Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

52 files changed, 982 insertions, 0 deletions

diff --git a/tests/ui/const-generics/defaults/auxiliary/const_defaulty.rs b/tests/ui/const-generics/defaults/auxiliary/const_defaulty.rs
new file mode 100644
index 000000000..eed982534
--- /dev/null
+++ b/tests/ui/const-generics/defaults/auxiliary/const_defaulty.rs
@@ -0,0 +1,11 @@
+pub struct Defaulted<const N: usize=3>;
+impl Defaulted {
+    pub fn new() -> Self {
+        Defaulted
+    }
+}
+impl<const N: usize> Defaulted<N> {
+    pub fn value(&self) -> usize {
+        N
+    }
+}
diff --git a/tests/ui/const-generics/defaults/auxiliary/trait_object_lt_defaults_lib.rs b/tests/ui/const-generics/defaults/auxiliary/trait_object_lt_defaults_lib.rs
new file mode 100644
index 000000000..26a2c47ff
--- /dev/null
+++ b/tests/ui/const-generics/defaults/auxiliary/trait_object_lt_defaults_lib.rs
@@ -0,0 +1 @@
+pub struct Foo<'a, const N: usize, T: 'a + ?Sized>(pub &'a T, [(); N]);
diff --git a/tests/ui/const-generics/defaults/complex-generic-default-expr.min.stderr b/tests/ui/const-generics/defaults/complex-generic-default-expr.min.stderr
new file mode 100644
index 000000000..b836cfeae
--- /dev/null
+++ b/tests/ui/const-generics/defaults/complex-generic-default-expr.min.stderr
@@ -0,0 +1,20 @@
+error: generic parameters may not be used in const operations
+  --> $DIR/complex-generic-default-expr.rs:6:47
+   |
+LL | struct Foo<const N: usize, const M: usize = { N + 1 }>;
+   |                                               ^ cannot perform const operation using `N`
+   |
+   = help: const parameters may only be used as standalone arguments, i.e. `N`
+   = help: use `#![feature(generic_const_exprs)]` to allow generic const expressions
+
+error: generic parameters may not be used in const operations
+  --> $DIR/complex-generic-default-expr.rs:9:62
+   |
+LL | struct Bar<T, const TYPE_SIZE: usize = { std::mem::size_of::<T>() }>(T);
+   |                                                              ^ cannot perform const operation using `T`
+   |
+   = note: type parameters may not be used in const expressions
+   = help: use `#![feature(generic_const_exprs)]` to allow generic const expressions
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/const-generics/defaults/complex-generic-default-expr.rs b/tests/ui/const-generics/defaults/complex-generic-default-expr.rs
new file mode 100644
index 000000000..7f50d4c9f
--- /dev/null
+++ b/tests/ui/const-generics/defaults/complex-generic-default-expr.rs
@@ -0,0 +1,12 @@
+// revisions: full min
+//[full] check-pass
+#![cfg_attr(full, feature(generic_const_exprs))]
+#![cfg_attr(full, allow(incomplete_features))]
+
+struct Foo<const N: usize, const M: usize = { N + 1 }>;
+//[min]~^ ERROR generic parameters may not be used in const operations
+
+struct Bar<T, const TYPE_SIZE: usize = { std::mem::size_of::<T>() }>(T);
+//[min]~^ ERROR generic parameters may not be used in const operations
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/complex-unord-param.rs b/tests/ui/const-generics/defaults/complex-unord-param.rs
new file mode 100644
index 000000000..aebc5975a
--- /dev/null
+++ b/tests/ui/const-generics/defaults/complex-unord-param.rs
@@ -0,0 +1,17 @@
+// run-pass
+// Checks a complicated usage of unordered params
+#![allow(dead_code)]
+
+struct NestedArrays<'a, const N: usize, A: 'a, const M: usize, T:'a =u32> {
+    args: &'a [&'a [T; M]; N],
+    specifier: A,
+}
+
+fn main() {
+    let array = [1, 2, 3];
+    let nest = [&array];
+    let _ = NestedArrays {
+        args: &nest,
+        specifier: true,
+    };
+}
diff --git a/tests/ui/const-generics/defaults/const-default.rs b/tests/ui/const-generics/defaults/const-default.rs
new file mode 100644
index 000000000..65cb0eb14
--- /dev/null
+++ b/tests/ui/const-generics/defaults/const-default.rs
@@ -0,0 +1,24 @@
+// run-pass
+pub struct ConstDefault<const N: usize = 3>;
+
+impl<const N: usize> ConstDefault<N> {
+    fn foo(self) -> usize {
+        N
+    }
+}
+
+impl ConstDefault {
+    fn new() -> Self {
+        ConstDefault
+    }
+
+    fn bar(self) {}
+}
+
+pub fn main() {
+    let s = ConstDefault::new();
+    assert_eq!(s.foo(), 3);
+
+    let w = ConstDefault::<3>;
+    w.bar();
+}
diff --git a/tests/ui/const-generics/defaults/const-param-as-default-value.rs b/tests/ui/const-generics/defaults/const-param-as-default-value.rs
new file mode 100644
index 000000000..c1c955d87
--- /dev/null
+++ b/tests/ui/const-generics/defaults/const-param-as-default-value.rs
@@ -0,0 +1,21 @@
+// run-pass
+struct Foo<const N: usize, const M: usize = N>([u8; N], [u8; M]);
+
+fn foo<const N: usize>() -> Foo<N> {
+    let x = [0; N];
+    Foo(x, x)
+}
+
+// To check that we actually apply the correct substs for const param defaults.
