Add keybinding action for clearing warns/errors

Since running `clear` inside of tmux doesn't actually clear any part of
the screen, but just resets the scrolling region, the warning and error
notices can't be removed without quitting tmux or Alacritty.

As a solution, a new action `ClearLogNotice` has been added which has
been bound to Ctrl+L by default. As a result, Ctrl+L can be used inside
of tmux to remove the messages, even though tmux doesn't clear the
screen.

This fixes #1811.

8 files changed, 38 insertions, 10 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5d3f2a8c..fd28ba3c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Option for evenly spreading extra padding around the terminal (`window.dynamic_padding`)
+- Display notice about errors and warnings inside Alacritty
+- Log all messages to both stderr and a log file in the system's temporary directory
+- New configuration option `persistent_logging` and CLI flag `--persistent-logging`,
+    for keeping the log file after closing Alacritty
+- `ClearLogNotice` action for removing the warning and error message
 
 ### Changed
 
@@ -31,10 +36,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - New `mouse.url.modifiers` option to specify keyboard modifiers for opening URLs on click
 - Binaries for macOS, Windows and Debian-based systems are now published with GitHub releases
 - The keys F16-F24 have been added as options for key bindings
-- Display notice about errors and warnings inside Alacritty
-- Log all messages to both stderr and a log file in the system's temporary directory
-- New configuration option `persistent_logging` and CLI flag `--persistent-logging`,
-    for keeping the log file after closing Alacritty
 
 ### Changed
 
diff --git a/alacritty.yml b/alacritty.yml
index b3b7e977..ebba9920 100644
--- a/alacritty.yml
+++ b/alacritty.yml
@@ -369,6 +369,7 @@ live_config_reload: true
 #   - ClearHistory
 #   - Hide
 #   - Quit
+#   - ClearLogNotice
 #
 # Values for `command`:
 #   The `command` field must be a map containing a `program` string and
@@ -393,6 +394,8 @@ key_bindings:
   - { key: Key0,     mods: Control, action: ResetFontSize                }
   - { key: Equals,   mods: Control, action: IncreaseFontSize             }
   - { key: Subtract, mods: Control, action: DecreaseFontSize             }
+  - { key: L,        mods: Control, action: ClearLogNotice               }
+  - { key: L,        mods: Control, chars: "\x0c"                        }
   - { key: Home,                    chars: "\x1bOH",   mode: AppCursor   }
   - { key: Home,                    chars: "\x1b[H",   mode: ~AppCursor  }
   - { key: End,                     chars: "\x1bOF",   mode: AppCursor   }
diff --git a/alacritty_macos.yml b/alacritty_macos.yml
index e4ead06d..db6fa8ca 100644
--- a/alacritty_macos.yml
+++ b/alacritty_macos.yml
@@ -366,6 +366,7 @@ live_config_reload: true
 #   - ClearHistory
 #   - Hide
 #   - Quit
+#   - ClearLogNotice
 #
 # Values for `command`:
 #   The `command` field must be a map containing a `program` string and
@@ -396,6 +397,8 @@ key_bindings:
   - { key: Minus,    mods: Command, action: DecreaseFontSize             }
   - { key: K,        mods: Command, action: ClearHistory                 }
   - { key: K,        mods: Command, chars: "\x0c"                        }
+  - { key: L,        mods: Control, action: ClearLogNotice               }
+  - { key: L,        mods: Control, chars: "\x0c"                        }
   - { key: PageUp,   mods: Shift,   chars: "\x1b[5;2~"                   }
   - { key: PageUp,   mods: Control, chars: "\x1b[5;5~"                   }
   - { key: PageUp,                  chars: "\x1b[5~"                     }
diff --git a/alacritty_windows.yml b/alacritty_windows.yml
index af429152..b37a4532 100644
--- a/alacritty_windows.yml
+++ b/alacritty_windows.yml
@@ -343,6 +343,7 @@ shell:
 #   - ClearHistory
 #   - Hide
 #   - Quit
+#   - ClearLogNotice
 #
 # Values for `command`:
 #   The `command` field must be a map containing a `program` string and
@@ -365,6 +366,8 @@ key_bindings:
   - { key: Key0,     mods: Control, action: ResetFontSize                }
   - { key: Equals,   mods: Control, action: IncreaseFontSize             }
   - { key: Subtract, mods: Control, action: DecreaseFontSize             }
+  - { key: L,        mods: Control, action: ClearLogNotice               }
+  - { key: L,        mods: Control, chars: "\x0c"                        }
   - { key: Home,                    chars: "\x1bOH",   mode: AppCursor   }
   - { key: Home,                    chars: "\x1b[H",   mode: ~AppCursor  }
   - { key: End,                     chars: "\x1bOF",   mode: AppCursor   }
diff --git a/src/config.rs b/src/config.rs
index 2028132f..d56e8578 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -746,7 +746,7 @@ impl<'a> de::Deserialize<'a> for ActionWrapper {
             fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
                 f.write_str("Paste, Copy, PasteSelection, IncreaseFontSize, DecreaseFontSize, \
                             ResetFontSize, ScrollPageUp, ScrollPageDown, ScrollToTop, \
-                            ScrollToBottom, ClearHistory, Hide, or Quit")
+                            ScrollToBottom, ClearHistory, Hide, ClearLogNotice or Quit")
             }
 
