9d92a7f355
Unfortunately, we can't always offer a machine-applicable suggestion when there are subpatterns from macro expansion. Co-Authored-By: Guillaume Boisseau <Nadrieril@users.noreply.github.com>
742 lines
30 KiB
Rust
742 lines
30 KiB
Rust
//! Validation of patterns/matches.
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mod check_match;
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mod const_to_pat;
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pub(crate) use self::check_match::check_match;
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use crate::errors::*;
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use crate::thir::util::UserAnnotatedTyHelpers;
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use rustc_errors::codes::*;
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use rustc_hir::def::{CtorOf, DefKind, Res};
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use rustc_hir::pat_util::EnumerateAndAdjustIterator;
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use rustc_hir::{self as hir, ByRef, Mutability, RangeEnd};
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use rustc_index::Idx;
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use rustc_lint as lint;
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use rustc_middle::mir::interpret::{ErrorHandled, GlobalId, LitToConstError, LitToConstInput};
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use rustc_middle::mir::{self, Const};
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use rustc_middle::thir::{
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Ascription, FieldPat, LocalVarId, Pat, PatKind, PatRange, PatRangeBoundary,
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};
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use rustc_middle::ty::layout::IntegerExt;
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use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt, TypeVisitableExt};
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use rustc_span::def_id::LocalDefId;
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use rustc_span::{ErrorGuaranteed, Span};
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use rustc_target::abi::{FieldIdx, Integer};
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use std::cmp::Ordering;
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struct PatCtxt<'a, 'tcx> {
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tcx: TyCtxt<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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typeck_results: &'a ty::TypeckResults<'tcx>,
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/// Used by the Rust 2024 migration lint.
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rust_2024_migration_suggestion: Option<Rust2024IncompatiblePatSugg>,
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}
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pub(super) fn pat_from_hir<'a, 'tcx>(
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tcx: TyCtxt<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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typeck_results: &'a ty::TypeckResults<'tcx>,
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pat: &'tcx hir::Pat<'tcx>,
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) -> Box<Pat<'tcx>> {
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let mut pcx = PatCtxt {
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tcx,
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param_env,
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typeck_results,
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rust_2024_migration_suggestion: typeck_results
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.rust_2024_migration_desugared_pats()
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.contains(pat.hir_id)
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.then_some(Rust2024IncompatiblePatSugg { suggestion: Vec::new() }),
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};
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let result = pcx.lower_pattern(pat);
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debug!("pat_from_hir({:?}) = {:?}", pat, result);
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if let Some(sugg) = pcx.rust_2024_migration_suggestion {
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tcx.emit_node_span_lint(
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lint::builtin::RUST_2024_INCOMPATIBLE_PAT,
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pat.hir_id,
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pat.span,
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Rust2024IncompatiblePat { sugg },
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);
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}
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result
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}
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impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
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fn lower_pattern(&mut self, pat: &'tcx hir::Pat<'tcx>) -> Box<Pat<'tcx>> {
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// When implicit dereferences have been inserted in this pattern, the unadjusted lowered
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// pattern has the type that results *after* dereferencing. For example, in this code:
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//
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// ```
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// match &&Some(0i32) {
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// Some(n) => { ... },
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// _ => { ... },
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// }
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// ```
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//
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// the type assigned to `Some(n)` in `unadjusted_pat` would be `Option<i32>` (this is
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// determined in rustc_hir_analysis::check::match). The adjustments would be
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//
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// `vec![&&Option<i32>, &Option<i32>]`.
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//
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// Applying the adjustments, we want to instead output `&&Some(n)` (as a THIR pattern). So
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// we wrap the unadjusted pattern in `PatKind::Deref` repeatedly, consuming the
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// adjustments in *reverse order* (last-in-first-out, so that the last `Deref` inserted
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// gets the least-dereferenced type).
