use rustc_middle::mir;
use rustc_span::Symbol;
use rustc_target::spec::abi::Abi;

use crate::*;
use shims::foreign_items::EmulateByNameResult;

impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}

pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
    fn emulate_foreign_item_by_name(
        &mut self,
        link_name: Symbol,
        abi: Abi,
        args: &[OpTy<'tcx, Tag>],
        dest: &PlaceTy<'tcx, Tag>,
        _ret: mir::BasicBlock,
    ) -> InterpResult<'tcx, EmulateByNameResult<'mir, 'tcx>> {
        let this = self.eval_context_mut();
        match link_name.as_str() {
            // Linux's `pthread_getattr_np` equivalent
            "pthread_attr_get_np" if this.frame_in_std() => {
                let [_thread, _attr] =
                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
                this.write_null(dest)?;
            }

            // errno
            "__error" => {
                let [] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
                let errno_place = this.last_error_place()?;
                this.write_scalar(errno_place.to_ref(this).to_scalar()?, dest)?;
            }

            _ => return Ok(EmulateByNameResult::NotSupported),
        }
        Ok(EmulateByNameResult::NeedsJumping)
    }
}

use rustc_middle::mir;
use rustc_span::Symbol;
use rustc_target::spec::abi::Abi;

use crate::*;
use shims::foreign_items::EmulateByNameResult;

impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}

pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
    fn emulate_foreign_item_by_name(
        &mut self,
        link_name: Symbol,
        abi: Abi,
        args: &[OpTy<'tcx, Tag>],
        dest: &PlaceTy<'tcx, Tag>,
        _ret: mir::BasicBlock,
    ) -> InterpResult<'tcx, EmulateByNameResult<'mir, 'tcx>> {
        let this = self.eval_context_mut();
        match link_name.as_str() {
            // Linux's `pthread_getattr_np` equivalent
            "pthread_attr_get_np" if this.frame_in_std() => {
                let [_thread, _attr] =
                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
                this.write_null(dest)?;
            }
            _ => return Ok(EmulateByNameResult::NotSupported),
        }
        Ok(EmulateByNameResult::NeedsJumping)
    }
}

--- 
+++ 
@@ -24,6 +24,14 @@
                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
                 this.write_null(dest)?;
             }
+
+            // errno
+            "__error" => {
+                let [] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
+                let errno_place = this.last_error_place()?;
+                this.write_scalar(errno_place.to_ref(this).to_scalar()?, dest)?;
+            }
+
             _ => return Ok(EmulateByNameResult::NotSupported),
         }
         Ok(EmulateByNameResult::NeedsJumping)
Add `__error` to freebsd shims

Signed-off-by: InfRandomness <869edcf8359095948eaaa37ad8a94f96bdf1079b@gmail.com>
