Unconditionally run RevealAll pass and run it earlier

Author: oli-obk

Diff for: compiler/rustc_mir_transform/src/lib.rs

@@ -480,6 +480,7 @@ fn run_runtime_lowering_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
     let passes: &[&dyn MirPass<'tcx>] = &[
         // These next passes must be executed together
         &add_call_guards::CriticalCallEdges,
+        &reveal_all::RevealAll, // has to be done before drop elaboration, since we need to drop opaque types, too.
         &elaborate_drops::ElaborateDrops,
         // This will remove extraneous landing pads which are no longer
         // necessary as well as well as forcing any call in a non-unwinding
@@ -526,7 +527,6 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         body,
         &[
             &check_alignment::CheckAlignment,
-            &reveal_all::RevealAll, // has to be done before inlining, since inlined code is in RevealAll mode.
             &lower_slice_len::LowerSliceLenCalls, // has to be done before inlining, otherwise actual call will be almost always inlined. Also simple, so can just do first
             &unreachable_prop::UnreachablePropagation,
             &uninhabited_enum_branching::UninhabitedEnumBranching,

Diff for: compiler/rustc_mir_transform/src/reveal_all.rs

@@ -8,10 +8,6 @@ use rustc_middle::ty::{self, Ty, TyCtxt};
 pub struct RevealAll;
 
 impl<'tcx> MirPass<'tcx> for RevealAll {
-    fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
-        sess.mir_opt_level() >= 3 || super::inline::Inline.is_enabled(sess)
-    }
-
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         // Do not apply this transformation to generators.
         if body.generator.is_some() {

Diff for: tests/ui/polymorphization/generators.rs

@@ -32,6 +32,7 @@ where
 
 #[rustc_polymorphize_error]
 pub fn unused_type<T>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin {
+    //~^ ERROR item has unused generic parameters
     || {
         //~^ ERROR item has unused generic parameters
         yield 1;
@@ -57,6 +58,7 @@ pub fn used_type_in_return<R: Default>() -> impl Generator<(), Yield = u32, Retu
 
 #[rustc_polymorphize_error]
 pub fn unused_const<const T: u32>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin {
+    //~^ ERROR item has unused generic parameters
     || {
         //~^ ERROR item has unused generic parameters
         yield 1;

Diff for: tests/ui/polymorphization/generators.stderr

@@ -8,20 +8,34 @@ LL | #![feature(generic_const_exprs, generators, generator_trait, rustc_attrs)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error: item has unused generic parameters
-  --> $DIR/generators.rs:35:5
+  --> $DIR/generators.rs:36:5
    |
 LL | pub fn unused_type<T>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin {
    |                    - generic parameter `T` is unused
+LL |
 LL |     || {
    |     ^^
 
 error: item has unused generic parameters
-  --> $DIR/generators.rs:60:5
+  --> $DIR/generators.rs:34:8
+   |
+LL | pub fn unused_type<T>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin {
+   |        ^^^^^^^^^^^ - generic parameter `T` is unused
+
+error: item has unused generic parameters
+  --> $DIR/generators.rs:62:5
    |
 LL | pub fn unused_const<const T: u32>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin {
    |                     ------------ generic parameter `T` is unused
+LL |
 LL |     || {
    |     ^^
 
-error: aborting due to 2 previous errors; 1 warning emitted
+error: item has unused generic parameters
+  --> $DIR/generators.rs:60:8
+   |
+LL | pub fn unused_const<const T: u32>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin {
+   |        ^^^^^^^^^^^^ ------------ generic parameter `T` is unused
+
+error: aborting due to 4 previous errors; 1 warning emitted
 

Diff for: tests/ui/type-alias-impl-trait/destructure_tait-ice-113594.rs

@@ -0,0 +1,18 @@
+// build-pass
+
+#![feature(type_alias_impl_trait)]
+
+pub struct Foo {
+    /// This type must have nontrivial drop glue
+    field: String,
+}
+
+pub type Tait = impl Sized;
+
+pub fn ice_cold(beverage: Tait) {
+    // Must destructure at least one field of `Foo`
+    let Foo { field } = beverage;
+    _ = field;
+}
+
+fn main() {}