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let unadjusted_pat = match pat.kind {
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hir::PatKind::Ref(inner, _)
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if self.typeck_results.skipped_ref_pats().contains(pat.hir_id) =>
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{
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self.lower_pattern(inner)
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}
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_ => self.lower_pattern_unadjusted(pat),
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};
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let adjustments: &[Ty<'tcx>] =
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self.typeck_results.pat_adjustments().get(pat.hir_id).map_or(&[], |v| &**v);
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let adjusted_pat = adjustments.iter().rev().fold(unadjusted_pat, |thir_pat, ref_ty| {
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debug!("{:?}: wrapping pattern with type {:?}", thir_pat, ref_ty);
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Box::new(Pat {
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span: thir_pat.span,
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ty: *ref_ty,
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kind: PatKind::Deref { subpattern: thir_pat },
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})
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});
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if let Some(s) = &mut self.rust_2024_migration_suggestion
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&& !adjustments.is_empty()
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{
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let suggestion_str: String = adjustments
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.iter()
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.map(|ref_ty| {
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let &ty::Ref(_, _, mutbl) = ref_ty.kind() else {
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span_bug!(pat.span, "pattern implicitly dereferences a non-ref type");
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};
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match mutbl {
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ty::Mutability::Not => "&",
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ty::Mutability::Mut => "&mut ",
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}
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})
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.collect();
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s.suggestion.push((pat.span.shrink_to_lo(), suggestion_str));
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};
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adjusted_pat
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}
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fn lower_pattern_range_endpoint(
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&mut self,
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expr: Option<&'tcx hir::Expr<'tcx>>,
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) -> Result<
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(Option<PatRangeBoundary<'tcx>>, Option<Ascription<'tcx>>, Option<LocalDefId>),
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ErrorGuaranteed,
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> {
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match expr {
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None => Ok((None, None, None)),
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Some(expr) => {
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let (kind, ascr, inline_const) = match self.lower_lit(expr) {
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PatKind::InlineConstant { subpattern, def } => {
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(subpattern.kind, None, Some(def))
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}
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PatKind::AscribeUserType { ascription, subpattern: box Pat { kind, .. } } => {
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(kind, Some(ascription), None)
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}
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kind => (kind, None, None),
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};
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let value = if let PatKind::Constant { value } = kind {
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value
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} else {
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let msg = format!(
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"found bad range pattern endpoint `{expr:?}` outside of error recovery"
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);
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return Err(self.tcx.dcx().span_delayed_bug(expr.span, msg));
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};
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Ok((Some(PatRangeBoundary::Finite(value)), ascr, inline_const))
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}
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}
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}
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/// Overflowing literals are linted against in a late pass. This is mostly fine, except when we
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/// encounter a range pattern like `-130i8..2`: if we believe `eval_bits`, this looks like a
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/// range where the endpoints are in the wrong order. To avoid a confusing error message, we
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/// check for overflow then.
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/// This is only called when the range is already known to be malformed.
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fn error_on_literal_overflow(
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&self,
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expr: Option<&'tcx hir::Expr<'tcx>>,
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ty: Ty<'tcx>,
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) -> Result<(), ErrorGuaranteed> {
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use hir::{ExprKind, UnOp};
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use rustc_ast::ast::LitKind;
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let Some(mut expr) = expr else {
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return Ok(());
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};
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let span = expr.span;
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// We need to inspect the original expression, because if we only inspect the output of
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// `eval_bits`, an overflowed value has already been wrapped around.
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// We mostly copy the logic from the `rustc_lint::OVERFLOWING_LITERALS` lint.
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let mut negated = false;
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if let ExprKind::Unary(UnOp::Neg, sub_expr) = expr.kind {
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negated = true;
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expr = sub_expr;
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}
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let ExprKind::Lit(lit) = expr.kind else {
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return Ok(());
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};
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let LitKind::Int(lit_val, _) = lit.node else {
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return Ok(());
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};
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let (min, max): (i128, u128) = match ty.kind() {
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ty::Int(ity) => {
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let size = Integer::from_int_ty(&self.tcx, *ity).size();
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(size.signed_int_min(), size.signed_int_max() as u128)
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}
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ty::Uint(uty) => {
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let size = Integer::from_uint_ty(&self.tcx, *uty).size();
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(0, size.unsigned_int_max())
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}
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_ => {
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return Ok(());
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}
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};
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// Detect literal value out of range `[min, max]` inclusive, avoiding use of `-min` to
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// prevent overflow/panic.
