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Rollup merge of #135044 - compiler-errors:better-infer-suggestions-in-const, r=oli-obk

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Improve infer (`_`) suggestions in `const`s and `static`s

Fixes https://github.com/rust-lang/rust/issues/135010.

This PR does a few things to (imo) greatly improve the error message when users write something like `static FOO: [i32; _] = [1, 2, 3]`.

Firstly, it adapts the recovery code for when we encounter `_` in a const/static to work a bit more like `fn foo() -> _`, and removes the somewhat redundant query `diagnostic_only_typeck`.

Secondly, it changes the lowering for `[T; _]` to always lower under the `feature(generic_arg_infer)` logic to `ConstArgKind::Infer`. We still issue the feature error, so it's not doing anything *observable* on the good path, but it does mean that we no longer erroneously interpret `[T; _]`'s array length as a `_` **wildcard expression** (à la destructuring assignment, like `(_, y) = expr`).

Lastly it makes the suggestions verbose and fixes (well, suppresses) a bug with stashing and suggestions.

r? oli-obk
This commit is contained in:
Matthias Krüger 2025-01-03 22:12:45 +01:00 • committed by GitHub
commit 12cc9b4b6f
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33 changed files with 396 additions and 324 deletions
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9
compiler/rustc_ast_lowering/src/lib.rs
View file

@ -2031,11 +2031,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
fn lower_array_length_to_const_arg(&mut self, c: &AnonConst) -> &'hir hir::ConstArg<'hir> {
match c.value.kind {
ExprKind::Underscore => {
if self.tcx.features().generic_arg_infer() {
let ct_kind = hir::ConstArgKind::Infer(self.lower_span(c.value.span));
self.arena
.alloc(hir::ConstArg { hir_id: self.lower_node_id(c.id), kind: ct_kind })
} else {
if !self.tcx.features().generic_arg_infer() {
feature_err(
&self.tcx.sess,
sym::generic_arg_infer,
@ -2043,8 +2039,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
fluent_generated::ast_lowering_underscore_array_length_unstable,
)
.stash(c.value.span, StashKey::UnderscoreForArrayLengths);
self.lower_anon_const_to_const_arg(c)
}
let ct_kind = hir::ConstArgKind::Infer(self.lower_span(c.value.span));
self.arena.alloc(hir::ConstArg { hir_id: self.lower_node_id(c.id), kind: ct_kind })
}
_ => self.lower_anon_const_to_const_arg(c),
}

2
compiler/rustc_hir/src/hir.rs
View file

@ -3387,7 +3387,7 @@ impl<'hir> FnRetTy<'hir> {
}
}
pub fn get_infer_ret_ty(&self) -> Option<&'hir Ty<'hir>> {
pub fn is_suggestable_infer_ty(&self) -> Option<&'hir Ty<'hir>> {
if let Self::Return(ty) = self {
if ty.is_suggestable_infer_ty() {
return Some(*ty);

