make unused flags work like they used to

Author: RalfJung

src/shims/backtrace.rs

@@ -104,8 +104,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 for (i, ptr) in ptrs.into_iter().enumerate() {
                     let offset = ptr_layout.size * i.try_into().unwrap();
 
-                    let op_place =
-                        buf_place.offset(offset, ptr_layout, this)?;
+                    let op_place = buf_place.offset(offset, ptr_layout, this)?;
 
                     this.write_pointer(ptr, &op_place.into())?;
                 }

src/shims/windows/foreign_items.rs

@@ -152,21 +152,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                     .collect();
 
                 // Set page size.
-                let page_size = system_info.offset(
-                    field_offsets[2],
-                    dword_layout,
-                    &this.tcx,
-                )?;
+                let page_size = system_info.offset(field_offsets[2], dword_layout, &this.tcx)?;
                 this.write_scalar(
                     Scalar::from_int(PAGE_SIZE, dword_layout.size),
                     &page_size.into(),
                 )?;
                 // Set number of processors.
-                let num_cpus = system_info.offset(
-                    field_offsets[6],
-                    dword_layout,
-                    &this.tcx,
-                )?;
+                let num_cpus = system_info.offset(field_offsets[6], dword_layout, &this.tcx)?;
                 this.write_scalar(Scalar::from_int(NUM_CPUS, dword_layout.size), &num_cpus.into())?;
             }
 

tests/compiletest.rs

@@ -19,9 +19,10 @@ fn run_tests(mode: Mode, path: &str, target: Option<String>) -> Result<()> {
         // Less aggressive warnings to make the rustc toolstate management less painful.
         // (We often get warnings when e.g. a feature gets stabilized or some lint gets added/improved.)
         flags.push("-Astable-features".to_owned());
+        flags.push("-Aunused".to_owned());
     } else {
         flags.push("-Dwarnings".to_owned());
-        flags.push("-Dunused".to_owned()); // overwrite the -Aunused in compiletest-rs
+        flags.push("-Dunused".to_owned());
     }
     if let Ok(sysroot) = env::var("MIRI_SYSROOT") {
         flags.push("--sysroot".to_string());