Remove opaque type obligation and just register opaque types as they are encountered.

This also registers obligations for the hidden type immediately.

2 files changed, 52 insertions, 32 deletions

diff --git a/src/test/ui/parser/fn-header-semantic-fail.rs b/src/test/ui/parser/fn-header-semantic-fail.rs
index cf5d3dab4aa..c2954868f78 100644
--- a/src/test/ui/parser/fn-header-semantic-fail.rs
+++ b/src/test/ui/parser/fn-header-semantic-fail.rs
@@ -27,6 +27,7 @@ fn main() {
     struct Y;
     impl X for Y {
         async fn ft1() {} //~ ERROR functions in traits cannot be declared `async`
+        //~^ ERROR impl has stricter requirements than trait
         unsafe fn ft2() {} // OK.
         const fn ft3() {} //~ ERROR functions in traits cannot be declared const
         extern "C" fn ft4() {}
@@ -35,6 +36,7 @@ fn main() {
         //~| ERROR functions in traits cannot be declared const
         //~| ERROR functions cannot be both `const` and `async`
         //~| ERROR cycle detected
+        //~| ERROR impl has stricter requirements than trait
     }
 
     impl Y {
diff --git a/src/test/ui/parser/fn-header-semantic-fail.stderr b/src/test/ui/parser/fn-header-semantic-fail.stderr
index 1d7460b8d36..bd3b9181123 100644
--- a/src/test/ui/parser/fn-header-semantic-fail.stderr
+++ b/src/test/ui/parser/fn-header-semantic-fail.stderr
@@ -62,19 +62,19 @@ LL |         async fn ft1() {}
    = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
 
 error[E0379]: functions in traits cannot be declared const
-  --> $DIR/fn-header-semantic-fail.rs:31:9
+  --> $DIR/fn-header-semantic-fail.rs:32:9
    |
 LL |         const fn ft3() {}
    |         ^^^^^ functions in traits cannot be const
 
 error[E0379]: functions in traits cannot be declared const
-  --> $DIR/fn-header-semantic-fail.rs:33:9
+  --> $DIR/fn-header-semantic-fail.rs:34:9
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |         ^^^^^ functions in traits cannot be const
 
 error[E0706]: functions in traits cannot be declared `async`
-  --> $DIR/fn-header-semantic-fail.rs:33:9
+  --> $DIR/fn-header-semantic-fail.rs:34:9
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |         ^^^^^^-----^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -85,7 +85,7 @@ LL |         const async unsafe extern "C" fn ft5() {}
    = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
 
 error: functions cannot be both `const` and `async`
-  --> $DIR/fn-header-semantic-fail.rs:33:9
+  --> $DIR/fn-header-semantic-fail.rs:34:9
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |         ^^^^^-^^^^^------------------------------
@@ -94,7 +94,7 @@ LL |         const async unsafe extern "C" fn ft5() {}
    |         `const` because of this
 
 error: functions cannot be both `const` and `async`
-  --> $DIR/fn-header-semantic-fail.rs:45:9
+  --> $DIR/fn-header-semantic-fail.rs:47:9
    |
 LL |         const async unsafe extern "C" fn fi5() {}
    |         ^^^^^-^^^^^------------------------------
@@ -103,7 +103,7 @@ LL |         const async unsafe extern "C" fn fi5() {}
    |         `const` because of this
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:51:18
+  --> $DIR/fn-header-semantic-fail.rs:53:18
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -116,7 +116,7 @@ LL |         fn fe1();
    |         ~~
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:52:19
+  --> $DIR/fn-header-semantic-fail.rs:54:19
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -130,7 +130,7 @@ LL |         fn fe2();
    |         ~~
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:53:18
+  --> $DIR/fn-header-semantic-fail.rs:55:18
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -144,7 +144,7 @@ LL |         fn fe3();
    |         ~~
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:54:23
+  --> $DIR/fn-header-semantic-fail.rs:56:23
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -158,7 +158,7 @@ LL |         fn fe4();
    |         ~~
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:55:42
+  --> $DIR/fn-header-semantic-fail.rs:57:42
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -172,7 +172,7 @@ LL |         fn fe5();
    |         ~~
 
 error: functions cannot be both `const` and `async`
-  --> $DIR/fn-header-semantic-fail.rs:55:9
+  --> $DIR/fn-header-semantic-fail.rs:57:9
    |
 LL |         const async unsafe extern "C" fn fe5();
    |         ^^^^^-^^^^^----------------------------
@@ -216,30 +216,48 @@ LL | |     }
 LL | | }
    | |_^
 