64
compiler/rustc_hir_analysis/src/collect.rs
View file

@ -131,19 +131,25 @@ pub struct ItemCtxt<'tcx> {
///////////////////////////////////////////////////////////////////////////
#[derive(Default)]
pub(crate) struct HirPlaceholderCollector(pub(crate) Vec<Span>);
pub(crate) struct HirPlaceholderCollector {
pub spans: Vec<Span>,
// If any of the spans points to a const infer var, then suppress any messages
// that may try to turn that const infer into a type parameter.
pub may_contain_const_infer: bool,
}
impl<'v> Visitor<'v> for HirPlaceholderCollector {
fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
if let hir::TyKind::Infer = t.kind {
self.0.push(t.span);
self.spans.push(t.span);
}
intravisit::walk_ty(self, t)
}
fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
match generic_arg {
hir::GenericArg::Infer(inf) => {
self.0.push(inf.span);
self.spans.push(inf.span);
self.may_contain_const_infer = true;
intravisit::walk_inf(self, inf);
}
hir::GenericArg::Type(t) => self.visit_ty(t),
@ -152,7 +158,8 @@ impl<'v> Visitor<'v> for HirPlaceholderCollector {
}
fn visit_const_arg(&mut self, const_arg: &'v hir::ConstArg<'v>) {
if let hir::ConstArgKind::Infer(span) = const_arg.kind {
self.0.push(span);
self.may_contain_const_infer = true;
self.spans.push(span);
}
intravisit::walk_const_arg(self, const_arg)
}
@ -277,8 +284,8 @@ fn reject_placeholder_type_signatures_in_item<'tcx>(
placeholder_type_error(
icx.lowerer(),
Some(generics),
visitor.0,
suggest,
visitor.spans,
suggest && !visitor.may_contain_const_infer,
None,
item.kind.descr(),
);
@ -607,16 +614,16 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
hir::FnRetTy::DefaultReturn(..) => tcx.types.unit,
};
if !(visitor.0.is_empty() && infer_replacements.is_empty()) {
if !(visitor.spans.is_empty() && infer_replacements.is_empty()) {
// We check for the presence of
// `ident_span` to not emit an error twice when we have `fn foo(_: fn() -> _)`.
let mut diag = crate::collect::placeholder_type_error_diag(
self,
generics,
visitor.0,
visitor.spans,
infer_replacements.iter().map(|(s, _)| *s).collect(),
true,
!visitor.may_contain_const_infer,
hir_ty,
"function",
);
@ -712,7 +719,7 @@ fn lower_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
placeholder_type_error(
icx.lowerer(),
None,
visitor.0,
visitor.spans,
false,
None,
"static variable",
@ -780,7 +787,7 @@ fn lower_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
placeholder_type_error(
icx.lowerer(),
None,
visitor.0,
visitor.spans,
false,
None,
it.kind.descr(),
@ -822,7 +829,7 @@ fn lower_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
placeholder_type_error(
icx.lowerer(),
None,
visitor.0,
visitor.spans,
false,
None,
"associated constant",
@ -837,7 +844,14 @@ fn lower_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
// Account for `type T = _;`.
let mut visitor = HirPlaceholderCollector::default();
visitor.visit_trait_item(trait_item);
placeholder_type_error(icx.lowerer(), None, visitor.0, false, None, "associated type");
placeholder_type_error(
icx.lowerer(),
None,
visitor.spans,
false,
None,
"associated type",
);
}
hir::TraitItemKind::Type(_, None) => {
@ -848,7 +862,14 @@ fn lower_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
let mut visitor = HirPlaceholderCollector::default();
visitor.visit_trait_item(trait_item);
placeholder_type_error(icx.lowerer(), None, visitor.0, false, None, "associated type");
placeholder_type_error(
icx.lowerer(),
None,
visitor.spans,
false,
None,
"associated type",
);
}
};
@ -872,7 +893,14 @@ fn lower_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
let mut visitor = HirPlaceholderCollector::default();
visitor.visit_impl_item(impl_item);
placeholder_type_error(icx.lowerer(), None, visitor.0, false, None, "associated type");
placeholder_type_error(
icx.lowerer(),
None,
visitor.spans,
false,
None,
"associated type",
);
}
hir::ImplItemKind::Const(ty, _) => {
// Account for `const T: _ = ..;`
@ -882,7 +910,7 @@ fn lower_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
placeholder_type_error(
icx.lowerer(),
None,
visitor.0,
visitor.spans,
false,
None,
"associated constant",
@ -1371,7 +1399,7 @@ fn lower_fn_sig_recovering_infer_ret_ty<'tcx>(
generics: &'tcx hir::Generics<'tcx>,
def_id: LocalDefId,
) -> ty::PolyFnSig<'tcx> {
if let Some(infer_ret_ty) = sig.decl.output.get_infer_ret_ty() {
if let Some(infer_ret_ty) = sig.decl.output.is_suggestable_infer_ty() {
return recover_infer_ret_ty(icx, infer_ret_ty, generics, def_id);
}
@ -1422,7 +1450,7 @@ fn recover_infer_ret_ty<'tcx>(
let mut visitor = HirPlaceholderCollector::default();
visitor.visit_ty(infer_ret_ty);
let mut diag = bad_placeholder(icx.lowerer(), visitor.0, "return type");
let mut diag = bad_placeholder(icx.lowerer(), visitor.spans, "return type");
let ret_ty = fn_sig.output();
// Don't leak types into signatures unless they're nameable!

48
compiler/rustc_hir_analysis/src/collect/type_of.rs
View file

@ -4,6 +4,7 @@ use rustc_errors::{Applicability, StashKey, Suggestions};
use rustc_hir as hir;
use rustc_hir::HirId;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::intravisit::Visitor;
use rustc_middle::query::plumbing::CyclePlaceholder;
use rustc_middle::ty::fold::fold_regions;
use rustc_middle::ty::print::with_forced_trimmed_paths;
@ -12,7 +13,7 @@ use rustc_middle::ty::{self, Article, IsSuggestable, Ty, TyCtxt, TypeVisitableEx
use rustc_middle::{bug, span_bug};
use rustc_span::{DUMMY_SP, Ident, Span};
use super::{ItemCtxt, bad_placeholder};
use super::{HirPlaceholderCollector, ItemCtxt, bad_placeholder};
use crate::errors::TypeofReservedKeywordUsed;
use crate::hir_ty_lowering::HirTyLowerer;
@ -412,7 +413,7 @@ fn infer_placeholder_type<'tcx>(
kind: &'static str,
) -> Ty<'tcx> {
let tcx = cx.tcx();
let ty = tcx.diagnostic_only_typeck(def_id).node_type(body_id.hir_id);
let ty = tcx.typeck(def_id).node_type(body_id.hir_id);
// If this came from a free `const` or `static mut?` item,
// then the user may have written e.g. `const A = 42;`.
@ -447,13 +448,37 @@ fn infer_placeholder_type<'tcx>(
}
})
.unwrap_or_else(|| {
let mut diag = bad_placeholder(cx, vec![span], kind);
let mut visitor = HirPlaceholderCollector::default();
let node = tcx.hir_node_by_def_id(def_id);
if let Some(ty) = node.ty() {
visitor.visit_ty(ty);
}
// If we have just one span, let's try to steal a const `_` feature error.
let try_steal_span = if !tcx.features().generic_arg_infer() && visitor.spans.len() == 1
{
visitor.spans.first().copied()
} else {
None
};
// If we didn't find any infer tys, then just fallback to `span`.
if visitor.spans.is_empty() {
visitor.spans.push(span);
}
let mut diag = bad_placeholder(cx, visitor.spans, kind);
if !ty.references_error() {
// HACK(#69396): Stashing and stealing diagnostics does not interact
// well with macros which may delay more than one diagnostic on the
// same span. If this happens, we will fall through to this arm, so
// we need to suppress the suggestion since it's invalid. Ideally we
// would suppress the duplicated error too, but that's really hard.
if span.is_empty() && span.from_expansion() {
// An approximately better primary message + no suggestion...
diag.primary_message("missing type for item");
} else if !ty.references_error() {
if let Some(ty) = ty.make_suggestable(tcx, false, None) {
diag.span_suggestion(
diag.span_suggestion_verbose(
span,
"replace with the correct type",
"replace this with a fully-specified type",
ty,
Applicability::MachineApplicable,
);
@ -464,7 +489,16 @@ fn infer_placeholder_type<'tcx>(
));
}
}
diag.emit()
if let Some(try_steal_span) = try_steal_span {
cx.dcx().try_steal_replace_and_emit_err(
try_steal_span,
StashKey::UnderscoreForArrayLengths,
diag,
)
} else {
diag.emit()
}
});
Ty::new_error(tcx, guar)
}

