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do use ty::Const in patterns and abstract consts

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This commit is contained in:
b-naber
2022-03-09 13:56:12 +01:00
parent b38077ea0b
commit ac60db231c
15 changed files with 105 additions and 127 deletions
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30
compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
View File

@@ -1,7 +1,7 @@
use rustc_hir as hir;
use rustc_index::vec::Idx;
use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
use rustc_middle::mir::{self, Field};
use rustc_middle::mir::Field;
use rustc_middle::thir::{FieldPat, Pat, PatKind};
use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt};
@@ -22,7 +22,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
#[instrument(level = "debug", skip(self))]
pub(super) fn const_to_pat(
&self,
cv: mir::ConstantKind<'tcx>,
cv: ty::Const<'tcx>,
id: hir::HirId,
span: Span,
mir_structural_match_violation: bool,
@@ -152,11 +152,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
ty.is_structural_eq_shallow(self.infcx.tcx)
}
fn to_pat(
&mut self,
cv: mir::ConstantKind<'tcx>,
mir_structural_match_violation: bool,
) -> Pat<'tcx> {
fn to_pat(&mut self, cv: ty::Const<'tcx>, mir_structural_match_violation: bool) -> Pat<'tcx> {
trace!(self.treat_byte_string_as_slice);
// This method is just a wrapper handling a validity check; the heavy lifting is
// performed by the recursive `recur` method, which is not meant to be
@@ -250,7 +246,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
fn field_pats(
&self,
vals: impl Iterator<Item = mir::ConstantKind<'tcx>>,
vals: impl Iterator<Item = ty::Const<'tcx>>,
) -> Result<Vec<FieldPat<'tcx>>, FallbackToConstRef> {
vals.enumerate()
.map(|(idx, val)| {
@@ -263,7 +259,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
// Recursive helper for `to_pat`; invoke that (instead of calling this directly).
fn recur(
&self,
cv: mir::ConstantKind<'tcx>,
cv: ty::Const<'tcx>,
mir_structural_match_violation: bool,
) -> Result<Pat<'tcx>, FallbackToConstRef> {
let id = self.id;
@@ -369,7 +365,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
PatKind::Wild
}
ty::Adt(adt_def, substs) if adt_def.is_enum() => {
let destructured = tcx.destructure_mir_constant(param_env.and(cv));
let destructured = tcx.destructure_const(param_env.and(cv));
PatKind::Variant {
adt_def: *adt_def,
substs,
@@ -380,12 +376,12 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
}
}
ty::Tuple(_) | ty::Adt(_, _) => {
let destructured = tcx.destructure_mir_constant(param_env.and(cv));
let destructured = tcx.destructure_const(param_env.and(cv));
PatKind::Leaf { subpatterns: self.field_pats(destructured.fields.iter().copied())? }
}
ty::Array(..) => PatKind::Array {
prefix: tcx
.destructure_mir_constant(param_env.and(cv))
.destructure_const(param_env.and(cv))
.fields
.iter()
.map(|val| self.recur(*val, false))
@@ -416,12 +412,12 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
// arrays.
ty::Array(..) if !self.treat_byte_string_as_slice => {
let old = self.behind_reference.replace(true);
let array = tcx.deref_mir_constant(self.param_env.and(cv));
let array = tcx.deref_const(self.param_env.and(cv));
let val = PatKind::Deref {
subpattern: Pat {
kind: Box::new(PatKind::Array {
prefix: tcx
.destructure_mir_constant(param_env.and(array))
.destructure_const(param_env.and(array))
.fields
.iter()
.map(|val| self.recur(*val, false))
@@ -442,12 +438,12 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
// pattern.
ty::Slice(elem_ty) => {
let old = self.behind_reference.replace(true);
let array = tcx.deref_mir_constant(self.param_env.and(cv));
let array = tcx.deref_const(self.param_env.and(cv));
let val = PatKind::Deref {
subpattern: Pat {
kind: Box::new(PatKind::Slice {
prefix: tcx
.destructure_mir_constant(param_env.and(array))
.destructure_const(param_env.and(array))
.fields
.iter()
.map(|val| self.recur(*val, false))
@@ -516,7 +512,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
// we fall back to a const pattern. If we do not do this, we may end up with
// a !structural-match constant that is not of reference type, which makes it
// very hard to invoke `PartialEq::eq` on it as a fallback.
let val = match self.recur(tcx.deref_mir_constant(self.param_env.and(cv)), false) {
let val = match self.recur(tcx.deref_const(self.param_env.and(cv)), false) {
Ok(subpattern) => PatKind::Deref { subpattern },
Err(_) => PatKind::Constant { value: cv },
};

