refactor(shell): Move tree's unicode detection to shell

Author: epage

src/bin/cargo/commands/tree.rs

@@ -7,7 +7,6 @@ use cargo::ops::Packages;
 use cargo::util::print_available_packages;
 use cargo::util::CargoResult;
 use std::collections::HashSet;
-use std::io::IsTerminal as _;
 use std::str::FromStr;
 
 pub fn cli() -> Command {
@@ -186,13 +185,6 @@ subtree of the package given to -p.\n\
         .map(|c| tree::Charset::from_str(c))
         .transpose()
         .map_err(|e| anyhow::anyhow!("{}", e))?;
-    let charset = charset.unwrap_or_else(|| {
-        if supports_unicode::supports_unicode() || !std::io::stdout().is_terminal() {
-            tree::Charset::Utf8
-        } else {
-            tree::Charset::Ascii
-        }
-    });
     let opts = tree::TreeOptions {
         cli_features: args.cli_features()?,
         packages,

src/cargo/core/shell.rs

@@ -53,6 +53,8 @@ impl Shell {
                 color_choice: auto_clr,
                 hyperlinks: supports_hyperlinks(),
                 stderr_tty: std::io::stderr().is_terminal(),
+                stdout_unicode: supports_unicode(&std::io::stdout()),
+                stderr_unicode: supports_unicode(&std::io::stderr()),
             },
             verbosity: Verbosity::Verbose,
             needs_clear: false,
@@ -259,6 +261,20 @@ impl Shell {
         Ok(())
     }
 
+    pub fn out_unicode(&self) -> bool {
+        match &self.output {
+            ShellOut::Write(_) => true,
+            ShellOut::Stream { stdout_unicode, .. } => *stdout_unicode,
+        }
+    }
+
+    pub fn err_unicode(&self) -> bool {
+        match &self.output {
+            ShellOut::Write(_) => true,
+            ShellOut::Stream { stderr_unicode, .. } => *stderr_unicode,
+        }
+    }
+
     /// Gets the current color choice.
     ///
     /// If we are not using a color stream, this will always return `Never`, even if the color
@@ -384,6 +400,8 @@ enum ShellOut {
         stderr_tty: bool,
         color_choice: ColorChoice,
         hyperlinks: bool,
+        stdout_unicode: bool,
+        stderr_unicode: bool,
     },
 }
 
@@ -519,6 +537,10 @@ fn supports_color(choice: anstream::ColorChoice) -> bool {
     }
 }
 
+fn supports_unicode(stream: &dyn IsTerminal) -> bool {
+    !stream.is_terminal() || supports_unicode::supports_unicode()
+}
+
 fn supports_hyperlinks() -> bool {
     #[allow(clippy::disallowed_methods)] // We are reading the state of the system, not config
     if std::env::var_os("TERM_PROGRAM").as_deref() == Some(std::ffi::OsStr::new("iTerm.app")) {

src/cargo/ops/tree/mod.rs

@@ -40,7 +40,7 @@ pub struct TreeOptions {
     /// `invert`.
     pub duplicates: bool,
     /// The style of characters to use.
-    pub charset: Charset,
+    pub charset: Option<Charset>,
     /// A format string indicating how each package should be displayed.
     pub format: String,
     /// Includes features in the tree as separate nodes.
@@ -68,6 +68,7 @@ impl Target {
     }
 }
 
+#[derive(Copy, Clone)]
 pub enum Charset {
     Utf8,
     Ascii,
@@ -236,7 +237,14 @@ fn print(
     let format = Pattern::new(&opts.format)
         .with_context(|| format!("tree format `{}` not valid", opts.format))?;
 
-    let symbols = match opts.charset {
+    let charset = opts.charset.unwrap_or_else(|| {
+        if gctx.shell().out_unicode() {
+            Charset::Utf8
+        } else {
+            Charset::Ascii
+        }
+    });
+    let symbols = match charset {
         Charset::Utf8 => &UTF8_SYMBOLS,
         Charset::Ascii => &ASCII_SYMBOLS,
     };