[INFO] cloning repository https://github.com/felix-d/Rust-Monkey-Intepreter
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/felix-d/Rust-Monkey-Intepreter" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffelix-d%2FRust-Monkey-Intepreter", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffelix-d%2FRust-Monkey-Intepreter'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] ab0be05834178fc064e732297bf71f22733486ec
[INFO] checking felix-d/Rust-Monkey-Intepreter against master#385fa9d845dd326c6bbfd58c22244215e431948a for absurd-question-mark-desugar
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffelix-d%2FRust-Monkey-Intepreter" "/workspace/builds/worker-7-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-7-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/felix-d/Rust-Monkey-Intepreter on toolchain 385fa9d845dd326c6bbfd58c22244215e431948a
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/felix-d/Rust-Monkey-Intepreter
[INFO] finished tweaking git repo https://github.com/felix-d/Rust-Monkey-Intepreter
[INFO] tweaked toml for git repo https://github.com/felix-d/Rust-Monkey-Intepreter written to /workspace/builds/worker-7-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/felix-d/Rust-Monkey-Intepreter 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" "+385fa9d845dd326c6bbfd58c22244215e431948a" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded aho-corasick v0.6.6
[INFO] [stderr]   Downloaded libc v0.2.42
[INFO] [stderr]   Downloaded lazy_static v1.0.2
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 806f9e17ca90bb561bc716db8b2df1d5354274feac78bac54a89e5c61fff3fcf
[INFO] running `Command { std: "docker" "start" "-a" "806f9e17ca90bb561bc716db8b2df1d5354274feac78bac54a89e5c61fff3fcf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "806f9e17ca90bb561bc716db8b2df1d5354274feac78bac54a89e5c61fff3fcf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "806f9e17ca90bb561bc716db8b2df1d5354274feac78bac54a89e5c61fff3fcf", kill_on_drop: false }`
[INFO] [stdout] 806f9e17ca90bb561bc716db8b2df1d5354274feac78bac54a89e5c61fff3fcf
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9e69200ebec5ed8d3b20feea207267f4c43506532b7513151879adfb8638886e
[INFO] running `Command { std: "docker" "start" "-a" "9e69200ebec5ed8d3b20feea207267f4c43506532b7513151879adfb8638886e", kill_on_drop: false }`
[INFO] [stderr]     Checking void v1.0.2
[INFO] [stderr]     Checking libc v0.2.42
[INFO] [stderr]    Compiling regex v0.2.11
[INFO] [stderr]     Checking ucd-util v0.1.1
[INFO] [stderr]     Checking lazy_static v1.0.2
[INFO] [stderr]     Checking utf8-ranges v1.0.0
[INFO] [stderr]     Checking unreachable v1.0.0
[INFO] [stderr]     Checking regex-syntax v0.5.6
[INFO] [stderr]     Checking thread_local v0.3.5
[INFO] [stderr]     Checking memchr v2.0.1
[INFO] [stderr]     Checking aho-corasick v0.6.6
[INFO] [stderr]     Checking interpreter v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:158:16
[INFO] [stdout]     |
[INFO] [stdout] 158 |             'a'...'z' | 'A'...'Z' | '_' => self.lex_identifier(),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]     = note: `#[warn(ellipsis_inclusive_range_patterns)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:158:28
[INFO] [stdout]     |
[INFO] [stdout] 158 |             'a'...'z' | 'A'...'Z' | '_' => self.lex_identifier(),
[INFO] [stdout]     |                            ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:159:16
[INFO] [stdout]     |
[INFO] [stdout] 159 |             '0'...'9' => self.lex_integer(),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:158:16
[INFO] [stdout]     |
[INFO] [stdout] 158 |             'a'...'z' | 'A'...'Z' | '_' => self.lex_identifier(),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]     = note: `#[warn(ellipsis_inclusive_range_patterns)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:158:28
[INFO] [stdout]     |
[INFO] [stdout] 158 |             'a'...'z' | 'A'...'Z' | '_' => self.lex_identifier(),
