Fix missing diagnostic span for impl Trait with const generics, and add various tests for min_const_generics and const_generics

compiler/rustc_feature/src/active.rs

@@ -581,7 +581,7 @@ declare_features! (
     /// Allows `if let` guard in match arms.
     (active, if_let_guard, "1.47.0", Some(51114), None),
 
-    /// Allows non trivial generic constants which have to be manually propageted upwards.
+    /// Allows non-trivial generic constants which have to be manually propageted upwards.
     (active, const_evaluatable_checked, "1.48.0", Some(76560), None),
 
     /// Allows basic arithmetic on floating point types in a `const fn`.

compiler/rustc_resolve/src/diagnostics.rs

@@ -469,7 +469,7 @@ impl<'a> Resolver<'a> {
             ResolutionError::ParamInNonTrivialAnonConst { name, is_type } => {
                 let mut err = self.session.struct_span_err(
                     span,
-                    "generic parameters must not be used inside of non trivial constant values",
+                    "generic parameters must not be used inside of non-trivial constant values",
                 );
                 err.span_label(
                     span,

compiler/rustc_resolve/src/lib.rs

@@ -218,7 +218,7 @@ enum ResolutionError<'a> {
     ParamInTyOfConstParam(Symbol),
     /// constant values inside of type parameter defaults must not depend on generic parameters.
     ParamInAnonConstInTyDefault(Symbol),
-    /// generic parameters must not be used inside of non trivial constant values.
+    /// generic parameters must not be used inside of non-trivial constant values.
     ///
     /// This error is only emitted when using `min_const_generics`.
     ParamInNonTrivialAnonConst { name: Symbol, is_type: bool },

compiler/rustc_typeck/src/astconv/generics.rs

@@ -562,7 +562,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 .args
                 .iter()
                 .filter_map(|arg| match arg {
-                    GenericArg::Type(_) => Some(arg.span()),
+                    GenericArg::Type(_) | GenericArg::Const(_) => Some(arg.span()),
                     _ => None,
                 })
                 .collect::<Vec<_>>();

compiler/rustc_typeck/src/collect.rs

@@ -222,6 +222,7 @@ impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
                 hir::GenericParamKind::Const { .. } => {
                     let def_id = self.tcx.hir().local_def_id(param.hir_id);
                     self.tcx.ensure().type_of(def_id);
+                    // FIXME(const_generics:defaults)
                 }
             }
         }

src/test/ui/const-generics/array-size-in-generic-struct-param.min.stderr

@@ -1,12 +1,12 @@
-error: generic parameters must not be used inside of non trivial constant values
+error: generic parameters must not be used inside of non-trivial constant values
   --> $DIR/array-size-in-generic-struct-param.rs:9:48
    |
 LL | struct ArithArrayLen<const N: usize>([u32; 0 + N]);
    |                                                ^ non-trivial anonymous constants must not depend on the parameter `N`
    |
    = help: it is currently only allowed to use either `N` or `{ N }` as generic constants
 
-error: generic parameters must not be used inside of non trivial constant values
+error: generic parameters must not be used inside of non-trivial constant values
   --> $DIR/array-size-in-generic-struct-param.rs:20:15
    |
 LL |     arr: [u8; CFG.arr_size],

src/test/ui/const-generics/array-size-in-generic-struct-param.rs

@@ -8,7 +8,7 @@
 #[allow(dead_code)]
 struct ArithArrayLen<const N: usize>([u32; 0 + N]);
 //[full]~^ ERROR constant expression depends on a generic parameter
-//[min]~^^ ERROR generic parameters must not be used inside of non trivial constant values
+//[min]~^^ ERROR generic parameters must not be used inside of non-trivial constant values
 
 #[derive(PartialEq, Eq)]
 struct Config {
@@ -19,7 +19,7 @@ struct B<const CFG: Config> {
     //[min]~^ ERROR `Config` is forbidden
     arr: [u8; CFG.arr_size],
     //[full]~^ ERROR constant expression depends on a generic parameter
-    //[min]~^^ ERROR generic parameters must not be used inside of non trivial
+    //[min]~^^ ERROR generic parameters must not be used inside of non-trivial
 }
 
 const C: Config = Config { arr_size: 5 };

