Auto merge of #2298 - InfRandomness:shim-error, r=RalfJung

Add `__error` to freebsd shims

Signed-off-by: InfRandomness <[email protected]>

Author: bors

ci.sh

@@ -60,7 +60,7 @@ case $HOST_TARGET in
     MIRI_TEST_TARGET=i686-unknown-linux-gnu run_tests
     MIRI_TEST_TARGET=aarch64-apple-darwin run_tests
     MIRI_TEST_TARGET=i686-pc-windows-msvc run_tests
-    MIRI_TEST_TARGET=x86_64-unknown-freebsd run_tests_minimal hello integer vec
+    MIRI_TEST_TARGET=x86_64-unknown-freebsd run_tests_minimal hello integer vec current_dir_with_isolation
     MIRI_TEST_TARGET=thumbv7em-none-eabihf MIRI_NO_STD=1 run_tests_minimal no_std # no_std embedded architecture
     ;;
   x86_64-apple-darwin)

src/shims/unix/freebsd/foreign_items.rs

@@ -24,6 +24,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                     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)