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Auto merge of #94876 - b-naber:thir-abstract-const-changes, r=lcnr

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Change Thir to lazily create constants

To allow `AbstractConst`s to work with the previous thir changes we made and those we want to make, i.e. to avoid problems due to `ValTree` and `ConstValue` conversions, we instead switch to a thir representation for constants that allows us to lazily create constants.

r? `@oli-obk`
This commit is contained in:
bors 2022-03-24 12:50:00 +00:00
commit 8d8135f003
17 changed files with 345 additions and 154 deletions
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1
compiler/rustc_middle/src/query/mod.rs
View File

@ -955,6 +955,7 @@ rustc_queries! {
desc { "get a &core::panic::Location referring to a span" }
}
// FIXME get rid of this with valtrees
query lit_to_const(
key: LitToConstInput<'tcx>
) -> Result<ty::Const<'tcx>, LitToConstError> {

33
compiler/rustc_middle/src/thir.rs
View File

@ -369,7 +369,8 @@ pub enum ExprKind<'tcx> {
},
/// An inline `const` block, e.g. `const {}`.
ConstBlock {
value: Const<'tcx>,
did: DefId,
substs: SubstsRef<'tcx>,
},
/// An array literal constructed from one repeated element, e.g. `[1; 5]`.
Repeat {
@ -408,13 +409,25 @@ pub enum ExprKind<'tcx> {
},
/// A literal.
Literal {
literal: Const<'tcx>,
user_ty: Option<Canonical<'tcx, UserType<'tcx>>>,
/// The `DefId` of the `const` item this literal
/// was produced from, if this is not a user-written
/// literal value.
const_id: Option<DefId>,
lit: &'tcx hir::Lit,
neg: bool,
},
/// For literals that don't correspond to anything in the HIR
NonHirLiteral {
lit: ty::ScalarInt,
user_ty: Option<Canonical<'tcx, UserType<'tcx>>>,
},
/// Associated constants and named constants
NamedConst {
def_id: DefId,
substs: SubstsRef<'tcx>,
user_ty: Option<Canonical<'tcx, UserType<'tcx>>>,
},
ConstParam {
param: ty::ParamConst,
def_id: DefId,
},
// FIXME improve docs for `StaticRef` by distinguishing it from `NamedConst`
/// A literal containing the address of a `static`.
///
/// This is only distinguished from `Literal` so that we can register some
@ -439,6 +452,12 @@ pub enum ExprKind<'tcx> {
},
}
impl<'tcx> ExprKind<'tcx> {
pub fn zero_sized_literal(user_ty: Option<Canonical<'tcx, UserType<'tcx>>>) -> Self {
ExprKind::NonHirLiteral { lit: ty::ScalarInt::ZST, user_ty }
}
}
/// Represents the association of a field identifier and an expression.
///
/// This is used in struct constructors.

20
compiler/rustc_middle/src/thir/visit.rs
View File

@ -1,7 +1,6 @@
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 {
fn thir(&self) -> &'a Thir<'tcx>;
@ -25,8 +24,6 @@ pub trait Visitor<'a, 'tcx: 'a>: Sized {
fn visit_pat(&mut self, pat: &Pat<'tcx>) {
walk_pat(self, pat);
}
fn visit_const(&mut self, _cnst: Const<'tcx>) {}
}
pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Expr<'tcx>) {
@ -93,10 +90,9 @@ pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Exp
visitor.visit_expr(&visitor.thir()[value])
}
}
ConstBlock { value } => visitor.visit_const(value),
Repeat { value, count } => {
ConstBlock { did: _, substs: _ } => {}
Repeat { value, count: _ } => {
visitor.visit_expr(&visitor.thir()[value]);
visitor.visit_const(count);
}
Array { ref fields } | Tuple { ref fields } => {
for &field in &**fields {
@ -122,7 +118,10 @@ pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Exp
visitor.visit_expr(&visitor.thir()[source])
}
Closure { closure_id: _, substs: _, upvars: _, movability: _, fake_reads: _ } => {}
Literal { literal, user_ty: _, const_id: _ } => visitor.visit_const(literal),
Literal { lit: _, neg: _ } => {}
NonHirLiteral { lit: _, user_ty: _ } => {}
NamedConst { def_id: _, substs: _, user_ty: _ } => {}
ConstParam { param: _, def_id: _ } => {}
StaticRef { alloc_id: _, ty: _, def_id: _ } => {}
InlineAsm { ref operands, template: _, options: _, line_spans: _ } => {
for op in &**operands {
@ -209,11 +208,8 @@ pub fn walk_pat<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, pat: &Pat<'
visitor.visit_pat(&subpattern.pattern);
}
}
Constant { value } => visitor.visit_const(*value),
Range(range) => {
visitor.visit_const(range.lo);
visitor.visit_const(range.hi);
}
Constant { value: _ } => {}
Range(_) => {}
Slice { prefix, slice, suffix } | Array { prefix, slice, suffix } => {
for subpattern in prefix {
visitor.visit_pat(&subpattern);