src/test/ui/const-generics/const-argument-if-length.full.stderr

@@ -0,0 +1,42 @@
+error[E0277]: the size for values of type `T` cannot be known at compilation time
+  --> $DIR/const-argument-if-length.rs:8:28
+   |
+LL | pub const fn is_zst<T: ?Sized>() -> usize {
+   |                     - this type parameter needs to be `Sized`
+LL |     if std::mem::size_of::<T>() == 0 {
+   |                            ^ doesn't have a size known at compile-time
+   | 
+  ::: $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[E0080]: evaluation of constant value failed
+  --> $DIR/const-argument-if-length.rs:19:15
+   |
+LL |     pad: [u8; is_zst::<T>()],
+   |               ^^^^^^^^^^^^^ referenced constant has errors
+
+error[E0277]: the size for values of type `T` cannot be known at compilation time
+  --> $DIR/const-argument-if-length.rs:17:12
+   |
+LL | pub struct AtLeastByte<T: ?Sized> {
+   |                        - this type parameter needs to be `Sized`
+LL |     value: T,
+   |            ^ doesn't have a size known at compile-time
+   |
+   = note: only the last field of a struct may have a dynamically sized type
+   = help: change the field's type to have a statically known size
+help: borrowed types always have a statically known size
+   |
+LL |     value: &T,
+   |            ^
+help: the `Box` type always has a statically known size and allocates its contents in the heap
+   |
+LL |     value: Box<T>,
+   |            ^^^^ ^
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0080, E0277.
+For more information about an error, try `rustc --explain E0080`.

src/test/ui/const-generics/const-argument-if-length.min.stderr

@@ -0,0 +1,30 @@
+error: generic parameters must not be used inside of non-trivial constant values
+  --> $DIR/const-argument-if-length.rs:19:24
+   |
+LL |     pad: [u8; is_zst::<T>()],
+   |                        ^ non-trivial anonymous constants must not depend on the parameter `T`
+   |
+   = note: type parameters are currently not permitted in anonymous constants
+
+error[E0277]: the size for values of type `T` cannot be known at compilation time
+  --> $DIR/const-argument-if-length.rs:17:12
+   |
+LL | pub struct AtLeastByte<T: ?Sized> {
+   |                        - this type parameter needs to be `Sized`
+LL |     value: T,
+   |            ^ doesn't have a size known at compile-time
+   |
+   = note: only the last field of a struct may have a dynamically sized type
+   = help: change the field's type to have a statically known size
+help: borrowed types always have a statically known size
+   |
+LL |     value: &T,
+   |            ^
+help: the `Box` type always has a statically known size and allocates its contents in the heap
+   |
+LL |     value: Box<T>,
+   |            ^^^^ ^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.

src/test/ui/const-generics/const-argument-if-length.rs

@@ -0,0 +1,24 @@
+// revisions: full min
+
+#![cfg_attr(full, allow(incomplete_features))]
+#![cfg_attr(full, feature(const_generics))]
+#![cfg_attr(min, feature(min_const_generics))]
+
+pub const fn is_zst<T: ?Sized>() -> usize {
+    if std::mem::size_of::<T>() == 0 {
+        //[full]~^ ERROR the size for values of type `T` cannot be known at compilation time
+        1
+    } else {
+        0
+    }
+}
+
+pub struct AtLeastByte<T: ?Sized> {
+    value: T,
+    //~^ ERROR the size for values of type `T` cannot be known at compilation time
+    pad: [u8; is_zst::<T>()],
+    //[min]~^ ERROR generic parameters must not be used inside of non-trivial constant values
+    //[full]~^^ ERROR evaluation of constant value failed
+}
+
+fn main() {}

src/test/ui/const-generics/const_evaluatable_checked/feature-gate-const_evaluatable_checked.min.stderr

@@ -1,4 +1,4 @@
-error: generic parameters must not be used inside of non trivial constant values
+error: generic parameters must not be used inside of non-trivial constant values
   --> $DIR/feature-gate-const_evaluatable_checked.rs:6:33
    |
 LL | type Arr<const N: usize> = [u8; N - 1];

src/test/ui/const-generics/const_evaluatable_checked/feature-gate-const_evaluatable_checked.rs

@@ -4,7 +4,7 @@
 #![cfg_attr(min, feature(min_const_generics))]
 
 type Arr<const N: usize> = [u8; N - 1];
-//[min]~^ ERROR generic parameters must not be used inside of non trivial constant values
+//[min]~^ ERROR generic parameters must not be used inside of non-trivial constant values
 
 fn test<const N: usize>() -> Arr<N> where Arr<N>: Default {
     //[full]~^ ERROR constant expression depends

src/test/ui/const-generics/const_evaluatable_checked/simple.min.stderr

@@ -1,12 +1,12 @@
-error: generic parameters must not be used inside of non trivial constant values
+error: generic parameters must not be used inside of non-trivial constant values
   --> $DIR/simple.rs:8:53
    |
 LL | fn test<const N: usize>() -> [u8; N - 1] where [u8; N - 1]: Default {
    |                                                     ^ non-trivial anonymous constants must not depend on the parameter `N`
    |
    = help: it is currently only allowed to use either `N` or `{ N }` as generic constants
 