             fn visit_str<E>(self, value: &str) -> ::std::result::Result<ActionWrapper, E>
@@ -766,6 +766,7 @@ impl<'a> de::Deserialize<'a> for ActionWrapper {
                     "ClearHistory" => Action::ClearHistory,
                     "Hide" => Action::Hide,
                     "Quit" => Action::Quit,
+                    "ClearLogNotice" => Action::ClearLogNotice,
                     _ => return Err(E::invalid_value(Unexpected::Str(value), &self)),
                 }))
             }
diff --git a/src/event.rs b/src/event.rs
index ece8ec6f..f69136df 100644
--- a/src/event.rs
+++ b/src/event.rs
@@ -171,6 +171,11 @@ impl<'a, N: Notify + 'a> input::ActionContext for ActionContext<'a, N> {
     fn hide_window(&mut self) {
         self.window_changes.hide = true;
     }
+
+    #[inline]
+    fn clear_log(&mut self) {
+        self.terminal.clear_log();
+    }
 }
 
 /// The ActionContext can't really have direct access to the Window
diff --git a/src/input.rs b/src/input.rs
index d2f8f6b5..051a38db 100644
--- a/src/input.rs
+++ b/src/input.rs
@@ -76,6 +76,7 @@ pub trait ActionContext {
     fn clear_history(&mut self);
     fn hide_window(&mut self);
     fn url(&self, _: Point<usize>) -> Option<String>;
+    fn clear_log(&mut self);
 }
 
 /// Describes a state and action to take in that state
@@ -200,6 +201,9 @@ pub enum Action {
 
     /// Quits Alacritty.
     Quit,
+
+    /// Clears warning and error notices.
+    ClearLogNotice,
 }
 
 impl Action {
@@ -292,6 +296,9 @@ impl Action {
             Action::ClearHistory => {
                 ctx.clear_history();
             },
+            Action::ClearLogNotice => {
+                ctx.clear_log();
+            }
         }
     }
 
@@ -885,6 +892,7 @@ mod tests {
         }
         fn hide_window(&mut self) {
         }
+        fn clear_log(&mut self) {}
     }
 
     macro_rules! test_clickstate {
diff --git a/src/term/mod.rs b/src/term/mod.rs
index 0f228f86..5107dc2d 100644
--- a/src/term/mod.rs
+++ b/src/term/mod.rs
@@ -877,6 +877,14 @@ impl Term {
         &self.grid.selection
     }
 
+    /// Clear displayed errors and warnings.
+    pub fn clear_log(&mut self) {
+        if let Some(ref mut logger_proxy) = self.logger_proxy {
+            logger_proxy.clear();
+        }
+    }
+
+
     pub fn selection_mut(&mut self) -> &mut Option<Selection> {
         &mut self.grid.selection
     }
@@ -1831,11 +1839,7 @@ 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.clear_log();
                 self.grid.region_mut(..).each(|c| c.reset(&template));
             },
             ansi::ClearMode::Above => {