Pretty-print generators with their generator_kind

After removing `GenFuture`, I special-cased async generators to pretty-print as `impl Future<Output = X>` mainly to avoid too much diagnostics changes originally.

This now reverses that change so that async fn/blocks are pretty-printed as `[$movability `async` $something@$source-position]` in various diagnostics, and updates the tests that this touches.

Author: Swatinem

compiler/rustc_const_eval/src/transform/check_consts/ops.rs

@@ -381,7 +381,7 @@ impl<'tcx> NonConstOp<'tcx> for Generator {
         ccx: &ConstCx<'_, 'tcx>,
         span: Span,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-        let msg = format!("{}s are not allowed in {}s", self.0, ccx.const_kind());
+        let msg = format!("{}s are not allowed in {}s", self.0.descr(), ccx.const_kind());
         if let hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Block) = self.0 {
             ccx.tcx.sess.create_feature_err(
                 UnallowedOpInConstContext { span, msg },

compiler/rustc_hir/src/hir.rs

@@ -1514,9 +1514,9 @@ pub enum AsyncGeneratorKind {
 impl fmt::Display for AsyncGeneratorKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str(match self {
-            AsyncGeneratorKind::Block => "`async` block",
-            AsyncGeneratorKind::Closure => "`async` closure body",
-            AsyncGeneratorKind::Fn => "`async fn` body",
+            AsyncGeneratorKind::Block => "async block",
+            AsyncGeneratorKind::Closure => "async closure body",
+            AsyncGeneratorKind::Fn => "async fn body",
         })
     }
 }

compiler/rustc_hir_typeck/src/generator_interior/mod.rs

@@ -118,7 +118,8 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
                 } else {
                     let note = format!(
                         "the type is part of the {} because of this {}",
-                        self.kind, yield_data.source
+                        self.kind.descr(),
+                        yield_data.source
                     );
 
                     self.fcx

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -681,25 +681,20 @@ pub trait PrettyPrinter<'tcx>:
             }
             ty::Str => p!("str"),
             ty::Generator(did, substs, movability) => {
-                // FIXME(swatinem): async constructs used to be pretty printed
-                // as `impl Future` previously due to the `from_generator` wrapping.
-                // lets special case this here for now to avoid churn in diagnostics.
-                let generator_kind = self.tcx().generator_kind(did);
-                if matches!(generator_kind, Some(hir::GeneratorKind::Async(..))) {
-                    let return_ty = substs.as_generator().return_ty();
-                    p!(write("impl Future<Output = {}>", return_ty));
-
-                    return Ok(self);
-                }
-
                 p!(write("["));
-                match movability {
-                    hir::Movability::Movable => {}
-                    hir::Movability::Static => p!("static "),
+                let generator_kind = self.tcx().generator_kind(did).unwrap();
+                let should_print_movability =
+                    self.should_print_verbose() || generator_kind == hir::GeneratorKind::Gen;
+
+                if should_print_movability {
+                    match movability {
+                        hir::Movability::Movable => {}
+                        hir::Movability::Static => p!("static "),
+                    }
                 }
 
                 if !self.should_print_verbose() {
-                    p!("generator");
+                    p!(write("{}", generator_kind));
                     // FIXME(eddyb) should use `def_span`.
                     if let Some(did) = did.as_local() {
                         let span = self.tcx().def_span(did);

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -2677,7 +2677,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                                 let sp = self.tcx.def_span(def_id);
 
                                 // Special-case this to say "async block" instead of `[static generator]`.
-                                let kind = tcx.generator_kind(def_id).unwrap();
+                                let kind = tcx.generator_kind(def_id).unwrap().descr();
                                 err.span_note(
                                     sp,
                                     &format!("required because it's used within this {}", kind),

src/test/ui/async-await/async-block-control-flow-static-semantics.rs

@@ -15,7 +15,7 @@ fn return_targets_async_block_not_fn() -> u8 {
         return 0u8;
     };
     let _: &dyn Future<Output = ()> = &block;
-    //~^ ERROR expected `impl Future<Output = u8>` to be a future that resolves to `()`, but it resolves to `u8`
+    //~^ ERROR to be a future that resolves to `()`, but it resolves to `u8`
 }
 
 async fn return_targets_async_block_not_async_fn() -> u8 {
@@ -24,7 +24,7 @@ async fn return_targets_async_block_not_async_fn() -> u8 {
         return 0u8;
     };
     let _: &dyn Future<Output = ()> = &block;
-    //~^ ERROR expected `impl Future<Output = u8>` to be a future that resolves to `()`, but it resolves to `u8`
+    //~^ ERROR to be a future that resolves to `()`, but it resolves to `u8`
 }
 