[INFO] [stdout]     |                            ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:159:16
[INFO] [stdout]     |
[INFO] [stdout] 159 |             '0'...'9' => self.lex_integer(),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function `new_let` is never used
[INFO] [stdout]   --> src/ast.rs:88:19
[INFO] [stdout]    |
[INFO] [stdout] 87 | impl Statement {
[INFO] [stdout]    | -------------- associated function in this implementation
[INFO] [stdout] 88 |     pub(crate) fn new_let(identifier: &str, value: Expression) -> Self {
[INFO] [stdout]    |                   ^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: panic message contains an unused formatting placeholder
[INFO] [stdout]    --> src/evaluator.rs:478:36
[INFO] [stdout]     |
[INFO] [stdout] 478 |             _ => unreachable!("Got {:?}, but expected Object::Function."),
[INFO] [stdout]     |                                    ^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this message is not used as a format string when given without arguments, but will be in Rust 2021
[INFO] [stdout]     = note: `#[warn(non_fmt_panics)]` on by default
[INFO] [stdout] help: add the missing argument
[INFO] [stdout]     |
[INFO] [stdout] 478 |             _ => unreachable!("Got {:?}, but expected Object::Function.", ...),
[INFO] [stdout]     |                                                                         +++++
[INFO] [stdout] help: or add a "{}" format string to use the message literally
[INFO] [stdout]     |
[INFO] [stdout] 478 |             _ => unreachable!("{}", "Got {:?}, but expected Object::Function."),
[INFO] [stdout]     |                               +++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 4.24s
[INFO] running `Command { std: "docker" "inspect" "9e69200ebec5ed8d3b20feea207267f4c43506532b7513151879adfb8638886e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9e69200ebec5ed8d3b20feea207267f4c43506532b7513151879adfb8638886e", kill_on_drop: false }`
[INFO] [stdout] 9e69200ebec5ed8d3b20feea207267f4c43506532b7513151879adfb8638886e
[INFO] checking felix-d/Rust-Monkey-Intepreter against try#645bb72776a6a56a1a8f52631a44bd082b2ba509 for absurd-question-mark-desugar
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffelix-d%2FRust-Monkey-Intepreter" "/workspace/builds/worker-7-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-7-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/felix-d/Rust-Monkey-Intepreter on toolchain 645bb72776a6a56a1a8f52631a44bd082b2ba509
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+645bb72776a6a56a1a8f52631a44bd082b2ba509" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/felix-d/Rust-Monkey-Intepreter
[INFO] finished tweaking git repo https://github.com/felix-d/Rust-Monkey-Intepreter
[INFO] tweaked toml for git repo https://github.com/felix-d/Rust-Monkey-Intepreter written to /workspace/builds/worker-7-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/felix-d/Rust-Monkey-Intepreter 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" "+645bb72776a6a56a1a8f52631a44bd082b2ba509" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc2/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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+645bb72776a6a56a1a8f52631a44bd082b2ba509" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 80832a37327fd79424d3c3652aabf03b0c888fe812107c44b5d2edc3a72a5134
[INFO] running `Command { std: "docker" "start" "-a" "80832a37327fd79424d3c3652aabf03b0c888fe812107c44b5d2edc3a72a5134", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "80832a37327fd79424d3c3652aabf03b0c888fe812107c44b5d2edc3a72a5134", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "80832a37327fd79424d3c3652aabf03b0c888fe812107c44b5d2edc3a72a5134", kill_on_drop: false }`
[INFO] [stdout] 80832a37327fd79424d3c3652aabf03b0c888fe812107c44b5d2edc3a72a5134
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc2/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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+645bb72776a6a56a1a8f52631a44bd082b2ba509" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 06d16ccc5744b98d024d67ecc0c3b7888d0d7d90d2958c2cc499239bcd03128d