118
compiler/rustc_mir_build/src/build/expr/as_constant.rs
View File

@ -1,22 +1,48 @@
//! See docs in build/expr/mod.rs
use crate::build::Builder;
use rustc_middle::mir::interpret::{ConstValue, Scalar};
use crate::thir::constant::parse_float;
use rustc_ast::ast;
use rustc_hir::def_id::DefId;
use rustc_middle::mir::interpret::{
Allocation, ConstValue, LitToConstError, LitToConstInput, Scalar,
};
use rustc_middle::mir::*;
use rustc_middle::thir::*;
use rustc_middle::ty::CanonicalUserTypeAnnotation;
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt};
use rustc_target::abi::Size;
impl<'a, 'tcx> Builder<'a, 'tcx> {
/// Compile `expr`, yielding a compile-time constant. Assumes that
/// `expr` is a valid compile-time constant!
crate fn as_constant(&mut self, expr: &Expr<'tcx>) -> Constant<'tcx> {
let create_uneval_from_def_id =
|tcx: TyCtxt<'tcx>, def_id: DefId, ty: Ty<'tcx>, substs: SubstsRef<'tcx>| {
let uneval = ty::Unevaluated::new(ty::WithOptConstParam::unknown(def_id), substs);
tcx.mk_const(ty::ConstS { val: ty::ConstKind::Unevaluated(uneval), ty })
};
let this = self;
let tcx = this.tcx;
let Expr { ty, temp_lifetime: _, span, ref kind } = *expr;
match *kind {
ExprKind::Scope { region_scope: _, lint_level: _, value } => {
this.as_constant(&this.thir[value])
}
ExprKind::Literal { literal, user_ty, const_id: _ } => {
ExprKind::Literal { lit, neg } => {
let literal =
match lit_to_constant(tcx, LitToConstInput { lit: &lit.node, ty, neg }) {
Ok(c) => c,
Err(LitToConstError::Reported) => ConstantKind::Ty(tcx.const_error(ty)),
Err(LitToConstError::TypeError) => {
bug!("encountered type error in `lit_to_constant")
}
};
Constant { span, user_ty: None, literal: literal.into() }
}
ExprKind::NonHirLiteral { lit, user_ty } => {
let user_ty = user_ty.map(|user_ty| {
this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation {
span,
@ -24,20 +50,92 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
inferred_ty: ty,
})
});
assert_eq!(literal.ty(), ty);
Constant { span, user_ty, literal: literal.into() }
let literal = ConstantKind::Val(ConstValue::Scalar(Scalar::Int(lit)), ty);
Constant { span, user_ty: user_ty, literal }
}
ExprKind::NamedConst { def_id, substs, user_ty } => {
let user_ty = user_ty.map(|user_ty| {
this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation {
span,
user_ty,
inferred_ty: ty,
})
});
let literal = ConstantKind::Ty(create_uneval_from_def_id(tcx, def_id, ty, substs));
Constant { user_ty, span, literal }
}
ExprKind::ConstParam { param, def_id: _ } => {
let const_param =
tcx.mk_const(ty::ConstS { val: ty::ConstKind::Param(param), ty: expr.ty });
let literal = ConstantKind::Ty(const_param);
Constant { user_ty: None, span, literal }
}
ExprKind::ConstBlock { did: def_id, substs } => {
let literal = ConstantKind::Ty(create_uneval_from_def_id(tcx, def_id, ty, substs));
Constant { user_ty: None, span, literal }
}
ExprKind::StaticRef { alloc_id, ty, .. } => {
let const_val =
ConstValue::Scalar(Scalar::from_pointer(alloc_id.into(), &this.tcx));
let const_val = ConstValue::Scalar(Scalar::from_pointer(alloc_id.into(), &tcx));
let literal = ConstantKind::Val(const_val, ty);
Constant { span, user_ty: None, literal }
}
ExprKind::ConstBlock { value } => {
Constant { span: span, user_ty: None, literal: value.into() }
}
_ => span_bug!(span, "expression is not a valid constant {:?}", kind),
}
}
}
crate fn lit_to_constant<'tcx>(
tcx: TyCtxt<'tcx>,
lit_input: LitToConstInput<'tcx>,
) -> Result<ConstantKind<'tcx>, LitToConstError> {
let LitToConstInput { lit, ty, neg } = lit_input;
let trunc = |n| {
let param_ty = ty::ParamEnv::reveal_all().and(ty);
let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
let result = width.truncate(n);
trace!("trunc result: {}", result);
Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
};
let value = match (lit, &ty.kind()) {
(ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
let s = s.as_str();
let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());
let allocation = tcx.intern_const_alloc(allocation);
ConstValue::Slice { data: allocation, start: 0, end: s.len() }
}
(ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
if matches!(inner_ty.kind(), ty::Slice(_)) =>
{
let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
let allocation = tcx.intern_const_alloc(allocation);
ConstValue::Slice { data: allocation, start: 0, end: data.len() }
}
(ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
let id = tcx.allocate_bytes(data);
ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
}
(ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
}
(ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
}
(ast::LitKind::Float(n, _), ty::Float(fty)) => {
parse_float(*n, *fty, neg).ok_or(LitToConstError::Reported)?
}
(ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
(ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
(ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported),
_ => return Err(LitToConstError::TypeError),
};
Ok(ConstantKind::Val(value, ty))
}

