fix name resolution for param defaults

src/test/ui/const-generics/defaults/complex-generic-default-expr.rs

@@ -0,0 +1,9 @@
+#![feature(const_generics, const_generics_defaults)]
+#![allow(incomplete_features)]
+
+struct Foo<const N: usize, const M: usize = { N + 1 }>;
+
+struct Bar<T, const TYPE_SIZE: usize = { std::mem::size_of::<T>() }>(T);
+//~^ ERROR the size for values of type `T` cannot be known at compilation time 
+
+fn main() {}

src/test/ui/const-generics/defaults/complex-generic-default-expr.stderr

@@ -0,0 +1,16 @@
+error[E0277]: the size for values of type `T` cannot be known at compilation time
+  --> $DIR/complex-generic-default-expr.rs:6:62
+   |
+LL | struct Bar<T, const TYPE_SIZE: usize = { std::mem::size_of::<T>() }>(T);
+   |            -                                                 ^ doesn't have a size known at compile-time
+   |            |
+   |            this type parameter needs to be `std::marker::Sized`
+   | 
+  ::: $SRC_DIR/core/src/mem/mod.rs:LL:COL
+   |
+LL | pub const fn size_of<T>() -> usize {
+   |                      - required by this bound in `std::mem::size_of`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.

src/test/ui/const-generics/defaults/default-on-impl.rs

@@ -0,0 +1,9 @@
+#![feature(const_generics, const_generics_defaults)]
+#![allow(incomplete_features)]
+
+struct Foo<const N: usize>;
+
+impl<const N: usize = 1> Foo<N> {}
+//~^ ERROR defaults for const parameters are only allowed
+
+fn main() {}

src/test/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:6:12
+   |
+LL | impl<const N: usize = 1> Foo<N> {}
+   |            ^
+
+error: aborting due to previous error
+

src/test/ui/const-generics/defaults/pretty-printing-ast.rs

@@ -10,4 +10,5 @@ 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 + LEN}>;
+struct Range<const FROM: usize = 0, const LEN: usize = 0, const TO: usize = FROM>;
+

src/test/ui/const-generics/defaults/pretty-printing-ast.stdout

@@ -17,4 +17,5 @@ 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 + LEN }>;
+             FROM>;
+

src/test/ui/const-generics/defaults/type-default-const-param-name.rs

@@ -0,0 +1,17 @@
+// check-pass
+#![feature(const_generics, const_generics_defaults)]
+#![allow(incomplete_features)]
+
+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();
+}

src/test/ui/const-generics/params-in-ct-in-ty-param-lazy-norm.full.stderr

@@ -6,17 +6,26 @@ LL | struct Bar<T = [u8; N], const N: usize>(T);
    |
    = note: using type defaults and const parameters in the same parameter list is currently not permitted
 
-error: constant values inside of type parameter defaults must not depend on generic parameters
-  --> $DIR/params-in-ct-in-ty-param-lazy-norm.rs:6:44
-   |
-LL | struct Foo<T, U = [u8; std::mem::size_of::<T>()]>(T, U);
-   |                                            ^ the anonymous constant must not depend on the parameter `T`
-
-error: constant values inside of type parameter defaults must not depend on generic parameters
+error[E0128]: generic parameters with a default cannot use forward declared identifiers
   --> $DIR/params-in-ct-in-ty-param-lazy-norm.rs:11:21
    |
 LL | struct Bar<T = [u8; N], const N: usize>(T);
-   |                     ^ the anonymous constant must not depend on the parameter `N`
+   |                     ^ defaulted generic parameters cannot be forward declared
+
+error[E0277]: the size for values of type `T` cannot be known at compilation time
+  --> $DIR/params-in-ct-in-ty-param-lazy-norm.rs:6:44
+   |
+LL | struct Foo<T, U = [u8; std::mem::size_of::<T>()]>(T, U);
+   |            -                               ^ doesn't have a size known at compile-time
+   |            |
+   |            this type parameter needs to be `std::marker::Sized`
+   | 
+  ::: $SRC_DIR/core/src/mem/mod.rs:LL:COL
+   |
+LL | pub const fn size_of<T>() -> usize {
+   |                      - required by this bound in `std::mem::size_of`
 
 error: aborting due to 3 previous errors
 
+Some errors have detailed explanations: E0128, E0277.
+For more information about an error, try `rustc --explain E0128`.

src/test/ui/const-generics/params-in-ct-in-ty-param-lazy-norm.min.stderr

@@ -15,11 +15,12 @@ LL | struct Foo<T, U = [u8; std::mem::size_of::<T>()]>(T, U);
    = note: type parameters may not be used in const expressions
    = help: use `#![feature(const_generics)]` and `#![feature(const_evaluatable_checked)]` to allow generic const expressions
 
-error: constant values inside of type parameter defaults must not depend on generic parameters
+error[E0128]: generic parameters with a default cannot use forward declared identifiers
   --> $DIR/params-in-ct-in-ty-param-lazy-norm.rs:11:21
    |
 LL | struct Bar<T = [u8; N], const N: usize>(T);
-   |                     ^ the anonymous constant must not depend on the parameter `N`
+   |                     ^ defaulted generic parameters cannot be forward declared
 
 error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0128`.

src/test/ui/const-generics/params-in-ct-in-ty-param-lazy-norm.rs

@@ -4,12 +4,12 @@
 #![cfg_attr(full, allow(incomplete_features))]
 
 struct Foo<T, U = [u8; std::mem::size_of::<T>()]>(T, U);
-//[full]~^ ERROR constant values inside of type parameter defaults
+//[full]~^ ERROR the size for values of type `T` cannot be known at compilation time
 //[min]~^^ ERROR generic parameters may not be used in const operations
 
 // FIXME(const_generics_defaults): We still don't know how to deal with type defaults.
 struct Bar<T = [u8; N], const N: usize>(T);
-//~^ ERROR constant values inside of type parameter defaults
+//~^ ERROR generic parameters with a default cannot use forward declared identifiers
 //~| ERROR generic parameters with a default
 
 fn main() {}

src/test/ui/generics/generic-non-trailing-defaults.rs

@@ -5,5 +5,6 @@ struct Vec<A = Heap, T>(A, T);
 
 struct Foo<A, B = Vec<C>, C>(A, B, C);
 //~^ ERROR generic parameters with a default must be trailing
+//~| ERROR generic parameters with a default cannot use
 
 fn main() {}

src/test/ui/generics/generic-non-trailing-defaults.stderr

@@ -10,5 +10,12 @@ error: generic parameters with a default must be trailing
 LL | struct Foo<A, B = Vec<C>, C>(A, B, C);
    |               ^
 
-error: aborting due to 2 previous errors
+error[E0128]: generic parameters with a default cannot use forward declared identifiers
+  --> $DIR/generic-non-trailing-defaults.rs:6:23
+   |
+LL | struct Foo<A, B = Vec<C>, C>(A, B, C);
+   |                       ^ defaulted generic parameters cannot be forward declared
 
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0128`.