba047cbcaf279b1630e0b81000b0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c6dacdfbf4a041e4efda8a4f12bf1575eec0ba047cbcaf279b1630e0b81000b0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c6dacdfbf4a041e4efda8a4f12bf1575eec0ba047cbcaf279b1630e0b81000b0", kill_on_drop: false }`
[INFO] [stdout] c6dacdfbf4a041e4efda8a4f12bf1575eec0ba047cbcaf279b1630e0b81000b0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+ad85bc524b1ad696e42061ad8338d382dffbdbe5" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 508563a40766a5ecfc4f6b07cc13012a1652720fc3a9c88d1420a56eb8ca0092
[INFO] running `Command { std: "docker" "start" "-a" "508563a40766a5ecfc4f6b07cc13012a1652720fc3a9c88d1420a56eb8ca0092", kill_on_drop: false }`
[INFO] [stderr]    Compiling exercises v0.0.0 (/opt/rustwide/workdir)
[INFO] [stderr] error: could not compile `exercises` (bin "vecs1") due to 1 previous error
[INFO] [stdout] error[E0425]: cannot find value `fruit` in module `delicious_snacks`
[INFO] [stdout]   --> exercises/10_modules/modules2.rs:23:27
[INFO] [stdout]    |
[INFO] [stdout] 23 |         delicious_snacks::fruit,
[INFO] [stdout]    |                           ^^^^^ not found in `delicious_snacks`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] error[E0425]: cannot find value `veggie` in module `delicious_snacks`
[INFO] [stdout]   --> exercises/10_modules/modules2.rs:24:27
[INFO] [stdout]    |
[INFO] [stdout] 24 |         delicious_snacks::veggie,
[INFO] [stdout]    |                           ^^^^^^ not found in `delicious_snacks`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0425]: cannot find value `v` in this scope
[INFO] [stdout]  --> exercises/05_vecs/vecs1.rs:8:9
[INFO] [stdout]   |
[INFO] [stdout] 8 |     (a, v)
[INFO] [stdout]   |         ^ help: a local variable with a similar name exists: `a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `message`
[INFO] [stdout]   --> exercises/08_enums/enums3.rs:46:27
[INFO] [stdout]    |
[INFO] [stdout] 46 |     fn process(&mut self, message: Message) {
[INFO] [stdout]    |                           ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_message`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `exercises` (bin "modules2") due to 2 previous errors
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:16:5
[INFO] [stdout]    |
[INFO] [stdout] 16 |     placeholder("blue");
[INFO] [stdout]    |     ^^^^^^^^^^^ ------ unexpected argument of type `&'static str`
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 16 -     placeholder("blue");
[INFO] [stdout] 16 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:18:5
[INFO] [stdout]    |
[INFO] [stdout] 18 |     placeholder("red".to_string());
[INFO] [stdout]    |     ^^^^^^^^^^^ ----------------- unexpected argument of type `String`
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 18 -     placeholder("red".to_string());
[INFO] [stdout] 18 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:20:5
[INFO] [stdout]    |
[INFO] [stdout] 20 |     placeholder(String::from("hi"));
[INFO] [stdout]    |     ^^^^^^^^^^^ ------------------ unexpected argument of type `String`
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 20 -     placeholder(String::from("hi"));
[INFO] [stdout] 20 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:22:5
[INFO] [stdout]    |
[INFO] [stdout] 22 |     placeholder("rust is fun!".to_owned());
[INFO] [stdout]    |     ^^^^^^^^^^^ ------------------------- unexpected argument of type `String`
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 22 -     placeholder("rust is fun!".to_owned());
[INFO] [stdout] 22 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:24:5
[INFO] [stdout]    |
[INFO] [stdout] 24 |     placeholder("nice weather".into());
[INFO] [stdout]    |     ^^^^^^^^^^^ --------------------- unexpected argument
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 24 -     placeholder("nice weather".into());
[INFO] [stdout] 24 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:26:5
[INFO] [stdout]    |
[INFO] [stdout] 26 |     placeholder(format!("Interpolation {}", "Station"));
[INFO] [stdout]    |     ^^^^^^^^^^^ -------------------------------------- unexpected argument of type `String`
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 26 -     placeholder(format!("Interpolation {}", "Station"));
[INFO] [stdout] 26 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:30:5
[INFO] [stdout]    |
[INFO] [stdout] 30 |     placeholder(&String::from("abc")[0..1]);
[INFO] [stdout]    |     ^^^^^^^^^^^ -------------------------- unexpected argument of type `&str`
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 30 -     placeholder(&String::from("abc")[0..1]);
[INFO] [stdout] 30 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:32:5
[INFO] [stdout]    |
[INFO] [stdout] 32 |     placeholder("  hello there ".trim());
[INFO] [stdout]    |     ^^^^^^^^^^^ ----------------------- unexpected argument of type `&str`
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 32 -     placeholder("  hello there ".trim());
[INFO] [stdout] 32 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:34:5
[INFO] [stdout]    |
[INFO] [stdout] 34 |     placeholder("Happy Monday!".replace("Mon", "Tues"));
[INFO] [stdout]    |     ^^^^^^^^^^^ -------------------------------------- unexpected argument of type `String`
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 34 -     placeholder("Happy Monday!".replace("Mon", "Tues"));