3
compiler/rustc_mir_build/src/build/expr/as_place.rs
View File

@ -566,6 +566,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
| ExprKind::Continue { .. }
| ExprKind::Return { .. }
| ExprKind::Literal { .. }
| ExprKind::NamedConst { .. }
| ExprKind::NonHirLiteral { .. }
| ExprKind::ConstParam { .. }
| ExprKind::ConstBlock { .. }
| ExprKind::StaticRef { .. }
| ExprKind::InlineAsm { .. }

3
compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
View File

@ -327,6 +327,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}
ExprKind::Yield { .. }
| ExprKind::Literal { .. }
| ExprKind::NamedConst { .. }
| ExprKind::NonHirLiteral { .. }
| ExprKind::ConstParam { .. }
| ExprKind::ConstBlock { .. }
| ExprKind::StaticRef { .. }
| ExprKind::Block { .. }

2
compiler/rustc_mir_build/src/build/expr/as_temp.rs
View File

@ -70,7 +70,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
local_decl.local_info =
Some(Box::new(LocalInfo::StaticRef { def_id, is_thread_local: true }));
}
ExprKind::Literal { const_id: Some(def_id), .. } => {
ExprKind::NamedConst { def_id, .. } | ExprKind::ConstParam { def_id, .. } => {
local_decl.local_info = Some(Box::new(LocalInfo::ConstRef { def_id }));
}
_ => {}

9
compiler/rustc_mir_build/src/build/expr/category.rs
View File

@ -69,9 +69,12 @@ impl Category {
| ExprKind::AssignOp { .. }
| ExprKind::ThreadLocalRef(_) => Some(Category::Rvalue(RvalueFunc::AsRvalue)),
ExprKind::ConstBlock { .. } | ExprKind::Literal { .. } | ExprKind::StaticRef { .. } => {
Some(Category::Constant)
}
ExprKind::ConstBlock { .. }
| ExprKind::Literal { .. }
| ExprKind::NonHirLiteral { .. }
| ExprKind::ConstParam { .. }
| ExprKind::StaticRef { .. }
| ExprKind::NamedConst { .. } => Some(Category::Constant),
ExprKind::Loop { .. }
| ExprKind::Block { .. }