39
compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
View File

@@ -52,7 +52,7 @@ use rustc_data_structures::captures::Captures;
use rustc_index::vec::Idx;
use rustc_hir::{HirId, RangeEnd};
use rustc_middle::mir::{self, Field};
use rustc_middle::mir::Field;
use rustc_middle::thir::{FieldPat, Pat, PatKind, PatRange};
use rustc_middle::ty::layout::IntegerExt;
use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
@@ -136,30 +136,20 @@ impl IntRange {
fn from_const<'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
value: mir::ConstantKind<'tcx>,
value: ty::Const<'tcx>,
) -> Option<IntRange> {
let ty = value.ty();
if let Some((target_size, bias)) = Self::integral_size_and_signed_bias(tcx, ty) {
let val = (|| {
match value {
mir::ConstantKind::Val(ConstValue::Scalar(scalar), _) => {
// For this specific pattern we can skip a lot of effort and go
// straight to the result, after doing a bit of checking. (We
// could remove this branch and just fall through, which
// is more general but much slower.)
if let Ok(bits) = scalar.to_bits_or_ptr_internal(target_size) {
return Some(bits);
}
if let ty::ConstKind::Value(ConstValue::Scalar(scalar)) = value.val() {
// For this specific pattern we can skip a lot of effort and go
// straight to the result, after doing a bit of checking. (We
// could remove this branch and just fall through, which
// is more general but much slower.)
if let Ok(bits) = scalar.to_bits_or_ptr_internal(target_size) {
return Some(bits);
}
mir::ConstantKind::Ty(c) => match c.val() {
ty::ConstKind::Value(_) => bug!(
"encountered ConstValue in mir::ConstantKind::Ty, whereas this is expected to be in ConstantKind::Val"
),
_ => {}
},
_ => {}
}
// This is a more general form of the previous case.
value.try_eval_bits(tcx, param_env, ty)
})()?;
@@ -244,8 +234,8 @@ impl IntRange {
let (lo, hi) = (lo ^ bias, hi ^ bias);
let env = ty::ParamEnv::empty().and(ty);
let lo_const = mir::ConstantKind::from_bits(tcx, lo, env);
let hi_const = mir::ConstantKind::from_bits(tcx, hi, env);
let lo_const = ty::Const::from_bits(tcx, lo, env);
let hi_const = ty::Const::from_bits(tcx, hi, env);
let kind = if lo == hi {
PatKind::Constant { value: lo_const }
@@ -640,9 +630,9 @@ pub(super) enum Constructor<'tcx> {
/// Ranges of integer literal values (`2`, `2..=5` or `2..5`).
IntRange(IntRange),
/// Ranges of floating-point literal values (`2.0..=5.2`).
FloatRange(mir::ConstantKind<'tcx>, mir::ConstantKind<'tcx>, RangeEnd),
FloatRange(ty::Const<'tcx>, ty::Const<'tcx>, RangeEnd),
/// String literals. Strings are not quite the same as `&[u8]` so we treat them separately.
Str(mir::ConstantKind<'tcx>),
Str(ty::Const<'tcx>),
/// Array and slice patterns.
Slice(Slice),
/// Constants that must not be matched structurally. They are treated as black
@@ -839,7 +829,8 @@ impl<'tcx> Constructor<'tcx> {
}
}
(Str(self_val), Str(other_val)) => {
// FIXME: there's probably a more direct way of comparing for equality
// FIXME Once valtrees are available we can directly use the bytes
// in the `Str` variant of the valtree for the comparison here.
match compare_const_vals(
pcx.cx.tcx,
*self_val,

