2 files changed, 38 insertions, 0 deletions
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index 8a697b4c514..f57197edeb7 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -328,6 +328,14 @@ pub(crate) struct TrackCallerOnMain {
 }
 
 #[derive(Diagnostic)]
+#[diag(hir_analysis_target_feature_on_main)]
+pub(crate) struct TargetFeatureOnMain {
+    #[primary_span]
+    #[label(hir_analysis_target_feature_on_main)]
+    pub main: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(hir_analysis_start_not_track_caller)]
 pub(crate) struct StartTrackCaller {
     #[primary_span]
@@ -337,6 +345,15 @@ pub(crate) struct StartTrackCaller {
 }
 
 #[derive(Diagnostic)]
+#[diag(hir_analysis_start_not_target_feature)]
+pub(crate) struct StartTargetFeature {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    pub start: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(hir_analysis_start_not_async, code = "E0752")]
 pub(crate) struct StartAsync {
     #[primary_span]
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index 6a4f5382878..62abcbbdc9f 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -283,6 +283,15 @@ fn check_main_fn_ty(tcx: TyCtxt<'_>, main_def_id: DefId) {
         error = true;
     }
 
+    if !tcx.codegen_fn_attrs(main_def_id).target_features.is_empty()
+        // Calling functions with `#[target_feature]` is not unsafe on WASM, see #84988
+        && !tcx.sess.target.is_like_wasm
+        && !tcx.sess.opts.actually_rustdoc
+    {
+        tcx.sess.emit_err(errors::TargetFeatureOnMain { main: main_span });
+        error = true;
+    }
+
     if error {
         return;
     }
@@ -373,6 +382,18 @@ fn check_start_fn_ty(tcx: TyCtxt<'_>, start_def_id: DefId) {
                             });
                             error = true;
                         }
+                        if attr.has_name(sym::target_feature)
+                            // Calling functions with `#[target_feature]` is
+                            // not unsafe on WASM, see #84988
+                            && !tcx.sess.target.is_like_wasm
+                            && !tcx.sess.opts.actually_rustdoc
+                        {
+                            tcx.sess.emit_err(errors::StartTargetFeature {
+                                span: attr.span,
+                                start: start_span,
+                            });
+                            error = true;
+                        }
                     }
 
                     if error {