2
compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs
View file

@ -187,7 +187,7 @@ impl TaitConstraintLocator<'_> {
"foreign items cannot constrain opaque types",
);
if let Some(hir_sig) = hir_node.fn_sig()
&& hir_sig.decl.output.get_infer_ret_ty().is_some()
&& hir_sig.decl.output.is_suggestable_infer_ty().is_some()
{
let guar = self.tcx.dcx().span_delayed_bug(
hir_sig.decl.output.span(),

7
compiler/rustc_hir_typeck/src/expr.rs
View file

@ -1771,12 +1771,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let parent_node = self.tcx.hir().parent_iter(expr.hir_id).find(|(_, node)| {
!matches!(node, hir::Node::Expr(hir::Expr { kind: hir::ExprKind::AddrOf(..), .. }))
});
let Some((
_,
hir::Node::LetStmt(hir::LetStmt { ty: Some(ty), .. })
| hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(ty, _, _), .. }),
)) = parent_node
else {
let Some((_, hir::Node::LetStmt(hir::LetStmt { ty: Some(ty), .. }))) = parent_node else {
return;
};
if let hir::TyKind::Array(_, ct) = ty.peel_refs().kind {

45
compiler/rustc_hir_typeck/src/lib.rs
View file

@ -87,21 +87,7 @@ fn used_trait_imports(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &UnordSet<LocalDef
}
fn typeck<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx ty::TypeckResults<'tcx> {
let fallback = move || tcx.type_of(def_id.to_def_id()).instantiate_identity();
typeck_with_fallback(tcx, def_id, fallback, None)
}
/// Used only to get `TypeckResults` for type inference during error recovery.
/// Currently only used for type inference of `static`s and `const`s to avoid type cycle errors.
fn diagnostic_only_typeck<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: LocalDefId,
) -> &'tcx ty::TypeckResults<'tcx> {
let fallback = move || {
let span = tcx.hir().span(tcx.local_def_id_to_hir_id(def_id));
Ty::new_error_with_message(tcx, span, "diagnostic only typeck table used")
};
typeck_with_fallback(tcx, def_id, fallback, None)
typeck_with_fallback(tcx, def_id, None)
}
/// Same as `typeck` but `inspect` is invoked on evaluation of each root obligation.
@ -113,15 +99,13 @@ pub fn inspect_typeck<'tcx>(
def_id: LocalDefId,
inspect: ObligationInspector<'tcx>,
) -> &'tcx ty::TypeckResults<'tcx> {
let fallback = move || tcx.type_of(def_id.to_def_id()).instantiate_identity();
typeck_with_fallback(tcx, def_id, fallback, Some(inspect))
typeck_with_fallback(tcx, def_id, Some(inspect))
}
#[instrument(level = "debug", skip(tcx, fallback, inspector), ret)]
#[instrument(level = "debug", skip(tcx, inspector), ret)]
fn typeck_with_fallback<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: LocalDefId,
fallback: impl Fn() -> Ty<'tcx> + 'tcx,
inspector: Option<ObligationInspector<'tcx>>,
) -> &'tcx ty::TypeckResults<'tcx> {
// Closures' typeck results come from their outermost function,
@ -150,7 +134,11 @@ fn typeck_with_fallback<'tcx>(
let mut fcx = FnCtxt::new(&root_ctxt, param_env, def_id);
if let Some(hir::FnSig { header, decl, .. }) = node.fn_sig() {
let fn_sig = if decl.output.get_infer_ret_ty().is_some() {
let fn_sig = if decl.output.is_suggestable_infer_ty().is_some() {
// In the case that we're recovering `fn() -> W<_>` or some other return
// type that has an infer in it, lower the type directly so that it'll
// be correctly filled with infer. We'll use this inference to provide
// a suggestion later on.
fcx.lowerer().lower_fn_ty(id, header.safety, header.abi, decl, None, None)
} else {
tcx.fn_sig(def_id).instantiate_identity()
@ -164,8 +152,19 @@ fn typeck_with_fallback<'tcx>(
check_fn(&mut fcx, fn_sig, None, decl, def_id, body, tcx.features().unsized_fn_params());
} else {
let expected_type = infer_type_if_missing(&fcx, node);
let expected_type = expected_type.unwrap_or_else(fallback);
let expected_type = if let Some(infer_ty) = infer_type_if_missing(&fcx, node) {
infer_ty
} else if let Some(ty) = node.ty()
&& ty.is_suggestable_infer_ty()
{
// In the case that we're recovering `const X: [T; _]` or some other
// type that has an infer in it, lower the type directly so that it'll
// be correctly filled with infer. We'll use this inference to provide
// a suggestion later on.
fcx.lowerer().lower_ty(ty)
} else {
tcx.type_of(def_id).instantiate_identity()
};
let expected_type = fcx.normalize(body.value.span, expected_type);
@ -506,5 +505,5 @@ fn fatally_break_rust(tcx: TyCtxt<'_>, span: Span) -> ! {
pub fn provide(providers: &mut Providers) {
method::provide(providers);
*providers = Providers { typeck, diagnostic_only_typeck, used_trait_imports, ..*providers };
*providers = Providers { typeck, used_trait_imports, ..*providers };
}