58
compiler/rustc_mir_build/src/thir/pattern/mod.rs
View File

@@ -17,7 +17,7 @@ use rustc_hir::RangeEnd;
use rustc_index::vec::Idx;
use rustc_middle::mir::interpret::{get_slice_bytes, ConstValue};
use rustc_middle::mir::interpret::{ErrorHandled, LitToConstError, LitToConstInput};
use rustc_middle::mir::{self, UserTypeProjection};
use rustc_middle::mir::UserTypeProjection;
use rustc_middle::mir::{BorrowKind, Field, Mutability};
use rustc_middle::thir::{Ascription, BindingMode, FieldPat, Pat, PatKind, PatRange, PatTyProj};
use rustc_middle::ty::subst::{GenericArg, SubstsRef};
@@ -121,8 +121,8 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
fn lower_pattern_range(
&mut self,
ty: Ty<'tcx>,
lo: mir::ConstantKind<'tcx>,
hi: mir::ConstantKind<'tcx>,
lo: ty::Const<'tcx>,
hi: ty::Const<'tcx>,
end: RangeEnd,
span: Span,
) -> PatKind<'tcx> {
@@ -177,24 +177,18 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
ty: Ty<'tcx>,
lo: Option<&PatKind<'tcx>>,
hi: Option<&PatKind<'tcx>>,
) -> Option<(mir::ConstantKind<'tcx>, mir::ConstantKind<'tcx>)> {
) -> Option<(ty::Const<'tcx>, ty::Const<'tcx>)> {
match (lo, hi) {
(Some(PatKind::Constant { value: lo }), Some(PatKind::Constant { value: hi })) => {
Some((*lo, *hi))
}
(Some(PatKind::Constant { value: lo }), None) => {
let hi = ty.numeric_max_val(self.tcx)?;
Some((
*lo,
mir::ConstantKind::from_bits(self.tcx, hi, ty::ParamEnv::empty().and(ty)),
))
Some((*lo, ty::Const::from_bits(self.tcx, hi, ty::ParamEnv::empty().and(ty))))
}
(None, Some(PatKind::Constant { value: hi })) => {
let lo = ty.numeric_min_val(self.tcx)?;
Some((
mir::ConstantKind::from_bits(self.tcx, lo, ty::ParamEnv::empty().and(ty)),
*hi,
))
Some((ty::Const::from_bits(self.tcx, lo, ty::ParamEnv::empty().and(ty)), *hi))
}
_ => None,
}
@@ -496,7 +490,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
match self.tcx.const_eval_instance(param_env_reveal_all, instance, Some(span)) {
Ok(value) => {
let const_ = mir::ConstantKind::Val(value, ty);
let const_ = ty::Const::from_value(self.tcx, value, ty);
let pattern = self.const_to_pat(const_, id, span, mir_structural_match_violation);
if !is_associated_const {
@@ -545,30 +539,25 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
span: Span,
) -> PatKind<'tcx> {
let anon_const_def_id = self.tcx.hir().local_def_id(anon_const.hir_id);
let value = mir::ConstantKind::from_inline_const(self.tcx, anon_const_def_id);
let value = ty::Const::from_inline_const(self.tcx, anon_const_def_id);
// Evaluate early like we do in `lower_path`.
let value = value.eval(self.tcx, self.param_env);
match value {
mir::ConstantKind::Ty(c) => {
match c.val() {
ConstKind::Param(_) => {
self.errors.push(PatternError::ConstParamInPattern(span));
return PatKind::Wild;
}
ConstKind::Unevaluated(_) => {
// If we land here it means the const can't be evaluated because it's `TooGeneric`.
self.tcx
.sess
.span_err(span, "constant pattern depends on a generic parameter");
return PatKind::Wild;
}
_ => bug!("Expected either ConstKind::Param or ConstKind::Unevaluated"),
}
match value.val() {
ConstKind::Param(_) => {
self.errors.push(PatternError::ConstParamInPattern(span));
return PatKind::Wild;
}
mir::ConstantKind::Val(_, _) => *self.const_to_pat(value, id, span, false).kind,
ConstKind::Unevaluated(_) => {
// If we land here it means the const can't be evaluated because it's `TooGeneric`.
self.tcx.sess.span_err(span, "constant pattern depends on a generic parameter");
return PatKind::Wild;
}
_ => (),
}
*self.const_to_pat(value, id, span, false).kind
}
/// Converts literals, paths and negation of literals to patterns.
@@ -595,7 +584,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
let lit_input =
LitToConstInput { lit: &lit.node, ty: self.typeck_results.expr_ty(expr), neg };
match self.tcx.at(expr.span).lit_to_mir_constant(lit_input) {
match self.tcx.at(expr.span).lit_to_const(lit_input) {
Ok(constant) => *self.const_to_pat(constant, expr.hir_id, lit.span, false).kind,
Err(LitToConstError::Reported) => PatKind::Wild,
Err(LitToConstError::TypeError) => bug!("lower_lit: had type error"),
@@ -750,11 +739,12 @@ impl<'tcx> PatternFoldable<'tcx> for PatKind<'tcx> {
}
}
// FIXME: Get rid of this function once valtrees land
#[instrument(skip(tcx), level = "debug")]
crate fn compare_const_vals<'tcx>(
tcx: TyCtxt<'tcx>,
a: mir::ConstantKind<'tcx>,
b: mir::ConstantKind<'tcx>,
a: ty::Const<'tcx>,
b: ty::Const<'tcx>,
param_env: ty::ParamEnv<'tcx>,
ty: Ty<'tcx>,
) -> Option<Ordering> {

