refactor(shell): Prepare for Reports being generated in more places (#15920)

### What does this PR try to resolve?

This is preparation for changes like #15917 where we start to use
`annotate_snippets::Report` for handling more of the rendering of our
user messages to be more consistent with rustc and more feature rich in
what we are able to render.

### How to test and review this PR?

Author: weihanglo

src/cargo/core/shell.rs

@@ -222,10 +222,7 @@ impl Shell {
 
     /// Prints an amber 'warning' message.
     pub fn warn<T: fmt::Display>(&mut self, message: T) -> CargoResult<()> {
-        match self.verbosity {
-            Verbosity::Quiet => Ok(()),
-            _ => self.print(&"warning", Some(&message), &WARN, false),
-        }
+        self.print(&"warning", Some(&message), &WARN, false)
     }
 
     /// Prints a cyan 'note' message.
@@ -407,16 +404,22 @@ impl Shell {
     }
 
     /// Prints the passed in [`Report`] to stderr
-    pub fn print_report(&mut self, report: Report<'_>) -> std::io::Result<()> {
+    pub fn print_report(&mut self, report: Report<'_>, force: bool) -> CargoResult<()> {
+        if !force && matches!(self.verbosity, Verbosity::Quiet) {
+            return Ok(());
+        }
+
+        if self.needs_clear {
+            self.err_erase_line();
+        }
         let term_width = self
             .err_width()
             .diagnostic_terminal_width()
             .unwrap_or(annotate_snippets::renderer::DEFAULT_TERM_WIDTH);
-        writeln!(
-            self.err(),
-            "{}",
-            Renderer::styled().term_width(term_width).render(report)
-        )
+        let rendered = Renderer::styled().term_width(term_width).render(report);
+        self.err().write_all(rendered.as_bytes())?;
+        self.err().write_all("\n".as_bytes())?;
+        Ok(())
     }
 }
 

src/cargo/util/lints.rs

@@ -171,7 +171,7 @@ fn verify_feature_enabled(
         }
 
         *error_count += 1;
-        gctx.shell().print_report(&report)?;
+        gctx.shell().print_report(&report, true)?;
     }
     Ok(())
 }
@@ -339,6 +339,15 @@ impl LintLevel {
             LintLevel::Forbid => Level::ERROR,
         }
     }
+
+    fn force(self) -> bool {
+        match self {
+            Self::Allow => false,
+            Self::Warn => true,
+            Self::Deny => true,
+            Self::Forbid => true,
+        }
+    }
 }
 
 impl From<TomlLintLevel> for LintLevel {
@@ -459,7 +468,7 @@ pub fn check_im_a_teapot(
             )
             .element(Level::NOTE.message(&emitted_reason))];
 
-        gctx.shell().print_report(report)?;
+        gctx.shell().print_report(report, lint_level.force())?;
     }
     Ok(())
 }
@@ -568,7 +577,7 @@ fn output_unknown_lints(
             );
         }
 
-        gctx.shell().print_report(&report)?;
+        gctx.shell().print_report(&report, lint_level.force())?;
     }
 
     Ok(())

src/cargo/util/toml/mod.rs

@@ -1930,7 +1930,7 @@ fn missing_dep_diagnostic(
         group.element(snippet)
     };
 
-    if let Err(err) = gctx.shell().print_report(&[group]) {
+    if let Err(err) = gctx.shell().print_report(&[group], true) {
         return Err(err.into());
     }
     Err(AlreadyPrintedError::new(anyhow!("").into()).into())
@@ -2798,7 +2798,7 @@ fn emit_diagnostic(
             .annotation(AnnotationKind::Primary.span(span)),
     );
 
-    if let Err(err) = gctx.shell().print_report(&[group]) {
+    if let Err(err) = gctx.shell().print_report(&[group], true) {
         return err.into();
     }
     return AlreadyPrintedError::new(e.into()).into();