3
compiler/rustc_middle/src/query/mod.rs
View file

@ -1100,9 +1100,6 @@ rustc_queries! {
desc { |tcx| "type-checking `{}`", tcx.def_path_str(key) }
cache_on_disk_if(tcx) { !tcx.is_typeck_child(key.to_def_id()) }
}
query diagnostic_only_typeck(key: LocalDefId) -> &'tcx ty::TypeckResults<'tcx> {
desc { |tcx| "type-checking `{}`", tcx.def_path_str(key) }
}
query used_trait_imports(key: LocalDefId) -> &'tcx UnordSet<LocalDefId> {
desc { |tcx| "finding used_trait_imports `{}`", tcx.def_path_str(key) }

2
compiler/rustc_ty_utils/src/sig_types.rs
View file

@ -31,7 +31,7 @@ pub fn walk_types<'tcx, V: SpannedTypeVisitor<'tcx>>(
// If the type of the item uses `_`, we're gonna error out anyway, but
// typeck (which type_of invokes below), will call back into opaque_types_defined_by
// causing a cycle. So we just bail out in this case.
if hir_sig.output.get_infer_ret_ty().is_some() {
if hir_sig.output.is_suggestable_infer_ty().is_some() {
return V::Result::output();
}
let ty_sig = tcx.fn_sig(item).instantiate_identity();

25
tests/ui/array-slice-vec/suggest-array-length.fixed
View file

@ -3,24 +3,21 @@
fn main() {
const Foo: [i32; 3] = [1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
const REF_FOO: &[u8; 1] = &[1];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
static Statik: [i32; 3] = [1, 2, 3];
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
static REF_STATIK: &[u8; 1] = &[1];
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
let foo: [i32; 3] = [1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let bar: [i32; 3] = [0; 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let ref_foo: &[i32; 3] = &[1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let ref_bar: &[i32; 3] = &[0; 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let multiple_ref_foo: &&[i32; 3] = &&[1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
}

25
tests/ui/array-slice-vec/suggest-array-length.rs
View file

@ -3,24 +3,21 @@
fn main() {
const Foo: [i32; _] = [1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
const REF_FOO: &[u8; _] = &[1];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
static Statik: [i32; _] = [1, 2, 3];
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
static REF_STATIK: &[u8; _] = &[1];
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
let foo: [i32; _] = [1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let bar: [i32; _] = [0; 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let ref_foo: &[i32; _] = &[1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let ref_bar: &[i32; _] = &[0; 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
}

105
tests/ui/array-slice-vec/suggest-array-length.stderr
View file

@ -1,67 +1,49 @@
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:11:20
|
LL | let foo: [i32; _] = [1, 2, 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:14:20
|
LL | let bar: [i32; _] = [0; 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:17:25
|
LL | let ref_foo: &[i32; _] = &[1, 2, 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:20:25
|
LL | let ref_bar: &[i32; _] = &[0; 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:23:35
|
LL | let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/suggest-array-length.rs:5:22
|
LL | const Foo: [i32; _] = [1, 2, 3];
| ^ `_` not allowed here
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const Foo: [i32; 3] = [1, 2, 3];
| ~~~~~~~~
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:8:26
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/suggest-array-length.rs:7:26
|
LL | const REF_FOO: &[u8; _] = &[1];
| ^ `_` not allowed here
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const REF_FOO: &[u8; 1] = &[1];
| ~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/suggest-array-length.rs:9:26
|
LL | static Statik: [i32; _] = [1, 2, 3];
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static Statik: [i32; 3] = [1, 2, 3];
| ~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/suggest-array-length.rs:11:30
|
LL | static REF_STATIK: &[u8; _] = &[1];
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static REF_STATIK: &[u8; 1] = &[1];
| ~~~~~~~~
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:5:22
|
LL | const Foo: [i32; _] = [1, 2, 3];
| ^ help: consider specifying the array length: `3`
|
= note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
= help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:8:26
|
LL | const REF_FOO: &[u8; _] = &[1];
| ^ help: consider specifying the array length: `1`
|
= note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
= help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:11:20
--> $DIR/suggest-array-length.rs:13:20
|
LL | let foo: [i32; _] = [1, 2, 3];
| ^ help: consider specifying the array length: `3`
@ -71,7 +53,7 @@ LL | let foo: [i32; _] = [1, 2, 3];
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:14:20
--> $DIR/suggest-array-length.rs:15:20
|
LL | let bar: [i32; _] = [0; 3];
| ^ help: consider specifying the array length: `3`
@ -91,7 +73,7 @@ LL | let ref_foo: &[i32; _] = &[1, 2, 3];
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:20:25
--> $DIR/suggest-array-length.rs:19:25
|
LL | let ref_bar: &[i32; _] = &[0; 3];
| ^ help: consider specifying the array length: `3`
@ -101,7 +83,7 @@ LL | let ref_bar: &[i32; _] = &[0; 3];
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:23:35
--> $DIR/suggest-array-length.rs:21:35
|
LL | let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3];
| ^ help: consider specifying the array length: `3`
@ -110,6 +92,7 @@ LL | let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3];
= help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error: aborting due to 14 previous errors
error: aborting due to 9 previous errors
For more information about this error, try `rustc --explain E0658`.
Some errors have detailed explanations: E0121, E0658.
For more information about an error, try `rustc --explain E0121`.