+fn concrete_foo() -> Foo<13> {
+    Foo(Default::default(), Default::default())
+}
+
+
+fn main() {
+    let val = foo::<13>();
+    assert_eq!(val.0, val.1);
+
+    let val = concrete_foo();
+    assert_eq!(val.0, val.1);
+}
diff --git a/tests/ui/const-generics/defaults/const-param-in-ty-defaults.rs b/tests/ui/const-generics/defaults/const-param-in-ty-defaults.rs
new file mode 100644
index 000000000..5f0cafe2e
--- /dev/null
+++ b/tests/ui/const-generics/defaults/const-param-in-ty-defaults.rs
@@ -0,0 +1,12 @@
+// run-pass
+struct Foo<const N: usize, T = [u8; N]>(T);
+
+impl<const N: usize> Foo<N> {
+    fn new() -> Self {
+        Foo([0; N])
+    }
+}
+
+fn main() {
+    assert_eq!(Foo::new().0, [0; 10]);
+}
diff --git a/tests/ui/const-generics/defaults/default-annotation.rs b/tests/ui/const-generics/defaults/default-annotation.rs
new file mode 100644
index 000000000..7a9f5732f
--- /dev/null
+++ b/tests/ui/const-generics/defaults/default-annotation.rs
@@ -0,0 +1,17 @@
+// run-pass
+#![feature(staged_api)]
+#![allow(incomplete_features)]
+// FIXME(const_generics_defaults): It seems like we aren't testing the right thing here,
+// I would assume that we want the attributes to apply to the const parameter defaults
+// themselves.
+#![stable(feature = "const_default_test", since="none")]
+
+#[unstable(feature = "const_default_stable", issue="none")]
+pub struct ConstDefaultUnstable<const N: usize = 3>;
+
+#[stable(feature = "const_default_unstable", since="none")]
+pub struct ConstDefaultStable<const N: usize = {
+    3
+}>;
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/default-const-param-cannot-reference-self.rs b/tests/ui/const-generics/defaults/default-const-param-cannot-reference-self.rs
new file mode 100644
index 000000000..45275e609
--- /dev/null
+++ b/tests/ui/const-generics/defaults/default-const-param-cannot-reference-self.rs
@@ -0,0 +1,14 @@
+struct Struct<const N: usize = { Self; 10 }>;
+//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735]
+
+enum Enum<const N: usize = { Self; 10 }> { }
+//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735]
+
+union Union<const N: usize = { Self; 10 }> { not_empty: () }
+//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735]
+
+fn main() {
+    let _: Struct;
+    let _: Enum;
+    let _: Union;
+}
diff --git a/tests/ui/const-generics/defaults/default-const-param-cannot-reference-self.stderr b/tests/ui/const-generics/defaults/default-const-param-cannot-reference-self.stderr
new file mode 100644
index 000000000..72d7001fd
--- /dev/null
+++ b/tests/ui/const-generics/defaults/default-const-param-cannot-reference-self.stderr
@@ -0,0 +1,21 @@
+error[E0735]: generic parameters cannot use `Self` in their defaults
+  --> $DIR/default-const-param-cannot-reference-self.rs:1:34
+   |
+LL | struct Struct<const N: usize = { Self; 10 }>;
+   |                                  ^^^^ `Self` in generic parameter default
+
+error[E0735]: generic parameters cannot use `Self` in their defaults
+  --> $DIR/default-const-param-cannot-reference-self.rs:4:30
+   |
+LL | enum Enum<const N: usize = { Self; 10 }> { }
+   |                              ^^^^ `Self` in generic parameter default
+
+error[E0735]: generic parameters cannot use `Self` in their defaults
+  --> $DIR/default-const-param-cannot-reference-self.rs:7:32
+   |
+LL | union Union<const N: usize = { Self; 10 }> { not_empty: () }
+   |                                ^^^^ `Self` in generic parameter default
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0735`.
diff --git a/tests/ui/const-generics/defaults/default-on-impl.rs b/tests/ui/const-generics/defaults/default-on-impl.rs
new file mode 100644
index 000000000..9ce46aa09
--- /dev/null
+++ b/tests/ui/const-generics/defaults/default-on-impl.rs
@@ -0,0 +1,6 @@
+struct Foo<const N: usize>;
+
+impl<const N: usize = 1> Foo<N> {}
+//~^ ERROR defaults for const parameters are only allowed
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/default-on-impl.stderr b/tests/ui/const-generics/defaults/default-on-impl.stderr
new file mode 100644
index 000000000..4b2b05742
--- /dev/null
+++ b/tests/ui/const-generics/defaults/default-on-impl.stderr
@@ -0,0 +1,8 @@
+error: defaults for const parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
+  --> $DIR/default-on-impl.rs:3:6
+   |
+LL | impl<const N: usize = 1> Foo<N> {}
+   |      ^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/tests/ui/const-generics/defaults/default-param-wf-concrete.rs b/tests/ui/const-generics/defaults/default-param-wf-concrete.rs
new file mode 100644
index 000000000..41a52c7eb
--- /dev/null
+++ b/tests/ui/const-generics/defaults/default-param-wf-concrete.rs
@@ -0,0 +1,3 @@
+struct Foo<const N: u8 = { 255 + 1 }>;
+//~^ ERROR evaluation of constant value failed
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/default-param-wf-concrete.stderr b/tests/ui/const-generics/defaults/default-param-wf-concrete.stderr
new file mode 100644
index 000000000..e8ebddade
--- /dev/null
+++ b/tests/ui/const-generics/defaults/default-param-wf-concrete.stderr
@@ -0,0 +1,9 @@
+error[E0080]: evaluation of constant value failed
+  --> $DIR/default-param-wf-concrete.rs:1:28
+   |
+LL | struct Foo<const N: u8 = { 255 + 1 }>;
+   |                            ^^^^^^^ attempt to compute `u8::MAX + 1_u8`, which would overflow
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0080`.
