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Rollup merge of #88709 - BoxyUwU:thir-abstract-const, r=lcnr

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generic_const_exprs: use thir for abstract consts instead of mir

Changes `AbstractConst` building to use `thir` instead of `mir` so that there's less chance of consts unifying when they shouldn't because lowering to mir dropped information (see `abstract-consts-as-cast-5.rs` test)

r? `@lcnr`
This commit is contained in:
Manish Goregaokar 2021-09-12 03:44:56 -07:00 committed by GitHub
commit f5ac5cadd3
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GPG Key ID: 4AEE18F83AFDEB23
35 changed files with 357 additions and 372 deletions
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9
compiler/rustc_metadata/src/rmeta/decoder.rs
View File

@ -26,6 +26,7 @@ use rustc_middle::middle::cstore::{ForeignModule, LinkagePreference, NativeLib};
use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
use rustc_middle::mir::interpret::{AllocDecodingSession, AllocDecodingState};
use rustc_middle::mir::{self, Body, Promoted};
use rustc_middle::thir;
use rustc_middle::ty::codec::TyDecoder;
use rustc_middle::ty::{self, Ty, TyCtxt, Visibility};
use rustc_serialize::{opaque, Decodable, Decoder};
@ -541,7 +542,7 @@ impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for Span {
}
}
impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for &'tcx [mir::abstract_const::Node<'tcx>] {
impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for &'tcx [thir::abstract_const::Node<'tcx>] {
fn decode(d: &mut DecodeContext<'a, 'tcx>) -> Result<Self, String> {
ty::codec::RefDecodable::decode(d)
}
@ -1196,14 +1197,14 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.decode((self, tcx))
}
fn get_mir_abstract_const(
fn get_thir_abstract_const(
&self,
tcx: TyCtxt<'tcx>,
id: DefIndex,
) -> Result<Option<&'tcx [mir::abstract_const::Node<'tcx>]>, ErrorReported> {
) -> Result<Option<&'tcx [thir::abstract_const::Node<'tcx>]>, ErrorReported> {
self.root
.tables
.mir_abstract_consts
.thir_abstract_consts
.get(self, id)
.map_or(Ok(None), |v| Ok(Some(v.decode((self, tcx)))))
}

2
compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
View File

@ -116,7 +116,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
optimized_mir => { tcx.arena.alloc(cdata.get_optimized_mir(tcx, def_id.index)) }
mir_for_ctfe => { tcx.arena.alloc(cdata.get_mir_for_ctfe(tcx, def_id.index)) }
promoted_mir => { tcx.arena.alloc(cdata.get_promoted_mir(tcx, def_id.index)) }
mir_abstract_const => { cdata.get_mir_abstract_const(tcx, def_id.index) }
thir_abstract_const => { cdata.get_thir_abstract_const(tcx, def_id.index) }
unused_generic_params => { cdata.get_unused_generic_params(def_id.index) }
const_param_default => { tcx.mk_const(cdata.get_const_param_default(tcx, def_id.index)) }
mir_const_qualif => { cdata.mir_const_qualif(def_id.index) }

8
compiler/rustc_metadata/src/rmeta/encoder.rs
View File

@ -23,6 +23,7 @@ use rustc_middle::middle::exported_symbols::{
metadata_symbol_name, ExportedSymbol, SymbolExportLevel,
};
use rustc_middle::mir::interpret;
use rustc_middle::thir;
use rustc_middle::traits::specialization_graph;
use rustc_middle::ty::codec::TyEncoder;
use rustc_middle::ty::{self, SymbolName, Ty, TyCtxt};
@ -344,7 +345,7 @@ impl<'a, 'tcx> TyEncoder<'tcx> for EncodeContext<'a, 'tcx> {
}
}
impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for &'tcx [mir::abstract_const::Node<'tcx>] {
impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for &'tcx [thir::abstract_const::Node<'tcx>] {
fn encode(&self, s: &mut EncodeContext<'a, 'tcx>) -> opaque::EncodeResult {
(**self).encode(s)
}
@ -1297,9 +1298,10 @@ impl EncodeContext<'a, 'tcx> {
if encode_const {
record!(self.tables.mir_for_ctfe[def_id.to_def_id()] <- self.tcx.mir_for_ctfe(def_id));
let abstract_const = self.tcx.mir_abstract_const(def_id);
// FIXME(generic_const_exprs): this feels wrong to have in `encode_mir`
let abstract_const = self.tcx.thir_abstract_const(def_id);
if let Ok(Some(abstract_const)) = abstract_const {
record!(self.tables.mir_abstract_consts[def_id.to_def_id()] <- abstract_const);
record!(self.tables.thir_abstract_consts[def_id.to_def_id()] <- abstract_const);
}
}
record!(self.tables.promoted_mir[def_id.to_def_id()] <- self.tcx.promoted_mir(def_id));

3
compiler/rustc_metadata/src/rmeta/mod.rs
View File

@ -15,6 +15,7 @@ use rustc_middle::hir::exports::Export;
use rustc_middle::middle::cstore::{CrateDepKind, ForeignModule, LinkagePreference, NativeLib};
use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
use rustc_middle::mir;
use rustc_middle::thir;
use rustc_middle::ty::{self, ReprOptions, Ty};
use rustc_serialize::opaque::Encoder;
use rustc_session::config::SymbolManglingVersion;
@ -305,7 +306,7 @@ define_tables! {
mir: Table<DefIndex, Lazy!(mir::Body<'tcx>)>,
mir_for_ctfe: Table<DefIndex, Lazy!(mir::Body<'tcx>)>,
promoted_mir: Table<DefIndex, Lazy!(IndexVec<mir::Promoted, mir::Body<'tcx>>)>,
mir_abstract_consts: Table<DefIndex, Lazy!(&'tcx [mir::abstract_const::Node<'tcx>])>,
thir_abstract_consts: Table<DefIndex, Lazy!(&'tcx [thir::abstract_const::Node<'tcx>])>,
const_defaults: Table<DefIndex, Lazy<rustc_middle::ty::Const<'tcx>>>,
unused_generic_params: Table<DefIndex, Lazy<FiniteBitSet<u32>>>,
// `def_keys` and `def_path_hashes` represent a lazy version of a

