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implement generic_arg_infer for array lengths

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This commit is contained in:
lcnr 2021-12-23 10:01:51 +01:00
parent 5aa0239b16
commit e3f5cc6c38
19 changed files with 161 additions and 51 deletions
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2
compiler/rustc_ast_lowering/src/expr.rs
View File

@ -34,7 +34,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
}
ExprKind::Repeat(ref expr, ref count) => {
let expr = self.lower_expr(expr);
let count = self.lower_anon_const(count);
let count = self.lower_array_length(count);
hir::ExprKind::Repeat(expr, count)
}
ExprKind::Tup(ref elts) => hir::ExprKind::Tup(self.lower_exprs(elts)),

23
compiler/rustc_ast_lowering/src/lib.rs
View File

@ -56,6 +56,7 @@ use rustc_hir::{ConstArg, GenericArg, ParamName};
use rustc_index::vec::{Idx, IndexVec};
use rustc_query_system::ich::StableHashingContext;
use rustc_session::lint::LintBuffer;
use rustc_session::parse::feature_err;
use rustc_session::utils::{FlattenNonterminals, NtToTokenstream};
use rustc_session::Session;
use rustc_span::hygiene::ExpnId;
@ -1248,7 +1249,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
))
}
TyKind::Array(ref ty, ref length) => {
hir::TyKind::Array(self.lower_ty(ty, itctx), self.lower_anon_const(length))
hir::TyKind::Array(self.lower_ty(ty, itctx), self.lower_array_length(length))
}
TyKind::Typeof(ref expr) => hir::TyKind::Typeof(self.lower_anon_const(expr)),
TyKind::TraitObject(ref bounds, kind) => {
@ -2039,6 +2040,26 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
self.expr_block(block, AttrVec::new())
}
fn lower_array_length(&mut self, c: &AnonConst) -> hir::ArrayLen {
match c.value.kind {
ExprKind::Underscore => {
if self.sess.features_untracked().generic_arg_infer {
hir::ArrayLen::Infer(self.lower_node_id(c.id), c.value.span)
} else {
feature_err(
&self.sess.parse_sess,
sym::generic_arg_infer,
c.value.span,
"using `_` for array lengths is unstable",
)
.emit();
hir::ArrayLen::Body(self.lower_anon_const(c))
}
}
_ => hir::ArrayLen::Body(self.lower_anon_const(c)),
}
}
fn lower_anon_const(&mut self, c: &AnonConst) -> hir::AnonConst {
self.with_new_scopes(|this| hir::AnonConst {
hir_id: this.lower_node_id(c.id),

18
compiler/rustc_hir/src/hir.rs
View File

@ -1407,6 +1407,20 @@ impl fmt::Display for ConstContext {
/// A literal.
pub type Lit = Spanned<LitKind>;
#[derive(Copy, Clone, PartialEq, Eq, Encodable, Debug, HashStable_Generic)]
pub enum ArrayLen {
Infer(HirId, Span),
Body(AnonConst),
}
impl ArrayLen {
pub fn hir_id(&self) -> HirId {
match self {
&ArrayLen::Infer(hir_id, _) | &ArrayLen::Body(AnonConst { hir_id, body: _ }) => hir_id,
}
}
}
/// A constant (expression) that's not an item or associated item,
/// but needs its own `DefId` for type-checking, const-eval, etc.
/// These are usually found nested inside types (e.g., array lengths)
@ -1756,7 +1770,7 @@ pub enum ExprKind<'hir> {
///
/// E.g., `[1; 5]`. The first expression is the element
/// to be repeated; the second is the number of times to repeat it.
Repeat(&'hir Expr<'hir>, AnonConst),
Repeat(&'hir Expr<'hir>, ArrayLen),
/// A suspension point for generators (i.e., `yield <expr>`).
Yield(&'hir Expr<'hir>, YieldSource),
@ -2266,7 +2280,7 @@ pub enum TyKind<'hir> {
/// A variable length slice (i.e., `[T]`).
Slice(&'hir Ty<'hir>),
/// A fixed length array (i.e., `[T; n]`).
Array(&'hir Ty<'hir>, AnonConst),
Array(&'hir Ty<'hir>, ArrayLen),
/// A raw pointer (i.e., `*const T` or `*mut T`).
Ptr(MutTy<'hir>),
/// A reference (i.e., `&'a T` or `&'a mut T`).

