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simplify const params diagnostic on stable
This commit is contained in:
Oliver Downard
parent
dd38eea722
commit
3b4589a309
@ -816,16 +816,69 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &hir::GenericParam<'_>) {
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hir::GenericParamKind::Const { ty: hir_ty, default: _ } => {
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let ty = tcx.type_of(tcx.hir().local_def_id(param.hir_id));
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let err_ty_str;
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let mut is_ptr = true;
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let err = if tcx.features().adt_const_params {
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match ty.peel_refs().kind() {
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if tcx.features().adt_const_params {
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let err = match ty.peel_refs().kind() {
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ty::FnPtr(_) => Some("function pointers"),
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ty::RawPtr(_) => Some("raw pointers"),
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_ => None,
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};
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if let Some(unsupported_type) = err {
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tcx.sess.span_err(
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hir_ty.span,
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&format!(
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"using {} as const generic parameters is forbidden",
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unsupported_type
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),
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);
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}
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if traits::search_for_structural_match_violation(param.span, tcx, ty).is_some() {
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// We use the same error code in both branches, because this is really the same
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// issue: we just special-case the message for type parameters to make it
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// clearer.
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if let ty::Param(_) = ty.peel_refs().kind() {
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// Const parameters may not have type parameters as their types,
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// because we cannot be sure that the type parameter derives `PartialEq`
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// and `Eq` (just implementing them is not enough for `structural_match`).
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struct_span_err!(
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tcx.sess,
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hir_ty.span,
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E0741,
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"`{}` is not guaranteed to `#[derive(PartialEq, Eq)]`, so may not be \
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used as the type of a const parameter",
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ty,
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)
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.span_label(
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hir_ty.span,
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format!("`{}` may not derive both `PartialEq` and `Eq`", ty),
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)
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.note(
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"it is not currently possible to use a type parameter as the type of a \
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const parameter",
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)
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.emit();
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} else {
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struct_span_err!(
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tcx.sess,
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hir_ty.span,
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E0741,
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"`{}` must be annotated with `#[derive(PartialEq, Eq)]` to be used as \
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the type of a const parameter",
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ty,
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)
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.span_label(
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hir_ty.span,
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format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty),
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)
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.emit();
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}
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}
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} else {
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match ty.kind() {
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let err_ty_str;
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let mut is_ptr = true;
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let err = match ty.kind() {
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ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Error(_) => None,
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ty::FnPtr(_) => Some("function pointers"),
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ty::RawPtr(_) => Some("raw pointers"),
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@ -834,74 +887,33 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &hir::GenericParam<'_>) {
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err_ty_str = format!("`{}`", ty);
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Some(err_ty_str.as_str())
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}
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}
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};
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if let Some(unsupported_type) = err {
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if is_ptr {
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tcx.sess.span_err(
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hir_ty.span,
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&format!(
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"using {} as const generic parameters is forbidden",
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unsupported_type
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),
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);
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} else {
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let mut err = tcx.sess.struct_span_err(
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hir_ty.span,
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&format!(
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"{} is forbidden as the type of a const generic parameter",
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unsupported_type
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),
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);
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err.note("the only supported types are integers, `bool` and `char`");
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if tcx.sess.is_nightly_build() {
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err.help(
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};
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if let Some(unsupported_type) = err {
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if is_ptr {
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tcx.sess.span_err(
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hir_ty.span,
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&format!(
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"using {} as const generic parameters is forbidden",
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unsupported_type
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),
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);
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} else {
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let mut err = tcx.sess.struct_span_err(
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hir_ty.span,
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&format!(
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"{} is forbidden as the type of a const generic parameter",
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unsupported_type
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),
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);
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err.note("the only supported types are integers, `bool` and `char`");
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if tcx.sess.is_nightly_build() {
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err.help(
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"more complex types are supported with `#![feature(adt_const_params)]`",
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);
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}
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err.emit();
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}
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err.emit();
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}
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};
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if traits::search_for_structural_match_violation(param.span, tcx, ty).is_some() {
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// We use the same error code in both branches, because this is really the same
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// issue: we just special-case the message for type parameters to make it
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// clearer.
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if let ty::Param(_) = ty.peel_refs().kind() {
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// Const parameters may not have type parameters as their types,
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// because we cannot be sure that the type parameter derives `PartialEq`
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// and `Eq` (just implementing them is not enough for `structural_match`).
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struct_span_err!(
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tcx.sess,
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hir_ty.span,
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E0741,
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"`{}` is not guaranteed to `#[derive(PartialEq, Eq)]`, so may not be \
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used as the type of a const parameter",
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ty,
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)
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.span_label(
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hir_ty.span,
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format!("`{}` may not derive both `PartialEq` and `Eq`", ty),
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)
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.note(
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"it is not currently possible to use a type parameter as the type of a \
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const parameter",
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)
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.emit();
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} else {
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struct_span_err!(
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tcx.sess,
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hir_ty.span,
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E0741,
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"`{}` must be annotated with `#[derive(PartialEq, Eq)]` to be used as \
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the type of a const parameter",
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ty,
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)
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.span_label(
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hir_ty.span,
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format!("`{}` doesn't derive both `PartialEq` and `Eq`", ty),
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)
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.emit();
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}
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}
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}
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@ -7,12 +7,5 @@ LL | fn test<const T: &'static dyn A>() {
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= note: the only supported types are integers, `bool` and `char`
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= help: more complex types are supported with `#![feature(adt_const_params)]`
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error[E0741]: `&'static (dyn A + 'static)` must be annotated with `#[derive(PartialEq, Eq)]` to be used as the type of a const parameter
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--> $DIR/issue-63322-forbid-dyn.rs:9:18
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LL | fn test<const T: &'static dyn A>() {
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| ^^^^^^^^^^^^^^ `&'static (dyn A + 'static)` doesn't derive both `PartialEq` and `Eq`
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error: aborting due to previous error
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0741`.
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@ -7,7 +7,7 @@ struct B;
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impl A for B {}
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fn test<const T: &'static dyn A>() {
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//~^ ERROR must be annotated with `#[derive(PartialEq, Eq)]` to be used
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//[full]~^ ERROR must be annotated with `#[derive(PartialEq, Eq)]` to be used
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//[min]~^^ ERROR `&'static (dyn A + 'static)` is forbidden
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unimplemented!()
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}
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@ -14,14 +14,5 @@ LL | | }]>;
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= note: the only supported types are integers, `bool` and `char`
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= help: more complex types are supported with `#![feature(adt_const_params)]`
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error[E0015]: cannot call non-const fn `Foo::{constant#0}::Foo::<17_usize>::value` in constants
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--> $DIR/nested-type.rs:15:5
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LL | Foo::<17>::value()
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| ^^^^^^^^^^^^^^^^^^
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= note: calls in constants are limited to constant functions, tuple structs and tuple variants
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error: aborting due to previous error
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0015`.
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@ -13,7 +13,7 @@ struct Foo<const N: [u8; { //[min]~ ERROR `[u8; _]` is forbidden
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}
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Foo::<17>::value()
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//~^ ERROR cannot call non-const fn
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//[full]~^ ERROR cannot call non-const fn
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}]>;
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fn main() {}
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