38
compiler/rustc_middle/src/mir/abstract_const.rs
View File

@ -1,38 +0,0 @@
//! A subset of a mir body used for const evaluatability checking.
use crate::mir::{self, CastKind};
use crate::ty::{self, Ty};
rustc_index::newtype_index! {
/// An index into an `AbstractConst`.
pub struct NodeId {
derive [HashStable]
DEBUG_FORMAT = "n{}",
}
}
/// A node of an `AbstractConst`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
pub enum Node<'tcx> {
Leaf(&'tcx ty::Const<'tcx>),
Binop(mir::BinOp, NodeId, NodeId),
UnaryOp(mir::UnOp, NodeId),
FunctionCall(NodeId, &'tcx [NodeId]),
Cast(CastKind, NodeId, Ty<'tcx>),
}
#[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
pub enum NotConstEvaluatable {
Error(rustc_errors::ErrorReported),
MentionsInfer,
MentionsParam,
}
impl From<rustc_errors::ErrorReported> for NotConstEvaluatable {
fn from(e: rustc_errors::ErrorReported) -> NotConstEvaluatable {
NotConstEvaluatable::Error(e)
}
}
TrivialTypeFoldableAndLiftImpls! {
NotConstEvaluatable,
}

1
compiler/rustc_middle/src/mir/mod.rs
View File

@ -40,7 +40,6 @@ use self::graph_cyclic_cache::GraphIsCyclicCache;
use self::predecessors::{PredecessorCache, Predecessors};
pub use self::query::*;
pub mod abstract_const;
pub mod coverage;
mod generic_graph;
pub mod generic_graphviz;

14
compiler/rustc_middle/src/mir/query.rs
View File

@ -1,6 +1,6 @@
//! Values computed by queries that use MIR.
use crate::mir::{abstract_const, Body, Promoted};
use crate::mir::{Body, Promoted};
use crate::ty::{self, Ty, TyCtxt};
use rustc_data_structures::sync::Lrc;
use rustc_data_structures::vec_map::VecMap;
@ -431,16 +431,4 @@ impl<'tcx> TyCtxt<'tcx> {
self.mir_for_ctfe(def.did)
}
}
#[inline]
pub fn mir_abstract_const_opt_const_arg(
self,
def: ty::WithOptConstParam<DefId>,
) -> Result<Option<&'tcx [abstract_const::Node<'tcx>]>, ErrorReported> {
if let Some((did, param_did)) = def.as_const_arg() {
self.mir_abstract_const_of_const_arg((did, param_did))
} else {
self.mir_abstract_const(def.did)
}
}
}

8
compiler/rustc_middle/src/query/mod.rs
View File

@ -303,17 +303,17 @@ rustc_queries! {
}
/// Try to build an abstract representation of the given constant.
query mir_abstract_const(
query thir_abstract_const(
key: DefId
) -> Result<Option<&'tcx [mir::abstract_const::Node<'tcx>]>, ErrorReported> {
) -> Result<Option<&'tcx [thir::abstract_const::Node<'tcx>]>, ErrorReported> {
desc {
|tcx| "building an abstract representation for {}", tcx.def_path_str(key),
}
}
/// Try to build an abstract representation of the given constant.
query mir_abstract_const_of_const_arg(
query thir_abstract_const_of_const_arg(
key: (LocalDefId, DefId)
) -> Result<Option<&'tcx [mir::abstract_const::Node<'tcx>]>, ErrorReported> {
) -> Result<Option<&'tcx [thir::abstract_const::Node<'tcx>]>, ErrorReported> {
desc {
|tcx|
"building an abstract representation for the const argument {}",

3
compiler/rustc_middle/src/thir.rs
View File

@ -33,6 +33,9 @@ use rustc_target::asm::InlineAsmRegOrRegClass;
use std::fmt;
use std::ops::Index;
pub mod abstract_const;
pub mod visit;
newtype_index! {
/// An index to an [`Arm`] stored in [`Thir::arms`]
#[derive(HashStable)]

61
compiler/rustc_middle/src/thir/abstract_const.rs Normal file
View File

@ -0,0 +1,61 @@
//! A subset of a mir body used for const evaluatability checking.
use crate::mir;
use crate::ty::{self, Ty, TyCtxt};
use rustc_errors::ErrorReported;
rustc_index::newtype_index! {
/// An index into an `AbstractConst`.
pub struct NodeId {
derive [HashStable]
DEBUG_FORMAT = "n{}",
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
pub enum CastKind {
/// thir::ExprKind::As
As,
/// thir::ExprKind::Use
Use,
}
/// A node of an `AbstractConst`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
pub enum Node<'tcx> {
Leaf(&'tcx ty::Const<'tcx>),
Binop(mir::BinOp, NodeId, NodeId),
UnaryOp(mir::UnOp, NodeId),
FunctionCall(NodeId, &'tcx [NodeId]),
Cast(CastKind, NodeId, Ty<'tcx>),
}
#[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
pub enum NotConstEvaluatable {
Error(ErrorReported),
MentionsInfer,
MentionsParam,
}
impl From<ErrorReported> for NotConstEvaluatable {
fn from(e: ErrorReported) -> NotConstEvaluatable {
NotConstEvaluatable::Error(e)
}
}
TrivialTypeFoldableAndLiftImpls! {
NotConstEvaluatable,
}
impl<'tcx> TyCtxt<'tcx> {
#[inline]
pub fn thir_abstract_const_opt_const_arg(
self,
def: ty::WithOptConstParam<rustc_hir::def_id::DefId>,
) -> Result<Option<&'tcx [Node<'tcx>]>, ErrorReported> {
if let Some((did, param_did)) = def.as_const_arg() {
self.thir_abstract_const_of_const_arg((did, param_did))
} else {
self.thir_abstract_const(def.did)
}
}
}

6
compiler/rustc_mir_build/src/thir/visit.rs → compiler/rustc_middle/src/thir/visit.rs
View File