4
tests/ui/async-await/issues/issue-95307.rs
View file

@ -5,8 +5,8 @@
pub trait C {
async fn new() -> [u8; _];
//~^ ERROR: using `_` for array lengths is unstable
//~| ERROR: in expressions, `_` can only be used on the left-hand side of an assignment
//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for functions
//~| ERROR using `_` for array lengths is unstable
}
fn main() {}

7
tests/ui/async-await/issues/issue-95307.stderr
View file

@ -1,8 +1,8 @@
error: in expressions, `_` can only be used on the left-hand side of an assignment
error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
--> $DIR/issue-95307.rs:7:28
|
LL | async fn new() -> [u8; _];
| ^ `_` not allowed here
| ^ not allowed in type signatures
error[E0658]: using `_` for array lengths is unstable
--> $DIR/issue-95307.rs:7:28
@ -16,4 +16,5 @@ LL | async fn new() -> [u8; _];
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0658`.
Some errors have detailed explanations: E0121, E0658.
For more information about an error, try `rustc --explain E0121`.

70
tests/ui/const-generics/generic_arg_infer/in-signature.stderr
View file

@ -27,52 +27,74 @@ LL | fn ty_fn_mixed() -> Bar<_, _> {
| help: replace with the correct return type: `Bar<i32, 3>`
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/in-signature.rs:22:15
--> $DIR/in-signature.rs:22:20
|
LL | const ARR_CT: [u8; _] = [0; 3];
| ^^^^^^^ not allowed in type signatures
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const ARR_CT: [u8; 3] = [0; 3];
| ~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/in-signature.rs:24:20
--> $DIR/in-signature.rs:24:25
|
LL | static ARR_STATIC: [u8; _] = [0; 3];
| ^^^^^^^ not allowed in type signatures
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static ARR_STATIC: [u8; 3] = [0; 3];
| ~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/in-signature.rs:26:14
--> $DIR/in-signature.rs:26:23
|
LL | const TY_CT: Bar<i32, _> = Bar::<i32, 3>(0);
| ^^^^^^^^^^^
| |
| not allowed in type signatures
| help: replace with the correct type: `Bar<i32, 3>`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const TY_CT: Bar<i32, 3> = Bar::<i32, 3>(0);
| ~~~~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/in-signature.rs:28:19
--> $DIR/in-signature.rs:28:28
|
LL | static TY_STATIC: Bar<i32, _> = Bar::<i32, 3>(0);
| ^^^^^^^^^^^
| |
| not allowed in type signatures
| help: replace with the correct type: `Bar<i32, 3>`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static TY_STATIC: Bar<i32, 3> = Bar::<i32, 3>(0);
| ~~~~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/in-signature.rs:30:20
--> $DIR/in-signature.rs:30:24
|
LL | const TY_CT_MIXED: Bar<_, _> = Bar::<i32, 3>(0);
| ^^^^^^^^^
| |
| not allowed in type signatures
| help: replace with the correct type: `Bar<i32, 3>`
| ^ ^ not allowed in type signatures
| |
| not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const TY_CT_MIXED: Bar<i32, 3> = Bar::<i32, 3>(0);
| ~~~~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/in-signature.rs:32:25
--> $DIR/in-signature.rs:32:29
|
LL | static TY_STATIC_MIXED: Bar<_, _> = Bar::<i32, 3>(0);
| ^^^^^^^^^
| |
| not allowed in type signatures
| help: replace with the correct type: `Bar<i32, 3>`
| ^ ^ not allowed in type signatures
| |
| not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static TY_STATIC_MIXED: Bar<i32, 3> = Bar::<i32, 3>(0);
| ~~~~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
--> $DIR/in-signature.rs:51:23

1
tests/ui/consts/issue-104768.rs
View file

@ -1,4 +1,5 @@
const A: &_ = 0_u32;
//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for constants
//~| ERROR: mismatched types
fn main() {}

32
tests/ui/consts/issue-104768.stderr
View file

@ -1,12 +1,28 @@
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/issue-104768.rs:1:10
error[E0308]: mismatched types
--> $DIR/issue-104768.rs:1:15
|
LL | const A: &_ = 0_u32;
| ^^
| |
| not allowed in type signatures
| help: replace with the correct type: `u32`
| ^^^^^ expected `&_`, found `u32`
|
= note: expected reference `&'static _`
found type `u32`
help: consider borrowing here
|
LL | const A: &_ = &0_u32;
| +
error: aborting due to 1 previous error
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/issue-104768.rs:1:11
|
LL | const A: &_ = 0_u32;
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const A: u32 = 0_u32;
| ~~~
For more information about this error, try `rustc --explain E0121`.
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0121, E0308.
For more information about an error, try `rustc --explain E0121`.