14
compiler/rustc_hir/src/intravisit.rs
View File

@ -383,6 +383,9 @@ pub trait Visitor<'v>: Sized {
fn visit_pat(&mut self, p: &'v Pat<'v>) {
walk_pat(self, p)
}
fn visit_array_length(&mut self, len: &'v ArrayLen) {
walk_array_len(self, len)
}
fn visit_anon_const(&mut self, c: &'v AnonConst) {
walk_anon_const(self, c)
}
@ -753,7 +756,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty<'v>) {
}
TyKind::Array(ref ty, ref length) => {
visitor.visit_ty(ty);
visitor.visit_anon_const(length)
visitor.visit_array_length(length)
}
TyKind::TraitObject(bounds, ref lifetime, _syntax) => {
for bound in bounds {
@ -1124,6 +1127,13 @@ pub fn walk_stmt<'v, V: Visitor<'v>>(visitor: &mut V, statement: &'v Stmt<'v>) {
}
}
pub fn walk_array_len<'v, V: Visitor<'v>>(visitor: &mut V, len: &'v ArrayLen) {
match len {
&ArrayLen::Infer(hir_id, _span) => visitor.visit_id(hir_id),
ArrayLen::Body(c) => visitor.visit_anon_const(c),
}
}
pub fn walk_anon_const<'v, V: Visitor<'v>>(visitor: &mut V, constant: &'v AnonConst) {
visitor.visit_id(constant.hir_id);
visitor.visit_nested_body(constant.body);
@ -1147,7 +1157,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>)
ExprKind::ConstBlock(ref anon_const) => visitor.visit_anon_const(anon_const),
ExprKind::Repeat(ref element, ref count) => {
visitor.visit_expr(element);
visitor.visit_anon_const(count)
visitor.visit_array_length(count)
}
ExprKind::Struct(ref qpath, fields, ref optional_base) => {
visitor.visit_qpath(qpath, expression.hir_id, expression.span);

13
compiler/rustc_hir_pretty/src/lib.rs
View File

@ -358,7 +358,7 @@ impl<'a> State<'a> {
self.word("[");
self.print_type(&ty);
self.word("; ");
self.print_anon_const(length);
self.print_array_length(length);
self.word("]");
}
hir::TyKind::Typeof(ref e) => {
@ -1065,6 +1065,13 @@ impl<'a> State<'a> {
self.print_else(elseopt)
}
pub fn print_array_length(&mut self, len: &hir::ArrayLen) {
match len {
hir::ArrayLen::Infer(_, _) => self.word("_"),
hir::ArrayLen::Body(ct) => self.print_anon_const(ct),
}
}
pub fn print_anon_const(&mut self, constant: &hir::AnonConst) {
self.ann.nested(self, Nested::Body(constant.body))
}
@ -1140,12 +1147,12 @@ impl<'a> State<'a> {
self.end()
}
fn print_expr_repeat(&mut self, element: &hir::Expr<'_>, count: &hir::AnonConst) {
fn print_expr_repeat(&mut self, element: &hir::Expr<'_>, count: &hir::ArrayLen) {
self.ibox(INDENT_UNIT);
self.word("[");
self.print_expr(element);
self.word_space(";");
self.print_anon_const(count);
self.print_array_length(count);
self.word("]");
self.end()
}

9
compiler/rustc_mir_build/src/thir/cx/expr.rs
View File

@ -583,9 +583,12 @@ impl<'tcx> Cx<'tcx> {
ExprKind::ConstBlock { value }
}
// Now comes the rote stuff:
hir::ExprKind::Repeat(ref v, ref count) => {
let count_def_id = self.tcx.hir().local_def_id(count.hir_id);
let count = ty::Const::from_anon_const(self.tcx, count_def_id);
hir::ExprKind::Repeat(ref v, _) => {
let ty = self.typeck_results().expr_ty(expr);
let count = match ty.kind() {
ty::Array(_, ct) => ct,
_ => span_bug!(expr.span, "unexpected repeat expr ty: {:?}", ty),
};
ExprKind::Repeat { value: self.mirror_expr(v), count }
}