[INFO] [stdout] 34 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0061]: this function takes 0 arguments but 1 argument was supplied
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:36:5
[INFO] [stdout]    |
[INFO] [stdout] 36 |     placeholder("mY sHiFt KeY iS sTiCkY".to_lowercase());
[INFO] [stdout]    |     ^^^^^^^^^^^ --------------------------------------- unexpected argument of type `String`
[INFO] [stdout]    |
[INFO] [stdout] note: function defined here
[INFO] [stdout]   --> exercises/09_strings/strings4.rs:2:4
[INFO] [stdout]    |
[INFO] [stdout]  2 | fn placeholder() {}
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] help: remove the extra argument
[INFO] [stdout]    |
[INFO] [stdout] 36 -     placeholder("mY sHiFt KeY iS sTiCkY".to_lowercase());
[INFO] [stdout] 36 +     placeholder();
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0061`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `exercises` (bin "strings4") due to 10 previous errors
[INFO] [stdout] error[E0072]: recursive type `List` has infinite size
[INFO] [stdout]   --> exercises/19_smart_pointers/box1.rs:14:1
[INFO] [stdout]    |
[INFO] [stdout] 14 | enum List {
[INFO] [stdout]    | ^^^^^^^^^
[INFO] [stdout] 15 |     Cons(i32, List),
[INFO] [stdout]    |               ---- recursive without indirection
[INFO] [stdout]    |
[INFO] [stdout] help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle
[INFO] [stdout]    |
[INFO] [stdout] 15 |     Cons(i32, Box<List>),
[INFO] [stdout]    |               ++++    +
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0391]: cycle detected when computing drop-check constraints for `List`
[INFO] [stdout]   --> exercises/19_smart_pointers/box1.rs:14:1
[INFO] [stdout]    |
[INFO] [stdout] 14 | enum List {
[INFO] [stdout]    | ^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: ...which immediately requires computing drop-check constraints for `List` again
[INFO] [stdout]    = note: cycle used when computing dropck types for `List`
[INFO] [stdout]    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0599]: no method named `as_ref` found for type parameter `T` in the current scope
[INFO] [stdout]  --> exercises/23_conversions/as_ref_mut.rs:9:9
[INFO] [stdout]   |
[INFO] [stdout] 8 | fn byte_counter<T>(arg: T) -> usize {
[INFO] [stdout]   |                 - method `as_ref` not found for this type parameter
[INFO] [stdout] 9 |     arg.as_ref().len()
[INFO] [stdout]   |         ^^^^^^ method not found in `T`
[INFO] [stdout]   |
[INFO] [stdout]   = help: items from traits can only be used if the type parameter is bounded by the trait
[INFO] [stdout] help: the following trait defines an item `as_ref`, perhaps you need to restrict type parameter `T` with it:
[INFO] [stdout]   |
[INFO] [stdout] 8 | fn byte_counter<T: AsRef</* T */>>(arg: T) -> usize {
[INFO] [stdout]   |                  ++++++++++++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0391]: cycle detected when computing when `List` needs drop
[INFO] [stdout]   --> exercises/19_smart_pointers/box1.rs:14:1
[INFO] [stdout]    |
[INFO] [stdout] 14 | enum List {
[INFO] [stdout]    | ^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: ...which immediately requires computing when `List` needs drop again
[INFO] [stdout]    = note: cycle used when computing whether `List` needs drop
[INFO] [stdout]    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] Some errors have detailed explanations: E0072, E0391.
[INFO] [stdout] 
[INFO] [stdout] For more information about an error, try `rustc --explain E0072`.
[INFO] [stdout] 
[INFO] [stdout] error[E0599]: no method named `as_ref` found for type parameter `T` in the current scope
[INFO] [stdout]   --> exercises/23_conversions/as_ref_mut.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 14 | fn char_counter<T>(arg: T) -> usize {
[INFO] [stdout]    |                 - method `as_ref` not found for this type parameter
[INFO] [stdout] 15 |     arg.as_ref().chars().count()
[INFO] [stdout]    |         ^^^^^^ method not found in `T`
[INFO] [stdout]    |
[INFO] [stdout]    = help: items from traits can only be used if the type parameter is bounded by the trait
[INFO] [stdout] help: the following trait defines an item `as_ref`, perhaps you need to restrict type parameter `T` with it:
[INFO] [stdout]    |
[INFO] [stdout] 14 | fn char_counter<T: AsRef</* T */>>(arg: T) -> usize {
[INFO] [stdout]    |                  ++++++++++++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `arg`
[INFO] [stdout]   --> exercises/23_conversions/as_ref_mut.rs:20:14
[INFO] [stdout]    |
[INFO] [stdout] 20 | fn num_sq<T>(arg: &mut T) {
[INFO] [stdout]    |              ^^^ help: if this is intentional, prefix it with an underscore: `_arg`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0599`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `exercises` (bin "box1") due to 3 previous errors
[INFO] [stderr] error: could not compile `exercises` (bin "as_ref_mut") due to 2 previous errors; 1 warning emitted
[INFO] running `Command { std: "docker" "inspect" "508563a40766a5ecfc4f6b07cc13012a1652720fc3a9c88d1420a56eb8ca0092", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "508563a40766a5ecfc4f6b07cc13012a1652720fc3a9c88d1420a56eb8ca0092", kill_on_drop: false }`
[INFO] [stdout] 508563a40766a5ecfc4f6b07cc13012a1652720fc3a9c88d1420a56eb8ca0092