check RPITs for invalid args

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -441,27 +441,17 @@ fn check_opaque_type_parameter_valid<'tcx>(
     opaque_type_key: OpaqueTypeKey<'tcx>,
     span: Span,
 ) -> Result<(), ErrorGuaranteed> {
-    let opaque_ty_hir = tcx.hir().expect_item(opaque_type_key.def_id);
-    let (_parent, is_ty_alias) = match opaque_ty_hir.expect_opaque_ty().origin {
-        OpaqueTyOrigin::TyAlias { parent, .. } => (parent, true),
-        OpaqueTyOrigin::AsyncFn(parent) | OpaqueTyOrigin::FnReturn(parent) => (parent, false),
-    };
-
     let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
     let opaque_env = LazyOpaqueTyEnv::new(tcx, opaque_type_key.def_id);
     let mut seen_params: FxIndexMap<_, Vec<_>> = FxIndexMap::default();
 
     for (i, arg) in opaque_type_key.iter_captured_args(tcx) {
         let arg_is_param = match arg.unpack() {
             GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
-            GenericArgKind::Lifetime(lt) if is_ty_alias => {
+            GenericArgKind::Lifetime(lt) => {
                 matches!(*lt, ty::ReEarlyParam(_) | ty::ReLateParam(_))
                     || (lt.is_static() && opaque_env.param_equal_static(i))
             }
-            // FIXME(#113916): we can't currently check for unique lifetime params,
-            // see that issue for more. We will also have to ignore unused lifetime
-            // params for RPIT, but that's comparatively trivial ✨
-            GenericArgKind::Lifetime(_) => continue,
             GenericArgKind::Const(ct) => matches!(ct.kind(), ty::ConstKind::Param(_)),
         };
 

tests/ui/impl-trait/defining-use-captured-non-universal-region.infer.stderr

@@ -0,0 +1,12 @@
+error[E0792]: expected generic lifetime parameter, found `'_`
+  --> $DIR/defining-use-captured-non-universal-region.rs:15:18
+   |
+LL | fn foo<'a>() -> impl Sized + 'a {
+   |                              -- this generic parameter must be used with a generic lifetime parameter
+...
+LL |     let i: i32 = foo::<'_>();
+   |                  ^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0792`.

tests/ui/impl-trait/defining-use-captured-non-universal-region.rs

@@ -0,0 +1,24 @@
+// This was an ICE. See #110726.
+// FIXME(aliemjay): outdated due to "once modulo regions" restriction.
+
+//@ revisions: statik infer fixed
+//@ [fixed] check-pass
+#![allow(unconditional_recursion)]
+
+fn foo<'a>() -> impl Sized + 'a {
+    #[cfg(statik)]
+    let i: i32 = foo::<'static>();
+    //[statik]~^ ERROR opaque type used twice with different lifetimes
+    //[statik]~| ERROR opaque type used twice with different lifetimes
+
+    #[cfg(infer)]
+    let i: i32 = foo::<'_>();
+    //[infer]~^ ERROR expected generic lifetime parameter, found `'_`
+
+    #[cfg(fixed)]
+    let i: i32 = foo::<'a>();
+
+    i
+}
+
+fn main() {}

tests/ui/impl-trait/defining-use-captured-non-universal-region.statik.stderr

@@ -0,0 +1,33 @@
+error: opaque type used twice with different lifetimes
+  --> $DIR/defining-use-captured-non-universal-region.rs:10:18
+   |
+LL |     let i: i32 = foo::<'static>();
+   |                  ^^^^^^^^^^^^^^^^ lifetime `'static` used here
+...
+LL |     i
+   |     - lifetime `'a` previously used here
+   |
+note: if all non-lifetime generic parameters are the same, but the lifetime parameters differ, it is not possible to differentiate the opaque types
+  --> $DIR/defining-use-captured-non-universal-region.rs:10:18
+   |
+LL |     let i: i32 = foo::<'static>();
+   |                  ^^^^^^^^^^^^^^^^
+
+error: opaque type used twice with different lifetimes
+  --> $DIR/defining-use-captured-non-universal-region.rs:10:18
+   |
+LL |     let i: i32 = foo::<'static>();
+   |                  ^^^^^^^^^^^^^^^^ lifetime `'static` used here
+...
+LL |     i
+   |     - lifetime `'a` previously used here
+   |
+note: if all non-lifetime generic parameters are the same, but the lifetime parameters differ, it is not possible to differentiate the opaque types
+  --> $DIR/defining-use-captured-non-universal-region.rs:10:18
+   |
+LL |     let i: i32 = foo::<'static>();
+   |                  ^^^^^^^^^^^^^^^^
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: aborting due to 2 previous errors
+