24
compiler/rustc_save_analysis/src/dump_visitor.rs
View File

@ -1326,12 +1326,18 @@ impl<'tcx> Visitor<'tcx> for DumpVisitor<'tcx> {
}
intravisit::walk_qpath(self, path, t.hir_id, t.span);
}
hir::TyKind::Array(ref ty, ref anon_const) => {
hir::TyKind::Array(ref ty, ref length) => {
self.visit_ty(ty);
let map = self.tcx.hir();
self.nest_typeck_results(self.tcx.hir().local_def_id(anon_const.hir_id), |v| {
match length {
// FIXME(generic_arg_infer): We probably want to
// output the inferred type here? :shrug:
hir::ArrayLen::Infer(..) => {}
hir::ArrayLen::Body(anon_const) => self
.nest_typeck_results(self.tcx.hir().local_def_id(anon_const.hir_id), |v| {
v.visit_expr(&map.body(anon_const.body).value)
});
}),
}
}
hir::TyKind::OpaqueDef(item_id, _) => {
let item = self.tcx.hir().item(item_id);
@ -1390,12 +1396,18 @@ impl<'tcx> Visitor<'tcx> for DumpVisitor<'tcx> {
v.visit_expr(&body.value)
});
}
hir::ExprKind::Repeat(ref expr, ref anon_const) => {
hir::ExprKind::Repeat(ref expr, ref length) => {
self.visit_expr(expr);
let map = self.tcx.hir();
self.nest_typeck_results(self.tcx.hir().local_def_id(anon_const.hir_id), |v| {
match length {
// FIXME(generic_arg_infer): We probably want to
// output the inferred type here? :shrug:
hir::ArrayLen::Infer(..) => {}
hir::ArrayLen::Body(anon_const) => self
.nest_typeck_results(self.tcx.hir().local_def_id(anon_const.hir_id), |v| {
v.visit_expr(&map.body(anon_const.body).value)
});
}),
}
}
// In particular, we take this branch for call and path expressions,
// where we'll index the idents involved just by continuing to walk.

8
compiler/rustc_save_analysis/src/sig.rs
View File

@ -310,9 +310,13 @@ impl<'hir> Sig for hir::Ty<'hir> {
let nested = bounds_to_string(&bounds);
Ok(text_sig(nested))
}
hir::TyKind::Array(ref ty, ref anon_const) => {
hir::TyKind::Array(ref ty, ref length) => {
let nested_ty = ty.make(offset + 1, id, scx)?;
let expr = id_to_string(&scx.tcx.hir(), anon_const.body.hir_id).replace('\n', " ");
let hir_id = match length {
&hir::ArrayLen::Infer(hir_id, _) => hir_id,
hir::ArrayLen::Body(anon_const) => anon_const.hir_id,
};
let expr = id_to_string(&scx.tcx.hir(), hir_id).replace('\n', " ");
let text = format!("[{}; {}]", nested_ty.text, expr);
Ok(replace_text(nested_ty, text))
}

2
compiler/rustc_typeck/src/astconv/generics.rs
View File

@ -104,7 +104,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
GenericArg::Type(hir::Ty { kind: hir::TyKind::Array(_, len), .. }),
GenericParamDefKind::Const { .. },
) if tcx.type_of(param.def_id) == tcx.types.usize => {
let snippet = sess.source_map().span_to_snippet(tcx.hir().span(len.hir_id));
let snippet = sess.source_map().span_to_snippet(tcx.hir().span(len.hir_id()));
if let Ok(snippet) = snippet {
err.span_suggestion(
arg.span(),