diff --git a/tests/ui/const-generics/defaults/doesnt_infer.rs b/tests/ui/const-generics/defaults/doesnt_infer.rs
new file mode 100644
index 000000000..9c59e672d
--- /dev/null
+++ b/tests/ui/const-generics/defaults/doesnt_infer.rs
@@ -0,0 +1,13 @@
+// test that defaulted const params are not used to help type inference
+
+struct Foo<const N: u32 = 2>;
+
+impl<const N: u32> Foo<N> {
+    fn foo() -> Self { loop {} }
+}
+
+fn main() {
+    let foo = Foo::<1>::foo();
+    let foo = Foo::foo();
+    //~^ error: type annotations needed for `Foo<N>`
+}
diff --git a/tests/ui/const-generics/defaults/doesnt_infer.stderr b/tests/ui/const-generics/defaults/doesnt_infer.stderr
new file mode 100644
index 000000000..227b2f402
--- /dev/null
+++ b/tests/ui/const-generics/defaults/doesnt_infer.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed for `Foo<N>`
+  --> $DIR/doesnt_infer.rs:11:9
+   |
+LL |     let foo = Foo::foo();
+   |         ^^^
+   |
+help: consider giving `foo` an explicit type, where the the value of const parameter `N` is specified
+   |
+LL |     let foo: Foo<N> = Foo::foo();
+   |            ++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/tests/ui/const-generics/defaults/external.rs b/tests/ui/const-generics/defaults/external.rs
new file mode 100644
index 000000000..25ec523cb
--- /dev/null
+++ b/tests/ui/const-generics/defaults/external.rs
@@ -0,0 +1,24 @@
+// aux-build:const_defaulty.rs
+// check-pass
+extern crate const_defaulty;
+use const_defaulty::Defaulted;
+
+struct Local<const N: usize=4>;
+impl Local {
+    fn new() -> Self {
+        Local
+    }
+}
+impl<const N: usize>Local<N> {
+    fn value(&self) -> usize {
+        N
+    }
+}
+
+fn main() {
+    let v = Defaulted::new();
+    assert_eq!(v.value(), 3);
+
+    let l = Local::new();
+    assert_eq!(l.value(), 4);
+}
diff --git a/tests/ui/const-generics/defaults/forward-declared.rs b/tests/ui/const-generics/defaults/forward-declared.rs
new file mode 100644
index 000000000..ede3d873b
--- /dev/null
+++ b/tests/ui/const-generics/defaults/forward-declared.rs
@@ -0,0 +1,13 @@
+struct Foo<const N: usize = M, const M: usize = 10>;
+//~^ ERROR generic parameters with a default cannot use forward declared identifiers
+
+enum Bar<const N: usize = M, const M: usize = 10> {}
+//~^ ERROR generic parameters with a default cannot use forward declared identifiers
+
+struct Foo2<const N: usize = N>;
+//~^ ERROR generic parameters with a default cannot use forward declared identifiers
+
+enum Bar2<const N: usize = N> {}
+//~^ ERROR generic parameters with a default cannot use forward declared identifiers
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/forward-declared.stderr b/tests/ui/const-generics/defaults/forward-declared.stderr
new file mode 100644
index 000000000..4856c7a1f
--- /dev/null
+++ b/tests/ui/const-generics/defaults/forward-declared.stderr
@@ -0,0 +1,27 @@
+error[E0128]: generic parameters with a default cannot use forward declared identifiers
+  --> $DIR/forward-declared.rs:1:29
+   |
+LL | struct Foo<const N: usize = M, const M: usize = 10>;
+   |                             ^ defaulted generic parameters cannot be forward declared
+
+error[E0128]: generic parameters with a default cannot use forward declared identifiers
+  --> $DIR/forward-declared.rs:4:27
+   |
+LL | enum Bar<const N: usize = M, const M: usize = 10> {}
+   |                           ^ defaulted generic parameters cannot be forward declared
+
+error[E0128]: generic parameters with a default cannot use forward declared identifiers
+  --> $DIR/forward-declared.rs:7:30
+   |
+LL | struct Foo2<const N: usize = N>;
+   |                              ^ defaulted generic parameters cannot be forward declared
+
+error[E0128]: generic parameters with a default cannot use forward declared identifiers
+  --> $DIR/forward-declared.rs:10:28
+   |
+LL | enum Bar2<const N: usize = N> {}
+   |                            ^ defaulted generic parameters cannot be forward declared
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0128`.
diff --git a/tests/ui/const-generics/defaults/generic-expr-default-concrete.rs b/tests/ui/const-generics/defaults/generic-expr-default-concrete.rs
new file mode 100644
index 000000000..f082bd8d2
--- /dev/null
+++ b/tests/ui/const-generics/defaults/generic-expr-default-concrete.rs
@@ -0,0 +1,14 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+struct Foo<const N: usize, const M: usize = { N + 1 }>;
+fn no_constraining() -> Foo<10> {
+    Foo::<10, 11>
+}
+
+pub fn different_than_default() -> Foo<10> {
+    Foo::<10, 12>
+    //~^ error: mismatched types
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/generic-expr-default-concrete.stderr b/tests/ui/const-generics/defaults/generic-expr-default-concrete.stderr
new file mode 100644
index 000000000..61b355118
--- /dev/null
+++ b/tests/ui/const-generics/defaults/generic-expr-default-concrete.stderr
@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/generic-expr-default-concrete.rs:10:5
+   |
+LL |     Foo::<10, 12>
+   |     ^^^^^^^^^^^^^ expected `11`, found `12`
+   |
+   = note: expected constant `11`
+              found constant `12`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/const-generics/defaults/generic-expr-default-mismatched-types.rs b/tests/ui/const-generics/defaults/generic-expr-default-mismatched-types.rs
new file mode 100644
index 000000000..777865d1c
--- /dev/null
+++ b/tests/ui/const-generics/defaults/generic-expr-default-mismatched-types.rs
