Add command line parameter to specify log file (#3807)

* Add command line parameter to specify log file

I had the logs of my debug helix mixed in with the logs from the
production helix.

Add a `--log` command line argument to redirect any logs to other
files, making my debugging easier :-)

* Update completion files with `--log` argument

6 files changed, 17 insertions, 2 deletions

diff --git a/contrib/completion/hx.bash b/contrib/completion/hx.bash
index 8a2d9777..89f3283c 100644
--- a/contrib/completion/hx.bash
+++ b/contrib/completion/hx.bash
@@ -16,7 +16,7 @@ _hx() {
 		COMPREPLY=($(compgen -W "$languages" -- $2))
 		;;
 	*)
-		COMPREPLY=($(compgen -fd -W "-h --help --tutor -V --version -v -vv -vvv --health -g --grammar --vsplit --hsplit -c --config" -- $2))
+		COMPREPLY=($(compgen -fd -W "-h --help --tutor -V --version -v -vv -vvv --health -g --grammar --vsplit --hsplit -c --config --log" -- $2))
 		;;
 	esac
 } && complete -F _hx hx
diff --git a/contrib/completion/hx.elv b/contrib/completion/hx.elv
index d3d227bc..42c88585 100644
--- a/contrib/completion/hx.elv
+++ b/contrib/completion/hx.elv
@@ -36,6 +36,11 @@ set edit:completion:arg-completer[hx] = {|@args|
       edit:complete-filename $args[-1] | each { |v| put $v[stem] }
       return
     } 
+    # When we have --log, we need a file
+    if (has-values "log" $args[-2]) {
+      edit:complete-filename $args[-1] | each { |v| put $v[stem] }
+      return
+    } 
   } 
   edit:complete-filename $args[-1] | each { |v| put $v[stem]}
   $candidate "--help" "(Prints help information)"
@@ -46,4 +51,5 @@ set edit:completion:arg-completer[hx] = {|@args|
   $candidate "--vsplit" "(Splits all given files vertically)"
   $candidate "--hsplit" "(Splits all given files horizontally)"
   $candidate "--config" "(Specifies a file to use for configuration)"
-}
\ No newline at end of file
+  $candidate "--log" "(Specifies a file to write log data into)"
+}
diff --git a/contrib/completion/hx.fish b/contrib/completion/hx.fish
index 65f248d4..71c74ab0 100644
--- a/contrib/completion/hx.fish
+++ b/contrib/completion/hx.fish
@@ -12,3 +12,4 @@ complete -c hx -s V -l version -d "Prints version information"
 complete -c hx -l vsplit -d "Splits all given files vertically into different windows"
 complete -c hx -l hsplit -d "Splits all given files horizontally into different windows"
 complete -c hx -s c -l config -d "Specifies a file to use for completion"
+complete -c hx -s c -l log -d "Specifies a file to write log data into"
diff --git a/contrib/completion/hx.zsh b/contrib/completion/hx.zsh
index e3375656..aaad6f84 100644
--- a/contrib/completion/hx.zsh
+++ b/contrib/completion/hx.zsh
@@ -18,6 +18,7 @@ _hx() {
 		"--hsplit[Splits all given files horizontally into different windows]" \
 		"-c[Specifies a file to use for configuration]" \
 		"--config[Specifies a file to use for configuration]" \
+		"--log[Specifies a file to write log data into]" \
 		"*:file:_files"
 
 	case "$state" in
diff --git a/helix-term/src/args.rs b/helix-term/src/args.rs
index d16d7dfd..48c86633 100644
--- a/helix-term/src/args.rs
+++ b/helix-term/src/args.rs
@@ -14,6 +14,7 @@ pub struct Args {
     pub build_grammars: bool,
     pub split: Option<Layout>,
     pub verbosity: u64,
+    pub log_file: Option<PathBuf>,
     pub config_file: Option<PathBuf>,
     pub files: Vec<(PathBuf, Position)>,
 }
@@ -48,6 +49,10 @@ impl Args {
                     Some(path) => args.config_file = Some(path.into()),
                     None => anyhow::bail!("--config must specify a path to read"),
                 },
+                "--log" => match argv.next().as_deref() {
+                    Some(path) => args.log_file = Some(path.into()),
+                    None => anyhow::bail!("--log must specify a path to write"),
+                },
                 arg if arg.starts_with("--") => {
                     anyhow::bail!("unexpected double dash argument: {}", arg)
                 }
diff --git a/helix-term/src/main.rs b/helix-term/src/main.rs
index d21d3e77..726bf9e3 100644
--- a/helix-term/src/main.rs
+++ b/helix-term/src/main.rs
@@ -67,6 +67,7 @@ FLAGS:
     -g, --grammar {{fetch|build}}    Fetches or builds tree-sitter grammars listed in languages.toml
     -c, --config <file>            Specifies a file to use for configuration
     -v                             Increases logging verbosity each use for up to 3 times
+    --log                          Specifies a file to use for logging
                                    (default file: {})
     -V, --version                  Prints version information
     --vsplit                       Splits all given files vertically into different windows
@@ -114,6 +115,7 @@ FLAGS:
         return Ok(0);
     }
 
+    let logpath = args.log_file.as_ref().cloned().unwrap_or(logpath);
     setup_logging(logpath, args.verbosity).context("failed to initialize logging")?;
 
     let config_dir = helix_loader::config_dir();