Auto merge of #126996 - oli-obk:do_not_count_errors, r=nnethercote

Automatically taint InferCtxt when errors are emitted

r? `@nnethercote`

Basically `InferCtxt::dcx` now returns a `DiagCtxt` that refers back to the `Cell<Option<ErrorGuaranteed>>` of the `InferCtxt` and thus when invoking `Diag::emit`, and the diagnostic is an error, we taint the `InferCtxt` directly.

That change on its own has no effect at all, because `InferCtxt` already tracks whether errors have been emitted by recording the global error count when it gets opened, and checking at the end whether the count changed. So I removed that error count check, which had a bit of fallout that I immediately fixed by invoking `InferCtxt::dcx` instead of `TyCtxt::dcx` in a bunch of places.

The remaining new errors are because an error was reported in another query, and never bubbled up. I think they are minor enough for this to be ok, and sometimes it actually improves diagnostics, by not silencing useful diagnostics anymore.

fixes #126485 (cc `@olafes)`

There are more improvements we can do (like tainting in hir ty lowering), but I would rather do that in follow up PRs, because it requires some refactorings.

14 files changed, 267 insertions, 79 deletions

diff --git a/tests/ui/const-generics/assoc_const_as_type_argument.rs b/tests/ui/const-generics/assoc_const_as_type_argument.rs
index ffc7f116a94..bec6102417c 100644
--- a/tests/ui/const-generics/assoc_const_as_type_argument.rs
+++ b/tests/ui/const-generics/assoc_const_as_type_argument.rs
@@ -8,6 +8,7 @@ fn foo<T: Trait>() {
     bar::<<T as Trait>::ASSOC>();
     //~^ ERROR: expected associated type, found associated constant `Trait::ASSOC`
     //~| ERROR: unresolved item provided when a constant was expected
+    //~| ERROR type annotations needed
 }
 
 fn main() {}
diff --git a/tests/ui/const-generics/assoc_const_as_type_argument.stderr b/tests/ui/const-generics/assoc_const_as_type_argument.stderr
index ac009546135..53edc19b28c 100644
--- a/tests/ui/const-generics/assoc_const_as_type_argument.stderr
+++ b/tests/ui/const-generics/assoc_const_as_type_argument.stderr
@@ -15,7 +15,19 @@ help: if this generic argument was intended as a const parameter, surround it wi
 LL |     bar::<{ <T as Trait>::ASSOC }>();
    |           +                     +
 