tests/ui/impl-trait/impl-fn-predefined-lifetimes.rs

@@ -2,10 +2,8 @@
 use std::fmt::Debug;
 
 fn a<'a>() -> impl Fn(&'a u8) -> (impl Debug + '_) {
-    //~^ ERROR cannot resolve opaque type
-
     |x| x
-    //~^ ERROR concrete type differs from previous defining opaque type use
+    //~^ ERROR expected generic lifetime parameter, found `'_`
 }
 
 fn _b<'a>() -> impl Fn(&'a u8) -> (impl Debug + 'a) {

tests/ui/impl-trait/impl-fn-predefined-lifetimes.stderr

@@ -1,21 +1,11 @@
-error: concrete type differs from previous defining opaque type use
-  --> $DIR/impl-fn-predefined-lifetimes.rs:7:9
-   |
-LL |     |x| x
-   |         ^ expected `impl Debug + '_`, got `&u8`
-   |
-note: previous use here
-  --> $DIR/impl-fn-predefined-lifetimes.rs:7:5
-   |
-LL |     |x| x
-   |     ^^^^^
-
-error[E0720]: cannot resolve opaque type
-  --> $DIR/impl-fn-predefined-lifetimes.rs:4:35
+error[E0792]: expected generic lifetime parameter, found `'_`
+  --> $DIR/impl-fn-predefined-lifetimes.rs:5:9
    |
 LL | fn a<'a>() -> impl Fn(&'a u8) -> (impl Debug + '_) {
-   |                                   ^^^^^^^^^^^^^^^ cannot resolve opaque type
+   |                                                -- this generic parameter must be used with a generic lifetime parameter
+LL |     |x| x
+   |         ^
 
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0720`.
+For more information about this error, try `rustc --explain E0792`.

tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.rs

@@ -5,6 +5,7 @@ trait Foo {
     fn bar<'other: 'a>() -> impl Sized + 'a {}
     //~^ ERROR use of undeclared lifetime name `'a`
     //~| ERROR use of undeclared lifetime name `'a`
+    //~| ERROR expected generic lifetime parameter, found `'static`
 }
 
 fn main() {}

tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.stderr

@@ -28,6 +28,15 @@ help: consider introducing lifetime `'a` here
 LL | trait Foo<'a> {
    |          ++++
 
-error: aborting due to 2 previous errors
+error[E0792]: expected generic lifetime parameter, found `'static`
+  --> $DIR/bad-item-bound-within-rpitit-2.rs:5:45
+   |
+LL |     fn bar<'other: 'a>() -> impl Sized + 'a {}
+   |            ------                           ^^
+   |            |
+   |            cannot use static lifetime; use a bound lifetime instead or remove the lifetime parameter from the opaque type
+
+error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0261`.
+Some errors have detailed explanations: E0261, E0792.
+For more information about an error, try `rustc --explain E0261`.

tests/ui/impl-trait/rpit/early_bound.rs

@@ -5,6 +5,7 @@ fn test<'a: 'a>(n: bool) -> impl Sized + 'a {
     let true = n else { loop {} };
     let _ = || {
         let _ = identity::<&'a ()>(test(false));
+        //~^ ERROR expected generic lifetime parameter, found `'_`
     };
     loop {}
 }

tests/ui/impl-trait/rpit/early_bound.stderr

@@ -1,3 +1,12 @@
+error[E0792]: expected generic lifetime parameter, found `'_`
+  --> $DIR/early_bound.rs:7:17
+   |
+LL | fn test<'a: 'a>(n: bool) -> impl Sized + 'a {
+   |                                          -- this generic parameter must be used with a generic lifetime parameter
+...
+LL |         let _ = identity::<&'a ()>(test(false));
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 error: concrete type differs from previous defining opaque type use
   --> $DIR/early_bound.rs:3:29
    |
@@ -10,5 +19,6 @@ note: previous use here
 LL |         let _ = identity::<&'a ()>(test(false));
    |                                    ^^^^^^^^^^^
 
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0792`.

tests/ui/impl-trait/rpit/non-defining-use-lifetimes.rs

@@ -1,6 +1,5 @@
 // issue: #111935
 // FIXME(aliemjay): outdated due to "once modulo regions" restriction.
-// FIXME(aliemjay): mod `infer` should fail.
 