@@ -0,0 +1,16 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+struct Foo<const N: usize, const M: usize = { N + 1 }>;
+fn should_unify<const N: usize>() -> Foo<N> where [(); { N + 1 }]: {
+    Foo::<N, { N + 1 }>
+}
+pub fn shouldnt_unify<const N: usize>() -> Foo<N>
+where
+    [(); { N + 1 }]:,
+    [(); { N + 2 }]:, {
+    Foo::<N, { N + 2 }>
+    //~^ error: mismatched types
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/generic-expr-default-mismatched-types.stderr b/tests/ui/const-generics/defaults/generic-expr-default-mismatched-types.stderr
new file mode 100644
index 000000000..e83f89a60
--- /dev/null
+++ b/tests/ui/const-generics/defaults/generic-expr-default-mismatched-types.stderr
@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/generic-expr-default-mismatched-types.rs:12:5
+   |
+LL |     Foo::<N, { N + 2 }>
+   |     ^^^^^^^^^^^^^^^^^^^ expected `{ N + 1 }`, found `{ N + 2 }`
+   |
+   = note: expected constant `{ N + 1 }`
+              found constant `{ N + 2 }`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/const-generics/defaults/generic-expr-default.rs b/tests/ui/const-generics/defaults/generic-expr-default.rs
new file mode 100644
index 000000000..8fe43feb7
--- /dev/null
+++ b/tests/ui/const-generics/defaults/generic-expr-default.rs
@@ -0,0 +1,24 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+pub struct Foo<const N: usize, const M: usize = { N + 1 }>;
+pub fn needs_evaluatable_bound<const N1: usize>() -> Foo<N1> {
+    //~^ error: unconstrained generic constant
+    loop {}
+}
+pub fn has_evaluatable_bound<const N1: usize>() -> Foo<N1> where [(); N1 + 1]: {
+    loop {}
+}
+
+type FooAlias<const N: usize, const NP: usize = { N + 1 }> = [(); NP];
+fn needs_evaluatable_bound_alias<T, const N: usize>() -> FooAlias<N>
+{
+    //~^^ error: unconstrained generic constant
+    todo!()
+}
+fn has_evaluatable_bound_alias<const N: usize>() -> FooAlias<N>
+where [(); N + 1]: {
+    todo!()
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/generic-expr-default.stderr b/tests/ui/const-generics/defaults/generic-expr-default.stderr
new file mode 100644
index 000000000..ada1498d1
--- /dev/null
+++ b/tests/ui/const-generics/defaults/generic-expr-default.stderr
@@ -0,0 +1,18 @@
+error: unconstrained generic constant
+  --> $DIR/generic-expr-default.rs:5:54
+   |
+LL | pub fn needs_evaluatable_bound<const N1: usize>() -> Foo<N1> {
+   |                                                      ^^^^^^^
+   |
+   = help: try adding a `where` bound using this expression: `where [(); { N + 1 }]:`
+
+error: unconstrained generic constant
+  --> $DIR/generic-expr-default.rs:14:58
+   |
+LL | fn needs_evaluatable_bound_alias<T, const N: usize>() -> FooAlias<N>
+   |                                                          ^^^^^^^^^^^
+   |
+   = help: try adding a `where` bound using this expression: `where [(); { N + 1 }]:`
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/const-generics/defaults/intermixed-lifetime.rs b/tests/ui/const-generics/defaults/intermixed-lifetime.rs
new file mode 100644
index 000000000..beaf7fc60
--- /dev/null
+++ b/tests/ui/const-generics/defaults/intermixed-lifetime.rs
@@ -0,0 +1,9 @@
+// Checks that lifetimes cannot be interspersed between consts and types.
+
+struct Foo<const N: usize, 'a, T = u32>(&'a (), T);
+//~^ ERROR lifetime parameters must be declared prior to type and const parameters
+
+struct Bar<const N: usize, T = u32, 'a>(&'a (), T);
+//~^ ERROR lifetime parameters must be declared prior to type and const parameters
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/intermixed-lifetime.stderr b/tests/ui/const-generics/defaults/intermixed-lifetime.stderr
new file mode 100644
index 000000000..5cff61dd9
--- /dev/null
+++ b/tests/ui/const-generics/defaults/intermixed-lifetime.stderr
@@ -0,0 +1,14 @@
+error: lifetime parameters must be declared prior to type and const parameters
+  --> $DIR/intermixed-lifetime.rs:3:28
+   |
+LL | struct Foo<const N: usize, 'a, T = u32>(&'a (), T);
+   |           -----------------^^---------- help: reorder the parameters: lifetimes, then consts and types: `<'a, const N: usize, T = u32>`
+
+error: lifetime parameters must be declared prior to type and const parameters
+  --> $DIR/intermixed-lifetime.rs:6:37
+   |
+LL | struct Bar<const N: usize, T = u32, 'a>(&'a (), T);
+   |           --------------------------^^- help: reorder the parameters: lifetimes, then consts and types: `<'a, const N: usize, T = u32>`
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/const-generics/defaults/mismatch.rs b/tests/ui/const-generics/defaults/mismatch.rs
new file mode 100644
index 000000000..ec131505e
--- /dev/null
+++ b/tests/ui/const-generics/defaults/mismatch.rs
@@ -0,0 +1,22 @@
+pub struct Example<const N: usize = 13>;
+pub struct Example2<T = u32, const N: usize = 13>(T);
+pub struct Example3<const N: usize = 13, T = u32>(T);
+pub struct Example4<const N: usize = 13, const M: usize = 4>;
+
+fn main() {
+    let e: Example<13> = ();
+    //~^ Error: mismatched types
+    //~| expected struct `Example`
+    let e: Example2<u32, 13> = ();
+    //~^ Error: mismatched types
+    //~| expected struct `Example2`
+    let e: Example3<13, u32> = ();
+    //~^ Error: mismatched types
+    //~| expected struct `Example3`
+    let e: Example3<7> = ();
+    //~^ Error: mismatched types
+    //~| expected struct `Example3<7>`
+    let e: Example4<7> = ();
+    //~^ Error: mismatched types
+    //~| expected struct `Example4<7>`
+}
diff --git a/tests/ui/const-generics/defaults/mismatch.stderr b/tests/ui/const-generics/defaults/mismatch.stderr