3
compiler/rustc_mir_build/src/build/expr/into.rs
View File

@ -533,6 +533,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
| ExprKind::Closure { .. }
| ExprKind::ConstBlock { .. }
| ExprKind::Literal { .. }
| ExprKind::NamedConst { .. }
| ExprKind::NonHirLiteral { .. }
| ExprKind::ConstParam { .. }
| ExprKind::ThreadLocalRef(_)
| ExprKind::StaticRef { .. } => {
debug_assert!(match Category::of(&expr.kind).unwrap() {

2
compiler/rustc_mir_build/src/build/expr/mod.rs
View File

@ -60,7 +60,7 @@
//! basically the point where the "by value" operations are bridged
//! over to the "by reference" mode (`as_place`).
mod as_constant;
crate mod as_constant;
mod as_operand;
pub mod as_place;
mod as_rvalue;

3
compiler/rustc_mir_build/src/check_unsafety.rs
View File

@ -303,6 +303,9 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
| ExprKind::Block { .. }
| ExprKind::Borrow { .. }
| ExprKind::Literal { .. }
| ExprKind::NamedConst { .. }
| ExprKind::NonHirLiteral { .. }
| ExprKind::ConstParam { .. }
| ExprKind::ConstBlock { .. }
| ExprKind::Deref { .. }
| ExprKind::Index { .. }

8
compiler/rustc_mir_build/src/thir/constant.rs
View File

@ -7,6 +7,7 @@ use rustc_middle::ty::{self, ParamEnv, TyCtxt};
use rustc_span::symbol::Symbol;
use rustc_target::abi::Size;
// FIXME Once valtrees are available, get rid of this function and the query
crate fn lit_to_const<'tcx>(
tcx: TyCtxt<'tcx>,
lit_input: LitToConstInput<'tcx>,
@ -57,7 +58,12 @@ crate fn lit_to_const<'tcx>(
Ok(ty::Const::from_value(tcx, lit, ty))
}
fn parse_float<'tcx>(num: Symbol, fty: ty::FloatTy, neg: bool) -> Option<ConstValue<'tcx>> {
// FIXME move this to rustc_mir_build::build
pub(crate) fn parse_float<'tcx>(
num: Symbol,
fty: ty::FloatTy,
neg: bool,
) -> Option<ConstValue<'tcx>> {
let num = num.as_str();
use rustc_apfloat::ieee::{Double, Single};
let scalar = match fty {

