rustc_driver: Enable the WARN log level by default

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -843,19 +843,18 @@ fn link_natively<'a, B: ArchiveBuilder<'a>>(
         let msg_bus = "clang: error: unable to execute command: Bus error: 10";
         if out.contains(msg_segv) || out.contains(msg_bus) {
             warn!(
+                ?cmd, %out,
                 "looks like the linker segfaulted when we tried to call it, \
-                 automatically retrying again. cmd = {:?}, out = {}.",
-                cmd, out,
+                 automatically retrying again",
             );
             continue;
         }
 
         if is_illegal_instruction(&output.status) {
             warn!(
+                ?cmd, %out, status = %output.status,
                 "looks like the linker hit an illegal instruction when we \
-                 tried to call it, automatically retrying again. cmd = {:?}, ]\
-                 out = {}, status = {}.",
-                cmd, out, output.status,
+                 tried to call it, automatically retrying again.",
             );
             continue;
         }

compiler/rustc_driver/src/lib.rs

@@ -1253,12 +1253,16 @@ pub fn init_rustc_env_logger() {
 /// tracing crate version. In contrast to `init_rustc_env_logger` it allows you to choose an env var
 /// other than `RUSTC_LOG`.
 pub fn init_env_logger(env: &str) {
-    // Don't register a dispatcher if there's no filter to print anything
-    match std::env::var(env) {
-        Err(_) => return,
-        Ok(s) if s.is_empty() => return,
-        Ok(_) => {}
-    }
+    use tracing_subscriber::{
+        filter::{self, EnvFilter, LevelFilter},
+        layer::SubscriberExt,
+    };
+
+    let filter = match std::env::var(env) {
+        Ok(env) => EnvFilter::from_env(env),
+        _ => EnvFilter::default().add_directive(filter::Directive::from(LevelFilter::WARN)),
+    };
+
     let color_logs = match std::env::var(String::from(env) + "_COLOR") {
         Ok(value) => match value.as_ref() {
             "always" => true,
@@ -1278,7 +1282,7 @@ pub fn init_env_logger(env: &str) {
             "non-Unicode log color value: expected one of always, never, or auto",
         ),
     };
-    let filter = tracing_subscriber::EnvFilter::from_env(env);
+
     let layer = tracing_tree::HierarchicalLayer::default()
         .with_writer(io::stderr)
         .with_indent_lines(true)
@@ -1288,7 +1292,6 @@ pub fn init_env_logger(env: &str) {
     #[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);
     tracing::subscriber::set_global_default(subscriber).unwrap();
 }

compiler/rustc_errors/src/emitter.rs

@@ -2308,7 +2308,7 @@ pub fn is_case_difference(sm: &SourceMap, suggested: &str, sp: Span) -> bool {
     let found = match sm.span_to_snippet(sp) {
         Ok(snippet) => snippet,
         Err(e) => {
-            warn!("Invalid span {:?}. Err={:?}", sp, e);
+            warn!(error = ?e, "Invalid span {:?}", sp);
             return false;
         }
     };

compiler/rustc_mir_dataflow/src/rustc_peek.rs

@@ -289,7 +289,7 @@ impl<'tcx> RustcPeekAt<'tcx> for MaybeMutBorrowedLocals<'_, 'tcx> {
         flow_state: &BitSet<Local>,
         call: PeekCall,
     ) {
-        warn!("peek_at: place={:?}", place);
+        info!(?place, "peek_at");
         let local = if let Some(l) = place.as_local() {
             l
         } else {
@@ -311,7 +311,7 @@ impl<'tcx> RustcPeekAt<'tcx> for MaybeLiveLocals {
         flow_state: &BitSet<Local>,
         call: PeekCall,
     ) {
-        warn!("peek_at: place={:?}", place);
+        info!(?place, "peek_at");
         let local = if let Some(l) = place.as_local() {
             l
         } else {

src/test/ui/consts/const_in_pattern/issue-73431.stderr

@@ -0,0 +1 @@
+WARN rustc_mir_build::thir::pattern::const_to_pat MIR const-checker found novel structural match violation. See #73448.