monormophize required_itms

Author: RalfJung

compiler/rustc_middle/src/mir/mod.rs

@@ -311,7 +311,7 @@ impl<'tcx> CoroutineInfo<'tcx> {
 }
 
 /// Some item that needs to monomorphize successfully for a MIR body to be considered well-formed.
-#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable, TypeVisitable)]
 pub enum RequiredItem<'tcx> {
     Fn(DefId, GenericArgsRef<'tcx>),
     Drop(Ty<'tcx>),

compiler/rustc_monomorphize/src/collector.rs

@@ -734,6 +734,17 @@ impl<'a, 'tcx> MirUsedCollector<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
+    fn visit_body(&mut self, body: &mir::Body<'tcx>) {
+        for item in &body.required_items {
+            // All these also need monomorphization to ensure that if that leads to error, we find
+            // those errors.
+            let item = self.monomorphize(*item);
+            visit_required_item(self.tcx, item, self.output);
+        }
+
+        self.super_body(body);
+    }
+
     fn visit_rvalue(&mut self, rvalue: &mir::Rvalue<'tcx>, location: Location) {
         debug!("visiting rvalue {:?}", *rvalue);
 
@@ -915,6 +926,25 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
     }
 }
 
+fn visit_required_item<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    item: mir::RequiredItem<'tcx>,
+    output: &mut MonoItems<'tcx>,
+) {
+    let instance = match item {
+        mir::RequiredItem::Fn(def_id, args) => {
+            Instance::expect_resolve(tcx, ty::ParamEnv::reveal_all(), def_id, args)
+        }
+        mir::RequiredItem::Drop(ty) => Instance::resolve_drop_in_place(tcx, ty),
+    };
+    // We pretend this is a direct call, just to make sure this is visited at all.
+    // "indirect" would mean we also generate some shims, but we don't care about the
+    // generated code, just about the side-effect of code generation causing errors, so we
+    // can skip the shims.
+    // FIXME: track the span so that we can show it here.
+    visit_instance_use(tcx, instance, /*is_direct_call*/ true, DUMMY_SP, output);
+}
+
 fn visit_drop_use<'tcx>(
     tcx: TyCtxt<'tcx>,
     ty: Ty<'tcx>,

tests/ui/consts/monomorphization/dead-code-in-called-fn.no-opt.stderr

@@ -7,10 +7,6 @@ LL |     const C: () = panic!();
    = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: the above error was encountered while instantiating `fn called::<i32>`
-  --> $DIR/dead-code-in-called-fn.rs:22:5
-   |
-LL |     called::<i32>();
-   |     ^^^^^^^^^^^^^^^
 
 error: aborting due to 1 previous error
 

tests/ui/consts/monomorphization/dead-code-in-called-fn.opt.stderr

@@ -7,10 +7,6 @@ LL |     const C: () = panic!();
    = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: the above error was encountered while instantiating `fn called::<i32>`
-  --> $DIR/dead-code-in-called-fn.rs:22:5
-   |
-LL |     called::<i32>();
-   |     ^^^^^^^^^^^^^^^
 
 error: aborting due to 1 previous error
 

tests/ui/consts/monomorphization/dead-code-in-dead-fn.no-opt.stderr

@@ -7,10 +7,6 @@ LL |     const C: () = panic!();
    = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: the above error was encountered while instantiating `fn not_called::<i32>`
-  --> $DIR/dead-code-in-dead-fn.rs:22:9
-   |
-LL |         not_called::<T>();
-   |         ^^^^^^^^^^^^^^^^^
 
 error: aborting due to 1 previous error
 

tests/ui/consts/monomorphization/dead-code-in-dead-fn.opt.stderr

@@ -6,6 +6,8 @@ LL |     const C: () = panic!();
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
+note: the above error was encountered while instantiating `fn not_called::<i32>`
+
 error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0080`.

tests/ui/generics/post_monomorphization_error_backtrace.stderr

@@ -7,10 +7,6 @@ LL |         const V: () = assert!(std::mem::size_of::<T>() == 0);
    = note: this error originates in the macro `assert` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: the above error was encountered while instantiating `fn assert_zst::<u32>`
-  --> $DIR/post_monomorphization_error_backtrace.rs:18:5
-   |
-LL |     assert_zst::<U>()
-   |     ^^^^^^^^^^^^^^^^^
 
 error[E0080]: evaluation of `assert_zst::F::<i32>::V` failed
   --> $DIR/post_monomorphization_error_backtrace.rs:6:23
@@ -21,10 +17,6 @@ LL |         const V: () = assert!(std::mem::size_of::<T>() == 0);
    = note: this error originates in the macro `assert` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: the above error was encountered while instantiating `fn assert_zst::<i32>`
-  --> $DIR/post_monomorphization_error_backtrace.rs:18:5
-   |
-LL |     assert_zst::<U>()
-   |     ^^^^^^^^^^^^^^^^^
 
 error: aborting due to 2 previous errors