@ -1,4 +1,6 @@
use rustc_middle::thir::{self, *};
use super::{
Arm, Block, Expr, ExprKind, Guard, InlineAsmOperand, Pat, PatKind, Stmt, StmtKind, Thir,
};
use rustc_middle::ty::Const;
pub trait Visitor<'a, 'tcx: 'a>: Sized {
@ -101,7 +103,7 @@ pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Exp
visitor.visit_expr(&visitor.thir()[field]);
}
}
Adt(box thir::Adt {
Adt(box crate::thir::Adt {
ref fields,
ref base,
adt_def: _,

2
compiler/rustc_middle/src/traits/mod.rs
View File

@ -9,7 +9,7 @@ pub mod specialization_graph;
mod structural_impls;
use crate::infer::canonical::Canonical;
use crate::mir::abstract_const::NotConstEvaluatable;
use crate::thir::abstract_const::NotConstEvaluatable;
use crate::ty::subst::SubstsRef;
use crate::ty::{self, AdtKind, Ty, TyCtxt};

5
compiler/rustc_middle/src/ty/codec.rs
View File

@ -12,6 +12,7 @@ use crate::mir::{
self,
interpret::{AllocId, Allocation},
};
use crate::thir;
use crate::ty::subst::SubstsRef;
use crate::ty::{self, List, Ty, TyCtxt};
use rustc_data_structures::fx::FxHashMap;
@ -362,7 +363,7 @@ impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for [(ty::Predicate<'tcx>,
}
}
impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for [mir::abstract_const::Node<'tcx>] {
impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for [thir::abstract_const::Node<'tcx>] {
fn decode(decoder: &mut D) -> Result<&'tcx Self, D::Error> {
Ok(decoder.tcx().arena.alloc_from_iter(
(0..decoder.read_usize()?)
@ -372,7 +373,7 @@ impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for [mir::abstract_const::N
}
}
impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for [mir::abstract_const::NodeId] {
impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for [thir::abstract_const::NodeId] {
fn decode(decoder: &mut D) -> Result<&'tcx Self, D::Error> {
Ok(decoder.tcx().arena.alloc_from_iter(
(0..decoder.read_usize()?)

6
compiler/rustc_mir_build/src/build/mod.rs
View File

@ -47,10 +47,12 @@ fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_
// Ensure unsafeck is ran before we steal the THIR.
match def {
ty::WithOptConstParam { did, const_param_did: Some(const_param_did) } => {
tcx.ensure().thir_check_unsafety_for_const_arg((did, const_param_did))
tcx.ensure().thir_check_unsafety_for_const_arg((did, const_param_did));
tcx.ensure().thir_abstract_const_of_const_arg((did, const_param_did));
}
ty::WithOptConstParam { did, const_param_did: None } => {
tcx.ensure().thir_check_unsafety(did)
tcx.ensure().thir_check_unsafety(did);
tcx.ensure().thir_abstract_const(did);
}
}

2
compiler/rustc_mir_build/src/check_unsafety.rs
View File

@ -1,5 +1,5 @@
use crate::build::ExprCategory;
use crate::thir::visit::{self, Visitor};
use rustc_middle::thir::visit::{self, Visitor};
use rustc_errors::struct_span_err;
use rustc_hir as hir;

1
compiler/rustc_mir_build/src/thir/mod.rs
View File

@ -11,4 +11,3 @@ crate mod cx;
crate mod pattern;
mod util;
pub mod visit;

1
compiler/rustc_mir_transform/src/lib.rs
View File

@ -306,7 +306,6 @@ fn mir_promoted(
// this point, before we steal the mir-const result.
// Also this means promotion can rely on all const checks having been done.
let _ = tcx.mir_const_qualif_opt_const_arg(def);
let _ = tcx.mir_abstract_const_opt_const_arg(def.to_global());
let mut body = tcx.mir_const(def).steal();
let mut required_consts = Vec::new();

2
compiler/rustc_privacy/src/lib.rs
View File

@ -19,8 +19,8 @@ use rustc_hir::{AssocItemKind, HirIdSet, Node, PatKind};
use rustc_middle::bug;
use rustc_middle::hir::map::Map;
use rustc_middle::middle::privacy::{AccessLevel, AccessLevels};
use rustc_middle::mir::abstract_const::Node as ACNode;
use rustc_middle::span_bug;
use rustc_middle::thir::abstract_const::Node as ACNode;
use rustc_middle::ty::fold::TypeVisitor;
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::subst::{InternalSubsts, Subst};

3
compiler/rustc_query_impl/src/on_disk_cache.rs
View File

@ -9,6 +9,7 @@ use rustc_index::vec::{Idx, IndexVec};
use rustc_middle::dep_graph::{DepNode, DepNodeIndex, SerializedDepNodeIndex};
use rustc_middle::mir::interpret::{AllocDecodingSession, AllocDecodingState};
use rustc_middle::mir::{self, interpret};
use rustc_middle::thir;
use rustc_middle::ty::codec::{RefDecodable, TyDecoder, TyEncoder};
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_query_system::dep_graph::DepContext;
@ -921,7 +922,7 @@ impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>>
}
}
impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [mir::abstract_const::Node<'tcx>] {
impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [thir::abstract_const::Node<'tcx>] {
fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> {
RefDecodable::decode(d)
}