[INFO] running `Command { std: "docker" "start" "-a" "06d16ccc5744b98d024d67ecc0c3b7888d0d7d90d2958c2cc499239bcd03128d", kill_on_drop: false }`
[INFO] [stderr]     Checking libc v0.2.42
[INFO] [stderr]     Checking void v1.0.2
[INFO] [stderr]     Checking ucd-util v0.1.1
[INFO] [stderr]     Checking lazy_static v1.0.2
[INFO] [stderr]    Compiling regex v0.2.11
[INFO] [stderr]     Checking utf8-ranges v1.0.0
[INFO] [stderr]     Checking unreachable v1.0.0
[INFO] [stderr]     Checking regex-syntax v0.5.6
[INFO] [stderr]     Checking thread_local v0.3.5
[INFO] [stderr]     Checking memchr v2.0.1
[INFO] [stderr]     Checking aho-corasick v0.6.6
[INFO] [stderr]     Checking interpreter v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:158:16
[INFO] [stdout]     |
[INFO] [stdout] 158 |             'a'...'z' | 'A'...'Z' | '_' => self.lex_identifier(),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]     = note: `#[warn(ellipsis_inclusive_range_patterns)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:158:28
[INFO] [stdout]     |
[INFO] [stdout] 158 |             'a'...'z' | 'A'...'Z' | '_' => self.lex_identifier(),
[INFO] [stdout]     |                            ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:159:16
[INFO] [stdout]     |
[INFO] [stdout] 159 |             '0'...'9' => self.lex_integer(),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:158:16
[INFO] [stdout]     |
[INFO] [stdout] 158 |             'a'...'z' | 'A'...'Z' | '_' => self.lex_identifier(),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]     = note: `#[warn(ellipsis_inclusive_range_patterns)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:158:28
[INFO] [stdout]     |
[INFO] [stdout] 158 |             'a'...'z' | 'A'...'Z' | '_' => self.lex_identifier(),
[INFO] [stdout]     |                            ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/lexer.rs:159:16
[INFO] [stdout]     |
[INFO] [stdout] 159 |             '0'...'9' => self.lex_integer(),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function `new_let` is never used
[INFO] [stdout]   --> src/ast.rs:88:19
[INFO] [stdout]    |
[INFO] [stdout] 87 | impl Statement {
[INFO] [stdout]    | -------------- associated function in this implementation
[INFO] [stdout] 88 |     pub(crate) fn new_let(identifier: &str, value: Expression) -> Self {
[INFO] [stdout]    |                   ^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: panic message contains an unused formatting placeholder
[INFO] [stdout]    --> src/evaluator.rs:478:36
[INFO] [stdout]     |
[INFO] [stdout] 478 |             _ => unreachable!("Got {:?}, but expected Object::Function."),
[INFO] [stdout]     |                                    ^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this message is not used as a format string when given without arguments, but will be in Rust 2021
[INFO] [stdout]     = note: `#[warn(non_fmt_panics)]` on by default
[INFO] [stdout] help: add the missing argument
[INFO] [stdout]     |
[INFO] [stdout] 478 |             _ => unreachable!("Got {:?}, but expected Object::Function.", ...),
[INFO] [stdout]     |                                                                         +++++
[INFO] [stdout] help: or add a "{}" format string to use the message literally
[INFO] [stdout]     |
[INFO] [stdout] 478 |             _ => unreachable!("{}", "Got {:?}, but expected Object::Function."),
[INFO] [stdout]     |                               +++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 4.28s
[INFO] running `Command { std: "docker" "inspect" "06d16ccc5744b98d024d67ecc0c3b7888d0d7d90d2958c2cc499239bcd03128d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "06d16ccc5744b98d024d67ecc0c3b7888d0d7d90d2958c2cc499239bcd03128d", kill_on_drop: false }`
[INFO] [stdout] 06d16ccc5744b98d024d67ecc0c3b7888d0d7d90d2958c2cc499239bcd03128d