 fn no_break_in_async_block() {

src/test/ui/async-await/async-block-control-flow-static-semantics.stderr

@@ -29,13 +29,13 @@ LL | |
 LL | | }
    | |_^ expected `u8`, found `()`
 
-error[E0271]: expected `impl Future<Output = u8>` to be a future that resolves to `()`, but it resolves to `u8`
+error[E0271]: expected `[async block@$DIR/async-block-control-flow-static-semantics.rs:23:17: 25:6]` to be a future that resolves to `()`, but it resolves to `u8`
   --> $DIR/async-block-control-flow-static-semantics.rs:26:39
    |
 LL |     let _: &dyn Future<Output = ()> = &block;
    |                                       ^^^^^^ expected `()`, found `u8`
    |
-   = note: required for the cast from `impl Future<Output = u8>` to the object type `dyn Future<Output = ()>`
+   = note: required for the cast from `[async block@$DIR/async-block-control-flow-static-semantics.rs:23:17: 25:6]` to the object type `dyn Future<Output = ()>`
 
 error[E0308]: mismatched types
   --> $DIR/async-block-control-flow-static-semantics.rs:12:43
@@ -45,13 +45,13 @@ LL | fn return_targets_async_block_not_fn() -> u8 {
    |    |
    |    implicitly returns `()` as its body has no tail or `return` expression
 
-error[E0271]: expected `impl Future<Output = u8>` to be a future that resolves to `()`, but it resolves to `u8`
+error[E0271]: expected `[async block@$DIR/async-block-control-flow-static-semantics.rs:14:17: 16:6]` to be a future that resolves to `()`, but it resolves to `u8`
   --> $DIR/async-block-control-flow-static-semantics.rs:17:39
    |
 LL |     let _: &dyn Future<Output = ()> = &block;
    |                                       ^^^^^^ expected `()`, found `u8`
    |
-   = note: required for the cast from `impl Future<Output = u8>` to the object type `dyn Future<Output = ()>`
+   = note: required for the cast from `[async block@$DIR/async-block-control-flow-static-semantics.rs:14:17: 16:6]` to the object type `dyn Future<Output = ()>`
 
 error[E0308]: mismatched types
   --> $DIR/async-block-control-flow-static-semantics.rs:49:44

src/test/ui/async-await/generator-desc.stderr

@@ -8,8 +8,8 @@ LL |     fun(async {}, async {});
    |         |         arguments to this function are incorrect
    |         the expected `async` block
    |
-   = note: expected `async` block `impl Future<Output = ()>` (`async` block)
-              found `async` block `impl Future<Output = ()>` (`async` block)
+   = note: expected `async` block `[async block@$DIR/generator-desc.rs:10:9: 10:17]`
+              found `async` block `[async block@$DIR/generator-desc.rs:10:19: 10:27]`
 note: function defined here
   --> $SRC_DIR/core/src/future/mod.rs:LL:COL
    |
@@ -53,8 +53,8 @@ LL |     fun((async || {})(), (async || {})());
    |     |             the expected `async` closure body
    |     arguments to this function are incorrect
    |
-   = note: expected `async` closure body `impl Future<Output = ()>` (`async` closure body)
-              found `async` closure body `impl Future<Output = ()>` (`async` closure body)
+   = note: expected `async` closure body `[async closure body@$DIR/generator-desc.rs:14:19: 14:21]`
+              found `async` closure body `[async closure body@$DIR/generator-desc.rs:14:36: 14:38]`
 note: function defined here
   --> $DIR/generator-desc.rs:8:4
    |

src/test/ui/async-await/issue-67252-unnamed-future.stderr

@@ -8,7 +8,7 @@ LL | |         AFuture.await;
 LL | |     });
    | |_____^ future created by async block is not `Send`
    |
-   = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `*mut ()`
+   = help: within `[async block@$DIR/issue-67252-unnamed-future.rs:18:11: 21:6]`, the trait `Send` is not implemented for `*mut ()`
 note: future is not `Send` as this value is used across an await
   --> $DIR/issue-67252-unnamed-future.rs:20:16
    |

src/test/ui/async-await/issue-86507.stderr

@@ -13,7 +13,7 @@ note: captured value is not `Send` because `&` references cannot be sent unless
    |
 LL |                     let x = x;
    |                             ^ has type `&T` which is not `Send`, because `T` is not `Sync`
-   = note: required for the cast from `impl Future<Output = ()>` to the object type `dyn Future<Output = ()> + Send`
+   = note: required for the cast from `[async block@$DIR/issue-86507.rs:18:17: 20:18]` to the object type `dyn Future<Output = ()> + Send`
 help: consider further restricting this bound
    |
 LL |     fn bar<'me, 'async_trait, T: Send + std::marker::Sync>(x: &'me T)