437
compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
View File

@ -6,16 +6,16 @@
//! this is not as easy.
//!
//! In this case we try to build an abstract representation of this constant using
//! `mir_abstract_const` which can then be checked for structural equality with other
//! `thir_abstract_const` which can then be checked for structural equality with other
//! generic constants mentioned in the `caller_bounds` of the current environment.
use rustc_errors::ErrorReported;
use rustc_hir::def::DefKind;
use rustc_index::bit_set::BitSet;
use rustc_index::vec::IndexVec;
use rustc_infer::infer::InferCtxt;
use rustc_middle::mir::abstract_const::{Node, NodeId, NotConstEvaluatable};
use rustc_middle::mir;
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::mir::{self, Rvalue, StatementKind, TerminatorKind};
use rustc_middle::thir;
use rustc_middle::thir::abstract_const::{self, Node, NodeId, NotConstEvaluatable};
use rustc_middle::ty::subst::{Subst, SubstsRef};
use rustc_middle::ty::{self, TyCtxt, TypeFoldable};
use rustc_session::lint;
@ -196,7 +196,7 @@ impl<'tcx> AbstractConst<'tcx> {
tcx: TyCtxt<'tcx>,
uv: ty::Unevaluated<'tcx, ()>,
) -> Result<Option<AbstractConst<'tcx>>, ErrorReported> {
let inner = tcx.mir_abstract_const_opt_const_arg(uv.def)?;
let inner = tcx.thir_abstract_const_opt_const_arg(uv.def)?;
debug!("AbstractConst::new({:?}) = {:?}", uv, inner);
Ok(inner.map(|inner| AbstractConst { inner, substs: uv.substs(tcx) }))
}
@ -223,35 +223,24 @@ impl<'tcx> AbstractConst<'tcx> {
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct WorkNode<'tcx> {
node: Node<'tcx>,
span: Span,
used: bool,
}
struct AbstractConstBuilder<'a, 'tcx> {
tcx: TyCtxt<'tcx>,
body: &'a mir::Body<'tcx>,
body_id: thir::ExprId,
body: &'a thir::Thir<'tcx>,
/// The current WIP node tree.
///
/// We require all nodes to be used in the final abstract const,
/// so we store this here. Note that we also consider nodes as used
/// if they are mentioned in an assert, so some used nodes are never
/// actually reachable by walking the [`AbstractConst`].
nodes: IndexVec<NodeId, WorkNode<'tcx>>,
locals: IndexVec<mir::Local, NodeId>,
/// We only allow field accesses if they access
/// the result of a checked operation.
checked_op_locals: BitSet<mir::Local>,
nodes: IndexVec<NodeId, Node<'tcx>>,
}
impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
fn root_span(&self) -> Span {
self.body.exprs[self.body_id].span
}
fn error(&mut self, span: Option<Span>, msg: &str) -> Result<!, ErrorReported> {
self.tcx
.sess
.struct_span_err(self.body.span, "overly complex generic constant")
.span_label(span.unwrap_or(self.body.span), msg)
.struct_span_err(self.root_span(), "overly complex generic constant")
.span_label(span.unwrap_or(self.root_span()), msg)
.help("consider moving this anonymous constant into a `const` function")
.emit();
@ -260,100 +249,51 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
fn new(
tcx: TyCtxt<'tcx>,
body: &'a mir::Body<'tcx>,
(body, body_id): (&'a thir::Thir<'tcx>, thir::ExprId),
) -> Result<Option<AbstractConstBuilder<'a, 'tcx>>, ErrorReported> {
let mut builder = AbstractConstBuilder {
tcx,
body,
nodes: IndexVec::new(),
locals: IndexVec::from_elem(NodeId::MAX, &body.local_decls),
checked_op_locals: BitSet::new_empty(body.local_decls.len()),
};
let builder = AbstractConstBuilder { tcx, body_id, body, nodes: IndexVec::new() };
// We don't have to look at concrete constants, as we
// can just evaluate them.
if !body.is_polymorphic {
struct IsThirPolymorphic<'a, 'tcx> {
is_poly: bool,
thir: &'a thir::Thir<'tcx>,
tcx: TyCtxt<'tcx>,
}
use thir::visit;
impl<'a, 'tcx: 'a> visit::Visitor<'a, 'tcx> for IsThirPolymorphic<'a, 'tcx> {
fn thir(&self) -> &'a thir::Thir<'tcx> {
&self.thir
}
fn visit_expr(&mut self, expr: &thir::Expr<'tcx>) {
self.is_poly |= expr.ty.definitely_has_param_types_or_consts(self.tcx);
if self.is_poly == false {
visit::walk_expr(self, expr)
}
}
fn visit_pat(&mut self, pat: &thir::Pat<'tcx>) {
self.is_poly |= pat.ty.definitely_has_param_types_or_consts(self.tcx);
if self.is_poly == false {
visit::walk_pat(self, pat);
}
}
fn visit_const(&mut self, ct: &'tcx ty::Const<'tcx>) {
self.is_poly |= ct.definitely_has_param_types_or_consts(self.tcx);
}
}
let mut is_poly_vis = IsThirPolymorphic { is_poly: false, thir: body, tcx };
visit::walk_expr(&mut is_poly_vis, &body[body_id]);
debug!("AbstractConstBuilder: is_poly={}", is_poly_vis.is_poly);
if is_poly_vis.is_poly == false {
return Ok(None);
}
// We only allow consts without control flow, so
// we check for cycles here which simplifies the
// rest of this implementation.
if body.is_cfg_cyclic() {
builder.error(None, "cyclic anonymous constants are forbidden")?;
}
Ok(Some(builder))
}
fn add_node(&mut self, node: Node<'tcx>, span: Span) -> NodeId {
// Mark used nodes.
match node {
Node::Leaf(_) => (),
Node::Binop(_, lhs, rhs) => {
self.nodes[lhs].used = true;
self.nodes[rhs].used = true;
}
Node::UnaryOp(_, input) => {
self.nodes[input].used = true;
}
Node::FunctionCall(func, nodes) => {
self.nodes[func].used = true;
nodes.iter().for_each(|&n| self.nodes[n].used = true);
}
Node::Cast(_, operand, _) => {
self.nodes[operand].used = true;
}
}
// Nodes start as unused.
self.nodes.push(WorkNode { node, span, used: false })
}
fn place_to_local(
&mut self,
span: Span,
p: &mir::Place<'tcx>,
) -> Result<mir::Local, ErrorReported> {
const ZERO_FIELD: mir::Field = mir::Field::from_usize(0);
// Do not allow any projections.
//
// One exception are field accesses on the result of checked operations,
// which are required to support things like `1 + 2`.
if let Some(p) = p.as_local() {
debug_assert!(!self.checked_op_locals.contains(p));
Ok(p)
} else if let &[mir::ProjectionElem::Field(ZERO_FIELD, _)] = p.projection.as_ref() {
// Only allow field accesses if the given local
// contains the result of a checked operation.
