Rollup merge of rust-lang#83228 - GuillaumeGomez:no-diff-if-no-tidy, r=jyn514

Don't show HTML diff if tidy isn't installed for rustdoc tests

The output without the `tidy` tool is just way too big to be of any use. It makes reading the error much more complicated.

r? ``@jyn514``

Author: Dylan-DPC

src/tools/compiletest/src/main.rs

@@ -44,7 +44,7 @@ fn main() {
     }
 
     if !config.has_tidy && config.mode == Mode::Rustdoc {
-        eprintln!("warning: `tidy` is not installed; generated diffs will be harder to read");
+        eprintln!("warning: `tidy` is not installed; diffs will not be generated");
     }
 
     log_config(&config);

src/tools/compiletest/src/runtest.rs

@@ -2367,6 +2367,9 @@ impl<'test> TestCx<'test> {
     }
 
     fn compare_to_default_rustdoc(&mut self, out_dir: &Path) {
+        if !self.config.has_tidy {
+            return;
+        }
         println!("info: generating a diff against nightly rustdoc");
 
         let suffix =
@@ -2428,10 +2431,8 @@ impl<'test> TestCx<'test> {
                 }
             }
         };
-        if self.config.has_tidy {
-            tidy_dir(out_dir);
-            tidy_dir(&compare_dir);
-        }
+        tidy_dir(out_dir);
+        tidy_dir(&compare_dir);
 
         let pager = {
             let output = Command::new("git").args(&["config", "--get", "core.pager"]).output().ok();