new file mode 100644
index 000000000..52c54aace
--- /dev/null
+++ b/tests/ui/const-generics/defaults/mismatch.stderr
@@ -0,0 +1,58 @@
+error[E0308]: mismatched types
+  --> $DIR/mismatch.rs:7:26
+   |
+LL |     let e: Example<13> = ();
+   |            -----------   ^^ expected struct `Example`, found `()`
+   |            |
+   |            expected due to this
+   |
+   = note: expected struct `Example`
+           found unit type `()`
+
+error[E0308]: mismatched types
+  --> $DIR/mismatch.rs:10:32
+   |
+LL |     let e: Example2<u32, 13> = ();
+   |            -----------------   ^^ expected struct `Example2`, found `()`
+   |            |
+   |            expected due to this
+   |
+   = note: expected struct `Example2`
+           found unit type `()`
+
+error[E0308]: mismatched types
+  --> $DIR/mismatch.rs:13:32
+   |
+LL |     let e: Example3<13, u32> = ();
+   |            -----------------   ^^ expected struct `Example3`, found `()`
+   |            |
+   |            expected due to this
+   |
+   = note: expected struct `Example3`
+           found unit type `()`
+
+error[E0308]: mismatched types
+  --> $DIR/mismatch.rs:16:26
+   |
+LL |     let e: Example3<7> = ();
+   |            -----------   ^^ expected struct `Example3`, found `()`
+   |            |
+   |            expected due to this
+   |
+   = note: expected struct `Example3<7>`
+           found unit type `()`
+
+error[E0308]: mismatched types
+  --> $DIR/mismatch.rs:19:26
+   |
+LL |     let e: Example4<7> = ();
+   |            -----------   ^^ expected struct `Example4`, found `()`
+   |            |
+   |            expected due to this
+   |
+   = note: expected struct `Example4<7>`
+           found unit type `()`
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/const-generics/defaults/mismatched_ty_const_in_trait_impl.rs b/tests/ui/const-generics/defaults/mismatched_ty_const_in_trait_impl.rs
new file mode 100644
index 000000000..5c9323261
--- /dev/null
+++ b/tests/ui/const-generics/defaults/mismatched_ty_const_in_trait_impl.rs
@@ -0,0 +1,41 @@
+trait Trait {
+    fn foo<U>() {}
+}
+impl Trait for () {
+    fn foo<const M: u64>() {}
+    //~^ error: method `foo` has an incompatible generic parameter for trait
+}
+
+trait Other {
+    fn bar<const M: u8>() {}
+}
+impl Other for () {
+    fn bar<T>() {}
+    //~^ error: method `bar` has an incompatible generic parameter for trait
+}
+
+trait Uwu {
+    fn baz<const N: u32>() {}
+}
+impl Uwu for () {
+    fn baz<const N: i32>() {}
+    //~^ error: method `baz` has an incompatible generic parameter for trait
+}
+
+trait Aaaaaa {
+    fn bbbb<const N: u32, T>() {}
+}
+impl Aaaaaa for () {
+    fn bbbb<T, const N: u32>() {}
+    //~^ error: method `bbbb` has an incompatible generic parameter for trait
+}
+
+trait Names {
+    fn abcd<T, const N: u32>() {}
+}
+impl Names for () {
+    fn abcd<const N: u32, T>() {}
+    //~^ error: method `abcd` has an incompatible generic parameter for trait
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/mismatched_ty_const_in_trait_impl.stderr b/tests/ui/const-generics/defaults/mismatched_ty_const_in_trait_impl.stderr
new file mode 100644
index 000000000..3455f2c8e
--- /dev/null
+++ b/tests/ui/const-generics/defaults/mismatched_ty_const_in_trait_impl.stderr
@@ -0,0 +1,68 @@
+error[E0053]: method `foo` has an incompatible generic parameter for trait `Trait`
+  --> $DIR/mismatched_ty_const_in_trait_impl.rs:5:12
+   |
+LL | trait Trait {
+   |       -----
+LL |     fn foo<U>() {}
+   |            - expected type parameter
+LL | }
+LL | impl Trait for () {
+   | -----------------
+LL |     fn foo<const M: u64>() {}
+   |            ^^^^^^^^^^^^ found const parameter of type `u64`
+
+error[E0053]: method `bar` has an incompatible generic parameter for trait `Other`
+  --> $DIR/mismatched_ty_const_in_trait_impl.rs:13:12
+   |
+LL | trait Other {
+   |       -----
+LL |     fn bar<const M: u8>() {}
+   |            ----------- expected const parameter of type `u8`
+LL | }
+LL | impl Other for () {
+   | -----------------
+LL |     fn bar<T>() {}
+   |            ^ found type parameter
+
+error[E0053]: method `baz` has an incompatible generic parameter for trait `Uwu`
+  --> $DIR/mismatched_ty_const_in_trait_impl.rs:21:12
+   |
+LL | trait Uwu {
+   |       ---
+LL |     fn baz<const N: u32>() {}
+   |            ------------ expected const parameter of type `u32`
+LL | }
+LL | impl Uwu for () {
+   | ---------------
+LL |     fn baz<const N: i32>() {}
+   |            ^^^^^^^^^^^^ found const parameter of type `i32`
+
+error[E0053]: method `bbbb` has an incompatible generic parameter for trait `Aaaaaa`
+  --> $DIR/mismatched_ty_const_in_trait_impl.rs:29:13
+   |
+LL | trait Aaaaaa {
+   |       ------
+LL |     fn bbbb<const N: u32, T>() {}
+   |             ------------ expected const parameter of type `u32`
+LL | }
+LL | impl Aaaaaa for () {
+   | ------------------
+LL |     fn bbbb<T, const N: u32>() {}
+   |             ^ found type parameter
+
+error[E0053]: method `abcd` has an incompatible generic parameter for trait `Names`
+  --> $DIR/mismatched_ty_const_in_trait_impl.rs:37:13
+   |
+LL | trait Names {
+   |       -----
+LL |     fn abcd<T, const N: u32>() {}
+   |             - expected type parameter
+LL | }
+LL | impl Names for () {
+   | -----------------
+LL |     fn abcd<const N: u32, T>() {}
+   |             ^^^^^^^^^^^^ found const parameter of type `u32`
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0053`.