-error: aborting due to 2 previous errors
+error[E0284]: type annotations needed
+  --> $DIR/assoc_const_as_type_argument.rs:8:5
+   |
+LL |     bar::<<T as Trait>::ASSOC>();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `bar`
+   |
+note: required by a const generic parameter in `bar`
+  --> $DIR/assoc_const_as_type_argument.rs:5:8
+   |
+LL | fn bar<const N: usize>() {}
+   |        ^^^^^^^^^^^^^^ required by this const generic parameter in `bar`
+
+error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0575, E0747.
-For more information about an error, try `rustc --explain E0575`.
+Some errors have detailed explanations: E0284, E0575, E0747.
+For more information about an error, try `rustc --explain E0284`.
diff --git a/tests/ui/const-generics/const-arg-in-const-arg.min.stderr b/tests/ui/const-generics/const-arg-in-const-arg.min.stderr
index ce7fce25993..2ea9d6b35b4 100644
--- a/tests/ui/const-generics/const-arg-in-const-arg.min.stderr
+++ b/tests/ui/const-generics/const-arg-in-const-arg.min.stderr
@@ -17,7 +17,7 @@ LL |     let _: [u8; bar::<N>()];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:18:23
+  --> $DIR/const-arg-in-const-arg.rs:19:23
    |
 LL |     let _: [u8; faz::<'a>(&())];
    |                       ^^ cannot perform const operation using `'a`
@@ -26,7 +26,7 @@ LL |     let _: [u8; faz::<'a>(&())];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:20:23
+  --> $DIR/const-arg-in-const-arg.rs:21:23
    |
 LL |     let _: [u8; baz::<'a>(&())];
    |                       ^^ cannot perform const operation using `'a`
@@ -35,7 +35,7 @@ LL |     let _: [u8; baz::<'a>(&())];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:21:23
+  --> $DIR/const-arg-in-const-arg.rs:22:23
    |
 LL |     let _: [u8; faz::<'b>(&())];
    |                       ^^ cannot perform const operation using `'b`
@@ -44,7 +44,7 @@ LL |     let _: [u8; faz::<'b>(&())];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:23:23
+  --> $DIR/const-arg-in-const-arg.rs:24:23
    |
 LL |     let _: [u8; baz::<'b>(&())];
    |                       ^^ cannot perform const operation using `'b`
@@ -53,7 +53,7 @@ LL |     let _: [u8; baz::<'b>(&())];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:26:23
+  --> $DIR/const-arg-in-const-arg.rs:27:23
    |
 LL |     let _ = [0; bar::<N>()];
    |                       ^ cannot perform const operation using `N`
@@ -62,7 +62,7 @@ LL |     let _ = [0; bar::<N>()];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:28:23
+  --> $DIR/const-arg-in-const-arg.rs:30:23
    |
 LL |     let _ = [0; faz::<'a>(&())];
    |                       ^^ cannot perform const operation using `'a`
@@ -71,7 +71,7 @@ LL |     let _ = [0; faz::<'a>(&())];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:30:23
+  --> $DIR/const-arg-in-const-arg.rs:32:23
    |
 LL |     let _ = [0; baz::<'a>(&())];
    |                       ^^ cannot perform const operation using `'a`
@@ -80,7 +80,7 @@ LL |     let _ = [0; baz::<'a>(&())];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:31:23
+  --> $DIR/const-arg-in-const-arg.rs:33:23
    |
 LL |     let _ = [0; faz::<'b>(&())];
    |                       ^^ cannot perform const operation using `'b`
@@ -89,7 +89,7 @@ LL |     let _ = [0; faz::<'b>(&())];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:33:23
+  --> $DIR/const-arg-in-const-arg.rs:35:23
    |
 LL |     let _ = [0; baz::<'b>(&())];
    |                       ^^ cannot perform const operation using `'b`
@@ -98,7 +98,7 @@ LL |     let _ = [0; baz::<'b>(&())];
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:34:24
+  --> $DIR/const-arg-in-const-arg.rs:36:24
    |
 LL |     let _: Foo<{ foo::<T>() }>;
    |                        ^ cannot perform const operation using `T`
@@ -107,7 +107,7 @@ LL |     let _: Foo<{ foo::<T>() }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:35:24
+  --> $DIR/const-arg-in-const-arg.rs:37:24
    |
 LL |     let _: Foo<{ bar::<N>() }>;
    |                        ^ cannot perform const operation using `N`
@@ -116,7 +116,7 @@ LL |     let _: Foo<{ bar::<N>() }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:37:24
+  --> $DIR/const-arg-in-const-arg.rs:40:24
    |
 LL |     let _: Foo<{ faz::<'a>(&()) }>;
    |                        ^^ cannot perform const operation using `'a`
@@ -125,7 +125,7 @@ LL |     let _: Foo<{ faz::<'a>(&()) }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:39:24
+  --> $DIR/const-arg-in-const-arg.rs:42:24
    |
 LL |     let _: Foo<{ baz::<'a>(&()) }>;
    |                        ^^ cannot perform const operation using `'a`
@@ -134,7 +134,7 @@ LL |     let _: Foo<{ baz::<'a>(&()) }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:40:24
+  --> $DIR/const-arg-in-const-arg.rs:43:24
    |
 LL |     let _: Foo<{ faz::<'b>(&()) }>;
    |                        ^^ cannot perform const operation using `'b`
@@ -143,7 +143,7 @@ LL |     let _: Foo<{ faz::<'b>(&()) }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:42:24
+  --> $DIR/const-arg-in-const-arg.rs:45:24
    |
 LL |     let _: Foo<{ baz::<'b>(&()) }>;
    |                        ^^ cannot perform const operation using `'b`
@@ -152,7 +152,7 @@ LL |     let _: Foo<{ baz::<'b>(&()) }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:43:27
+  --> $DIR/const-arg-in-const-arg.rs:46:27
    |
 LL |     let _ = Foo::<{ foo::<T>() }>;
    |                           ^ cannot perform const operation using `T`
@@ -161,7 +161,7 @@ LL |     let _ = Foo::<{ foo::<T>() }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:44:27
+  --> $DIR/const-arg-in-const-arg.rs:47:27
    |
 LL |     let _ = Foo::<{ bar::<N>() }>;
    |                           ^ cannot perform const operation using `N`
@@ -170,7 +170,7 @@ LL |     let _ = Foo::<{ bar::<N>() }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:46:27
+  --> $DIR/const-arg-in-const-arg.rs:50:27
    |
 LL |     let _ = Foo::<{ faz::<'a>(&()) }>;
    |                           ^^ cannot perform const operation using `'a`
@@ -179,7 +179,7 @@ LL |     let _ = Foo::<{ faz::<'a>(&()) }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:48:27
+  --> $DIR/const-arg-in-const-arg.rs:52:27
    |
 LL |     let _ = Foo::<{ baz::<'a>(&()) }>;
    |                           ^^ cannot perform const operation using `'a`
@@ -188,7 +188,7 @@ LL |     let _ = Foo::<{ baz::<'a>(&()) }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:49:27
+  --> $DIR/const-arg-in-const-arg.rs:53:27
    |
 LL |     let _ = Foo::<{ faz::<'b>(&()) }>;
    |                           ^^ cannot perform const operation using `'b`
@@ -197,7 +197,7 @@ LL |     let _ = Foo::<{ faz::<'b>(&()) }>;
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/const-arg-in-const-arg.rs:51:27
+  --> $DIR/const-arg-in-const-arg.rs:55:27
    |
 LL |     let _ = Foo::<{ baz::<'b>(&()) }>;
    |                           ^^ cannot perform const operation using `'b`
@@ -216,8 +216,20 @@ help: if this generic argument was intended as a const parameter, surround it wi
 LL |     let _: [u8; bar::<{ N }>()];
    |                       +   +
 
