3 files changed, 11 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_ssa/messages.ftl b/compiler/rustc_codegen_ssa/messages.ftl
index de37de09f5a..186b8171dd8 100644
--- a/compiler/rustc_codegen_ssa/messages.ftl
+++ b/compiler/rustc_codegen_ssa/messages.ftl
@@ -30,6 +30,8 @@ codegen_ssa_copy_path = could not copy {$from} to {$to}: {$error}
 
 codegen_ssa_copy_path_buf = unable to copy {$source_file} to {$output_path}: {$error}
 
+codegen_ssa_cpu_required = target requires explicitly specifying a cpu with `-C target-cpu`
+
 codegen_ssa_create_temp_dir = couldn't create a temp dir: {$error}
 
 codegen_ssa_dlltool_fail_import_library =
diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs
index e438bd70c51..83a9e6e2309 100644
--- a/compiler/rustc_codegen_ssa/src/base.rs
+++ b/compiler/rustc_codegen_ssa/src/base.rs
@@ -615,6 +615,11 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
         return ongoing_codegen;
     }
 
+    if tcx.sess.target.need_explicit_cpu && tcx.sess.opts.cg.target_cpu.is_none() {
+        // The target has no default cpu, but none is set explicitly
+        tcx.dcx().emit_fatal(errors::CpuRequired);
+    }
+
     let cgu_name_builder = &mut CodegenUnitNameBuilder::new(tcx);
 
     // Run the monomorphization collector and partition the collected items into
diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs
index 5e684632fb2..f3afb37a9ef 100644
--- a/compiler/rustc_codegen_ssa/src/errors.rs
+++ b/compiler/rustc_codegen_ssa/src/errors.rs
@@ -524,6 +524,10 @@ pub(crate) struct CheckInstalledVisualStudio;
 pub(crate) struct InsufficientVSCodeProduct;
 
 #[derive(Diagnostic)]
+#[diag(codegen_ssa_cpu_required)]
+pub(crate) struct CpuRequired;
+
+#[derive(Diagnostic)]
 #[diag(codegen_ssa_processing_dymutil_failed)]
 #[note]
 pub(crate) struct ProcessingDymutilFailed {