diff --git a/tests/ui/const-generics/defaults/param-order-err-pretty-prints-default.rs b/tests/ui/const-generics/defaults/param-order-err-pretty-prints-default.rs
new file mode 100644
index 000000000..f928fc9e7
--- /dev/null
+++ b/tests/ui/const-generics/defaults/param-order-err-pretty-prints-default.rs
@@ -0,0 +1,4 @@
+struct Foo<const M: usize = 10, 'a>(&'a u32);
+//~^ ERROR lifetime parameters must be declared prior to type and const parameters
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/param-order-err-pretty-prints-default.stderr b/tests/ui/const-generics/defaults/param-order-err-pretty-prints-default.stderr
new file mode 100644
index 000000000..ba08b4646
--- /dev/null
+++ b/tests/ui/const-generics/defaults/param-order-err-pretty-prints-default.stderr
@@ -0,0 +1,8 @@
+error: lifetime parameters must be declared prior to type and const parameters
+  --> $DIR/param-order-err-pretty-prints-default.rs:1:33
+   |
+LL | struct Foo<const M: usize = 10, 'a>(&'a u32);
+   |           ----------------------^^- help: reorder the parameters: lifetimes, then consts and types: `<'a, const M: usize = 10>`
+
+error: aborting due to previous error
+
diff --git a/tests/ui/const-generics/defaults/pretty-printing-ast.rs b/tests/ui/const-generics/defaults/pretty-printing-ast.rs
new file mode 100644
index 000000000..e202d4e86
--- /dev/null
+++ b/tests/ui/const-generics/defaults/pretty-printing-ast.rs
@@ -0,0 +1,11 @@
+// Test the AST pretty printer correctly handles default values for const generics
+// check-pass
+// compile-flags: -Z unpretty=expanded
+
+#![crate_type = "lib"]
+
+trait Foo<const KIND: bool = true> {}
+
+fn foo<const SIZE: usize = 5>() {}
+
+struct Range<const FROM: usize = 0, const LEN: usize = 0, const TO: usize = FROM>;
diff --git a/tests/ui/const-generics/defaults/pretty-printing-ast.stdout b/tests/ui/const-generics/defaults/pretty-printing-ast.stdout
new file mode 100644
index 000000000..121138605
--- /dev/null
+++ b/tests/ui/const-generics/defaults/pretty-printing-ast.stdout
@@ -0,0 +1,18 @@
+#![feature(prelude_import)]
+#![no_std]
+// Test the AST pretty printer correctly handles default values for const generics
+// check-pass
+// compile-flags: -Z unpretty=expanded
+
+#![crate_type = "lib"]
+#[prelude_import]
+use ::std::prelude::rust_2015::*;
+#[macro_use]
+extern crate std;
+
+trait Foo<const KIND : bool = true> {}
+
+fn foo<const SIZE : usize = 5>() {}
+
+struct Range<const FROM : usize = 0, const LEN : usize = 0, const TO : usize =
+    FROM>;
diff --git a/tests/ui/const-generics/defaults/repr-c-issue-82792.rs b/tests/ui/const-generics/defaults/repr-c-issue-82792.rs
new file mode 100644
index 000000000..118da2723
--- /dev/null
+++ b/tests/ui/const-generics/defaults/repr-c-issue-82792.rs
@@ -0,0 +1,11 @@
+// Regression test for #82792.
+
+// run-pass
+
+#[repr(C)]
+pub struct Loaf<T: Sized, const N: usize = 1> {
+    head: [T; N],
+    slice: [T],
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/rp_impl_trait.rs b/tests/ui/const-generics/defaults/rp_impl_trait.rs
new file mode 100644
index 000000000..dde8eea45
--- /dev/null
+++ b/tests/ui/const-generics/defaults/rp_impl_trait.rs
@@ -0,0 +1,29 @@
+// run-pass
+struct Uwu<const N: u32 = 1, const M: u32 = N>;
+
+trait Trait {}
+impl<const N: u32> Trait for Uwu<N> {}
+
+fn rawr<const N: u32>() -> impl Trait {
+    Uwu::<N>
+}
+
+trait Traitor<const N: u8 = 1, const M: u8 = N> { }
+
+impl<const N: u8> Traitor<N> for u32 {}
+impl Traitor<1, 1> for u64 {}
+
+fn uwu<const N: u8>() -> impl Traitor<N> {
+    1_u32
+}
+
+fn owo() -> impl Traitor {
+    1_u64
+}
+
+fn main() {
+    rawr::<3>();
+    rawr::<7>();
+    uwu::<{ u8::MAX }>();
+    owo();
+}
diff --git a/tests/ui/const-generics/defaults/rp_impl_trait_fail.rs b/tests/ui/const-generics/defaults/rp_impl_trait_fail.rs
new file mode 100644
index 000000000..80013e7b4
--- /dev/null
+++ b/tests/ui/const-generics/defaults/rp_impl_trait_fail.rs
@@ -0,0 +1,30 @@
+struct Uwu<const N: u32 = 1, const M: u32 = N>;
+
+trait Trait {}
+impl<const N: u32> Trait for Uwu<N> {}
+
+fn rawr() -> impl Trait {
+    //~^ error: the trait bound `Uwu<10, 12>: Trait` is not satisfied
+    Uwu::<10, 12>
+}
+
+trait Traitor<const N: u8 = 1, const M: u8 = N> {}
+
+impl<const N: u8> Traitor<N, 2> for u32 {}
+impl Traitor<1, 2> for u64 {}
+
+fn uwu<const N: u8>() -> impl Traitor<N> {
+    //~^ error: the trait bound `u32: Traitor<N>` is not satisfied
+    1_u32
+}
+
+fn owo() -> impl Traitor {
+    //~^ error: the trait bound `u64: Traitor` is not satisfied
+    1_u64
+}
+
+fn main() {
+    rawr();
+    uwu();
+    owo();
+}
diff --git a/tests/ui/const-generics/defaults/rp_impl_trait_fail.stderr b/tests/ui/const-generics/defaults/rp_impl_trait_fail.stderr
new file mode 100644
index 000000000..a46bd5352
--- /dev/null
+++ b/tests/ui/const-generics/defaults/rp_impl_trait_fail.stderr
@@ -0,0 +1,36 @@
+error[E0277]: the trait bound `Uwu<10, 12>: Trait` is not satisfied
+  --> $DIR/rp_impl_trait_fail.rs:6:14
+   |
+LL | fn rawr() -> impl Trait {
+   |              ^^^^^^^^^^ the trait `Trait` is not implemented for `Uwu<10, 12>`