-error: generic parameters must not be used inside of non trivial constant values
+error: generic parameters must not be used inside of non-trivial constant values
   --> $DIR/simple.rs:8:35
    |
 LL | fn test<const N: usize>() -> [u8; N - 1] where [u8; N - 1]: Default {

src/test/ui/const-generics/const_evaluatable_checked/simple_fail.min.stderr

@@ -1,4 +1,4 @@
-error: generic parameters must not be used inside of non trivial constant values
+error: generic parameters must not be used inside of non-trivial constant values
   --> $DIR/simple_fail.rs:7:33
    |
 LL | type Arr<const N: usize> = [u8; N - 1];

src/test/ui/const-generics/const_evaluatable_checked/simple_fail.rs

@@ -5,7 +5,7 @@
 #![allow(incomplete_features)]
 
 type Arr<const N: usize> = [u8; N - 1]; //[full]~ ERROR evaluation of constant
-//[min]~^ ERROR generic parameters must not be used inside of non trivial constant values
+//[min]~^ ERROR generic parameters must not be used inside of non-trivial constant values
 
 fn test<const N: usize>() -> Arr<N> where Arr<N>: Sized {
     todo!()

src/test/ui/const-generics/generic-function-call-in-array-length.full.stderr

@@ -0,0 +1,10 @@
+error: constant expression depends on a generic parameter
+  --> $DIR/generic-function-call-in-array-length.rs:9:29
+   |
+LL | fn bar<const N: usize>() -> [u32; foo(N)] {
+   |                             ^^^^^^^^^^^^^
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error: aborting due to previous error
+

src/test/ui/const-generics/generic-function-call-in-array-length.min.stderr

@@ -0,0 +1,18 @@
+error: generic parameters must not be used inside of non-trivial constant values
+  --> $DIR/generic-function-call-in-array-length.rs:9:39
+   |
+LL | fn bar<const N: usize>() -> [u32; foo(N)] {
+   |                                       ^ non-trivial anonymous constants must not depend on the parameter `N`
+   |
+   = help: it is currently only allowed to use either `N` or `{ N }` as generic constants
+
+error: generic parameters must not be used inside of non-trivial constant values
+  --> $DIR/generic-function-call-in-array-length.rs:12:13
+   |
+LL |     [0; foo(N)]
+   |             ^ non-trivial anonymous constants must not depend on the parameter `N`
+   |
+   = help: it is currently only allowed to use either `N` or `{ N }` as generic constants
+
+error: aborting due to 2 previous errors
+

src/test/ui/const-generics/generic-function-call-in-array-length.rs

@@ -0,0 +1,16 @@
+// revisions: full min
+
+#![cfg_attr(full, allow(incomplete_features))]
+#![cfg_attr(full, feature(const_generics))]
+#![cfg_attr(min, feature(min_const_generics))]
+
+const fn foo(n: usize) -> usize { n * 2 }
+
+fn bar<const N: usize>() -> [u32; foo(N)] {
+    //[min]~^ ERROR generic parameters must not be used inside of non-trivial constant values
+    //[full]~^^ ERROR constant expression depends on a generic parameter
+    [0; foo(N)]
+    //[min]~^ ERROR generic parameters must not be used inside of non-trivial constant values
+}
+
+fn main() {}

src/test/ui/const-generics/generic-sum-in-array-length.full.stderr

@@ -0,0 +1,10 @@
+error: constant expression depends on a generic parameter
+  --> $DIR/generic-sum-in-array-length.rs:7:45
+   |
+LL | fn foo<const A: usize, const B: usize>(bar: [usize; A + B]) {}
+   |                                             ^^^^^^^^^^^^^^
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error: aborting due to previous error
+