+error[E0284]: type annotations needed
+  --> $DIR/const-arg-in-const-arg.rs:16:17
+   |
+LL |     let _: [u8; bar::<N>()];
+   |                 ^^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `bar`
+   |
+note: required by a const generic parameter in `bar`
+  --> $DIR/const-arg-in-const-arg.rs:9:14
+   |
+LL | const fn bar<const N: usize>() -> usize { N }
+   |              ^^^^^^^^^^^^^^ required by this const generic parameter in `bar`
+
 error[E0794]: cannot specify lifetime arguments explicitly if late bound lifetime parameters are present
-  --> $DIR/const-arg-in-const-arg.rs:18:23
+  --> $DIR/const-arg-in-const-arg.rs:19:23
    |
 LL |     let _: [u8; faz::<'a>(&())];
    |                       ^^
@@ -229,7 +241,7 @@ LL | const fn faz<'a>(_: &'a ()) -> usize { 13 }
    |              ^^
 
 error[E0794]: cannot specify lifetime arguments explicitly if late bound lifetime parameters are present
-  --> $DIR/const-arg-in-const-arg.rs:21:23
+  --> $DIR/const-arg-in-const-arg.rs:22:23
    |
 LL |     let _: [u8; faz::<'b>(&())];
    |                       ^^
@@ -241,7 +253,7 @@ LL | const fn faz<'a>(_: &'a ()) -> usize { 13 }
    |              ^^
 
 error[E0747]: unresolved item provided when a constant was expected
-  --> $DIR/const-arg-in-const-arg.rs:35:24
+  --> $DIR/const-arg-in-const-arg.rs:37:24
    |
 LL |     let _: Foo<{ bar::<N>() }>;
    |                        ^
@@ -251,8 +263,20 @@ help: if this generic argument was intended as a const parameter, surround it wi
 LL |     let _: Foo<{ bar::<{ N }>() }>;
    |                        +   +
 
+error[E0284]: type annotations needed
+  --> $DIR/const-arg-in-const-arg.rs:37:18
+   |
+LL |     let _: Foo<{ bar::<N>() }>;
+   |                  ^^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `bar`
+   |
+note: required by a const generic parameter in `bar`
+  --> $DIR/const-arg-in-const-arg.rs:9:14
+   |
+LL | const fn bar<const N: usize>() -> usize { N }
+   |              ^^^^^^^^^^^^^^ required by this const generic parameter in `bar`
+
 error[E0794]: cannot specify lifetime arguments explicitly if late bound lifetime parameters are present
-  --> $DIR/const-arg-in-const-arg.rs:37:24
+  --> $DIR/const-arg-in-const-arg.rs:40:24
    |
 LL |     let _: Foo<{ faz::<'a>(&()) }>;
    |                        ^^
@@ -264,7 +288,7 @@ LL | const fn faz<'a>(_: &'a ()) -> usize { 13 }
    |              ^^
 
 error[E0794]: cannot specify lifetime arguments explicitly if late bound lifetime parameters are present
-  --> $DIR/const-arg-in-const-arg.rs:40:24
+  --> $DIR/const-arg-in-const-arg.rs:43:24
    |
 LL |     let _: Foo<{ faz::<'b>(&()) }>;
    |                        ^^
@@ -276,7 +300,7 @@ LL | const fn faz<'a>(_: &'a ()) -> usize { 13 }
    |              ^^
 
 error: constant expression depends on a generic parameter
-  --> $DIR/const-arg-in-const-arg.rs:25:17
+  --> $DIR/const-arg-in-const-arg.rs:26:17
    |
 LL |     let _ = [0; foo::<T>()];
    |                 ^^^^^^^^^^
@@ -284,7 +308,7 @@ LL |     let _ = [0; foo::<T>()];
    = note: this may fail depending on what value the parameter takes
 
 error[E0747]: unresolved item provided when a constant was expected
-  --> $DIR/const-arg-in-const-arg.rs:26:23
+  --> $DIR/const-arg-in-const-arg.rs:27:23
    |
 LL |     let _ = [0; bar::<N>()];
    |                       ^
@@ -294,8 +318,20 @@ help: if this generic argument was intended as a const parameter, surround it wi
 LL |     let _ = [0; bar::<{ N }>()];
    |                       +   +
 
+error[E0284]: type annotations needed
+  --> $DIR/const-arg-in-const-arg.rs:27:17
+   |
+LL |     let _ = [0; bar::<N>()];
+   |                 ^^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `bar`
+   |
+note: required by a const generic parameter in `bar`
+  --> $DIR/const-arg-in-const-arg.rs:9:14
+   |
+LL | const fn bar<const N: usize>() -> usize { N }
+   |              ^^^^^^^^^^^^^^ required by this const generic parameter in `bar`
+
 error[E0794]: cannot specify lifetime arguments explicitly if late bound lifetime parameters are present
-  --> $DIR/const-arg-in-const-arg.rs:28:23
+  --> $DIR/const-arg-in-const-arg.rs:30:23
    |
 LL |     let _ = [0; faz::<'a>(&())];
    |                       ^^
@@ -307,7 +343,7 @@ LL | const fn faz<'a>(_: &'a ()) -> usize { 13 }
    |              ^^
 