+LL |
+LL |     Uwu::<10, 12>
+   |     ------------- return type was inferred to be `Uwu<10, 12>` here
+   |
+   = help: the trait `Trait` is implemented for `Uwu<N>`
+
+error[E0277]: the trait bound `u32: Traitor<N>` is not satisfied
+  --> $DIR/rp_impl_trait_fail.rs:16:26
+   |
+LL | fn uwu<const N: u8>() -> impl Traitor<N> {
+   |                          ^^^^^^^^^^^^^^^ the trait `Traitor<N>` is not implemented for `u32`
+LL |
+LL |     1_u32
+   |     ----- return type was inferred to be `u32` here
+   |
+   = help: the trait `Traitor<N, 2>` is implemented for `u32`
+
+error[E0277]: the trait bound `u64: Traitor` is not satisfied
+  --> $DIR/rp_impl_trait_fail.rs:21:13
+   |
+LL | fn owo() -> impl Traitor {
+   |             ^^^^^^^^^^^^ the trait `Traitor` is not implemented for `u64`
+LL |
+LL |     1_u64
+   |     ----- return type was inferred to be `u64` here
+   |
+   = help: the trait `Traitor<1, 2>` is implemented for `u64`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/const-generics/defaults/self-referential.rs b/tests/ui/const-generics/defaults/self-referential.rs
new file mode 100644
index 000000000..14a870dc3
--- /dev/null
+++ b/tests/ui/const-generics/defaults/self-referential.rs
@@ -0,0 +1,4 @@
+trait Foo<const M: u8, const M: u8 = M> {}
+//~^ ERROR the name `M` is already used for a generic parameter in this item's generic parameters
+impl Foo<2> for () {}
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/self-referential.stderr b/tests/ui/const-generics/defaults/self-referential.stderr
new file mode 100644
index 000000000..170c1f7f7
--- /dev/null
+++ b/tests/ui/const-generics/defaults/self-referential.stderr
@@ -0,0 +1,11 @@
+error[E0403]: the name `M` is already used for a generic parameter in this item's generic parameters
+  --> $DIR/self-referential.rs:1:30
+   |
+LL | trait Foo<const M: u8, const M: u8 = M> {}
+   |                 -            ^ already used
+   |                 |
+   |                 first use of `M`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0403`.
diff --git a/tests/ui/const-generics/defaults/simple-defaults.rs b/tests/ui/const-generics/defaults/simple-defaults.rs
new file mode 100644
index 000000000..6a782d223
--- /dev/null
+++ b/tests/ui/const-generics/defaults/simple-defaults.rs
@@ -0,0 +1,13 @@
+// run-pass
+// Checks that type param defaults are allowed after const params.
+#![allow(dead_code)]
+
+struct FixedOutput<'a, const N: usize, T=u32> {
+    out: &'a [T; N],
+}
+
+trait FixedOutputter {
+    fn out(&self) -> FixedOutput<'_, 10>;
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/trait_object_lt_defaults.rs b/tests/ui/const-generics/defaults/trait_object_lt_defaults.rs
new file mode 100644
index 000000000..a1828727e
--- /dev/null
+++ b/tests/ui/const-generics/defaults/trait_object_lt_defaults.rs
@@ -0,0 +1,24 @@
+// aux-build:trait_object_lt_defaults_lib.rs
+// run-pass
+#![allow(dead_code)]
+extern crate trait_object_lt_defaults_lib;
+
+// Tests that `A<'a, 3, dyn Test>` is short for `A<'a, 3, dyn Test + 'a>`
+// and `Foo<'a, 3, dyn Test>` is short for `Foo<'a, 3, dyn Test + 'a>`
+// Test is in `const-generics/defaults` because it relies on param ordering
+
+trait Test {}
+
+struct A<'a, const N: usize, T: ?Sized + 'a>(&'a T, [(); N]);
+fn blah<'a>(mut a: A<'a, 3, dyn Test>, arg: &'a (dyn Test + 'a)) {
+    a.0 = arg;
+}
+
+fn other_blah<'a>(
+    mut a: trait_object_lt_defaults_lib::Foo<'a, 3, dyn Test>,
+    arg: &'a (dyn Test + 'a),
+) {
+    a.0 = arg;
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/trait_objects.rs b/tests/ui/const-generics/defaults/trait_objects.rs
new file mode 100644
index 000000000..750e40313
--- /dev/null
+++ b/tests/ui/const-generics/defaults/trait_objects.rs
@@ -0,0 +1,43 @@
+// run-pass
+trait Trait<const N: u8 = 12> {
+    fn uwu(&self) -> u8 {
+        N
+    }
+}
+
+impl Trait for u32 {}
+
+impl Trait<12> for u64 {
+    fn uwu(&self) -> u8 {
+        *self as u8
+    }
+}
+
+fn foo(arg: &dyn Trait) -> u8 {
+    arg.uwu()
+}
+
+trait Traitor<const N: u8 = 1, const M: u8 = N> {
+    fn owo(&self) -> u8 {
+        M
+    }
+}
+
+impl Traitor<2> for bool { }
+impl Traitor for u8 {
+    fn owo(&self) -> u8 {
+        *self
+    }
+}
+
+fn bar<const N: u8>(arg: &dyn Traitor<N>) -> u8 {
+    arg.owo()
+}
+
+fn main() {
+    assert_eq!(foo(&10_u32), 12);
+    assert_eq!(foo(&3_u64), 3);
+
+    assert_eq!(bar(&true), 2);
+    assert_eq!(bar(&1_u8), 1);
+}
diff --git a/tests/ui/const-generics/defaults/trait_objects_fail.rs b/tests/ui/const-generics/defaults/trait_objects_fail.rs
new file mode 100644
index 000000000..6ab803f99
--- /dev/null
+++ b/tests/ui/const-generics/defaults/trait_objects_fail.rs
@@ -0,0 +1,30 @@
+trait Trait<const N: u8 = 12> {
+    fn uwu(&self) -> u8 {
+        N
+    }
+}
+
+impl Trait<2> for u32 {}
+
+fn foo(arg: &dyn Trait) -> u8 {
+    arg.uwu()
+}
+
+trait Traitor<const N: u8 = 1, const M: u8 = N> {
+    fn owo(&self) -> u8 {
+        M
+    }
+}
+
+impl Traitor<2, 3> for bool {}
+
+fn bar<const N: u8>(arg: &dyn Traitor<N>) -> u8 {
+    arg.owo()
