ralfs comments

Author: Ellen Arteca

src/machine.rs

@@ -363,6 +363,7 @@ pub struct Evaluator<'mir, 'tcx> {
 
 impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
     pub(crate) fn new(config: &MiriConfig, layout_cx: LayoutCx<'tcx, TyCtxt<'tcx>>) -> Self {
+        let target_triple = &layout_cx.tcx.sess.opts.target_triple.to_string();
         let local_crates = helpers::get_local_crates(layout_cx.tcx);
         let layouts =
             PrimitiveLayouts::new(layout_cx).expect("Couldn't get layouts of primitive types");
@@ -414,6 +415,12 @@ impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
             report_progress: config.report_progress,
             since_progress_report: 0,
             external_so_lib: config.external_so_file.as_ref().map(|lib_file_path| {
+                // Check if host target == the session target.
+                if option_env!("TARGET") == Some(target_triple) {
+                    panic!(
+                        "calling external C functions in linked .so file requires target and host to be the same"
+                    );
+                }
                 // Note: it is the user's responsibility to provide a correct SO file.
                 // WATCH OUT: If an invalid/incorrect SO file is specified, this can cause
                 // undefined behaviour in Miri itself!

src/shims/ffi_support.rs

@@ -221,16 +221,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
 
         let this = self.eval_context_mut();
 
-        // Check if host target == the session target.
-        // This check needs to happen _after_ we check if the shared object file does not
-        // export the function: we don't want to throw an error if we are just going to use
-        // one of the shims.
-        if option_env!("TARGET") == Some(&this.tcx.sess.opts.target_triple.to_string()) {
-            throw_ub_format!(
-                "calling external C functions in linked .so file requires target and host to be the same"
-            );
-        }
-
         // Get the function arguments, and convert them to `libffi`-compatible form.
         let mut libffi_args = Vec::<CArg>::with_capacity(args.len());
         for cur_arg in args.iter() {