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if (negated && lit_val > max + 1) || (!negated && lit_val > max) {
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return Err(self.tcx.dcx().emit_err(LiteralOutOfRange { span, ty, min, max }));
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}
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Ok(())
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}
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fn lower_pattern_range(
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&mut self,
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lo_expr: Option<&'tcx hir::Expr<'tcx>>,
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hi_expr: Option<&'tcx hir::Expr<'tcx>>,
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end: RangeEnd,
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ty: Ty<'tcx>,
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span: Span,
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) -> Result<PatKind<'tcx>, ErrorGuaranteed> {
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if lo_expr.is_none() && hi_expr.is_none() {
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let msg = "found twice-open range pattern (`..`) outside of error recovery";
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self.tcx.dcx().span_bug(span, msg);
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}
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let (lo, lo_ascr, lo_inline) = self.lower_pattern_range_endpoint(lo_expr)?;
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let (hi, hi_ascr, hi_inline) = self.lower_pattern_range_endpoint(hi_expr)?;
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let lo = lo.unwrap_or(PatRangeBoundary::NegInfinity);
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let hi = hi.unwrap_or(PatRangeBoundary::PosInfinity);
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let cmp = lo.compare_with(hi, ty, self.tcx, self.param_env);
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let mut kind = PatKind::Range(Box::new(PatRange { lo, hi, end, ty }));
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match (end, cmp) {
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// `x..y` where `x < y`.
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(RangeEnd::Excluded, Some(Ordering::Less)) => {}
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// `x..=y` where `x < y`.
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(RangeEnd::Included, Some(Ordering::Less)) => {}
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// `x..=y` where `x == y` and `x` and `y` are finite.
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(RangeEnd::Included, Some(Ordering::Equal)) if lo.is_finite() && hi.is_finite() => {
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kind = PatKind::Constant { value: lo.as_finite().unwrap() };
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}
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// `..=x` where `x == ty::MIN`.
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(RangeEnd::Included, Some(Ordering::Equal)) if !lo.is_finite() => {}
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// `x..` where `x == ty::MAX` (yes, `x..` gives `RangeEnd::Included` since it is meant
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// to include `ty::MAX`).
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(RangeEnd::Included, Some(Ordering::Equal)) if !hi.is_finite() => {}
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// `x..y` where `x >= y`, or `x..=y` where `x > y`. The range is empty => error.
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_ => {
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// Emit a more appropriate message if there was overflow.
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self.error_on_literal_overflow(lo_expr, ty)?;
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self.error_on_literal_overflow(hi_expr, ty)?;
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let e = match end {
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RangeEnd::Included => {
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self.tcx.dcx().emit_err(LowerRangeBoundMustBeLessThanOrEqualToUpper {
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span,
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teach: self.tcx.sess.teach(E0030).then_some(()),
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})
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}
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RangeEnd::Excluded => {
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self.tcx.dcx().emit_err(LowerRangeBoundMustBeLessThanUpper { span })
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}
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};
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return Err(e);
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}
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}
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// If we are handling a range with associated constants (e.g.
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// `Foo::<'a>::A..=Foo::B`), we need to put the ascriptions for the associated
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// constants somewhere. Have them on the range pattern.
