Construct DiagCtxt a bit earlier in build_session

Author: bjorn3

compiler/rustc_interface/src/interface.rs

@@ -442,7 +442,6 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
             locale_resources.push(codegen_backend.locale_resource());
 
             let mut sess = rustc_session::build_session(
-                early_dcx,
                 config.opts,
                 CompilerIO {
                     input: config.input,

compiler/rustc_interface/src/tests.rs

@@ -65,7 +65,6 @@ where
         static USING_INTERNAL_FEATURES: AtomicBool = AtomicBool::new(false);
 
         let sess = build_session(
-            early_dcx,
             sessopts,
             io,
             None,

compiler/rustc_session/src/session.rs

@@ -967,7 +967,6 @@ fn default_emitter(
 #[allow(rustc::bad_opt_access)]
 #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 pub fn build_session(
-    early_dcx: EarlyDiagCtxt,
     sopts: config::Options,
     io: CompilerIO,
     bundle: Option<Lrc<rustc_errors::FluentBundle>>,
@@ -992,14 +991,6 @@ pub fn build_session(
     let cap_lints_allow = sopts.lint_cap.is_some_and(|cap| cap == lint::Allow);
     let can_emit_warnings = !(warnings_allow || cap_lints_allow);
 
-    let host_triple = TargetTuple::from_tuple(config::host_tuple());
-    let (host, target_warnings) = Target::search(&host_triple, &sysroot).unwrap_or_else(|e| {
-        early_dcx.early_fatal(format!("Error loading host specification: {e}"))
-    });
-    for warning in target_warnings.warning_messages() {
-        early_dcx.early_warn(warning)
-    }
-
     let fallback_bundle = fallback_fluent_bundle(
         fluent_resources,
         sopts.unstable_opts.translate_directionality_markers,
@@ -1014,9 +1005,12 @@ pub fn build_session(
         dcx = dcx.with_ice_file(ice_file);
     }
 
-    // Now that the proper handler has been constructed, drop early_dcx to
-    // prevent accidental use.
-    drop(early_dcx);
+    let host_triple = TargetTuple::from_tuple(config::host_tuple());
+    let (host, target_warnings) = Target::search(&host_triple, &sysroot)
+        .unwrap_or_else(|e| dcx.handle().fatal(format!("Error loading host specification: {e}")));
+    for warning in target_warnings.warning_messages() {
+        dcx.handle().warn(warning)
+    }
 
     let self_profiler = if let SwitchWithOptPath::Enabled(ref d) = sopts.unstable_opts.self_profile
     {