132
compiler/rustc_mir_build/src/thir/cx/expr.rs
View File

@ -14,7 +14,9 @@ use rustc_middle::ty::adjustment::{
Adjust, Adjustment, AutoBorrow, AutoBorrowMutability, PointerCast,
};
use rustc_middle::ty::subst::{InternalSubsts, SubstsRef};
use rustc_middle::ty::{self, AdtKind, Ty, UpvarSubsts, UserType};
use rustc_middle::ty::{
self, AdtKind, InlineConstSubsts, InlineConstSubstsParts, ScalarInt, Ty, UpvarSubsts, UserType,
};
use rustc_span::def_id::DefId;
use rustc_span::Span;
use rustc_target::abi::VariantIdx;
@ -290,11 +292,7 @@ impl<'tcx> Cx<'tcx> {
}
}
hir::ExprKind::Lit(ref lit) => ExprKind::Literal {
literal: self.const_eval_literal(&lit.node, expr_ty, lit.span, false),
user_ty: None,
const_id: None,
},
hir::ExprKind::Lit(ref lit) => ExprKind::Literal { lit, neg: false },
hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
if self.typeck_results().is_method_call(expr) {
@ -359,11 +357,7 @@ impl<'tcx> Cx<'tcx> {
let arg = self.mirror_expr(arg);
self.overloaded_operator(expr, Box::new([arg]))
} else if let hir::ExprKind::Lit(ref lit) = arg.kind {
ExprKind::Literal {
literal: self.const_eval_literal(&lit.node, expr_ty, lit.span, true),
user_ty: None,
const_id: None,
}
ExprKind::Literal { lit, neg: true }
} else {
ExprKind::Unary { op: UnOp::Neg, arg: self.mirror_expr(arg) }
}
@ -524,11 +518,7 @@ impl<'tcx> Cx<'tcx> {
ty,
temp_lifetime,
span: expr.span,
kind: ExprKind::Literal {
literal: ty::Const::zero_sized(self.tcx, ty),
user_ty,
const_id: None,
},
kind: ExprKind::zero_sized_literal(user_ty),
}),
}
}
@ -550,11 +540,7 @@ impl<'tcx> Cx<'tcx> {
ty,
temp_lifetime,
span: expr.span,
kind: ExprKind::Literal {
literal: ty::Const::zero_sized(self.tcx, ty),
user_ty: None,
const_id: None,
},
kind: ExprKind::zero_sized_literal(None),
}),
}
}
@ -568,13 +554,21 @@ impl<'tcx> Cx<'tcx> {
},
hir::ExprKind::ConstBlock(ref anon_const) => {
let anon_const_def_id = self.tcx.hir().local_def_id(anon_const.hir_id);
let tcx = self.tcx;
let local_def_id = tcx.hir().local_def_id(anon_const.hir_id);
let anon_const_def_id = local_def_id.to_def_id();
// FIXME Do we want to use `from_inline_const` once valtrees
// are introduced? This would create `ValTree`s that will never be used...
let value = ty::Const::from_inline_const(self.tcx, anon_const_def_id);
// Need to include the parent substs
let hir_id = tcx.hir().local_def_id_to_hir_id(local_def_id);
let ty = tcx.typeck(local_def_id).node_type(hir_id);
let typeck_root_def_id = tcx.typeck_root_def_id(anon_const_def_id);
let parent_substs =
tcx.erase_regions(InternalSubsts::identity_for_item(tcx, typeck_root_def_id));
let substs =
InlineConstSubsts::new(tcx, InlineConstSubstsParts { parent_substs, ty })
.substs;
ExprKind::ConstBlock { value }
ExprKind::ConstBlock { did: anon_const_def_id, substs }
}
// Now comes the rote stuff:
hir::ExprKind::Repeat(ref v, _) => {
@ -692,32 +686,36 @@ impl<'tcx> Cx<'tcx> {
};
let source = if let Some((did, offset, var_ty)) = var {
let mk_const = |literal| Expr {
let param_env_ty = self.param_env.and(var_ty);
let size = self
.tcx
.layout_of(param_env_ty)
.unwrap_or_else(|e| {
panic!("could not compute layout for {:?}: {:?}", param_env_ty, e)
})
.size;
let lit = ScalarInt::try_from_uint(offset as u128, size).unwrap();
let kind = ExprKind::NonHirLiteral { lit, user_ty: None };
let offset = self.thir.exprs.push(Expr {
temp_lifetime,
ty: var_ty,
span: expr.span,
kind: ExprKind::Literal { literal, user_ty: None, const_id: None },
};
let offset = self.thir.exprs.push(mk_const(ty::Const::from_bits(
self.tcx,
offset as u128,
self.param_env.and(var_ty),
)));
kind,
});
match did {
Some(did) => {
// in case we are offsetting from a computed discriminant
// and not the beginning of discriminants (which is always `0`)
let substs = InternalSubsts::identity_for_item(self.tcx(), did);
let lhs = ty::ConstS {
val: ty::ConstKind::Unevaluated(ty::Unevaluated::new(
ty::WithOptConstParam::unknown(did),
substs,
)),
let kind =
ExprKind::NamedConst { def_id: did, substs, user_ty: None };
let lhs = self.thir.exprs.push(Expr {
temp_lifetime,
ty: var_ty,
};
let lhs = self.thir.exprs.push(mk_const(self.tcx().mk_const(lhs)));
let bin =
ExprKind::Binary { op: BinOp::Add, lhs: lhs, rhs: offset };
span: expr.span,
kind,
});
let bin = ExprKind::Binary { op: BinOp::Add, lhs, rhs: offset };
self.thir.exprs.push(Expr {
temp_lifetime,
ty: var_ty,
@ -832,16 +830,7 @@ impl<'tcx> Cx<'tcx> {
}
};
let ty = self.tcx().mk_fn_def(def_id, substs);
Expr {
temp_lifetime,
ty,
span,
kind: ExprKind::Literal {
literal: ty::Const::zero_sized(self.tcx(), ty),
user_ty,
const_id: None,
},
}
Expr { temp_lifetime, ty, span, kind: ExprKind::zero_sized_literal(user_ty) }
}
fn convert_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) -> ArmId {
@ -868,17 +857,9 @@ impl<'tcx> Cx<'tcx> {
Res::Def(DefKind::Fn, _)
| Res::Def(DefKind::AssocFn, _)
| Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
| Res::SelfCtor(..) => {
| Res::SelfCtor(_) => {
let user_ty = self.user_substs_applied_to_res(expr.hir_id, res);
debug!("convert_path_expr: user_ty={:?}", user_ty);
ExprKind::Literal {
literal: ty::Const::zero_sized(
self.tcx,
self.typeck_results().node_type(expr.hir_id),
),
user_ty,
const_id: None,
}
ExprKind::zero_sized_literal(user_ty)
}
Res::Def(DefKind::ConstParam, def_id) => {
@ -888,31 +869,14 @@ impl<'tcx> Cx<'tcx> {
let generics = self.tcx.generics_of(item_def_id);
let index = generics.param_def_id_to_index[&def_id];
let name = self.tcx.hir().name(hir_id);
let val = ty::ConstKind::Param(ty::ParamConst::new(index, name));
ExprKind::Literal {
literal: self.tcx.mk_const(ty::ConstS {
val,
ty: self.typeck_results().node_type(expr.hir_id),
}),
user_ty: None,
const_id: Some(def_id),
}
let param = ty::ParamConst::new(index, name);
ExprKind::ConstParam { param, def_id }
}
Res::Def(DefKind::Const, def_id) | Res::Def(DefKind::AssocConst, def_id) => {
let user_ty = self.user_substs_applied_to_res(expr.hir_id, res);
debug!("convert_path_expr: (const) user_ty={:?}", user_ty);
ExprKind::Literal {
literal: self.tcx.mk_const(ty::ConstS {
val: ty::ConstKind::Unevaluated(ty::Unevaluated::new(
ty::WithOptConstParam::unknown(def_id),
substs,
)),
ty: self.typeck_results().node_type(expr.hir_id),
}),
user_ty,
const_id: Some(def_id),
}
ExprKind::NamedConst { def_id, substs, user_ty: user_ty }
}
Res::Def(DefKind::Ctor(_, CtorKind::Const), def_id) => {