10
tests/ui/error-codes/E0121.stderr
View file

@ -11,10 +11,12 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
--> $DIR/E0121.rs:3:13
|
LL | static BAR: _ = "test";
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `&str`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static BAR: &str = "test";
| ~~~~
error: aborting due to 2 previous errors

18
tests/ui/feature-gates/feature-gate-generic_arg_infer.normal.stderr
View file

@ -1,17 +1,5 @@
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/feature-gate-generic_arg_infer.rs:11:27
|
LL | let _x: [u8; 3] = [0; _];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/feature-gate-generic_arg_infer.rs:14:18
|
LL | let _y: [u8; _] = [0; 3];
| ^ `_` not allowed here
error[E0658]: using `_` for array lengths is unstable
--> $DIR/feature-gate-generic_arg_infer.rs:14:18
--> $DIR/feature-gate-generic_arg_infer.rs:13:18
|
LL | let _y: [u8; _] = [0; 3];
| ^ help: consider specifying the array length: `3`
@ -21,7 +9,7 @@ LL | let _y: [u8; _] = [0; 3];
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0747]: type provided when a constant was expected
--> $DIR/feature-gate-generic_arg_infer.rs:20:20
--> $DIR/feature-gate-generic_arg_infer.rs:18:20
|
LL | let _x = foo::<_>([1,2]);
| ^
@ -42,7 +30,7 @@ LL | let _x: [u8; 3] = [0; _];
= help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error: aborting due to 5 previous errors
error: aborting due to 3 previous errors
Some errors have detailed explanations: E0658, E0747.
For more information about an error, try `rustc --explain E0658`.

2
tests/ui/feature-gates/feature-gate-generic_arg_infer.rs
View file

@ -10,10 +10,8 @@ fn foo<const N: usize>(_: [u8; N]) -> [u8; N] {
fn bar() {
let _x: [u8; 3] = [0; _];
//[normal]~^ ERROR: using `_` for array lengths is unstable
//[normal]~| ERROR: in expressions, `_` can only be used on the left-hand side of an assignment
let _y: [u8; _] = [0; 3];
//[normal]~^ ERROR: using `_` for array lengths is unstable
//[normal]~| ERROR: in expressions, `_` can only be used on the left-hand side of an assignment
}
fn main() {

1
tests/ui/generic-const-items/assoc-const-missing-type.rs
View file

@ -12,7 +12,6 @@ impl Trait for () {
const K<T> = ();
//~^ ERROR missing type for `const` item
//~| ERROR mismatched types
//~| ERROR mismatched types
const Q = "";
//~^ ERROR missing type for `const` item
//~| ERROR lifetime parameters or bounds on const `Q` do not match the trait declaration

18
tests/ui/generic-const-items/assoc-const-missing-type.stderr
View file

@ -16,7 +16,7 @@ LL | const K<T> = ();
| ^ help: provide a type for the associated constant: `()`
error[E0195]: lifetime parameters or bounds on const `Q` do not match the trait declaration
--> $DIR/assoc-const-missing-type.rs:16:12
--> $DIR/assoc-const-missing-type.rs:15:12
|
LL | const Q<'a>: &'a str;
| ---- lifetimes in impl do not match this const in trait
@ -25,24 +25,12 @@ LL | const Q = "";
| ^ lifetimes do not match const in trait
error: missing type for `const` item
--> $DIR/assoc-const-missing-type.rs:16:12
--> $DIR/assoc-const-missing-type.rs:15:12
|
LL | const Q = "";
| ^ help: provide a type for the associated constant: `: &str`
error[E0308]: mismatched types
--> $DIR/assoc-const-missing-type.rs:12:18
|
LL | const K<T> = ();
| - ^^ expected type parameter `T`, found `()`
| |
| expected this type parameter
|
= note: expected type parameter `T`
found unit type `()`
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
error: aborting due to 5 previous errors
error: aborting due to 4 previous errors
Some errors have detailed explanations: E0195, E0308.
For more information about an error, try `rustc --explain E0195`.