if self.checked_op_locals.contains(p.local) {
Ok(p.local)
} else {
self.error(Some(span), "unsupported projection")?;
}
} else {
self.error(Some(span), "unsupported projection")?;
}
}
fn operand_to_node(
&mut self,
span: Span,
op: &mir::Operand<'tcx>,
) -> Result<NodeId, ErrorReported> {
debug!("operand_to_node: op={:?}", op);
match op {
mir::Operand::Copy(p) | mir::Operand::Move(p) => {
let local = self.place_to_local(span, p)?;
Ok(self.locals[local])
}
mir::Operand::Constant(ct) => match ct.literal {
mir::ConstantKind::Ty(ct) => Ok(self.add_node(Node::Leaf(ct), span)),
mir::ConstantKind::Val(..) => self.error(Some(span), "unsupported constant")?,
},
}
}
/// We do not allow all binary operations in abstract consts, so filter disallowed ones.
fn check_binop(op: mir::BinOp) -> bool {
use mir::BinOp::*;
@ -373,170 +313,126 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
}
}
fn build_statement(&mut self, stmt: &mir::Statement<'tcx>) -> Result<(), ErrorReported> {
debug!("AbstractConstBuilder: stmt={:?}", stmt);
let span = stmt.source_info.span;
match stmt.kind {
StatementKind::Assign(box (ref place, ref rvalue)) => {
let local = self.place_to_local(span, place)?;
match *rvalue {
Rvalue::Use(ref operand) => {
self.locals[local] = self.operand_to_node(span, operand)?;
Ok(())
}
Rvalue::BinaryOp(op, box (ref lhs, ref rhs)) if Self::check_binop(op) => {
let lhs = self.operand_to_node(span, lhs)?;
let rhs = self.operand_to_node(span, rhs)?;
self.locals[local] = self.add_node(Node::Binop(op, lhs, rhs), span);
if op.is_checkable() {
bug!("unexpected unchecked checkable binary operation");
} else {
Ok(())
}
}
Rvalue::CheckedBinaryOp(op, box (ref lhs, ref rhs))
if Self::check_binop(op) =>
{
let lhs = self.operand_to_node(span, lhs)?;
let rhs = self.operand_to_node(span, rhs)?;
self.locals[local] = self.add_node(Node::Binop(op, lhs, rhs), span);
self.checked_op_locals.insert(local);
Ok(())
}
Rvalue::UnaryOp(op, ref operand) if Self::check_unop(op) => {
let operand = self.operand_to_node(span, operand)?;
self.locals[local] = self.add_node(Node::UnaryOp(op, operand), span);
Ok(())
}
Rvalue::Cast(cast_kind, ref operand, ty) => {
let operand = self.operand_to_node(span, operand)?;
self.locals[local] =
self.add_node(Node::Cast(cast_kind, operand, ty), span);
Ok(())
}
_ => self.error(Some(span), "unsupported rvalue")?,
}
}
// These are not actually relevant for us here, so we can ignore them.
StatementKind::AscribeUserType(..)
| StatementKind::StorageLive(_)
| StatementKind::StorageDead(_) => Ok(()),
_ => self.error(Some(stmt.source_info.span), "unsupported statement")?,
}
}
/// Possible return values:
///
/// - `None`: unsupported terminator, stop building
/// - `Some(None)`: supported terminator, finish building
/// - `Some(Some(block))`: support terminator, build `block` next
fn build_terminator(
&mut self,
terminator: &mir::Terminator<'tcx>,
) -> Result<Option<mir::BasicBlock>, ErrorReported> {
debug!("AbstractConstBuilder: terminator={:?}", terminator);
match terminator.kind {
TerminatorKind::Goto { target } => Ok(Some(target)),
TerminatorKind::Return => Ok(None),
TerminatorKind::Call {
ref func,
ref args,
destination: Some((ref place, target)),
// We do not care about `cleanup` here. Any branch which
// uses `cleanup` will fail const-eval and they therefore
// do not matter when checking for const evaluatability.
//
// Do note that even if `panic::catch_unwind` is made const,
// we still do not have to care about this, as we do not look
// into functions.
cleanup: _,
// Do not allow overloaded operators for now,
// we probably do want to allow this in the future.
//
// This is currently fairly irrelevant as it requires `const Trait`s.
from_hir_call: true,
fn_span,
} => {
let local = self.place_to_local(fn_span, place)?;
let func = self.operand_to_node(fn_span, func)?;
let args = self.tcx.arena.alloc_from_iter(
args.iter()
.map(|arg| self.operand_to_node(terminator.source_info.span, arg))
.collect::<Result<Vec<NodeId>, _>>()?,
);
self.locals[local] = self.add_node(Node::FunctionCall(func, args), fn_span);
Ok(Some(target))
}
TerminatorKind::Assert { ref cond, expected: false, target, .. } => {
let p = match cond {
mir::Operand::Copy(p) | mir::Operand::Move(p) => p,
mir::Operand::Constant(_) => bug!("unexpected assert"),
};
const ONE_FIELD: mir::Field = mir::Field::from_usize(1);
debug!("proj: {:?}", p.projection);
if let Some(p) = p.as_local() {
debug_assert!(!self.checked_op_locals.contains(p));
// Mark locals directly used in asserts as used.
//
// This is needed because division does not use `CheckedBinop` but instead
// adds an explicit assert for `divisor != 0`.
self.nodes[self.locals[p]].used = true;
return Ok(Some(target));
} else if let &[mir::ProjectionElem::Field(ONE_FIELD, _)] = p.projection.as_ref() {
// Only allow asserts checking the result of a checked operation.
if self.checked_op_locals.contains(p.local) {
return Ok(Some(target));
}
}
self.error(Some(terminator.source_info.span), "unsupported assertion")?;
}
_ => self.error(Some(terminator.source_info.span), "unsupported terminator")?,
}
}
/// Builds the abstract const by walking the mir from start to finish
/// and bailing out when encountering an unsupported operation.
/// Builds the abstract const by walking the thir and bailing out when
/// encountering an unspported operation.
fn build(mut self) -> Result<&'tcx [Node<'tcx>], ErrorReported> {
let mut block = &self.body.basic_blocks()[mir::START_BLOCK];
// We checked for a cyclic cfg above, so this should terminate.
loop {
debug!("AbstractConstBuilder: block={:?}", block);
for stmt in block.statements.iter() {
self.build_statement(stmt)?;
}
debug!("Abstractconstbuilder::build: body={:?}", &*self.body);
self.recurse_build(self.body_id)?;
if let Some(next) = self.build_terminator(block.terminator())? {
block = &self.body.basic_blocks()[next];