 error[E0794]: cannot specify lifetime arguments explicitly if late bound lifetime parameters are present
-  --> $DIR/const-arg-in-const-arg.rs:31:23
+  --> $DIR/const-arg-in-const-arg.rs:33:23
    |
 LL |     let _ = [0; faz::<'b>(&())];
    |                       ^^
@@ -319,7 +355,7 @@ LL | const fn faz<'a>(_: &'a ()) -> usize { 13 }
    |              ^^
 
 error[E0747]: unresolved item provided when a constant was expected
-  --> $DIR/const-arg-in-const-arg.rs:44:27
+  --> $DIR/const-arg-in-const-arg.rs:47:27
    |
 LL |     let _ = Foo::<{ bar::<N>() }>;
    |                           ^
@@ -329,8 +365,20 @@ help: if this generic argument was intended as a const parameter, surround it wi
 LL |     let _ = Foo::<{ bar::<{ N }>() }>;
    |                           +   +
 
+error[E0284]: type annotations needed
+  --> $DIR/const-arg-in-const-arg.rs:47:21
+   |
+LL |     let _ = Foo::<{ bar::<N>() }>;
+   |                     ^^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `bar`
+   |
+note: required by a const generic parameter in `bar`
+  --> $DIR/const-arg-in-const-arg.rs:9:14
+   |
+LL | const fn bar<const N: usize>() -> usize { N }
+   |              ^^^^^^^^^^^^^^ required by this const generic parameter in `bar`
+
 error[E0794]: cannot specify lifetime arguments explicitly if late bound lifetime parameters are present
-  --> $DIR/const-arg-in-const-arg.rs:46:27
+  --> $DIR/const-arg-in-const-arg.rs:50:27
    |
 LL |     let _ = Foo::<{ faz::<'a>(&()) }>;
    |                           ^^
@@ -342,7 +390,7 @@ LL | const fn faz<'a>(_: &'a ()) -> usize { 13 }
    |              ^^
 
 error[E0794]: cannot specify lifetime arguments explicitly if late bound lifetime parameters are present
-  --> $DIR/const-arg-in-const-arg.rs:49:27
+  --> $DIR/const-arg-in-const-arg.rs:53:27
    |
 LL |     let _ = Foo::<{ faz::<'b>(&()) }>;
    |                           ^^
@@ -353,7 +401,7 @@ note: the late bound lifetime parameter is introduced here
 LL | const fn faz<'a>(_: &'a ()) -> usize { 13 }
    |              ^^
 
-error: aborting due to 36 previous errors
+error: aborting due to 40 previous errors
 
-Some errors have detailed explanations: E0747, E0794.
-For more information about an error, try `rustc --explain E0747`.
+Some errors have detailed explanations: E0284, E0747, E0794.
+For more information about an error, try `rustc --explain E0284`.
diff --git a/tests/ui/const-generics/const-arg-in-const-arg.rs b/tests/ui/const-generics/const-arg-in-const-arg.rs
index 27b74489fe8..b95c63309f7 100644
--- a/tests/ui/const-generics/const-arg-in-const-arg.rs
+++ b/tests/ui/const-generics/const-arg-in-const-arg.rs
@@ -15,6 +15,7 @@ fn test<'a, 'b, T, const N: usize>() where &'b (): Sized {
     let _: [u8; foo::<T>()]; //[min]~ ERROR generic parameters may not
     let _: [u8; bar::<N>()]; //[min]~ ERROR generic parameters may not
                              //[min]~^ ERROR unresolved item provided when a constant was expected
+                             //[min]~| ERROR type annotations needed
     let _: [u8; faz::<'a>(&())]; //[min]~ ERROR generic parameters may not
                                  //[min]~^ ERROR cannot specify lifetime arguments
     let _: [u8; baz::<'a>(&())]; //[min]~ ERROR generic parameters may not
@@ -25,6 +26,7 @@ fn test<'a, 'b, T, const N: usize>() where &'b (): Sized {
     let _ = [0; foo::<T>()]; //[min]~ ERROR constant expression depends on a generic parameter
     let _ = [0; bar::<N>()]; //[min]~ ERROR generic parameters may not
                              //[min]~^ ERROR unresolved item provided when a constant was expected
+                             //[min]~| ERROR type annotations needed
     let _ = [0; faz::<'a>(&())]; //[min]~ ERROR generic parameters may not
                                  //[min]~^ ERROR cannot specify lifetime arguments
     let _ = [0; baz::<'a>(&())]; //[min]~ ERROR generic parameters may not
@@ -34,6 +36,7 @@ fn test<'a, 'b, T, const N: usize>() where &'b (): Sized {
     let _: Foo<{ foo::<T>() }>; //[min]~ ERROR generic parameters may not
     let _: Foo<{ bar::<N>() }>; //[min]~ ERROR generic parameters may not
                                 //[min]~^ ERROR unresolved item provided when a constant was expected
+                                //[min]~| ERROR type annotations needed
     let _: Foo<{ faz::<'a>(&()) }>; //[min]~ ERROR generic parameters may not
                                     //[min]~^ ERROR cannot specify lifetime arguments
     let _: Foo<{ baz::<'a>(&()) }>; //[min]~ ERROR generic parameters may not
@@ -43,6 +46,7 @@ fn test<'a, 'b, T, const N: usize>() where &'b (): Sized {
     let _ = Foo::<{ foo::<T>() }>; //[min]~ ERROR generic parameters may not
     let _ = Foo::<{ bar::<N>() }>; //[min]~ ERROR generic parameters may not
                                    //[min]~^ ERROR unresolved item provided when a constant was expected
+                                   //[min]~| ERROR type annotations needed
     let _ = Foo::<{ faz::<'a>(&()) }>; //[min]~ ERROR generic parameters may not
                                        //[min]~^ ERROR cannot specify lifetime arguments
     let _ = Foo::<{ baz::<'a>(&()) }>; //[min]~ ERROR generic parameters may not
diff --git a/tests/ui/const-generics/generic_const_exprs/opaque_type.rs b/tests/ui/const-generics/generic_const_exprs/opaque_type.rs
index 56b8acbf88c..7209290a36e 100644
--- a/tests/ui/const-generics/generic_const_exprs/opaque_type.rs
+++ b/tests/ui/const-generics/generic_const_exprs/opaque_type.rs
@@ -2,6 +2,7 @@
 #![allow(incomplete_features)]
 
