mod check_match;
mod const_to_pat;
use std::cmp::Ordering;
use rustc_errors::codes::*;
use rustc_hir::def::{CtorOf, DefKind, Res};
use rustc_hir::pat_util::EnumerateAndAdjustIterator;
use rustc_hir::{self as hir, ByRef, Mutability, RangeEnd};
use rustc_index::Idx;
use rustc_lint as lint;
use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput};
use rustc_middle::thir::{
Ascription, FieldPat, LocalVarId, Pat, PatKind, PatRange, PatRangeBoundary,
};
use rustc_middle::ty::layout::IntegerExt;
use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt, TypeVisitableExt};
use rustc_middle::{bug, span_bug};
use rustc_span::def_id::LocalDefId;
use rustc_span::{ErrorGuaranteed, Span};
use rustc_target::abi::{FieldIdx, Integer};
use tracing::{debug, instrument};
pub(crate) use self::check_match::check_match;
use crate::errors::*;
use crate::thir::util::UserAnnotatedTyHelpers;
struct PatCtxt<'a, 'tcx> {
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
typeck_results: &'a ty::TypeckResults<'tcx>,
rust_2024_migration_suggestion: Option<Rust2024IncompatiblePatSugg>,
}
pub(super) fn pat_from_hir<'a, 'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
typeck_results: &'a ty::TypeckResults<'tcx>,
pat: &'tcx hir::Pat<'tcx>,
) -> Box<Pat<'tcx>> {
let mut pcx = PatCtxt {
tcx,
param_env,
typeck_results,
rust_2024_migration_suggestion: typeck_results
.rust_2024_migration_desugared_pats()
.contains(pat.hir_id)
.then_some(Rust2024IncompatiblePatSugg { suggestion: Vec::new() }),
};
let result = pcx.lower_pattern(pat);
debug!("pat_from_hir({:?}) = {:?}", pat, result);
if let Some(sugg) = pcx.rust_2024_migration_suggestion {
tcx.emit_node_span_lint(
lint::builtin::RUST_2024_INCOMPATIBLE_PAT,
pat.hir_id,
pat.span,
Rust2024IncompatiblePat { sugg },
);
}
result
}
impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
fn lower_pattern(&mut self, pat: &'tcx hir::Pat<'tcx>) -> Box<Pat<'tcx>> {
let unadjusted_pat = match pat.kind {
hir::PatKind::Ref(inner, _)
if self.typeck_results.skipped_ref_pats().contains(pat.hir_id) =>
{
self.lower_pattern(inner)
}
_ => self.lower_pattern_unadjusted(pat),
};
let adjustments: &[Ty<'tcx>] =
self.typeck_results.pat_adjustments().get(pat.hir_id).map_or(&[], |v| &**v);
let adjusted_pat = adjustments.iter().rev().fold(unadjusted_pat, |thir_pat, ref_ty| {
debug!("{:?}: wrapping pattern with type {:?}", thir_pat, ref_ty);
Box::new(Pat {
span: thir_pat.span,
ty: *ref_ty,
kind: PatKind::Deref { subpattern: thir_pat },
})
});
if let Some(s) = &mut self.rust_2024_migration_suggestion
&& !adjustments.is_empty()
{
let suggestion_str: String = adjustments
.iter()
.map(|ref_ty| {
let &ty::Ref(_, _, mutbl) = ref_ty.kind() else {
span_bug!(pat.span, "pattern implicitly dereferences a non-ref type");
};
match mutbl {
ty::Mutability::Not => "&",
ty::Mutability::Mut => "&mut ",
}
})
.collect();
s.suggestion.push((pat.span.shrink_to_lo(), suggestion_str));
};
adjusted_pat
}
fn lower_pattern_range_endpoint(
&mut self,
expr: Option<&'tcx hir::Expr<'tcx>>,
) -> Result<
(Option<PatRangeBoundary<'tcx>>, Option<Ascription<'tcx>>, Option<LocalDefId>),
ErrorGuaranteed,
> {
match expr {
None => Ok((None, None, None)),
