Add log variable to justfile (#621)

Allows logging to be controlled with, for example:

    just log=trace run

Cargo.toml

@@ -15,20 +15,20 @@ help4help2man = []
 summary       = []
 
 [dependencies]
-ansi_term      = "0.12.0"
-atty           = "0.2.0"
-clap           = "2.33.0"
-derivative     = "2.0.0"
-dotenv         = "0.15.0"
-edit-distance  = "2.0.0"
-env_logger     = "0.7.0"
-lazy_static    = "1.0.0"
-libc           = "0.2.0"
-log            = "0.4.4"
-snafu          = "0.6.0"
-target         = "1.0.0"
-tempfile       = "3.0.0"
-unicode-width  = "0.1.0"
+ansi_term     = "0.12.0"
+atty          = "0.2.0"
+clap          = "2.33.0"
+derivative    = "2.0.0"
+dotenv        = "0.15.0"
+edit-distance = "2.0.0"
+env_logger    = "0.7.0"
+lazy_static   = "1.0.0"
+libc          = "0.2.0"
+log           = "0.4.4"
+snafu         = "0.6.0"
+target        = "1.0.0"
+tempfile      = "3.0.0"
+unicode-width = "0.1.0"
 
 [dependencies.ctrlc]
 version  = "3.1.1"

justfile

@@ -10,12 +10,19 @@ bt := '0'
 
 export RUST_BACKTRACE := bt
 
+log := "warn"
+
+export JUST_LOG := log
+
 test:
 	cargo test
 
 fuzz:
 	cargo +nightly fuzz run fuzz-compiler
 
+run:
+	cargo run
+
 @spam:
 	{ \
 		figlet test; \

src/common.rs

@@ -29,7 +29,7 @@ pub(crate) use crate::{node::Node, tree::Tree};
 pub(crate) use derivative::Derivative;
 pub(crate) use edit_distance::edit_distance;
 pub(crate) use libc::EXIT_FAILURE;
-pub(crate) use log::warn;
+pub(crate) use log::{info, warn};
 pub(crate) use snafu::{ResultExt, Snafu};
 pub(crate) use unicode_width::UnicodeWidthChar;
 

src/run.rs

@@ -13,6 +13,7 @@ pub fn run() -> Result<(), i32> {
 
   let app = Config::app();
 
+  info!("Parsing command line arguments…");
   let matches = app.get_matches();
 
   let config = Config::from_matches(&matches).eprint(Color::auto())?;