10
compiler/rustc_typeck/src/astconv/mod.rs
View File

@ -2363,8 +2363,14 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
self.normalize_ty(span, tcx.at(span).type_of(def_id).subst(tcx, substs))
}
hir::TyKind::Array(ref ty, ref length) => {
let length_def_id = tcx.hir().local_def_id(length.hir_id);
let length = ty::Const::from_anon_const(tcx, length_def_id);
let length = match length {
&hir::ArrayLen::Infer(_, span) => self.ct_infer(tcx.types.usize, None, span),
hir::ArrayLen::Body(constant) => {
let length_def_id = tcx.hir().local_def_id(constant.hir_id);
ty::Const::from_anon_const(tcx, length_def_id)
}
};
let array_ty = tcx.mk_ty(ty::Array(self.ast_ty_to_ty(ty), length));
self.normalize_ty(ast_ty.span, array_ty)
}

4
compiler/rustc_typeck/src/check/expr.rs
View File

@ -1238,12 +1238,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
fn check_expr_repeat(
&self,
element: &'tcx hir::Expr<'tcx>,
count: &'tcx hir::AnonConst,
count: &'tcx hir::ArrayLen,
expected: Expectation<'tcx>,
_expr: &'tcx hir::Expr<'tcx>,
) -> Ty<'tcx> {
let tcx = self.tcx;
let count = self.to_const(count);
let count = self.array_length_to_const(count);
let uty = match expected {
ExpectHasType(uty) => match *uty.kind() {

7
compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
View File

@ -498,6 +498,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
ty
}
pub fn array_length_to_const(&self, length: &hir::ArrayLen) -> &'tcx ty::Const<'tcx> {
match length {
&hir::ArrayLen::Infer(_, span) => self.ct_infer(self.tcx.types.usize, None, span),
hir::ArrayLen::Body(anon_const) => self.to_const(anon_const),
}
}
pub fn to_const(&self, ast_c: &hir::AnonConst) -> &'tcx ty::Const<'tcx> {
let const_def_id = self.tcx.hir().local_def_id(ast_c.hir_id);
let c = ty::Const::from_anon_const(self.tcx, const_def_id);

18
compiler/rustc_typeck/src/collect.rs
View File

@ -182,7 +182,7 @@ crate fn placeholder_type_error<'tcx>(
sugg.push((span, format!(", {}", type_name)));
}
let mut err = bad_placeholder_type(tcx, placeholder_types, kind);
let mut err = bad_placeholder(tcx, "type", placeholder_types, kind);
// Suggest, but only if it is not a function in const or static
if suggest {
@ -314,8 +314,9 @@ impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
///////////////////////////////////////////////////////////////////////////
// Utility types and common code for the above passes.
fn bad_placeholder_type<'tcx>(
fn bad_placeholder<'tcx>(
tcx: TyCtxt<'tcx>,
placeholder_kind: &'static str,
mut spans: Vec<Span>,
kind: &'static str,
) -> rustc_errors::DiagnosticBuilder<'tcx> {
@ -326,7 +327,8 @@ fn bad_placeholder_type<'tcx>(
tcx.sess,
spans.clone(),
E0121,
"the type placeholder `_` is not allowed within types on item signatures for {}",
"the {} placeholder `_` is not allowed within types on item signatures for {}",
placeholder_kind,
kind
);
for span in spans {
@ -393,7 +395,7 @@ impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
_: Option<&ty::GenericParamDef>,
span: Span,
) -> &'tcx Const<'tcx> {
bad_placeholder_type(self.tcx(), vec![span], "generic").emit();
bad_placeholder(self.tcx(), "const", vec![span], "generic").emit();
// Typeck doesn't expect erased regions to be returned from `type_of`.
let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match r {
ty::ReErased => self.tcx.lifetimes.re_static,
@ -1482,7 +1484,11 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
// `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
// as they shouldn't be able to cause query cycle errors.
Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
| Node::Variant(Variant { disr_expr: Some(ref constant), .. })
if constant.hir_id() == hir_id =>
{
Some(parent_def_id.to_def_id())
}
Node::Variant(Variant { disr_expr: Some(ref constant), .. })
if constant.hir_id == hir_id =>
{
Some(parent_def_id.to_def_id())
@ -1788,7 +1794,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
let mut visitor = PlaceholderHirTyCollector::default();
visitor.visit_ty(ty);
let mut diag = bad_placeholder_type(tcx, visitor.0, "return type");
let mut diag = bad_placeholder(tcx, "type", visitor.0, "return type");
let ret_ty = fn_sig.skip_binder().output();
if !ret_ty.references_error() {
if !ret_ty.is_closure() {