Some(expr) => {
let (kind, ascr, inline_const) = match self.lower_lit(expr) {
PatKind::InlineConstant { subpattern, def } => {
(subpattern.kind, None, Some(def))
}
PatKind::AscribeUserType { ascription, subpattern: box Pat { kind, .. } } => {
(kind, Some(ascription), None)
}
kind => (kind, None, None),
};
let value = if let PatKind::Constant { value } = kind {
value
} else {
let msg = format!(
"found bad range pattern endpoint `{expr:?}` outside of error recovery"
);
return Err(self.tcx.dcx().span_delayed_bug(expr.span, msg));
};
Ok((Some(PatRangeBoundary::Finite(value)), ascr, inline_const))
}
}
}
fn error_on_literal_overflow(
&self,
expr: Option<&'tcx hir::Expr<'tcx>>,
ty: Ty<'tcx>,
) -> Result<(), ErrorGuaranteed> {
use hir::{ExprKind, UnOp};
use rustc_ast::ast::LitKind;
let Some(mut expr) = expr else {
return Ok(());
};
let span = expr.span;
let mut negated = false;
if let ExprKind::Unary(UnOp::Neg, sub_expr) = expr.kind {
negated = true;
expr = sub_expr;
}
let ExprKind::Lit(lit) = expr.kind else {
return Ok(());
};
let LitKind::Int(lit_val, _) = lit.node else {
return Ok(());
};
let (min, max): (i128, u128) = match ty.kind() {
ty::Int(ity) => {
let size = Integer::from_int_ty(&self.tcx, *ity).size();
(size.signed_int_min(), size.signed_int_max() as u128)
}
ty::Uint(uty) => {
let size = Integer::from_uint_ty(&self.tcx, *uty).size();
(0, size.unsigned_int_max())
}
_ => {
return Ok(());
}
};
if (negated && lit_val > max + 1) || (!negated && lit_val > max) {
return Err(self.tcx.dcx().emit_err(LiteralOutOfRange { span, ty, min, max }));
}
Ok(())
}
fn lower_pattern_range(
&mut self,
lo_expr: Option<&'tcx hir::Expr<'tcx>>,
hi_expr: Option<&'tcx hir::Expr<'tcx>>,
end: RangeEnd,
ty: Ty<'tcx>,
span: Span,
) -> Result<PatKind<'tcx>, ErrorGuaranteed> {
if lo_expr.is_none() && hi_expr.is_none() {
let msg = "found twice-open range pattern (`..`) outside of error recovery";
self.tcx.dcx().span_bug(span, msg);
}
let (lo, lo_ascr, lo_inline) = self.lower_pattern_range_endpoint(lo_expr)?;
let (hi, hi_ascr, hi_inline) = self.lower_pattern_range_endpoint(hi_expr)?;
let lo = lo.unwrap_or(PatRangeBoundary::NegInfinity);
let hi = hi.unwrap_or(PatRangeBoundary::PosInfinity);
let cmp = lo.compare_with(hi, ty, self.tcx, self.param_env);
let mut kind = PatKind::Range(Box::new(PatRange { lo, hi, end, ty }));
match (end, cmp) {
(RangeEnd::Excluded, Some(Ordering::Less)) => {}
(RangeEnd::Included, Some(Ordering::Less)) => {}
(RangeEnd::Included, Some(Ordering::Equal)) if lo.is_finite() && hi.is_finite() => {
kind = PatKind::Constant { value: lo.as_finite().unwrap() };
}
(RangeEnd::Included, Some(Ordering::Equal)) if !lo.is_finite() => {}
(RangeEnd::Included, Some(Ordering::Equal)) if !hi.is_finite() => {}
_ => {
self.error_on_literal_overflow(lo_expr, ty)?;
self.error_on_literal_overflow(hi_expr, ty)?;
let e = match end {
RangeEnd::Included => {
self.tcx.dcx().emit_err(LowerRangeBoundMustBeLessThanOrEqualToUpper {
span,
teach: self.tcx.sess.teach(E0030),
})
}
RangeEnd::Excluded => {
self.tcx.dcx().emit_err(LowerRangeBoundMustBeLessThanUpper { span })
}
};
return Err(e);
}
}
for ascription in [lo_ascr, hi_ascr].into_iter().flatten() {