} else {
break;
}
}
assert_eq!(self.locals[mir::RETURN_PLACE], self.nodes.last().unwrap());
for n in self.nodes.iter() {
if let Node::Leaf(ty::Const { val: ty::ConstKind::Unevaluated(ct), ty: _ }) = n.node {
if let Node::Leaf(ty::Const { val: ty::ConstKind::Unevaluated(ct), ty: _ }) = n {
// `AbstractConst`s should not contain any promoteds as they require references which
// are not allowed.
assert_eq!(ct.promoted, None);
}
}
self.nodes[self.locals[mir::RETURN_PLACE]].used = true;
if let Some(&unused) = self.nodes.iter().find(|n| !n.used) {
self.error(Some(unused.span), "dead code")?;
}
Ok(self.tcx.arena.alloc_from_iter(self.nodes.into_iter()))
}
Ok(self.tcx.arena.alloc_from_iter(self.nodes.into_iter().map(|n| n.node)))
fn recurse_build(&mut self, node: thir::ExprId) -> Result<NodeId, ErrorReported> {
use thir::ExprKind;
let node = &self.body.exprs[node];
debug!("recurse_build: node={:?}", node);
Ok(match &node.kind {
// I dont know if handling of these 3 is correct
&ExprKind::Scope { value, .. } => self.recurse_build(value)?,
&ExprKind::PlaceTypeAscription { source, .. } |
&ExprKind::ValueTypeAscription { source, .. } => self.recurse_build(source)?,
// subtle: associated consts are literals this arm handles
// `<T as Trait>::ASSOC` as well as `12`
&ExprKind::Literal { literal, .. } => self.nodes.push(Node::Leaf(literal)),
ExprKind::Call { fun, args, .. } => {
let fun = self.recurse_build(*fun)?;
let mut new_args = Vec::<NodeId>::with_capacity(args.len());
for &id in args.iter() {
new_args.push(self.recurse_build(id)?);
}
let new_args = self.tcx.arena.alloc_slice(&new_args);
self.nodes.push(Node::FunctionCall(fun, new_args))
},
&ExprKind::Binary { op, lhs, rhs } if Self::check_binop(op) => {
let lhs = self.recurse_build(lhs)?;
let rhs = self.recurse_build(rhs)?;
self.nodes.push(Node::Binop(op, lhs, rhs))
}
&ExprKind::Unary { op, arg } if Self::check_unop(op) => {
let arg = self.recurse_build(arg)?;
self.nodes.push(Node::UnaryOp(op, arg))
},
// This is necessary so that the following compiles:
//
// ```
// fn foo<const N: usize>(a: [(); N + 1]) {
// bar::<{ N + 1 }>();
// }
// ```
ExprKind::Block { body: thir::Block { stmts: box [], expr: Some(e), .. }} => self.recurse_build(*e)?,
// `ExprKind::Use` happens when a `hir::ExprKind::Cast` is a
// "coercion cast" i.e. using a coercion or is a no-op.
// This is important so that `N as usize as usize` doesnt unify with `N as usize`. (untested)
&ExprKind::Use { source } => {
let arg = self.recurse_build(source)?;
self.nodes.push(Node::Cast(abstract_const::CastKind::Use, arg, node.ty))
},
&ExprKind::Cast { source } => {
let arg = self.recurse_build(source)?;
self.nodes.push(Node::Cast(abstract_const::CastKind::As, arg, node.ty))
},
// FIXME(generic_const_exprs): We may want to support these.
ExprKind::AddressOf { .. }
| ExprKind::Borrow { .. }
| ExprKind::Deref { .. }
| ExprKind::Repeat { .. }
| ExprKind::Array { .. }
| ExprKind::Block { .. }
| ExprKind::NeverToAny { .. }
| ExprKind::Tuple { .. }
| ExprKind::Index { .. }
| ExprKind::Field { .. }
| ExprKind::ConstBlock { .. }
| ExprKind::Adt(_) => self.error(
Some(node.span),
"unsupported operation in generic constant, this may be supported in the future",
)?,
ExprKind::Match { .. }
// we dont permit let stmts so `VarRef` and `UpvarRef` cant happen
| ExprKind::VarRef { .. }
| ExprKind::UpvarRef { .. }
| ExprKind::Closure { .. }
| ExprKind::Let { .. } // let expressions imply control flow
| ExprKind::Loop { .. }
| ExprKind::Assign { .. }
| ExprKind::StaticRef { .. }
| ExprKind::LogicalOp { .. }
// we handle valid unary/binary ops above
| ExprKind::Unary { .. }
| ExprKind::Binary { .. }
| ExprKind::Break { .. }
| ExprKind::Continue { .. }
| ExprKind::If { .. }
| ExprKind::Pointer { .. } // dont know if this is correct
| ExprKind::ThreadLocalRef(_)
| ExprKind::LlvmInlineAsm { .. }
| ExprKind::Return { .. }
| ExprKind::Box { .. } // allocations not allowed in constants
| ExprKind::AssignOp { .. }
| ExprKind::InlineAsm { .. }
| ExprKind::Yield { .. } => self.error(Some(node.span), "unsupported operation in generic constant")?,
})
}
}
/// Builds an abstract const, do not use this directly, but use `AbstractConst::new` instead.
pub(super) fn mir_abstract_const<'tcx>(
pub(super) fn thir_abstract_const<'tcx>(
tcx: TyCtxt<'tcx>,
def: ty::WithOptConstParam<LocalDefId>,
) -> Result<Option<&'tcx [mir::abstract_const::Node<'tcx>]>, ErrorReported> {
) -> Result<Option<&'tcx [thir::abstract_const::Node<'tcx>]>, ErrorReported> {
if tcx.features().generic_const_exprs {
match tcx.def_kind(def.did) {
// FIXME(generic_const_exprs): We currently only do this for anonymous constants,
@ -547,8 +443,16 @@ pub(super) fn mir_abstract_const<'tcx>(
DefKind::AnonConst => (),
_ => return Ok(None),
}
let body = tcx.mir_const(def).borrow();
AbstractConstBuilder::new(tcx, &body)?.map(AbstractConstBuilder::build).transpose()
let body = tcx.thir_body(def);
if body.0.borrow().exprs.is_empty() {
// type error in constant, there is no thir
return Err(ErrorReported);
}
AbstractConstBuilder::new(tcx, (&*body.0.borrow(), body.1))?
.map(AbstractConstBuilder::build)
.transpose()
} else {
Ok(None)
}
@ -682,11 +586,16 @@ pub(super) fn try_unify<'tcx>(
&& iter::zip(a_args, b_args)
.all(|(&an, &bn)| try_unify(tcx, a.subtree(an), b.subtree(bn)))
}
(Node::Cast(a_cast_kind, a_operand, a_ty), Node::Cast(b_cast_kind, b_operand, b_ty))
if (a_ty == b_ty) && (a_cast_kind == b_cast_kind) =>
(Node::Cast(a_kind, a_operand, a_ty), Node::Cast(b_kind, b_operand, b_ty))
if (a_ty == b_ty) && (a_kind == b_kind) =>
{
try_unify(tcx, a.subtree(a_operand), b.subtree(b_operand))
}
_ => false,
// use this over `_ => false` to make adding variants to `Node` less error prone
(Node::Cast(..), _)
| (Node::FunctionCall(..), _)
| (Node::UnaryOp(..), _)
| (Node::Binop(..), _)
| (Node::Leaf(..), _) => false,
}
}