+}
+
+fn main() {
+    foo(&10_u32);
+    //~^ error: the trait bound `u32: Trait` is not satisfied
+    bar(&true);
+    //~^ error: the trait bound `bool: Traitor<_>` is not satisfied
+}
diff --git a/tests/ui/const-generics/defaults/trait_objects_fail.stderr b/tests/ui/const-generics/defaults/trait_objects_fail.stderr
new file mode 100644
index 000000000..0e8334d03
--- /dev/null
+++ b/tests/ui/const-generics/defaults/trait_objects_fail.stderr
@@ -0,0 +1,21 @@
+error[E0277]: the trait bound `u32: Trait` is not satisfied
+  --> $DIR/trait_objects_fail.rs:26:9
+   |
+LL |     foo(&10_u32);
+   |         ^^^^^^^ the trait `Trait` is not implemented for `u32`
+   |
+   = help: the trait `Trait<2>` is implemented for `u32`
+   = note: required for the cast from `u32` to the object type `dyn Trait`
+
+error[E0277]: the trait bound `bool: Traitor<_>` is not satisfied
+  --> $DIR/trait_objects_fail.rs:28:9
+   |
+LL |     bar(&true);
+   |         ^^^^^ the trait `Traitor<_>` is not implemented for `bool`
+   |
+   = help: the trait `Traitor<2, 3>` is implemented for `bool`
+   = note: required for the cast from `bool` to the object type `dyn Traitor<_>`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/const-generics/defaults/type-default-const-param-name.rs b/tests/ui/const-generics/defaults/type-default-const-param-name.rs
new file mode 100644
index 000000000..405664ded
--- /dev/null
+++ b/tests/ui/const-generics/defaults/type-default-const-param-name.rs
@@ -0,0 +1,14 @@
+// check-pass
+struct N;
+
+struct Foo<const N: usize = 1, T = N>(T);
+
+impl Foo {
+    fn new() -> Self {
+        Foo(N)
+    }
+}
+
+fn main() {
+    let Foo::<1, N>(N) = Foo::new();
+}
diff --git a/tests/ui/const-generics/defaults/wfness.rs b/tests/ui/const-generics/defaults/wfness.rs
new file mode 100644
index 000000000..a93f67081
--- /dev/null
+++ b/tests/ui/const-generics/defaults/wfness.rs
@@ -0,0 +1,23 @@
+struct Ooopsies<const N: u8 = { u8::MAX + 1 }>;
+//~^ error: evaluation of constant value failed
+
+trait Trait<const N: u8> {}
+impl Trait<3> for () {}
+struct WhereClause<const N: u8 = 2>
+where
+    (): Trait<N>;
+//~^ error: the trait bound `(): Trait<2>` is not satisfied
+
+trait Traitor<T, const N: u8> {}
+struct WhereClauseTooGeneric<T = u32, const N: u8 = 2>(T)
+where
+    (): Traitor<T, N>;
+
+// no error on struct def
+struct DependentDefaultWfness<const N: u8 = 1, T = WhereClause<N>>(T);
+fn foo() -> DependentDefaultWfness {
+    //~^ error: the trait bound `(): Trait<1>` is not satisfied
+    loop {}
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/wfness.stderr b/tests/ui/const-generics/defaults/wfness.stderr
new file mode 100644
index 000000000..25038f830
--- /dev/null
+++ b/tests/ui/const-generics/defaults/wfness.stderr
@@ -0,0 +1,34 @@
+error[E0080]: evaluation of constant value failed
+  --> $DIR/wfness.rs:1:33
+   |
+LL | struct Ooopsies<const N: u8 = { u8::MAX + 1 }>;
+   |                                 ^^^^^^^^^^^ attempt to compute `u8::MAX + 1_u8`, which would overflow
+
+error[E0277]: the trait bound `(): Trait<2>` is not satisfied
+  --> $DIR/wfness.rs:8:9
+   |
+LL |     (): Trait<N>;
+   |         ^^^^^^^^ the trait `Trait<2>` is not implemented for `()`
+   |
+   = help: the trait `Trait<3>` is implemented for `()`
+
+error[E0277]: the trait bound `(): Trait<1>` is not satisfied
+  --> $DIR/wfness.rs:18:13
+   |
+LL | fn foo() -> DependentDefaultWfness {
+   |             ^^^^^^^^^^^^^^^^^^^^^^ the trait `Trait<1>` is not implemented for `()`
+   |
+   = help: the trait `Trait<3>` is implemented for `()`
+note: required by a bound in `WhereClause`
+  --> $DIR/wfness.rs:8:9
+   |
+LL | struct WhereClause<const N: u8 = 2>
+   |        ----------- required by a bound in this
+LL | where
+LL |     (): Trait<N>;
+   |         ^^^^^^^^ required by this bound in `WhereClause`
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0080, E0277.
+For more information about an error, try `rustc --explain E0080`.
diff --git a/tests/ui/const-generics/defaults/wrong-order.rs b/tests/ui/const-generics/defaults/wrong-order.rs
new file mode 100644
index 000000000..d53d56f41
--- /dev/null
+++ b/tests/ui/const-generics/defaults/wrong-order.rs
@@ -0,0 +1,9 @@
+struct A<T = u32, const N: usize> {
+    //~^ ERROR generic parameters with a default must be trailing
+    arg: T,
+}
+
+struct Foo<const N: u8 = 3, T>(T);
+//~^ error: generic parameters with a default must be trailing
+
+fn main() {}
diff --git a/tests/ui/const-generics/defaults/wrong-order.stderr b/tests/ui/const-generics/defaults/wrong-order.stderr
new file mode 100644
index 000000000..4d2628d03
--- /dev/null
+++ b/tests/ui/const-generics/defaults/wrong-order.stderr
@@ -0,0 +1,14 @@
+error: generic parameters with a default must be trailing
+  --> $DIR/wrong-order.rs:1:10
+   |
+LL | struct A<T = u32, const N: usize> {
+   |          ^
+
+error: generic parameters with a default must be trailing
+  --> $DIR/wrong-order.rs:6:18
+   |
+LL | struct Foo<const N: u8 = 3, T>(T);
+   |                  ^
+
+error: aborting due to 2 previous errors
+