 #![allow(unconditional_recursion)]
 
@@ -22,6 +21,7 @@ mod infer {
     // invalid defining use: Opaque<'_> := ()
     fn foo<'a>(_: Lt<'a>) -> impl Sized + 'a {
         let _: () = foo(Lt::<'_>::None);
+        //~^ ERROR expected generic lifetime parameter, found `'_`
     }
 }
 

tests/ui/impl-trait/rpit/non-defining-use-lifetimes.stderr

@@ -1,5 +1,5 @@
 error: opaque type used twice with different lifetimes
-  --> $DIR/non-defining-use-lifetimes.rs:15:16
+  --> $DIR/non-defining-use-lifetimes.rs:14:16
    |
 LL |       fn foo<'a>(_: Lt<'a>) -> impl Sized + 'a {
    |  ______________________________________________-
@@ -10,11 +10,19 @@ LL | |     }
    | |_____- lifetime `'a` previously used here
    |
 note: if all non-lifetime generic parameters are the same, but the lifetime parameters differ, it is not possible to differentiate the opaque types
-  --> $DIR/non-defining-use-lifetimes.rs:15:16
+  --> $DIR/non-defining-use-lifetimes.rs:14:16
    |
 LL |         let _: () = foo(Lt::<'static>::None);
    |                ^^
 
+error[E0792]: expected generic lifetime parameter, found `'_`
+  --> $DIR/non-defining-use-lifetimes.rs:23:16
+   |
+LL |     fn foo<'a>(_: Lt<'a>) -> impl Sized + 'a {
+   |                                           -- this generic parameter must be used with a generic lifetime parameter
+LL |         let _: () = foo(Lt::<'_>::None);
+   |                ^^
+
 error: opaque type used twice with different lifetimes
   --> $DIR/non-defining-use-lifetimes.rs:33:16
    |
@@ -32,5 +40,6 @@ note: if all non-lifetime generic parameters are the same, but the lifetime para
 LL |         let _: () = foo(Lt::<'a>::None, Lt::<'a>::None);
    |                ^^
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0792`.

tests/ui/type-alias-impl-trait/hkl_forbidden4.rs

@@ -13,6 +13,7 @@ type FutNothing<'a> = impl 'a + Future<Output = ()>;
 async fn operation(_: &mut ()) -> () {
     //~^ ERROR: concrete type differs from previous
     call(operation).await
+    //~^ ERROR: expected generic lifetime parameter, found `'any`
 }
 
 async fn call<F>(_f: F)

tests/ui/type-alias-impl-trait/hkl_forbidden4.stderr

@@ -6,20 +6,17 @@ LL | type FutNothing<'a> = impl 'a + Future<Output = ()>;
    |
    = note: `FutNothing` must be used in combination with a concrete type within the same module
 
-error: concrete type differs from previous defining opaque type use
-  --> $DIR/hkl_forbidden4.rs:13:1
-   |
-LL | async fn operation(_: &mut ()) -> () {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `FutNothing<'_>`, got `{async fn body of operation()}`
-   |
-note: previous use here
+error[E0792]: expected generic lifetime parameter, found `'any`
   --> $DIR/hkl_forbidden4.rs:15:5
    |
+LL | async fn operation(_: &mut ()) -> () {
+   |                       - this generic parameter must be used with a generic lifetime parameter
+LL |
 LL |     call(operation).await
    |     ^^^^^^^^^^^^^^^
 
 error[E0792]: expected generic lifetime parameter, found `'any`
-  --> $DIR/hkl_forbidden4.rs:21:1
+  --> $DIR/hkl_forbidden4.rs:22:1
    |
 LL |   type FutNothing<'a> = impl 'a + Future<Output = ()>;
    |                   -- this generic parameter must be used with a generic lifetime parameter
@@ -29,6 +26,18 @@ LL | |
 LL | | }
    | |_^
 
-error: aborting due to 3 previous errors
+error: concrete type differs from previous defining opaque type use
+  --> $DIR/hkl_forbidden4.rs:13:1
+   |
+LL | async fn operation(_: &mut ()) -> () {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `FutNothing<'_>`, got `{async fn body of operation()}`
+   |
+note: previous use here
+  --> $DIR/hkl_forbidden4.rs:15:5
+   |
+LL |     call(operation).await
+   |     ^^^^^^^^^^^^^^^
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0792`.