2
tests/ui/macros/issue-69396-const-no-type-in-macro.rs
View file

@ -4,7 +4,7 @@ macro_rules! suite {
const A = "A".$fn();
//~^ ERROR the name `A` is defined multiple times
//~| ERROR missing type for `const` item
//~| ERROR the placeholder `_` is not allowed within types on item signatures for constants
//~| ERROR missing type for item
)*
}
}

7
tests/ui/macros/issue-69396-const-no-type-in-macro.stderr
View file

@ -27,14 +27,11 @@ LL | | }
|
= note: this error originates in the macro `suite` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
error[E0121]: missing type for item
--> $DIR/issue-69396-const-no-type-in-macro.rs:4:20
|
LL | const A = "A".$fn();
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `bool`
| ^ not allowed in type signatures
...
LL | / suite! {
LL | | len;

1
tests/ui/parser/issues/issue-89574.rs
View file

@ -2,5 +2,4 @@ fn main() {
const EMPTY_ARRAY = [];
//~^ missing type for `const` item
//~| ERROR type annotations needed
//~| ERROR type annotations needed
}

10
tests/ui/parser/issues/issue-89574.stderr
View file

@ -15,14 +15,6 @@ help: provide a type for the item
LL | const EMPTY_ARRAY: <type> = [];
| ++++++++
error[E0282]: type annotations needed
--> $DIR/issue-89574.rs:2:25
|
LL | const EMPTY_ARRAY = [];
| ^^ cannot infer type
|
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
error: aborting due to 3 previous errors
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0282`.

2
tests/ui/suggestions/unnamable-types.rs
View file

@ -10,7 +10,7 @@ const A = 5;
static B: _ = "abc";
//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for static variables
//~| NOTE: not allowed in type signatures
//~| HELP: replace with the correct type
//~| HELP: replace this with a fully-specified type
// FIXME: this should also suggest a function pointer, as the closure is non-capturing

10
tests/ui/suggestions/unnamable-types.stderr
View file

@ -8,10 +8,12 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
--> $DIR/unnamable-types.rs:10:11
|
LL | static B: _ = "abc";
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `&str`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static B: &str = "abc";
| ~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/unnamable-types.rs:17:10

6
tests/ui/typeck/issue-79040.rs
View file

@ -1,6 +1,6 @@
fn main() {
const FOO = "hello" + 1; //~ ERROR cannot add `{integer}` to `&str`
//~^ missing type for `const` item
//~| ERROR cannot add `{integer}` to `&str`
const FOO = "hello" + 1;
//~^ ERROR cannot add `{integer}` to `&str`
//~| missing type for `const` item
println!("{}", FOO);
}

12
tests/ui/typeck/issue-79040.stderr
View file

@ -17,16 +17,6 @@ help: provide a type for the item
LL | const FOO: <type> = "hello" + 1;
| ++++++++
error[E0369]: cannot add `{integer}` to `&str`
--> $DIR/issue-79040.rs:2:25
|
LL | const FOO = "hello" + 1;
| ------- ^ - {integer}
| |
| &str
|
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
error: aborting due to 3 previous errors
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0369`.

1
tests/ui/typeck/typeck_type_placeholder_item.rs
View file

@ -221,6 +221,7 @@ fn value() -> Option<&'static _> {
const _: Option<_> = map(value);
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
//~| ERROR cannot call non-const function `map::<u8>` in constants
fn evens_squared(n: usize) -> _ {
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types