23
compiler/rustc_mir_build/src/thir/cx/mod.rs
View File

@ -5,7 +5,6 @@
use crate::thir::pattern::pat_from_hir;
use crate::thir::util::UserAnnotatedTyHelpers;
use rustc_ast as ast;
use rustc_data_structures::steal::Steal;
use rustc_errors::ErrorGuaranteed;
use rustc_hir as hir;
@ -13,9 +12,8 @@ use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::HirId;
use rustc_hir::Node;
use rustc_middle::middle::region;
use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput};
use rustc_middle::thir::*;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::ty::{self, TyCtxt};
use rustc_span::Span;
crate fn thir_body<'tcx>(
@ -77,25 +75,6 @@ impl<'tcx> Cx<'tcx> {
}
}
crate fn const_eval_literal(
&mut self,
lit: &'tcx ast::LitKind,
ty: Ty<'tcx>,
sp: Span,
neg: bool,
) -> ty::Const<'tcx> {
trace!("const_eval_literal: {:#?}, {:?}, {:?}, {:?}", lit, ty, sp, neg);
match self.tcx.at(sp).lit_to_const(LitToConstInput { lit, ty, neg }) {
Ok(c) => c,
Err(LitToConstError::Reported) => {
// create a dummy value and continue compiling
self.tcx.const_error(ty)
}
Err(LitToConstError::TypeError) => bug!("const_eval_literal: had type error"),
}
}
crate fn pattern_from_hir(&mut self, p: &hir::Pat<'_>) -> Pat<'tcx> {
let p = match self.tcx.hir().get(p.hir_id) {
Node::Pat(p) | Node::Binding(p) => p,