-error[E0391]: cycle detected when computing type of `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 38:6>::ft5::{opaque#0}`
-  --> $DIR/fn-header-semantic-fail.rs:33:48
+error[E0276]: impl has stricter requirements than trait
+  --> $DIR/fn-header-semantic-fail.rs:29:9
+   |
+LL |         async fn ft1();
+   |         --------------- definition of `ft1` from trait
+...
+LL |         async fn ft1() {}
+   |         ^^^^^^^^^^^^^^ impl has extra requirement `(): Future`
+
+error[E0276]: impl has stricter requirements than trait
+  --> $DIR/fn-header-semantic-fail.rs:34:9
+   |
+LL |         const async unsafe extern "C" fn ft5();
+   |         --------------------------------------- definition of `ft5` from trait
+...
+LL |         const async unsafe extern "C" fn ft5() {}
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `(): Future`
+
+error[E0391]: cycle detected when computing type of `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 40:6>::ft5::{opaque#0}`
+  --> $DIR/fn-header-semantic-fail.rs:34:48
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |                                                ^
    |
-note: ...which requires borrow-checking `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 38:6>::ft5`...
-  --> $DIR/fn-header-semantic-fail.rs:33:9
+note: ...which requires borrow-checking `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 40:6>::ft5`...
+  --> $DIR/fn-header-semantic-fail.rs:34:9
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires processing `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 38:6>::ft5`...
-  --> $DIR/fn-header-semantic-fail.rs:33:9
+note: ...which requires processing `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 40:6>::ft5`...
+  --> $DIR/fn-header-semantic-fail.rs:34:9
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires const checking `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 38:6>::ft5`...
-  --> $DIR/fn-header-semantic-fail.rs:33:9
+note: ...which requires const checking `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 40:6>::ft5`...
+  --> $DIR/fn-header-semantic-fail.rs:34:9
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: ...which requires computing whether `impl core::future::future::Future<Output = ()>` is freeze...
    = note: ...which requires evaluating trait selection obligation `impl core::future::future::Future<Output = ()>: core::marker::Freeze`...
-   = note: ...which again requires computing type of `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 38:6>::ft5::{opaque#0}`, completing the cycle
+   = note: ...which again requires computing type of `main::<impl at $DIR/fn-header-semantic-fail.rs:28:5: 40:6>::ft5::{opaque#0}`, completing the cycle
 note: cycle used when checking item types in top-level module
   --> $DIR/fn-header-semantic-fail.rs:5:1
    |
@@ -252,30 +270,30 @@ LL | |     }
 LL | | }
    | |_^
 
-error[E0391]: cycle detected when computing type of `main::<impl at $DIR/fn-header-semantic-fail.rs:40:5: 48:6>::fi5::{opaque#0}`
-  --> $DIR/fn-header-semantic-fail.rs:45:48
+error[E0391]: cycle detected when computing type of `main::<impl at $DIR/fn-header-semantic-fail.rs:42:5: 50:6>::fi5::{opaque#0}`
+  --> $DIR/fn-header-semantic-fail.rs:47:48
    |
 LL |         const async unsafe extern "C" fn fi5() {}
    |                                                ^
    |
-note: ...which requires borrow-checking `main::<impl at $DIR/fn-header-semantic-fail.rs:40:5: 48:6>::fi5`...
-  --> $DIR/fn-header-semantic-fail.rs:45:9
+note: ...which requires borrow-checking `main::<impl at $DIR/fn-header-semantic-fail.rs:42:5: 50:6>::fi5`...
+  --> $DIR/fn-header-semantic-fail.rs:47:9
    |
 LL |         const async unsafe extern "C" fn fi5() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires processing `main::<impl at $DIR/fn-header-semantic-fail.rs:40:5: 48:6>::fi5`...
-  --> $DIR/fn-header-semantic-fail.rs:45:9
+note: ...which requires processing `main::<impl at $DIR/fn-header-semantic-fail.rs:42:5: 50:6>::fi5`...
+  --> $DIR/fn-header-semantic-fail.rs:47:9
    |
 LL |         const async unsafe extern "C" fn fi5() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires const checking `main::<impl at $DIR/fn-header-semantic-fail.rs:40:5: 48:6>::fi5`...
-  --> $DIR/fn-header-semantic-fail.rs:45:9
+note: ...which requires const checking `main::<impl at $DIR/fn-header-semantic-fail.rs:42:5: 50:6>::fi5`...
+  --> $DIR/fn-header-semantic-fail.rs:47:9
    |
 LL |         const async unsafe extern "C" fn fi5() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: ...which requires computing whether `impl core::future::future::Future<Output = ()>` is freeze...
    = note: ...which requires evaluating trait selection obligation `impl core::future::future::Future<Output = ()>: core::marker::Freeze`...
-   = note: ...which again requires computing type of `main::<impl at $DIR/fn-header-semantic-fail.rs:40:5: 48:6>::fi5::{opaque#0}`, completing the cycle
+   = note: ...which again requires computing type of `main::<impl at $DIR/fn-header-semantic-fail.rs:42:5: 50:6>::fi5::{opaque#0}`, completing the cycle
 note: cycle used when checking item types in top-level module
   --> $DIR/fn-header-semantic-fail.rs:5:1
    |
@@ -288,7 +306,7 @@ LL | |     }
 LL | | }
    | |_^
 
-error: aborting due to 21 previous errors
+error: aborting due to 23 previous errors
 
-Some errors have detailed explanations: E0379, E0391, E0706.
-For more information about an error, try `rustc --explain E0379`.
+Some errors have detailed explanations: E0276, E0379, E0391, E0706.
+For more information about an error, try `rustc --explain E0276`.