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for ascription in [lo_ascr, hi_ascr].into_iter().flatten() {
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kind = PatKind::AscribeUserType {
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ascription,
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subpattern: Box::new(Pat { span, ty, kind }),
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};
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}
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for def in [lo_inline, hi_inline].into_iter().flatten() {
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kind = PatKind::InlineConstant { def, subpattern: Box::new(Pat { span, ty, kind }) };
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}
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Ok(kind)
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}
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#[instrument(skip(self), level = "debug")]
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fn lower_pattern_unadjusted(&mut self, pat: &'tcx hir::Pat<'tcx>) -> Box<Pat<'tcx>> {
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let mut ty = self.typeck_results.node_type(pat.hir_id);
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let mut span = pat.span;
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let kind = match pat.kind {
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hir::PatKind::Wild => PatKind::Wild,
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hir::PatKind::Never => PatKind::Never,
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hir::PatKind::Lit(value) => self.lower_lit(value),
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hir::PatKind::Range(ref lo_expr, ref hi_expr, end) => {
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let (lo_expr, hi_expr) = (lo_expr.as_deref(), hi_expr.as_deref());
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self.lower_pattern_range(lo_expr, hi_expr, end, ty, span)
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.unwrap_or_else(PatKind::Error)
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}
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hir::PatKind::Path(ref qpath) => {
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return self.lower_path(qpath, pat.hir_id, pat.span);
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}
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hir::PatKind::Deref(subpattern) => {
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let mutable = self.typeck_results.pat_has_ref_mut_binding(subpattern);
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let mutability = if mutable { hir::Mutability::Mut } else { hir::Mutability::Not };
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PatKind::DerefPattern { subpattern: self.lower_pattern(subpattern), mutability }
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}
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hir::PatKind::Ref(subpattern, _) | hir::PatKind::Box(subpattern) => {
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PatKind::Deref { subpattern: self.lower_pattern(subpattern) }
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}
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hir::PatKind::Slice(prefix, slice, suffix) => {
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self.slice_or_array_pattern(pat.span, ty, prefix, slice, suffix)
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}
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hir::PatKind::Tuple(pats, ddpos) => {
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let ty::Tuple(tys) = ty.kind() else {
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span_bug!(pat.span, "unexpected type for tuple pattern: {:?}", ty);
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};
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let subpatterns = self.lower_tuple_subpats(pats, tys.len(), ddpos);
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PatKind::Leaf { subpatterns }
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}
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hir::PatKind::Binding(explicit_ba, id, ident, sub) => {
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if let Some(ident_span) = ident.span.find_ancestor_inside(span) {
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span = span.with_hi(ident_span.hi());
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}
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let mode = *self
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.typeck_results
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.pat_binding_modes()
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.get(pat.hir_id)
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.expect("missing binding mode");
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if let Some(s) = &mut self.rust_2024_migration_suggestion
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&& explicit_ba.0 == ByRef::No
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&& let ByRef::Yes(mutbl) = mode.0
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{
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let sugg_str = match mutbl {
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Mutability::Not => "ref ",
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Mutability::Mut => "ref mut ",
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};
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s.suggestion.push((
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pat.span.with_lo(ident.span.lo()).shrink_to_lo(),
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sugg_str.to_owned(),
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))
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}
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// A ref x pattern is the same node used for x, and as such it has
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// x's type, which is &T, where we want T (the type being matched).
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let var_ty = ty;
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if let hir::ByRef::Yes(_) = mode.0 {
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if let ty::Ref(_, rty, _) = ty.kind() {
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ty = *rty;
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} else {
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bug!("`ref {}` has wrong type {}", ident, ty);
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}
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};
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PatKind::Binding {
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mode,
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name: ident.name,
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var: LocalVarId(id),
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ty: var_ty,