2
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
View File

@ -19,7 +19,7 @@ use rustc_hir::intravisit::Visitor;
use rustc_hir::GenericParam;
use rustc_hir::Item;
use rustc_hir::Node;
use rustc_middle::mir::abstract_const::NotConstEvaluatable;
use rustc_middle::thir::abstract_const::NotConstEvaluatable;
use rustc_middle::ty::error::ExpectedFound;
use rustc_middle::ty::fold::TypeFolder;
use rustc_middle::ty::{

2
compiler/rustc_trait_selection/src/traits/fulfill.rs
View File

@ -5,8 +5,8 @@ use rustc_data_structures::obligation_forest::{ObligationForest, ObligationProce
use rustc_errors::ErrorReported;
use rustc_hir as hir;
use rustc_infer::traits::{SelectionError, TraitEngine, TraitEngineExt as _, TraitObligation};
use rustc_middle::mir::abstract_const::NotConstEvaluatable;
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::thir::abstract_const::NotConstEvaluatable;
use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::ToPredicate;

10
compiler/rustc_trait_selection/src/traits/mod.rs
View File

@ -827,16 +827,16 @@ pub fn provide(providers: &mut ty::query::Providers) {
vtable_entries,
vtable_trait_upcasting_coercion_new_vptr_slot,
subst_and_check_impossible_predicates,
mir_abstract_const: |tcx, def_id| {
thir_abstract_const: |tcx, def_id| {
let def_id = def_id.expect_local();
if let Some(def) = ty::WithOptConstParam::try_lookup(def_id, tcx) {
tcx.mir_abstract_const_of_const_arg(def)
tcx.thir_abstract_const_of_const_arg(def)
} else {
const_evaluatable::mir_abstract_const(tcx, ty::WithOptConstParam::unknown(def_id))
const_evaluatable::thir_abstract_const(tcx, ty::WithOptConstParam::unknown(def_id))
}
},
mir_abstract_const_of_const_arg: |tcx, (did, param_did)| {
const_evaluatable::mir_abstract_const(
thir_abstract_const_of_const_arg: |tcx, (did, param_did)| {
const_evaluatable::thir_abstract_const(
tcx,
ty::WithOptConstParam { did, const_param_did: Some(param_did) },
)

2
compiler/rustc_trait_selection/src/traits/object_safety.rs
View File

@ -836,7 +836,7 @@ fn contains_illegal_self_type_reference<'tcx, T: TypeFoldable<'tcx>>(
//
// This shouldn't really matter though as we can't really use any
// constants which are not considered const evaluatable.
use rustc_middle::mir::abstract_const::Node;
use rustc_middle::thir::abstract_const::Node;
if let Ok(Some(ct)) = AbstractConst::new(self.tcx, uv.shrink()) {
const_evaluatable::walk_abstract_const(self.tcx, ct, |node| match node.root() {
Node::Leaf(leaf) => {

2
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@ -34,8 +34,8 @@ use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_infer::infer::LateBoundRegionConversionTime;
use rustc_middle::dep_graph::{DepKind, DepNodeIndex};
use rustc_middle::mir::abstract_const::NotConstEvaluatable;
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::thir::abstract_const::NotConstEvaluatable;
use rustc_middle::ty::fast_reject;
use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::relate::TypeRelation;

11
src/test/ui/const-generics/generic_const_exprs/abstract-consts-as-cast-5.rs Normal file
View File

@ -0,0 +1,11 @@
#![feature(generic_const_exprs)]
#![allow(incomplete_features)]
fn foo<const N: u8>(a: [(); N as usize]) {
bar::<{ N as usize as usize }>();
//~^ error: unconstrained generic constant
}
fn bar<const N: usize>() {}
fn main() {}

10
src/test/ui/const-generics/generic_const_exprs/abstract-consts-as-cast-5.stderr Normal file
View File

