Allow writing to &mut dyn WriteStyle

codespan-reporting/src/term/config.rs

@@ -308,7 +308,7 @@ pub mod styles {
 #[cfg(feature = "termcolor")]
 impl<T> super::renderer::WriteStyle for T
 where
-    T: termcolor::WriteColor,
+    T: termcolor::WriteColor + ?Sized,
 {
     fn set_header(
         &mut self,

codespan-reporting/src/term/mod.rs

@@ -40,7 +40,7 @@ pub fn emit_to_string<'files, F: Files<'files> + ?Sized>(
     {
         let mut buffer = Vec::new();
         emit_with_style(
-            &mut renderer::PlainWriter::new(&mut buffer),
+            renderer::PlainWriter::new(&mut buffer),
             config,
             files,
             diagnostic,
@@ -54,7 +54,7 @@ pub fn emit_to_string<'files, F: Files<'files> + ?Sized>(
     #[cfg(not(feature = "std"))]
     {
         emit_with_style(
-            &mut renderer::PlainWriter::new(writer),
+            renderer::PlainWriter::new(writer),
             config,
             files,
             diagnostic,
@@ -63,27 +63,32 @@ pub fn emit_to_string<'files, F: Files<'files> + ?Sized>(
 }
 
 #[cfg(feature = "std")]
-pub fn emit_to_io_write<'files, F: Files<'files> + ?Sized, W: std::io::Write>(
+pub fn emit_to_io_write<'files, F: Files<'files> + ?Sized, W: std::io::Write + ?Sized>(
     writer: &mut W,
     config: &Config,
     files: &'files F,
     diagnostic: &Diagnostic<F::FileId>,
 ) -> Result<(), super::files::Error> {
     emit_with_style(
-        &mut renderer::PlainWriter::new(writer),
+        renderer::PlainWriter::new(writer),
         config,
         files,
         diagnostic,
     )
 }
 
-pub fn emit_to_write_style<'files, F: Files<'files> + ?Sized, W: WriteStyle>(
+pub fn emit_to_write_style<'files, F: Files<'files> + ?Sized, W: WriteStyle + ?Sized>(
     writer: &mut W,
     config: &Config,
     files: &'files F,
     diagnostic: &Diagnostic<F::FileId>,
 ) -> Result<(), super::files::Error> {
-    emit_with_style(writer, config, files, diagnostic)
+    emit_with_style(
+        renderer::WriteStyleByRef::new(writer),
+        config,
+        files,
+        diagnostic,
+    )
 }
 
 #[deprecated(
@@ -96,27 +101,27 @@ pub fn emit_to_write_style<'files, F: Files<'files> + ?Sized, W: WriteStyle>(
 /// * a file was removed from the file database.
 /// * a file was changed so that it is too small to have an index
 /// * IO fails
-pub fn emit<'files, F: Files<'files> + ?Sized, W: renderer::GeneralWrite>(
+pub fn emit<'files, F: Files<'files> + ?Sized, W: renderer::GeneralWrite + ?Sized>(
     writer: &mut W,
     config: &Config,
     files: &'files F,
     diagnostic: &Diagnostic<F::FileId>,
 ) -> Result<(), super::files::Error> {
     emit_with_style(
-        &mut renderer::PlainWriter::new(writer),
+        renderer::PlainWriter::new(writer),
         config,
         files,
         diagnostic,
     )
 }
 
 fn emit_with_style<'files, F: Files<'files> + ?Sized, W: WriteStyle>(
-    writer: &mut W,
+    mut writer: W,
     config: &Config,
     files: &'files F,
     diagnostic: &Diagnostic<F::FileId>,
 ) -> Result<(), super::files::Error> {
-    let mut renderer = Renderer::new(writer, config);
+    let mut renderer = Renderer::new(&mut writer, config);
     match config.display_style {
         DisplayStyle::Rich => RichDiagnostic::new(diagnostic, config).render(files, &mut renderer),
         DisplayStyle::Medium => ShortDiagnostic::new(diagnostic, true).render(files, &mut renderer),

codespan-reporting/src/term/renderer.rs

@@ -108,6 +108,84 @@ impl<W: GeneralWrite> WriteStyle for PlainWriter<W> {
     }
 }
 
+pub(crate) struct WriteStyleByRef<'a, W: ?Sized> {
+    w: &'a mut W,
+}
+
+impl<'a, W> WriteStyleByRef<'a, W>
+where
+    W: ?Sized,
+{
+    pub fn new(writer: &'a mut W) -> Self {
+        Self { w: writer }
+    }
+}
+
+#[cfg(feature = "std")]
+impl<'a, W> std::io::Write for WriteStyleByRef<'a, W>
+where
+    W: std::io::Write + ?Sized,
+{
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        self.w.write(buf)
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        self.w.flush()
+    }
+}
+
+#[cfg(not(feature = "std"))]
+impl<'a, W> core::fmt::Write for WriteStyleByRef<'a, W>
+where
+    W: core::fmt::Write + ?Sized,
+{
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
+        self.w.write_str(s)
+    }
+
+    fn write_char(&mut self, c: char) -> core::fmt::Result {
+        self.w.write_char(c)
+    }
+
+    fn write_fmt(&mut self, args: core::fmt::Arguments<'_>) -> core::fmt::Result {
+        self.w.write_fmt(args)
+    }
+}
+
+impl<'a, W> WriteStyle for WriteStyleByRef<'a, W>
+where
+    W: WriteStyle + ?Sized,
+{
+    fn set_header(&mut self, severity: Severity) -> GeneralWriteResult {
+        self.w.set_header(severity)
+    }
+
+    fn set_header_message(&mut self) -> GeneralWriteResult {
+        self.w.set_header_message()
+    }
+
+    fn set_line_number(&mut self) -> GeneralWriteResult {
+        self.w.set_line_number()
+    }
+
+    fn set_note_bullet(&mut self) -> GeneralWriteResult {
+        self.w.set_note_bullet()
+    }
+
+    fn set_source_border(&mut self) -> GeneralWriteResult {
+        self.w.set_source_border()
+    }
+
+    fn set_label(&mut self, severity: Severity, label_style: LabelStyle) -> GeneralWriteResult {
+        self.w.set_label(severity, label_style)
+    }
+
+    fn reset(&mut self) -> GeneralWriteResult {
+        self.w.reset()
+    }
+}
+
 /// The 'location focus' of a source code snippet.
 pub struct Locus {
     /// The user-facing name of the file.