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subpattern: self.lower_opt_pattern(sub),
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is_primary: id == pat.hir_id,
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}
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}
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hir::PatKind::TupleStruct(ref qpath, pats, ddpos) => {
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let res = self.typeck_results.qpath_res(qpath, pat.hir_id);
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let ty::Adt(adt_def, _) = ty.kind() else {
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span_bug!(pat.span, "tuple struct pattern not applied to an ADT {:?}", ty);
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};
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let variant_def = adt_def.variant_of_res(res);
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let subpatterns = self.lower_tuple_subpats(pats, variant_def.fields.len(), ddpos);
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self.lower_variant_or_leaf(res, pat.hir_id, pat.span, ty, subpatterns)
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}
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hir::PatKind::Struct(ref qpath, fields, _) => {
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let res = self.typeck_results.qpath_res(qpath, pat.hir_id);
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let subpatterns = fields
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.iter()
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.map(|field| FieldPat {
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field: self.typeck_results.field_index(field.hir_id),
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pattern: self.lower_pattern(field.pat),
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})
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.collect();
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self.lower_variant_or_leaf(res, pat.hir_id, pat.span, ty, subpatterns)
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}
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hir::PatKind::Or(pats) => PatKind::Or { pats: self.lower_patterns(pats) },
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hir::PatKind::Err(guar) => PatKind::Error(guar),
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};
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|
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Box::new(Pat { span, ty, kind })
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}
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fn lower_tuple_subpats(
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&mut self,
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pats: &'tcx [hir::Pat<'tcx>],
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expected_len: usize,
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gap_pos: hir::DotDotPos,
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) -> Vec<FieldPat<'tcx>> {
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pats.iter()
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.enumerate_and_adjust(expected_len, gap_pos)
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.map(|(i, subpattern)| FieldPat {
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field: FieldIdx::new(i),
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pattern: self.lower_pattern(subpattern),
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})
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.collect()
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}
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fn lower_patterns(&mut self, pats: &'tcx [hir::Pat<'tcx>]) -> Box<[Box<Pat<'tcx>>]> {
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pats.iter().map(|p| self.lower_pattern(p)).collect()
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}
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fn lower_opt_pattern(&mut self, pat: Option<&'tcx hir::Pat<'tcx>>) -> Option<Box<Pat<'tcx>>> {
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pat.map(|p| self.lower_pattern(p))
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}
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|
|
fn slice_or_array_pattern(
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&mut self,
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span: Span,
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ty: Ty<'tcx>,
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|
prefix: &'tcx [hir::Pat<'tcx>],
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slice: Option<&'tcx hir::Pat<'tcx>>,
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suffix: &'tcx [hir::Pat<'tcx>],
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) -> PatKind<'tcx> {
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let prefix = self.lower_patterns(prefix);
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let slice = self.lower_opt_pattern(slice);
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let suffix = self.lower_patterns(suffix);
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match ty.kind() {
|
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// Matching a slice, `[T]`.
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ty::Slice(..) => PatKind::Slice { prefix, slice, suffix },
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// Fixed-length array, `[T; len]`.
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|
ty::Array(_, len) => {
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let len = len.eval_target_usize(self.tcx, self.param_env);
|
|
assert!(len >= prefix.len() as u64 + suffix.len() as u64);
|
|
PatKind::Array { prefix, slice, suffix }
|
|
}
|
|
_ => span_bug!(span, "bad slice pattern type {:?}", ty),
|
|
}
|
|
}
|
|
|
|
fn lower_variant_or_leaf(
|
|
&mut self,
|
|
res: Res,
|
|
hir_id: hir::HirId,
|
|
span: Span,
|
|
ty: Ty<'tcx>,
|
|
subpatterns: Vec<FieldPat<'tcx>>,
|
|
) -> PatKind<'tcx> {
|
|
let res = match res {
|
|
Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_id) => {
|
|
let variant_id = self.tcx.parent(variant_ctor_id);
|
|
Res::Def(DefKind::Variant, variant_id)
|
|
}
|
|
res => res,
|
|
};
|
|
|
|
let mut kind = match res {
|
|
Res::Def(DefKind::Variant, variant_id) => {
|
|
let enum_id = self.tcx.parent(variant_id);
|
|
let adt_def = self.tcx.adt_def(enum_id);
|
|
if adt_def.is_enum() {
|
|
let args = match ty.kind() {
|
|
ty::Adt(_, args) | ty::FnDef(_, args) => args,
|
|
ty::Error(e) => {
|
|
// Avoid ICE (#50585)
|
|
return PatKind::Error(*e);
|
|
}
|
|
_ => bug!("inappropriate type for def: {:?}", ty),
|
|
};
|
|
PatKind::Variant {
|
|
adt_def,
|
|
args,
|
|
variant_index: adt_def.variant_index_with_id(variant_id),
|
|
subpatterns,
|
|
}
|
|
} else {
|
|
PatKind::Leaf { subpatterns }
|
|
}
|
|
}
|
|
|
|
Res::Def(
|
|
DefKind::Struct
|
|
| DefKind::Ctor(CtorOf::Struct, ..)