6
compiler/rustc_typeck/src/collect/type_of.rs
View File

@ -13,7 +13,7 @@ use rustc_span::symbol::Ident;
use rustc_span::{Span, DUMMY_SP};
use super::ItemCtxt;
use super::{bad_placeholder_type, is_suggestable_infer_ty};
use super::{bad_placeholder, is_suggestable_infer_ty};
/// Computes the relevant generic parameter for a potential generic const argument.
///
@ -490,7 +490,7 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
match parent_node {
Node::Ty(&Ty { kind: TyKind::Array(_, ref constant), .. })
| Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
if constant.hir_id == hir_id =>
if constant.hir_id() == hir_id =>
{
tcx.types.usize
}
@ -788,7 +788,7 @@ fn infer_placeholder_type<'a>(
err.emit();
}
None => {
let mut diag = bad_placeholder_type(tcx, vec![span], kind);
let mut diag = bad_placeholder(tcx, "type", vec![span], kind);
if !ty.references_error() {
let mut mk_nameable = MakeNameable::new(tcx);

12
src/test/ui/const-generics/generic_arg_infer/array-in-sig.rs Normal file
View File

@ -0,0 +1,12 @@
// To avoid having to `or` gate `_` as an expr.
#![feature(generic_arg_infer)]
fn foo() -> [u8; _] {
//~^ ERROR the const placeholder `_` is not allowed within types on item signatures for generics
// FIXME(generic_arg_infer): this error message should say in the return type or sth like that.
[0; 3]
}
fn main() {
foo();
}

9
src/test/ui/const-generics/generic_arg_infer/array-in-sig.stderr Normal file
View File

@ -0,0 +1,9 @@
error[E0121]: the const placeholder `_` is not allowed within types on item signatures for generics
--> $DIR/array-in-sig.rs:4:18
|
LL | fn foo() -> [u8; _] {
| ^ not allowed in type signatures
error: aborting due to previous error
For more information about this error, try `rustc --explain E0121`.

13
src/test/ui/const-generics/generic_arg_infer/array-repeat-expr.rs Normal file
View File

@ -0,0 +1,13 @@
// run-pass
// To avoid having to `or` gate `_` as an expr.
#![feature(generic_arg_infer)]
fn foo() -> [u8; 3] {
let x: [u8; _] = [0; _];
x
}
fn main() {
assert_eq!([0; _], foo());
}

2
src/test/ui/inference/infer-arg-test.rs → src/test/ui/const-generics/generic_arg_infer/infer-arg-test.rs
View File

@ -18,7 +18,5 @@ fn main() {
let a: All<_, _, _>;
all_fn();
let v: [u8; _];
//~^ ERROR in expressions
let v: [u8; 10] = [0; _];
//~^ ERROR in expressions
}

14
src/test/ui/inference/infer-arg-test.stderr → src/test/ui/const-generics/generic_arg_infer/infer-arg-test.stderr
View File

@ -10,18 +10,6 @@ error: expected identifier, found reserved identifier `_`
LL | fn bad_infer_fn<_>() {}
| ^ expected identifier, found reserved identifier
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/infer-arg-test.rs:20:15
|
LL | let v: [u8; _];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/infer-arg-test.rs:22:25
|
LL | let v: [u8; 10] = [0; _];
| ^ `_` not allowed here
error[E0392]: parameter `_` is never used
--> $DIR/infer-arg-test.rs:7:17
|
@ -31,6 +19,6 @@ LL | struct BadInfer<_>;
= help: consider removing `_`, referring to it in a field, or using a marker such as `PhantomData`
= help: if you intended `_` to be a const parameter, use `const _: usize` instead
error: aborting due to 5 previous errors
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0392`.