@ -0,0 +1,10 @@
error: unconstrained generic constant
--> $DIR/abstract-consts-as-cast-5.rs:5:11
|
LL | bar::<{ N as usize as usize }>();
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= help: try adding a `where` bound using this expression: `where [(); { N as usize as usize }]:`
error: aborting due to previous error

2
src/test/ui/const-generics/generic_const_exprs/array-size-in-generic-struct-param.full.stderr
View File

@ -10,7 +10,7 @@ error: overly complex generic constant
--> $DIR/array-size-in-generic-struct-param.rs:19:15
|
LL | arr: [u8; CFG.arr_size],
| ^^^^^^^^^^^^ unsupported projection
| ^^^^^^^^^^^^ unsupported operation in generic constant, this may be supported in the future
|
= help: consider moving this anonymous constant into a `const` function

2
src/test/ui/const-generics/generic_const_exprs/closures.stderr
View File

@ -4,7 +4,7 @@ error: overly complex generic constant
LL | fn test<const N: usize>() -> [u8; N + (|| 42)()] {}
| ^^^^-------^^
| |
| unsupported rvalue
| unsupported operation in generic constant, this may be supported in the future
|
= help: consider moving this anonymous constant into a `const` function

8
src/test/ui/const-generics/generic_const_exprs/let-bindings.stderr
View File

@ -2,9 +2,7 @@ error: overly complex generic constant
--> $DIR/let-bindings.rs:6:68
|
LL | fn test<const N: usize>() -> [u8; { let x = N; N + 1 }] where [u8; { let x = N; N + 1 }]: Default {
| ^^^^^^-^^^^^^^^^^^^^
| |
| unsupported statement
| ^^^^^^^^^^^^^^^^^^^^ unsupported operation in generic constant, this may be supported in the future
|
= help: consider moving this anonymous constant into a `const` function
@ -12,9 +10,7 @@ error: overly complex generic constant
--> $DIR/let-bindings.rs:6:35
|
LL | fn test<const N: usize>() -> [u8; { let x = N; N + 1 }] where [u8; { let x = N; N + 1 }]: Default {
| ^^^^^^-^^^^^^^^^^^^^
| |
| unsupported statement
| ^^^^^^^^^^^^^^^^^^^^ unsupported operation in generic constant, this may be supported in the future
|
= help: consider moving this anonymous constant into a `const` function

35
src/test/ui/const-generics/generic_const_exprs/unify-op-with-fn-call.rs Normal file
View File

@ -0,0 +1,35 @@
#![feature(generic_const_exprs, adt_const_params, const_trait_impl)]
#![allow(incomplete_features)]
// test `N + N` unifies with explicit function calls for non-builtin-types
#[derive(PartialEq, Eq)]
struct Foo(u8);
impl const std::ops::Add for Foo {
type Output = Self;
fn add(self, rhs: Self) -> Self::Output {
self
}
}
struct Evaluatable<const N: Foo>;
fn foo<const N: Foo>(a: Evaluatable<{ N + N }>) {
bar::<{ std::ops::Add::add(N, N) }>();
}
fn bar<const N: Foo>() {}
// test that `N + N` unifies with explicit function calls for builin-types
struct Evaluatable2<const N: usize>;
fn foo2<const N: usize>(a: Evaluatable2<{ N + N }>) {
bar2::<{ std::ops::Add::add(N, N) }>();
//~^ error: unconstrained generic constant
// FIXME(generic_const_exprs) make this not an error
}
fn bar2<const N: usize>() {}
fn main() {}

10
src/test/ui/const-generics/generic_const_exprs/unify-op-with-fn-call.stderr Normal file
View File

@ -0,0 +1,10 @@
error: unconstrained generic constant
--> $DIR/unify-op-with-fn-call.rs:28:12
|
LL | bar2::<{ std::ops::Add::add(N, N) }>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: try adding a `where` bound using this expression: `where [(); { std::ops::Add::add(N, N) }]:`
error: aborting due to previous error

12
src/test/ui/const-generics/generic_const_exprs/unused_expr.stderr
View File

@ -2,9 +2,7 @@ error: overly complex generic constant
--> $DIR/unused_expr.rs:4:34
|
LL | fn add<const N: usize>() -> [u8; { N + 1; 5 }] {
| ^^-----^^^^^
| |
| dead code
| ^^^^^^^^^^^^ unsupported operation in generic constant, this may be supported in the future
|
= help: consider moving this anonymous constant into a `const` function
@ -12,9 +10,7 @@ error: overly complex generic constant
--> $DIR/unused_expr.rs:9:34
|
LL | fn div<const N: usize>() -> [u8; { N / 1; 5 }] {
| ^^-----^^^^^
| |
| dead code
| ^^^^^^^^^^^^ unsupported operation in generic constant, this may be supported in the future
|
= help: consider moving this anonymous constant into a `const` function
@ -22,9 +18,7 @@ error: overly complex generic constant
--> $DIR/unused_expr.rs:16:38
|
LL | fn fn_call<const N: usize>() -> [u8; { foo(N); 5 }] {
| ^^------^^^^^
| |
| dead code
| ^^^^^^^^^^^^^ unsupported operation in generic constant, this may be supported in the future
|
= help: consider moving this anonymous constant into a `const` function

6
src/test/ui/const-generics/issues/issue-67375.full.stderr
View File

@ -2,9 +2,9 @@ error: overly complex generic constant
--> $DIR/issue-67375.rs:7:17
|
LL | inner: [(); { [|_: &T| {}; 0].len() }],
| ^^^----------^^^^^^^^^^^^
| |
| unsupported rvalue
| ^^---------------^^^^^^^^
| |
| unsupported operation in generic constant
|
= help: consider moving this anonymous constant into a `const` function

3
src/test/ui/const-generics/issues/issue-67945-2.full.stderr
View File

@ -5,11 +5,10 @@ LL | A: [(); {
| _____________^
LL | |
LL | | let x: Option<Box<Self>> = None;
| | ---- unsupported rvalue
LL | |
LL | | 0
LL | | }],
| |_____^
| |_____^ unsupported operation in generic constant, this may be supported in the future
|
= help: consider moving this anonymous constant into a `const` function