|
|
| DefKind::Union
|
|
| DefKind::TyAlias
|
|
| DefKind::AssocTy,
|
|
_,
|
|
)
|
|
| Res::SelfTyParam { .. }
|
|
| Res::SelfTyAlias { .. }
|
|
| Res::SelfCtor(..) => PatKind::Leaf { subpatterns },
|
|
_ => {
|
|
let e = match res {
|
|
Res::Def(DefKind::ConstParam, _) => {
|
|
self.tcx.dcx().emit_err(ConstParamInPattern { span })
|
|
}
|
|
Res::Def(DefKind::Static { .. }, _) => {
|
|
self.tcx.dcx().emit_err(StaticInPattern { span })
|
|
}
|
|
_ => self.tcx.dcx().emit_err(NonConstPath { span }),
|
|
};
|
|
PatKind::Error(e)
|
|
}
|
|
};
|
|
|
|
if let Some(user_ty) = self.user_args_applied_to_ty_of_hir_id(hir_id) {
|
|
debug!("lower_variant_or_leaf: kind={:?} user_ty={:?} span={:?}", kind, user_ty, span);
|
|
let annotation = CanonicalUserTypeAnnotation {
|
|
user_ty: Box::new(user_ty),
|
|
span,
|
|
inferred_ty: self.typeck_results.node_type(hir_id),
|
|
};
|
|
kind = PatKind::AscribeUserType {
|
|
subpattern: Box::new(Pat { span, ty, kind }),
|
|
ascription: Ascription { annotation, variance: ty::Variance::Covariant },
|
|
};
|
|
}
|
|
|
|
kind
|
|
}
|
|
|
|
/// Takes a HIR Path. If the path is a constant, evaluates it and feeds
|
|
/// it to `const_to_pat`. Any other path (like enum variants without fields)
|
|
/// is converted to the corresponding pattern via `lower_variant_or_leaf`.
|
|
#[instrument(skip(self), level = "debug")]
|
|
fn lower_path(&mut self, qpath: &hir::QPath<'_>, id: hir::HirId, span: Span) -> Box<Pat<'tcx>> {
|
|
let ty = self.typeck_results.node_type(id);
|
|
let res = self.typeck_results.qpath_res(qpath, id);
|
|
|
|
let pat_from_kind = |kind| Box::new(Pat { span, ty, kind });
|
|
|
|
let (def_id, is_associated_const) = match res {
|
|
Res::Def(DefKind::Const, def_id) => (def_id, false),
|
|
Res::Def(DefKind::AssocConst, def_id) => (def_id, true),
|
|
|
|
_ => return pat_from_kind(self.lower_variant_or_leaf(res, id, span, ty, vec![])),
|
|
};
|
|
|
|
// Use `Reveal::All` here because patterns are always monomorphic even if their function
|
|
// isn't.
|
|
let param_env_reveal_all = self.param_env.with_reveal_all_normalized(self.tcx);
|
|
// N.B. There is no guarantee that args collected in typeck results are fully normalized,
|
|
// so they need to be normalized in order to pass to `Instance::resolve`, which will ICE
|
|
// if given unnormalized types.
|
|
let args = self
|
|
.tcx
|
|
.normalize_erasing_regions(param_env_reveal_all, self.typeck_results.node_args(id));
|
|
let instance = match ty::Instance::resolve(self.tcx, param_env_reveal_all, def_id, args) {
|
|
Ok(Some(i)) => i,
|
|
Ok(None) => {
|
|
// It should be assoc consts if there's no error but we cannot resolve it.