 type Foo = impl Sized;
+//~^ ERROR: unconstrained opaque type
 
 fn with_bound<const N: usize>() -> Foo
 where
diff --git a/tests/ui/const-generics/generic_const_exprs/opaque_type.stderr b/tests/ui/const-generics/generic_const_exprs/opaque_type.stderr
index e9fb8c0f403..c7a266205b4 100644
--- a/tests/ui/const-generics/generic_const_exprs/opaque_type.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/opaque_type.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/opaque_type.rs:10:17
+  --> $DIR/opaque_type.rs:11:17
    |
 LL | type Foo = impl Sized;
    |            ---------- the found opaque type
@@ -11,12 +11,20 @@ LL |     let _: [u8; (N / 2) as Foo] = [0; (N / 2) as usize];
            found opaque type `Foo`
 
 error[E0605]: non-primitive cast: `usize` as `Foo`
-  --> $DIR/opaque_type.rs:10:17
+  --> $DIR/opaque_type.rs:11:17
    |
 LL |     let _: [u8; (N / 2) as Foo] = [0; (N / 2) as usize];
    |                 ^^^^^^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object
 
-error: aborting due to 2 previous errors
+error: unconstrained opaque type
+  --> $DIR/opaque_type.rs:4:12
+   |
+LL | type Foo = impl Sized;
+   |            ^^^^^^^^^^
+   |
+   = note: `Foo` must be used in combination with a concrete type within the same module
+
+error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0308, E0605.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/const-generics/issues/issue-62878.min.stderr b/tests/ui/const-generics/issues/issue-62878.min.stderr
index 5205726d738..3fd50bbe298 100644
--- a/tests/ui/const-generics/issues/issue-62878.min.stderr
+++ b/tests/ui/const-generics/issues/issue-62878.min.stderr
@@ -30,7 +30,31 @@ help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
 LL + #![feature(generic_arg_infer)]
    |
 
-error: aborting due to 3 previous errors
+error[E0284]: type annotations needed
+  --> $DIR/issue-62878.rs:10:5
+   |
+LL |     foo::<_, { [1] }>();
+   |     ^^^^^^^^^^^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `foo`
+   |
+note: required by a const generic parameter in `foo`
+  --> $DIR/issue-62878.rs:5:8
+   |
+LL | fn foo<const N: usize, const A: [u8; N]>() {}
+   |        ^^^^^^^^^^^^^^ required by this const generic parameter in `foo`
+
+error[E0284]: type annotations needed
+  --> $DIR/issue-62878.rs:10:5
+   |
+LL |     foo::<_, { [1] }>();
+   |     ^^^^^^^^^^^^^^^^^ cannot infer the value of the const parameter `A` declared on the function `foo`
+   |
+note: required by a const generic parameter in `foo`
+  --> $DIR/issue-62878.rs:5:24
+   |
+LL | fn foo<const N: usize, const A: [u8; N]>() {}
+   |                        ^^^^^^^^^^^^^^^^ required by this const generic parameter in `foo`
+
+error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0747, E0770.
-For more information about an error, try `rustc --explain E0747`.
+Some errors have detailed explanations: E0284, E0747, E0770.
+For more information about an error, try `rustc --explain E0284`.
diff --git a/tests/ui/const-generics/issues/issue-62878.rs b/tests/ui/const-generics/issues/issue-62878.rs
index 0b5269df85e..c784e95edd8 100644
--- a/tests/ui/const-generics/issues/issue-62878.rs
+++ b/tests/ui/const-generics/issues/issue-62878.rs
@@ -9,4 +9,6 @@ fn foo<const N: usize, const A: [u8; N]>() {}
 fn main() {
     foo::<_, { [1] }>();
     //[min]~^ ERROR: type provided when a constant was expected
+    //[min]~| ERROR type annotations needed
+    //[min]~| ERROR type annotations needed
 }
diff --git a/tests/ui/const-generics/min_const_generics/const-expression-suggest-missing-braces.rs b/tests/ui/const-generics/min_const_generics/const-expression-suggest-missing-braces.rs
index e12e07a28e7..497c020bde4 100644
--- a/tests/ui/const-generics/min_const_generics/const-expression-suggest-missing-braces.rs
+++ b/tests/ui/const-generics/min_const_generics/const-expression-suggest-missing-braces.rs
@@ -12,6 +12,7 @@ fn b() {
     //~^ ERROR expected trait, found constant `BAR`
     //~| ERROR expected trait, found constant `BAR`
     //~| ERROR type provided when a constant was expected
+    //~| ERROR type annotations needed
 }
 fn c() {
     foo::<3 + 3>(); //~ ERROR expressions must be enclosed in braces
diff --git a/tests/ui/const-generics/min_const_generics/const-expression-suggest-missing-braces.stderr b/tests/ui/const-generics/min_const_generics/const-expression-suggest-missing-braces.stderr
index d9bcc523b1f..c2ba517f609 100644
--- a/tests/ui/const-generics/min_const_generics/const-expression-suggest-missing-braces.stderr
+++ b/tests/ui/const-generics/min_const_generics/const-expression-suggest-missing-braces.stderr
@@ -10,7 +10,7 @@ LL |     foo::<{ BAR + 3 }>();
    |           +         +
 
