Use DFT_LOG as the internal logging environment variable

Fixes #519

CHANGELOG.md

@@ -1,5 +1,11 @@
 ## 0.48 (unreleased)
 
+### Internals
+
+Difftastic's logging is now configured with the environment variable
+`DFT_LOG`. This was previously `RUST_LOG`, which could interfere with
+users configuring logging for their own development work.
+
 ## 0.47 (released 16th May 2023)
 
 ### Language Detection

manual/src/contributing.md

@@ -73,7 +73,7 @@ Difftastic uses the `pretty_env_logger` library to log some additional
 debug information.
 
 ```
-$ RUST_LOG=debug cargo run sample_files/old.jsx sample_files/new.jsx
+$ DFT_LOG=debug cargo run sample_files/old.jsx sample_files/new.jsx
 ```
 
 See the [`env_logger`

src/main.rs

@@ -94,7 +94,8 @@ fn reset_sigpipe() {
 
 /// The entrypoint.
 fn main() {
-    pretty_env_logger::init_timed();
+    pretty_env_logger::try_init_timed_custom_env("DFT_LOG")
+        .expect("The logger has not been previously initalized");
     reset_sigpipe();
 
     match options::parse_args() {

translation/zh-CN/manual-zh-CN/src/contributing.md

@@ -62,7 +62,7 @@ $ GIT_EXTERNAL_DIFF=./target/release/difft git log -p --ext-diff -- src
 Difftastic使用`pretty_env_logger`库来记录一些额外的调试信息。
 
 ```
-$ RUST_LOG=debug cargo run sample_files/old.jsx sample_files/new.jsx
+$ DFT_LOG=debug cargo run sample_files/old.jsx sample_files/new.jsx
 ```
 
 请参阅[`env_logger`](https://docs.rs/env_logger/0.9.0/env_logger/)以获得完整的细节。