|
|
debug_assert!(is_associated_const);
|
|
|
|
let e = self.tcx.dcx().emit_err(AssocConstInPattern { span });
|
|
return pat_from_kind(PatKind::Error(e));
|
|
}
|
|
|
|
Err(_) => {
|
|
let e = self.tcx.dcx().emit_err(CouldNotEvalConstPattern { span });
|
|
return pat_from_kind(PatKind::Error(e));
|
|
}
|
|
};
|
|
|
|
let cid = GlobalId { instance, promoted: None };
|
|
// Prefer valtrees over opaque constants.
|
|
let const_value = self
|
|
.tcx
|
|
.const_eval_global_id_for_typeck(param_env_reveal_all, cid, span)
|
|
.map(|val| match val {
|
|
Some(valtree) => mir::Const::Ty(ty::Const::new_value(self.tcx, valtree, ty)),
|
|
None => mir::Const::Val(
|
|
self.tcx
|
|
.const_eval_global_id(param_env_reveal_all, cid, span)
|
|
.expect("const_eval_global_id_for_typeck should have already failed"),
|
|
ty,
|
|
),
|
|
});
|
|
|
|
match const_value {
|
|
Ok(const_) => {
|
|
let pattern = self.const_to_pat(const_, id, span);
|
|
|
|
if !is_associated_const {
|
|
return pattern;
|
|
}
|
|
|
|
let user_provided_types = self.typeck_results().user_provided_types();
|
|
if let Some(&user_ty) = user_provided_types.get(id) {
|
|
let annotation = CanonicalUserTypeAnnotation {
|
|
user_ty: Box::new(user_ty),
|
|
span,
|
|
inferred_ty: self.typeck_results().node_type(id),
|
|
};
|
|
Box::new(Pat {
|
|
span,
|
|
kind: PatKind::AscribeUserType {
|
|
subpattern: pattern,
|
|
ascription: Ascription {
|
|
annotation,
|
|
// Note that use `Contravariant` here. See the
|
|
// `variance` field documentation for details.
|
|
variance: ty::Variance::Contravariant,
|
|
},
|
|
},
|
|
ty: const_.ty(),
|
|
})
|
|
} else {
|
|
pattern
|
|
}
|
|
}
|
|
Err(ErrorHandled::TooGeneric(_)) => {
|
|
// While `Reported | Linted` cases will have diagnostics emitted already
|
|
// it is not true for TooGeneric case, so we need to give user more information.
|
|
let e = self.tcx.dcx().emit_err(ConstPatternDependsOnGenericParameter { span });
|
|
pat_from_kind(PatKind::Error(e))
|
|
}
|
|
Err(_) => {
|
|
let e = self.tcx.dcx().emit_err(CouldNotEvalConstPattern { span });
|
|
pat_from_kind(PatKind::Error(e))
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Converts inline const patterns.
|
|
fn lower_inline_const(
|
|
&mut self,
|
|
block: &'tcx hir::ConstBlock,
|
|
id: hir::HirId,
|
|
span: Span,
|
|
) -> PatKind<'tcx> {
|
|
let tcx = self.tcx;
|
|
let def_id = block.def_id;
|
|
let body_id = block.body;
|
|
let expr = &tcx.hir().body(body_id).value;
|
|
let ty = tcx.typeck(def_id).node_type(block.hir_id);
|
|
|
|
// Special case inline consts that are just literals. This is solely
|
|
// a performance optimization, as we could also just go through the regular
|
|
// const eval path below.
|
|
// FIXME: investigate the performance impact of removing this.
|
|
let lit_input = match expr.kind {
|
|
hir::ExprKind::Lit(lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
|
|
hir::ExprKind::Unary(hir::UnOp::Neg, expr) => match expr.kind {
|
|
hir::ExprKind::Lit(lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: true }),
|
|
_ => None,
|
|
},
|
|
_ => None,
|
|
};
|
|
if let Some(lit_input) = lit_input {
|
|
match tcx.at(expr.span).lit_to_const(lit_input) {
|
|
Ok(c) => return self.const_to_pat(Const::Ty(c), id, span).kind,
|
|
// If an error occurred, ignore that it's a literal
|
|
// and leave reporting the error up to const eval of
|
|
// the unevaluated constant below.
