Display errors and warnings

To make sure that all error and information reporting to the user is
unified, all instances of `print!`, `eprint!`, `println!` and
`eprintln!` have been removed and replaced by logging.

When `RUST_LOG` is not specified, the default Alacritty logger now also
prints to both the stderr and a log file. The log file is only created
when a message is written to it and its name is printed to stdout the
first time it is used.

Whenever a warning or an error has been written to the log file/stderr,
a message is now displayed in Alacritty which points to the log file
where the full error is documented.

The message is cleared whenever the screen is cleared using either the
`clear` command or the `Ctrl+L` key binding.

To make sure that log files created by root don't prevent normal users
from interacting with them, the Alacritty log file is `/tmp/Alacritty-$PID.log`.

Since it's still possible that the log file can't be created, the UI
error/warning message now informs the user if the message was only
written to stderr. The reason why it couldn't be created is then printed
to stderr.

To make sure the deletion of the log file at runtime doesn't create any
issues, the file is re-created if a write is attempted without the file
being present.

To help with debugging Alacritty issues, a timestamp and the error
level are printed in all log messages.

All log messages now follow this format:
    [YYYY-MM-DD HH:MM] [LEVEL] Message

Since it's not unusual to spawn a lot of different terminal emulators
without restarting, Alacritty can create a ton of different log files.

To combat this problem, logfiles are removed by default after
Alacritty has been closed. If the user wants to persist the log of a
single session, the `--persistent_logging` option can be used. For
persisting all log files, the `persistent_logging` option can be set in
the configuration file

1 files changed, 14 insertions, 0 deletions

diff --git a/src/term/mod.rs b/src/term/mod.rs
index 39213ee2..0f228f86 100644
--- a/src/term/mod.rs
+++ b/src/term/mod.rs
@@ -31,6 +31,7 @@ use config::{Config, VisualBellAnimation};
 use {MouseCursor, Rgb};
 use copypasta::{Clipboard, Load, Store};
 use input::FONT_SIZE_STEP;
+use logging::LoggerProxy;
 
 pub mod cell;
 pub mod color;
@@ -810,6 +811,9 @@ pub struct Term {
 
     /// Automatically scroll to bottom when new lines are added
     auto_scroll: bool,
+
+    /// Proxy object for clearing displayed errors and warnings
+    logger_proxy: Option<LoggerProxy>,
 }
 
 /// Terminal size info
@@ -936,9 +940,14 @@ impl Term {
             dynamic_title: config.dynamic_title(),
             tabspaces,
             auto_scroll: config.scrolling().auto_scroll,
+            logger_proxy: None,
         }
     }
 
+    pub fn set_logger_proxy(&mut self, logger_proxy: LoggerProxy) {
+        self.logger_proxy = Some(logger_proxy);
+    }
+
     pub fn change_font_size(&mut self, delta: f32) {
         // Saturating addition with minimum font size FONT_SIZE_STEP
         let new_size = self.font_size + Size::new(delta);
@@ -1822,6 +1831,11 @@ impl ansi::Handler for Term {
                 }
             },
             ansi::ClearMode::All => {
+                // Clear displayed errors and warnings
+                if let Some(ref mut logger_proxy) = self.logger_proxy {
+                    logger_proxy.clear();
+                }
+
                 self.grid.region_mut(..).each(|c| c.reset(&template));
             },
             ansi::ClearMode::Above => {