129
tests/ui/typeck/typeck_type_placeholder_item.stderr
View file

@ -67,25 +67,36 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:13:15
|
LL | static TEST3: _ = "test";
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `&str`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static TEST3: &str = "test";
| ~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/typeck_type_placeholder_item.rs:16:15
|
LL | static TEST4: _ = 145;
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `i32`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static TEST4: i32 = 145;
| ~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/typeck_type_placeholder_item.rs:19:15
--> $DIR/typeck_type_placeholder_item.rs:19:16
|
LL | static TEST5: (_, _) = (1, 2);
| ^^^^^^ not allowed in type signatures
| ^ ^ not allowed in type signatures
| |
| not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static TEST5: (i32, i32) = (1, 2);
| ~~~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
--> $DIR/typeck_type_placeholder_item.rs:22:13
@ -220,16 +231,23 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:75:15
|
LL | static B: _ = 42;
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `i32`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static B: i32 = 42;
| ~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/typeck_type_placeholder_item.rs:77:15
--> $DIR/typeck_type_placeholder_item.rs:77:22
|
LL | static C: Option<_> = Some(42);
| ^^^^^^^^^ not allowed in type signatures
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static C: Option<i32> = Some(42);
| ~~~~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
--> $DIR/typeck_type_placeholder_item.rs:79:21
@ -254,25 +272,36 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:85:22
|
LL | static FN_TEST3: _ = "test";
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `&str`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static FN_TEST3: &str = "test";
| ~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/typeck_type_placeholder_item.rs:88:22
|
LL | static FN_TEST4: _ = 145;
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `i32`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static FN_TEST4: i32 = 145;
| ~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/typeck_type_placeholder_item.rs:91:22
--> $DIR/typeck_type_placeholder_item.rs:91:23
|
LL | static FN_TEST5: (_, _) = (1, 2);
| ^^^^^^ not allowed in type signatures
| ^ ^ not allowed in type signatures
| |
| not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | static FN_TEST5: (i32, i32) = (1, 2);
| ~~~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
--> $DIR/typeck_type_placeholder_item.rs:94:20
@ -539,10 +568,12 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:194:14
|
LL | const D: _ = 42;
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `i32`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const D: i32 = 42;
| ~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated constants
--> $DIR/typeck_type_placeholder_item.rs:209:14
@ -569,16 +600,18 @@ LL | fn value() -> Option<&'static _> {
| help: replace with the correct return type: `Option<&'static u8>`
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/typeck_type_placeholder_item.rs:222:10
--> $DIR/typeck_type_placeholder_item.rs:222:17
|
LL | const _: Option<_> = map(value);
| ^^^^^^^^^
| |
| not allowed in type signatures
| help: replace with the correct type: `Option<u8>`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const _: Option<u8> = map(value);
| ~~~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
--> $DIR/typeck_type_placeholder_item.rs:225:31
--> $DIR/typeck_type_placeholder_item.rs:226:31
|
LL | fn evens_squared(n: usize) -> _ {
| ^
@ -587,13 +620,13 @@ LL | fn evens_squared(n: usize) -> _ {
| help: replace with an appropriate return type: `impl Iterator<Item = usize>`
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/typeck_type_placeholder_item.rs:230:10
--> $DIR/typeck_type_placeholder_item.rs:231:10
|
LL | const _: _ = (1..10).filter(|x| x % 2 == 0).map(|x| x * x);
| ^ not allowed in type signatures
|
note: however, the inferred type `Map<Filter<Range<i32>, {closure@typeck_type_placeholder_item.rs:230:29}>, {closure@typeck_type_placeholder_item.rs:230:49}>` cannot be named
--> $DIR/typeck_type_placeholder_item.rs:230:14
note: however, the inferred type `Map<Filter<Range<i32>, {closure@typeck_type_placeholder_item.rs:231:29}>, {closure@typeck_type_placeholder_item.rs:231:49}>` cannot be named
--> $DIR/typeck_type_placeholder_item.rs:231:14
|
LL | const _: _ = (1..10).filter(|x| x % 2 == 0).map(|x| x * x);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -668,23 +701,31 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
LL | type F: std::ops::Fn(_);
| ^ not allowed in type signatures
error[E0015]: cannot call non-const method `<std::ops::Range<i32> as Iterator>::filter::<{closure@$DIR/typeck_type_placeholder_item.rs:230:29: 230:32}>` in constants
--> $DIR/typeck_type_placeholder_item.rs:230:22
error[E0015]: cannot call non-const function `map::<u8>` in constants
--> $DIR/typeck_type_placeholder_item.rs:222:22
|
LL | const _: Option<_> = map(value);
| ^^^^^^^^^^
|
= note: calls in constants are limited to constant functions, tuple structs and tuple variants
error[E0015]: cannot call non-const method `<std::ops::Range<i32> as Iterator>::filter::<{closure@$DIR/typeck_type_placeholder_item.rs:231:29: 231:32}>` in constants
--> $DIR/typeck_type_placeholder_item.rs:231:22
|
LL | const _: _ = (1..10).filter(|x| x % 2 == 0).map(|x| x * x);
| ^^^^^^^^^^^^^^^^^^^^^^
|
= note: calls in constants are limited to constant functions, tuple structs and tuple variants
error[E0015]: cannot call non-const method `<Filter<std::ops::Range<i32>, {closure@$DIR/typeck_type_placeholder_item.rs:230:29: 230:32}> as Iterator>::map::<i32, {closure@$DIR/typeck_type_placeholder_item.rs:230:49: 230:52}>` in constants
--> $DIR/typeck_type_placeholder_item.rs:230:45
error[E0015]: cannot call non-const method `<Filter<std::ops::Range<i32>, {closure@$DIR/typeck_type_placeholder_item.rs:231:29: 231:32}> as Iterator>::map::<i32, {closure@$DIR/typeck_type_placeholder_item.rs:231:49: 231:52}>` in constants
--> $DIR/typeck_type_placeholder_item.rs:231:45
|
LL | const _: _ = (1..10).filter(|x| x % 2 == 0).map(|x| x * x);
| ^^^^^^^^^^^^^^
|
= note: calls in constants are limited to constant functions, tuple structs and tuple variants
error: aborting due to 74 previous errors
error: aborting due to 75 previous errors
Some errors have detailed explanations: E0015, E0046, E0121, E0282, E0403.
For more information about an error, try `rustc --explain E0015`.

40
tests/ui/typeck/typeck_type_placeholder_item_help.stderr
View file

@ -11,19 +11,23 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item_help.rs:7:14
|
LL | const TEST2: _ = 42u32;
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `u32`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const TEST2: u32 = 42u32;
| ~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/typeck_type_placeholder_item_help.rs:10:14
|
LL | const TEST3: _ = Some(42);
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `Option<i32>`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const TEST3: Option<i32> = Some(42);
| ~~~~~~~~~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
--> $DIR/typeck_type_placeholder_item_help.rs:13:22
@ -41,19 +45,23 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item_help.rs:25:18
|
LL | const TEST6: _ = 13;
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `i32`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const TEST6: i32 = 13;
| ~~~
error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated constants
--> $DIR/typeck_type_placeholder_item_help.rs:18:18
|
LL | const TEST5: _ = 42;
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `i32`
| ^ not allowed in type signatures
|
help: replace this with a fully-specified type
|
LL | const TEST5: i32 = 42;
| ~~~
error[E0308]: mismatched types
--> $DIR/typeck_type_placeholder_item_help.rs:30:28