97
compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
View File

@ -14,7 +14,9 @@ use rustc_hir::def::DefKind;
use rustc_index::vec::IndexVec;
use rustc_infer::infer::InferCtxt;
use rustc_middle::mir;
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::mir::interpret::{
ConstValue, ErrorHandled, LitToConstError, LitToConstInput, Scalar,
};
use rustc_middle::thir;
use rustc_middle::thir::abstract_const::{self, Node, NodeId, NotConstEvaluatable};
use rustc_middle::ty::subst::{Subst, SubstsRef};
@ -28,13 +30,13 @@ use std::iter;
use std::ops::ControlFlow;
/// Check if a given constant can be evaluated.
#[instrument(skip(infcx), level = "debug")]
pub fn is_const_evaluatable<'cx, 'tcx>(
infcx: &InferCtxt<'cx, 'tcx>,
uv: ty::Unevaluated<'tcx, ()>,
param_env: ty::ParamEnv<'tcx>,
span: Span,
) -> Result<(), NotConstEvaluatable> {
debug!("is_const_evaluatable({:?})", uv);
let tcx = infcx.tcx;
if tcx.features().generic_const_exprs {
@ -304,6 +306,7 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
Err(reported)
}
#[instrument(skip(tcx, body, body_id), level = "debug")]
fn new(
tcx: TyCtxt<'tcx>,
(body, body_id): (&'a thir::Thir<'tcx>, thir::ExprId),
@ -315,29 +318,61 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
thir: &'a thir::Thir<'tcx>,
}
use crate::rustc_middle::thir::visit::Visitor;
use thir::visit;
impl<'a, 'tcx: 'a> visit::Visitor<'a, 'tcx> for IsThirPolymorphic<'a, 'tcx> {
impl<'a, 'tcx> IsThirPolymorphic<'a, 'tcx> {
fn expr_is_poly(&mut self, expr: &thir::Expr<'tcx>) -> bool {
if expr.ty.has_param_types_or_consts() {
return true;
}
match expr.kind {
thir::ExprKind::NamedConst { substs, .. } => substs.has_param_types_or_consts(),
thir::ExprKind::ConstParam { .. } => true,
thir::ExprKind::Repeat { value, count } => {
self.visit_expr(&self.thir()[value]);
count.has_param_types_or_consts()
}
_ => false,
}
}
fn pat_is_poly(&mut self, pat: &thir::Pat<'tcx>) -> bool {
if pat.ty.has_param_types_or_consts() {
return true;
}
match pat.kind.as_ref() {
thir::PatKind::Constant { value } => value.has_param_types_or_consts(),
thir::PatKind::Range(thir::PatRange { lo, hi, .. }) => {
lo.has_param_types_or_consts() || hi.has_param_types_or_consts()
}
_ => false,
}
}
}
impl<'a, 'tcx> visit::Visitor<'a, 'tcx> for IsThirPolymorphic<'a, 'tcx> {
fn thir(&self) -> &'a thir::Thir<'tcx> {
&self.thir
}
#[instrument(skip(self), level = "debug")]
fn visit_expr(&mut self, expr: &thir::Expr<'tcx>) {
self.is_poly |= expr.ty.has_param_types_or_consts();
self.is_poly |= self.expr_is_poly(expr);
if !self.is_poly {
visit::walk_expr(self, expr)
}
}
#[instrument(skip(self), level = "debug")]
fn visit_pat(&mut self, pat: &thir::Pat<'tcx>) {
self.is_poly |= pat.ty.has_param_types_or_consts();
self.is_poly |= self.pat_is_poly(pat);
if !self.is_poly {
visit::walk_pat(self, pat);
}
}
fn visit_const(&mut self, ct: ty::Const<'tcx>) {
self.is_poly |= ct.has_param_types_or_consts();
}
}
let mut is_poly_vis = IsThirPolymorphic { is_poly: false, thir: body };
@ -393,16 +428,49 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
fn recurse_build(&mut self, node: thir::ExprId) -> Result<NodeId, ErrorGuaranteed> {
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)?,
&ExprKind::Literal { lit, neg} => {
let sp = node.span;
let constant =
match self.tcx.at(sp).lit_to_const(LitToConstInput { lit: &lit.node, ty: node.ty, neg }) {
Ok(c) => c,
Err(LitToConstError::Reported) => {
self.tcx.const_error(node.ty)
}
Err(LitToConstError::TypeError) => {
bug!("encountered type error in lit_to_const")
}
};
// 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)),
self.nodes.push(Node::Leaf(constant))
}
&ExprKind::NonHirLiteral { lit , user_ty: _} => {
// FIXME Construct a Valtree from this ScalarInt when introducing Valtrees
let const_value = ConstValue::Scalar(Scalar::Int(lit));
self.nodes.push(Node::Leaf(ty::Const::from_value(self.tcx, const_value, node.ty)))
}
&ExprKind::NamedConst { def_id, substs, user_ty: _ } => {
let uneval = ty::Unevaluated::new(ty::WithOptConstParam::unknown(def_id), substs);
let constant = self.tcx.mk_const(ty::ConstS {
val: ty::ConstKind::Unevaluated(uneval),
ty: node.ty,
});
self.nodes.push(Node::Leaf(constant))
}
ExprKind::ConstParam {param, ..} => {
let const_param = self.tcx.mk_const(ty::ConstS {
val: ty::ConstKind::Param(*param),
ty: node.ty,
});
self.nodes.push(Node::Leaf(const_param))
}
ExprKind::Call { fun, args, .. } => {
let fun = self.recurse_build(*fun)?;
@ -585,6 +653,7 @@ pub(super) fn try_unify_abstract_consts<'tcx>(
// on `ErrorGuaranteed`.
}
#[instrument(skip(tcx, f), level = "debug")]
pub fn walk_abstract_const<'tcx, R, F>(
tcx: TyCtxt<'tcx>,
ct: AbstractConst<'tcx>,
@ -593,6 +662,7 @@ pub fn walk_abstract_const<'tcx, R, F>(
where
F: FnMut(AbstractConst<'tcx>) -> ControlFlow<R>,
{
#[instrument(skip(tcx, f), level = "debug")]
fn recurse<'tcx, R>(
tcx: TyCtxt<'tcx>,
ct: AbstractConst<'tcx>,
@ -600,6 +670,7 @@ where
) -> ControlFlow<R> {
f(ct)?;
let root = ct.root(tcx);
debug!(?root);
match root {
Node::Leaf(_) => ControlFlow::CONTINUE,
Node::Binop(_, l, r) => {

