Use null Ui in completion to prevent writing warnings into completions

cli/src/cli_util.rs

@@ -3714,7 +3714,7 @@ impl CliRunner {
         ui.reset(&config)?;
 
         if env::var_os("COMPLETE").is_some() {
-            return handle_shell_completion(ui, &self.app, &config, &cwd);
+            return handle_shell_completion(&Ui::null(), &self.app, &config, &cwd);
         }
 
         let string_args = expand_args(ui, &self.app, env::args_os(), &config)?;

cli/src/complete.rs

@@ -758,7 +758,7 @@ fn get_jj_command() -> Result<(JjBuilder, UserSettings), CommandError> {
     // required.
     let app = crate::commands::default_app();
     let mut raw_config = config_from_environment(default_config_layers());
-    let ui = Ui::with_config(raw_config.as_ref()).expect("default config should be valid");
+    let ui = Ui::null();
     let cwd = std::env::current_dir()
         .and_then(dunce::canonicalize)
         .map_err(user_error)?;

cli/src/ui.rs

@@ -60,6 +60,7 @@ enum UiOutput {
         err_wr: PipeWriter,
         pager_thread: JoinHandle<streampager::Result<()>>,
     },
+    Null,
 }
 
 impl UiOutput {
@@ -140,6 +141,7 @@ impl UiOutput {
                     }
                 }
             }
+            UiOutput::Null => {}
         }
     }
 }
@@ -148,12 +150,14 @@ pub enum UiStdout<'a> {
     Terminal(StdoutLock<'static>),
     Paged(&'a ChildStdin),
     Builtin(&'a PipeWriter),
+    Null(io::Sink),
 }
 
 pub enum UiStderr<'a> {
     Terminal(StderrLock<'static>),
     Paged(&'a ChildStdin),
     Builtin(&'a PipeWriter),
+    Null(io::Sink),
 }
 
 macro_rules! for_outputs {
@@ -162,6 +166,7 @@ macro_rules! for_outputs {
             $ty::Terminal($pat) => $expr,
             $ty::Paged($pat) => $expr,
             $ty::Builtin($pat) => $expr,
+            $ty::Null($pat) => $expr,
         }
     };
 }
@@ -254,6 +259,17 @@ pub enum PaginationChoice {
 }
 
 impl Ui {
+    pub fn null() -> Ui {
+        Ui {
+            quiet: true,
+            pager_cmd: CommandNameAndArgs::String(String::new()),
+            paginate: PaginationChoice::Never,
+            progress_indicator: false,
+            formatter_factory: FormatterFactory::plain_text(),
+            output: UiOutput::Null,
+        }
+    }
+
     pub fn with_config(config: &StackedConfig) -> Result<Ui, CommandError> {
         let formatter_factory = prepare_formatter_factory(config, &io::stdout())?;
         Ok(Ui {
@@ -336,6 +352,7 @@ impl Ui {
             UiOutput::Terminal { stdout, .. } => UiStdout::Terminal(stdout.lock()),
             UiOutput::Paged { child_stdin, .. } => UiStdout::Paged(child_stdin),
             UiOutput::BuiltinPaged { out_wr, .. } => UiStdout::Builtin(out_wr),
+            UiOutput::Null => UiStdout::Null(io::sink()),
         }
     }
 
@@ -353,6 +370,7 @@ impl Ui {
             UiOutput::Terminal { stderr, .. } => UiStderr::Terminal(stderr.lock()),
             UiOutput::Paged { child_stdin, .. } => UiStderr::Paged(child_stdin),
             UiOutput::BuiltinPaged { err_wr, .. } => UiStderr::Builtin(err_wr),
+            UiOutput::Null => UiStderr::Null(io::sink()),
         }
     }
 
@@ -367,6 +385,7 @@ impl Ui {
             UiOutput::Terminal { .. } => Ok(Stdio::inherit()),
             UiOutput::Paged { child_stdin, .. } => Ok(duplicate_child_stdin(child_stdin)?.into()),
             UiOutput::BuiltinPaged { err_wr, .. } => Ok(err_wr.try_clone()?.into()),
+            UiOutput::Null => Ok(Stdio::null()),
         }
     }
 
@@ -377,6 +396,7 @@ impl Ui {
             UiOutput::Terminal { stderr, .. } => self.progress_indicator && stderr.is_terminal(),
             UiOutput::Paged { .. } => false,
             UiOutput::BuiltinPaged { .. } => false,
+            UiOutput::Null => false,
         }
     }