Auto merge of #78976 - GuillaumeGomez:rollup-endkih3, r=GuillaumeGomez

Rollup of 5 pull requests

Successful merges:

 - #78916 (extend const generics test suite)
 - #78921 (Improve the page title switch handling between search and doc)
 - #78933 (Don't print thread ids and names in `tracing` logs)
 - #78960 (Test default values for const parameters.)
 - #78971 (Update books)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_driver/src/lib.rs b/compiler/rustc_driver/src/lib.rs
index f434673c39e..a192c2eb94e 100644
--- a/compiler/rustc_driver/src/lib.rs
+++ b/compiler/rustc_driver/src/lib.rs
@@ -1288,12 +1288,12 @@ pub fn init_env_logger(env: &str) {
         .with_indent_lines(true)
         .with_ansi(true)
         .with_targets(true)
-        .with_thread_ids(true)
-        .with_thread_names(true)
         .with_wraparound(10)
         .with_verbose_exit(true)
         .with_verbose_entry(true)
         .with_indent_amount(2);
+    #[cfg(parallel_compiler)]
+    let layer = layer.with_thread_ids(true).with_thread_names(true);
 
     use tracing_subscriber::layer::SubscriberExt;
     let subscriber = tracing_subscriber::Registry::default().with(filter).with(layer);