|
|
Err(_) => {}
|
|
}
|
|
}
|
|
|
|
let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id());
|
|
let parent_args =
|
|
tcx.erase_regions(ty::GenericArgs::identity_for_item(tcx, typeck_root_def_id));
|
|
let args = ty::InlineConstArgs::new(tcx, ty::InlineConstArgsParts { parent_args, ty }).args;
|
|
|
|
let uneval = mir::UnevaluatedConst { def: def_id.to_def_id(), args, promoted: None };
|
|
debug_assert!(!args.has_free_regions());
|
|
|
|
let ct = ty::UnevaluatedConst { def: def_id.to_def_id(), args };
|
|
// First try using a valtree in order to destructure the constant into a pattern.
|
|
// FIXME: replace "try to do a thing, then fall back to another thing"
|
|
// but something more principled, like a trait query checking whether this can be turned into a valtree.
|
|
if let Ok(Some(valtree)) = self.tcx.const_eval_resolve_for_typeck(self.param_env, ct, span)
|
|
{
|
|
let subpattern =
|
|
self.const_to_pat(Const::Ty(ty::Const::new_value(self.tcx, valtree, ty)), id, span);
|
|
PatKind::InlineConstant { subpattern, def: def_id }
|
|
} else {
|
|
// If that fails, convert it to an opaque constant pattern.
|
|
match tcx.const_eval_resolve(self.param_env, uneval, span) {
|
|
Ok(val) => self.const_to_pat(mir::Const::Val(val, ty), id, span).kind,
|
|
Err(ErrorHandled::TooGeneric(_)) => {
|
|
// If we land here it means the const can't be evaluated because it's `TooGeneric`.
|
|
let e = self.tcx.dcx().emit_err(ConstPatternDependsOnGenericParameter { span });
|
|
PatKind::Error(e)
|
|
}
|
|
Err(ErrorHandled::Reported(err, ..)) => PatKind::Error(err.into()),
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Converts literals, paths and negation of literals to patterns.
|
|
/// The special case for negation exists to allow things like `-128_i8`
|
|
/// which would overflow if we tried to evaluate `128_i8` and then negate
|
|
/// afterwards.
|
|
fn lower_lit(&mut self, expr: &'tcx hir::Expr<'tcx>) -> PatKind<'tcx> {
|
|
let (lit, neg) = match expr.kind {
|
|
hir::ExprKind::Path(ref qpath) => {
|
|
return self.lower_path(qpath, expr.hir_id, expr.span).kind;
|
|
}
|
|
hir::ExprKind::ConstBlock(ref anon_const) => {
|
|
return self.lower_inline_const(anon_const, expr.hir_id, expr.span);
|
|
}
|
|
hir::ExprKind::Lit(ref lit) => (lit, false),
|
|
hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => {
|
|
let hir::ExprKind::Lit(ref lit) = expr.kind else {
|
|
span_bug!(expr.span, "not a literal: {:?}", expr);
|
|
};
|
|
(lit, true)
|
|
}
|
|
_ => span_bug!(expr.span, "not a literal: {:?}", expr),
|
|
};
|
|
|
|
let lit_input =
|
|
LitToConstInput { lit: &lit.node, ty: self.typeck_results.expr_ty(expr), neg };
|
|
match self.tcx.at(expr.span).lit_to_const(lit_input) {
|
|
Ok(constant) => self.const_to_pat(Const::Ty(constant), expr.hir_id, lit.span).kind,
|
|
Err(LitToConstError::Reported(e)) => PatKind::Error(e),
|
|
Err(LitToConstError::TypeError) => bug!("lower_lit: had type error"),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> UserAnnotatedTyHelpers<'tcx> for PatCtxt<'_, 'tcx> {
|
|
fn tcx(&self) -> TyCtxt<'tcx> {
|
|
self.tcx
|
|
}
|
|
|
|
fn typeck_results(&self) -> &ty::TypeckResults<'tcx> {
|
|
self.typeck_results
|
|
}
|
|
}
|