 error: expressions must be enclosed in braces to be used as const generic arguments
-  --> $DIR/const-expression-suggest-missing-braces.rs:17:11
+  --> $DIR/const-expression-suggest-missing-braces.rs:18:11
    |
 LL |     foo::<3 + 3>();
    |           ^^^^^
@@ -21,7 +21,7 @@ LL |     foo::<{ 3 + 3 }>();
    |           +       +
 
 error: expected one of `,` or `>`, found `-`
-  --> $DIR/const-expression-suggest-missing-braces.rs:20:15
+  --> $DIR/const-expression-suggest-missing-braces.rs:21:15
    |
 LL |     foo::<BAR - 3>();
    |               ^ expected one of `,` or `>`
@@ -32,7 +32,7 @@ LL |     foo::<{ BAR - 3 }>();
    |           +         +
 
 error: expected one of `,` or `>`, found `-`
-  --> $DIR/const-expression-suggest-missing-braces.rs:23:15
+  --> $DIR/const-expression-suggest-missing-braces.rs:24:15
    |
 LL |     foo::<BAR - BAR>();
    |               ^ expected one of `,` or `>`
@@ -43,7 +43,7 @@ LL |     foo::<{ BAR - BAR }>();
    |           +           +
 
 error: expressions must be enclosed in braces to be used as const generic arguments
-  --> $DIR/const-expression-suggest-missing-braces.rs:26:11
+  --> $DIR/const-expression-suggest-missing-braces.rs:27:11
    |
 LL |     foo::<100 - BAR>();
    |           ^^^^^^^^^
@@ -54,7 +54,7 @@ LL |     foo::<{ 100 - BAR }>();
    |           +           +
 
 error: expected one of `,` or `>`, found `(`
-  --> $DIR/const-expression-suggest-missing-braces.rs:29:19
+  --> $DIR/const-expression-suggest-missing-braces.rs:30:19
    |
 LL |     foo::<bar<i32>()>();
    |                   ^ expected one of `,` or `>`
@@ -65,7 +65,7 @@ LL |     foo::<{ bar<i32>() }>();
    |           +            +
 
 error: expected one of `,` or `>`, found `(`
-  --> $DIR/const-expression-suggest-missing-braces.rs:32:21
+  --> $DIR/const-expression-suggest-missing-braces.rs:33:21
    |
 LL |     foo::<bar::<i32>()>();
    |                     ^ expected one of `,` or `>`
@@ -76,7 +76,7 @@ LL |     foo::<{ bar::<i32>() }>();
    |           +              +
 
 error: expected one of `,` or `>`, found `(`
-  --> $DIR/const-expression-suggest-missing-braces.rs:35:21
+  --> $DIR/const-expression-suggest-missing-braces.rs:36:21
    |
 LL |     foo::<bar::<i32>() + BAR>();
    |                     ^ expected one of `,` or `>`
@@ -87,7 +87,7 @@ LL |     foo::<{ bar::<i32>() + BAR }>();
    |           +                    +
 
 error: expected one of `,` or `>`, found `(`
-  --> $DIR/const-expression-suggest-missing-braces.rs:38:21
+  --> $DIR/const-expression-suggest-missing-braces.rs:39:21
    |
 LL |     foo::<bar::<i32>() - BAR>();
    |                     ^ expected one of `,` or `>`
@@ -98,7 +98,7 @@ LL |     foo::<{ bar::<i32>() - BAR }>();
    |           +                    +
 
 error: expected one of `,` or `>`, found `-`
-  --> $DIR/const-expression-suggest-missing-braces.rs:41:15
+  --> $DIR/const-expression-suggest-missing-braces.rs:42:15
    |
 LL |     foo::<BAR - bar::<i32>()>();
    |               ^ expected one of `,` or `>`
@@ -109,7 +109,7 @@ LL |     foo::<{ BAR - bar::<i32>() }>();
    |           +                    +
 
 error: expected one of `,` or `>`, found `-`
-  --> $DIR/const-expression-suggest-missing-braces.rs:44:15
+  --> $DIR/const-expression-suggest-missing-braces.rs:45:15
    |
 LL |     foo::<BAR - bar::<i32>()>();
    |               ^ expected one of `,` or `>`
@@ -137,7 +137,19 @@ error[E0747]: type provided when a constant was expected
 LL |     foo::<BAR + BAR>();
    |           ^^^^^^^^^
 