20
src/test/ui/mir/thir-constparam-temp.rs Normal file
View File

@ -0,0 +1,20 @@
// build-pass
#![feature(adt_const_params)]
#![allow(incomplete_features)]
#[derive(PartialEq, Eq)]
struct Yikes;
impl Yikes {
fn mut_self(&mut self) {}
}
fn foo<const YIKES: Yikes>() {
YIKES.mut_self()
//~^ WARNING taking a mutable reference
}
fn main() {
foo::<{ Yikes }>()
}

22
src/test/ui/mir/thir-constparam-temp.stderr Normal file
View File

@ -0,0 +1,22 @@
warning: taking a mutable reference to a `const` item
--> $DIR/thir-constparam-temp.rs:14:5
|
LL | YIKES.mut_self()
| ^^^^^^^^^^^^^^^^
|
= note: `#[warn(const_item_mutation)]` on by default
= note: each usage of a `const` item creates a new temporary
= note: the mutable reference will refer to this temporary, not the original `const` item
note: mutable reference created due to call to this method
--> $DIR/thir-constparam-temp.rs:10:5
|
LL | fn mut_self(&mut self) {}
| ^^^^^^^^^^^^^^^^^^^^^^
note: `const` item defined here
--> $DIR/thir-constparam-temp.rs:13:14
|
LL | fn foo<const YIKES: Yikes>() {
| ^^^^^
warning: 1 warning emitted