src/test/ui/const-generics/generic-sum-in-array-length.min.stderr

@@ -0,0 +1,18 @@
+error: generic parameters must not be used inside of non-trivial constant values
+  --> $DIR/generic-sum-in-array-length.rs:7:53
+   |
+LL | fn foo<const A: usize, const B: usize>(bar: [usize; A + B]) {}
+   |                                                     ^ non-trivial anonymous constants must not depend on the parameter `A`
+   |
+   = help: it is currently only allowed to use either `A` or `{ A }` as generic constants
+
+error: generic parameters must not be used inside of non-trivial constant values
+  --> $DIR/generic-sum-in-array-length.rs:7:57
+   |
+LL | fn foo<const A: usize, const B: usize>(bar: [usize; A + B]) {}
+   |                                                         ^ non-trivial anonymous constants must not depend on the parameter `B`
+   |
+   = help: it is currently only allowed to use either `B` or `{ B }` as generic constants
+
+error: aborting due to 2 previous errors
+

src/test/ui/const-generics/generic-sum-in-array-length.rs

@@ -0,0 +1,12 @@
+// revisions: full min
+
+#![cfg_attr(full, allow(incomplete_features))]
+#![cfg_attr(full, feature(const_generics))]
+#![cfg_attr(min, feature(min_const_generics))]
+
+fn foo<const A: usize, const B: usize>(bar: [usize; A + B]) {}
+//[min]~^ ERROR generic parameters must not be used inside of non-trivial constant values
+//[min]~| ERROR generic parameters must not be used inside of non-trivial constant values
+//[full]~^^^ ERROR constant expression depends on a generic parameter
+
+fn main() {}

src/test/ui/const-generics/impl-trait-with-const-arguments.full.stderr

@@ -0,0 +1,8 @@
+error[E0632]: cannot provide explicit generic arguments when `impl Trait` is used in argument position
+  --> $DIR/impl-trait-with-const-arguments.rs:24:20
+   |
+LL |     assert_eq!(f::<4usize>(Usizable), 20usize);
+   |                    ^^^^^^ explicit generic argument not allowed
+
+error: aborting due to previous error
+

src/test/ui/const-generics/impl-trait-with-const-arguments.min.stderr

@@ -0,0 +1,8 @@
+error[E0632]: cannot provide explicit generic arguments when `impl Trait` is used in argument position
+  --> $DIR/impl-trait-with-const-arguments.rs:24:20
+   |
+LL |     assert_eq!(f::<4usize>(Usizable), 20usize);
+   |                    ^^^^^^ explicit generic argument not allowed
+
+error: aborting due to previous error
+

src/test/ui/const-generics/impl-trait-with-const-arguments.rs

@@ -0,0 +1,26 @@
+// revisions: full min
+
+#![cfg_attr(full, allow(incomplete_features))]
+#![cfg_attr(full, feature(const_generics))]
+#![cfg_attr(min, feature(min_const_generics))]
+
+trait Usizer {
+    fn m(self) -> usize;
+}
+
+fn f<const N: usize>(u: impl Usizer) -> usize {
+    N + u.m()
+}
+
+struct Usizable;
+
+impl Usizer for Usizable {
+    fn m(self) -> usize {
+        16
+    }
+}
+
+fn main() {
+    assert_eq!(f::<4usize>(Usizable), 20usize);
+//~^ ERROR cannot provide explicit generic arguments when `impl Trait` is used in argument position
+}

src/test/ui/const-generics/intrinsics-type_name-as-const-argument.full.stderr

@@ -0,0 +1,10 @@
+error: constant expression depends on a generic parameter
+  --> $DIR/intrinsics-type_name-as-const-argument.rs:15:8
+   |
+LL |     T: Trait<{std::intrinsics::type_name::<T>()}>
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error: aborting due to previous error
+

src/test/ui/const-generics/intrinsics-type_name-as-const-argument.min.stderr

@@ -0,0 +1,19 @@
+error: generic parameters must not be used inside of non-trivial constant values
+  --> $DIR/intrinsics-type_name-as-const-argument.rs:15:44
+   |
+LL |     T: Trait<{std::intrinsics::type_name::<T>()}>
+   |                                            ^ non-trivial anonymous constants must not depend on the parameter `T`
+   |
+   = note: type parameters are currently not permitted in anonymous constants
+
+error: `&'static str` is forbidden as the type of a const generic parameter
+  --> $DIR/intrinsics-type_name-as-const-argument.rs:10:22
+   |
+LL | trait Trait<const S: &'static str> {}
+   |                      ^^^^^^^^^^^^
+   |
+   = note: the only supported types are integers, `bool` and `char`
+   = note: more complex types are supported with `#[feature(const_generics)]`
+
+error: aborting due to 2 previous errors
+