-error: aborting due to 14 previous errors
+error[E0284]: type annotations needed
+  --> $DIR/const-expression-suggest-missing-braces.rs:11:5
+   |
+LL |     foo::<BAR + BAR>();
+   |     ^^^^^^^^^^^^^^^^ cannot infer the value of the const parameter `C` declared on the function `foo`
+   |
+note: required by a const generic parameter in `foo`
+  --> $DIR/const-expression-suggest-missing-braces.rs:1:8
+   |
+LL | fn foo<const C: usize>() {}
+   |        ^^^^^^^^^^^^^^ required by this const generic parameter in `foo`
+
+error: aborting due to 15 previous errors
 
-Some errors have detailed explanations: E0404, E0747.
-For more information about an error, try `rustc --explain E0404`.
+Some errors have detailed explanations: E0284, E0404, E0747.
+For more information about an error, try `rustc --explain E0284`.
diff --git a/tests/ui/const-generics/min_const_generics/macro-fail.rs b/tests/ui/const-generics/min_const_generics/macro-fail.rs
index 2f101ecfb1f..25726490c2c 100644
--- a/tests/ui/const-generics/min_const_generics/macro-fail.rs
+++ b/tests/ui/const-generics/min_const_generics/macro-fail.rs
@@ -16,6 +16,7 @@ fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
   //~| ERROR: type provided when a constant was expected
   Example::<gimme_a_const!(marker)>
   //~^ ERROR: type provided when a constant was expected
+  //~| ERROR type annotations needed
 }
 
 fn from_marker(_: impl Marker<{
@@ -35,9 +36,11 @@ fn main() {
   }>;
 
   let _fail = Example::<external_macro!()>;
-  //~^ ERROR: type provided when a constant was expected
+  //~^ ERROR: type provided when a constant
+  //~| ERROR type annotations needed
 
   let _fail = Example::<gimme_a_const!()>;
   //~^ ERROR unexpected end of macro invocation
   //~| ERROR: type provided when a constant was expected
+  //~| ERROR type annotations needed
 }
diff --git a/tests/ui/const-generics/min_const_generics/macro-fail.stderr b/tests/ui/const-generics/min_const_generics/macro-fail.stderr
index 34764982bb0..4e183fe5b1c 100644
--- a/tests/ui/const-generics/min_const_generics/macro-fail.stderr
+++ b/tests/ui/const-generics/min_const_generics/macro-fail.stderr
@@ -1,5 +1,5 @@
 error: expected type, found `{`
-  --> $DIR/macro-fail.rs:30:27
+  --> $DIR/macro-fail.rs:31:27
    |
 LL | fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
    |                                 ----------------------
@@ -13,7 +13,7 @@ LL |       ($rusty: ident) => {{ let $rusty = 3; *&$rusty }}
    = note: this error originates in the macro `gimme_a_const` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected type, found `{`
-  --> $DIR/macro-fail.rs:30:27
+  --> $DIR/macro-fail.rs:31:27
    |
 LL |   Example::<gimme_a_const!(marker)>
    |             ----------------------
@@ -41,7 +41,7 @@ LL |   let _fail = Example::<external_macro!()>;
    = note: this error originates in the macro `external_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: unexpected end of macro invocation
-  --> $DIR/macro-fail.rs:40:25
+  --> $DIR/macro-fail.rs:42:25
    |
 LL |     macro_rules! gimme_a_const {
    |     -------------------------- when calling this macro
@@ -50,7 +50,7 @@ LL |   let _fail = Example::<gimme_a_const!()>;
    |                         ^^^^^^^^^^^^^^^^ missing tokens in macro arguments
    |
 note: while trying to match meta-variable `$rusty:ident`
-  --> $DIR/macro-fail.rs:30:8
+  --> $DIR/macro-fail.rs:31:8
    |
 LL |       ($rusty: ident) => {{ let $rusty = 3; *&$rusty }}
    |        ^^^^^^^^^^^^^
@@ -75,18 +75,63 @@ error[E0747]: type provided when a constant was expected
 LL |   Example::<gimme_a_const!(marker)>
    |             ^^^^^^^^^^^^^^^^^^^^^^
 
+error[E0284]: type annotations needed
+  --> $DIR/macro-fail.rs:17:3
+   |
+LL |   Example::<gimme_a_const!(marker)>
+   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer the value of the const parameter `N` declared on the struct `Example`
+   |
+note: required by a const generic parameter in `Example`
+  --> $DIR/macro-fail.rs:1:16
+   |
+LL | struct Example<const N: usize>;
+   |                ^^^^^^^^^^^^^^ required by this const generic parameter in `Example`
+
 error[E0747]: type provided when a constant was expected
-  --> $DIR/macro-fail.rs:37:25
+  --> $DIR/macro-fail.rs:38:25
    |
 LL |   let _fail = Example::<external_macro!()>;
    |                         ^^^^^^^^^^^^^^^^^
 
 error[E0747]: type provided when a constant was expected
-  --> $DIR/macro-fail.rs:40:25
+  --> $DIR/macro-fail.rs:42:25
    |
 LL |   let _fail = Example::<gimme_a_const!()>;
    |                         ^^^^^^^^^^^^^^^^
 