13
compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
View File

@@ -765,10 +765,7 @@ fn lint_non_exhaustive_omitted_patterns<'p, 'tcx>(
/// `is_under_guard` is used to inform if the pattern has a guard. If it
/// has one it must not be inserted into the matrix. This shouldn't be
/// relied on for soundness.
#[instrument(
level = "debug",
skip(cx, matrix, witness_preference, hir_id, is_under_guard, is_top_level)
)]
#[instrument(level = "debug", skip(cx, matrix, hir_id))]
fn is_useful<'p, 'tcx>(
cx: &MatchCheckCtxt<'p, 'tcx>,
matrix: &Matrix<'p, 'tcx>,
@@ -800,6 +797,7 @@ fn is_useful<'p, 'tcx>(
let ty = v.head().ty();
let is_non_exhaustive = cx.is_foreign_non_exhaustive_enum(ty);
debug!("v.head: {:?}, v.span: {:?}", v.head(), v.head().span());
let pcx = PatCtxt { cx, ty, span: v.head().span(), is_top_level, is_non_exhaustive };
// If the first pattern is an or-pattern, expand it.
@@ -809,9 +807,11 @@ fn is_useful<'p, 'tcx>(
// We try each or-pattern branch in turn.
let mut matrix = matrix.clone();
for v in v.expand_or_pat() {
debug!(?v);
let usefulness = ensure_sufficient_stack(|| {
is_useful(cx, &matrix, &v, witness_preference, hir_id, is_under_guard, false)
});
debug!(?usefulness);
ret.extend(usefulness);
// If pattern has a guard don't add it to the matrix.
if !is_under_guard {
@@ -822,6 +822,7 @@ fn is_useful<'p, 'tcx>(
}
} else {
let v_ctor = v.head().ctor();
debug!(?v_ctor);
if let Constructor::IntRange(ctor_range) = &v_ctor {
// Lint on likely incorrect range patterns (#63987)
ctor_range.lint_overlapping_range_endpoints(
@@ -895,7 +896,7 @@ fn is_useful<'p, 'tcx>(
}
/// The arm of a match expression.
#[derive(Clone, Copy)]
#[derive(Clone, Copy, Debug)]
crate struct MatchArm<'p, 'tcx> {
/// The pattern must have been lowered through `check_match::MatchVisitor::lower_pattern`.
crate pat: &'p DeconstructedPat<'p, 'tcx>,
@@ -928,6 +929,7 @@ crate struct UsefulnessReport<'p, 'tcx> {
///
/// Note: the input patterns must have been lowered through
/// `check_match::MatchVisitor::lower_pattern`.
#[instrument(skip(cx, arms), level = "debug")]
crate fn compute_match_usefulness<'p, 'tcx>(
cx: &MatchCheckCtxt<'p, 'tcx>,
arms: &[MatchArm<'p, 'tcx>],
@@ -939,6 +941,7 @@ crate fn compute_match_usefulness<'p, 'tcx>(
.iter()
.copied()
.map(|arm| {
debug!(?arm);
let v = PatStack::from_pattern(arm.pat);
is_useful(cx, &matrix, &v, RealArm, arm.hir_id, arm.has_guard, true);
if !arm.has_guard {