-error: aborting due to 9 previous errors
+error[E0284]: type annotations needed for `Example<_>`
+  --> $DIR/macro-fail.rs:38:7
+   |
+LL |   let _fail = Example::<external_macro!()>;
+   |       ^^^^^   ---------------------------- type must be known at this point
+   |
+note: required by a const generic parameter in `Example`
+  --> $DIR/macro-fail.rs:1:16
+   |
+LL | struct Example<const N: usize>;
+   |                ^^^^^^^^^^^^^^ required by this const generic parameter in `Example`
+help: consider giving `_fail` an explicit type, where the value of const parameter `N` is specified
+   |
+LL |   let _fail: Example<N> = Example::<external_macro!()>;
+   |            ++++++++++++
+
+error[E0284]: type annotations needed for `Example<_>`
+  --> $DIR/macro-fail.rs:42:7
+   |
+LL |   let _fail = Example::<gimme_a_const!()>;
+   |       ^^^^^   --------------------------- type must be known at this point
+   |
+note: required by a const generic parameter in `Example`
+  --> $DIR/macro-fail.rs:1:16
+   |
+LL | struct Example<const N: usize>;
+   |                ^^^^^^^^^^^^^^ required by this const generic parameter in `Example`
+help: consider giving `_fail` an explicit type, where the value of const parameter `N` is specified
+   |
+LL |   let _fail: Example<N> = Example::<gimme_a_const!()>;
+   |            ++++++++++++
+
+error: aborting due to 12 previous errors
 
-For more information about this error, try `rustc --explain E0747`.
+Some errors have detailed explanations: E0284, E0747.
+For more information about an error, try `rustc --explain E0284`.
diff --git a/tests/ui/const-generics/suggest_const_for_array.rs b/tests/ui/const-generics/suggest_const_for_array.rs
index f3e5a3186cd..4d29d069375 100644
--- a/tests/ui/const-generics/suggest_const_for_array.rs
+++ b/tests/ui/const-generics/suggest_const_for_array.rs
@@ -3,8 +3,10 @@
 fn example<const N: usize>() {}
 
 fn other() {
-  example::<[usize; 3]>();
-  //~^ ERROR type provided when a const
-  example::<[usize; 4+5]>();
-  //~^ ERROR type provided when a const
+    example::<[usize; 3]>();
+    //~^ ERROR type provided when a const
+    //~| ERROR type annotations needed
+    example::<[usize; 4 + 5]>();
+    //~^ ERROR type provided when a const
+    //~| ERROR type annotations needed
 }
diff --git a/tests/ui/const-generics/suggest_const_for_array.stderr b/tests/ui/const-generics/suggest_const_for_array.stderr
index a617bf2bb0d..c867914070b 100644
--- a/tests/ui/const-generics/suggest_const_for_array.stderr
+++ b/tests/ui/const-generics/suggest_const_for_array.stderr
@@ -1,15 +1,40 @@
 error[E0747]: type provided when a constant was expected
-  --> $DIR/suggest_const_for_array.rs:6:13
+  --> $DIR/suggest_const_for_array.rs:6:15
    |
-LL |   example::<[usize; 3]>();
-   |             ^^^^^^^^^^ help: array type provided where a `usize` was expected, try: `{ 3 }`
+LL |     example::<[usize; 3]>();
+   |               ^^^^^^^^^^ help: array type provided where a `usize` was expected, try: `{ 3 }`
 
 error[E0747]: type provided when a constant was expected
-  --> $DIR/suggest_const_for_array.rs:8:13
+  --> $DIR/suggest_const_for_array.rs:9:15
    |
-LL |   example::<[usize; 4+5]>();
-   |             ^^^^^^^^^^^^ help: array type provided where a `usize` was expected, try: `{ 4+5 }`
+LL |     example::<[usize; 4 + 5]>();
+   |               ^^^^^^^^^^^^^^ help: array type provided where a `usize` was expected, try: `{ 4 + 5 }`
 
-error: aborting due to 2 previous errors
+error[E0284]: type annotations needed
+  --> $DIR/suggest_const_for_array.rs:6:5
+   |
+LL |     example::<[usize; 3]>();
+   |     ^^^^^^^^^^^^^^^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `example`
+   |
+note: required by a const generic parameter in `example`
+  --> $DIR/suggest_const_for_array.rs:3:12
+   |
+LL | fn example<const N: usize>() {}
+   |            ^^^^^^^^^^^^^^ required by this const generic parameter in `example`
+
+error[E0284]: type annotations needed
+  --> $DIR/suggest_const_for_array.rs:9:5
+   |
+LL |     example::<[usize; 4 + 5]>();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `example`
+   |
+note: required by a const generic parameter in `example`
+  --> $DIR/suggest_const_for_array.rs:3:12
+   |
+LL | fn example<const N: usize>() {}
+   |            ^^^^^^^^^^^^^^ required by this const generic parameter in `example`
+
+error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0747`.
+Some errors have detailed explanations: E0284, E0747.
+For more information about an error, try `rustc --explain E0284`.