kind = PatKind::AscribeUserType {
ascription,
subpattern: Box::new(Pat { span, ty, kind }),
};
}
for def in [lo_inline, hi_inline].into_iter().flatten() {
kind = PatKind::InlineConstant { def, subpattern: Box::new(Pat { span, ty, kind }) };
}
Ok(kind)
}
#[instrument(skip(self), level = "debug")]
fn lower_pattern_unadjusted(&mut self, pat: &'tcx hir::Pat<'tcx>) -> Box<Pat<'tcx>> {
let mut ty = self.typeck_results.node_type(pat.hir_id);
let mut span = pat.span;
let kind = match pat.kind {
hir::PatKind::Wild => PatKind::Wild,
hir::PatKind::Never => PatKind::Never,
hir::PatKind::Lit(value) => self.lower_lit(value),
hir::PatKind::Range(ref lo_expr, ref hi_expr, end) => {
let (lo_expr, hi_expr) = (lo_expr.as_deref(), hi_expr.as_deref());
self.lower_pattern_range(lo_expr, hi_expr, end, ty, span)
.unwrap_or_else(PatKind::Error)
}
hir::PatKind::Path(ref qpath) => {
return self.lower_path(qpath, pat.hir_id, pat.span);
}
hir::PatKind::Deref(subpattern) => {
let mutable = self.typeck_results.pat_has_ref_mut_binding(subpattern);
let mutability = if mutable { hir::Mutability::Mut } else { hir::Mutability::Not };
PatKind::DerefPattern { subpattern: self.lower_pattern(subpattern), mutability }
}
hir::PatKind::Ref(subpattern, _) | hir::PatKind::Box(subpattern) => {
PatKind::Deref { subpattern: self.lower_pattern(subpattern) }
}
hir::PatKind::Slice(prefix, slice, suffix) => {
self.slice_or_array_pattern(pat.span, ty, prefix, slice, suffix)
}
hir::PatKind::Tuple(pats, ddpos) => {
let ty::Tuple(tys) = ty.kind() else {
span_bug!(pat.span, "unexpected type for tuple pattern: {:?}", ty);
};
let subpatterns = self.lower_tuple_subpats(pats, tys.len(), ddpos);
PatKind::Leaf { subpatterns }
}
hir::PatKind::Binding(explicit_ba, id, ident, sub) => {
if let Some(ident_span) = ident.span.find_ancestor_inside(span) {
span = span.with_hi(ident_span.hi());
}
let mode = *self
.typeck_results
.pat_binding_modes()
.get(pat.hir_id)
.expect("missing binding mode");
if let Some(s) = &mut self.rust_2024_migration_suggestion
&& explicit_ba.0 == ByRef::No
&& let ByRef::Yes(mutbl) = mode.0
{
let sugg_str = match mutbl {
Mutability::Not => "ref ",
Mutability::Mut => "ref mut ",
};
s.suggestion.push((
pat.span.with_lo(ident.span.lo()).shrink_to_lo(),
sugg_str.to_owned(),
))
}
let var_ty = ty;
if let hir::ByRef::Yes(_) = mode.0 {
if let ty::Ref(_, rty, _) = ty.kind() {
ty = *rty;
} else {
bug!("`ref {}` has wrong type {}", ident, ty);
}
};
PatKind::Binding {
mode,
name: ident.name,
var: LocalVarId(id),
ty: var_ty,
subpattern: self.lower_opt_pattern(sub),
is_primary: id == pat.hir_id,
}
}
hir::PatKind::TupleStruct(ref qpath, pats, ddpos) => {
let res = self.typeck_results.qpath_res(qpath, pat.hir_id);
let ty::Adt(adt_def, _) = ty.kind() else {
span_bug!(pat.span, "tuple struct pattern not applied to an ADT {:?}", ty);
};
let variant_def = adt_def.variant_of_res(res);
let subpatterns = self.lower_tuple_subpats(pats, variant_def.fields.len(), ddpos);
self.lower_variant_or_leaf(res, pat.hir_id, pat.span, ty, subpatterns)
}
hir::PatKind::Struct(ref qpath, fields, _) => {
let res = self.typeck_results.qpath_res(qpath, pat.hir_id);
let subpatterns = fields
.iter()
.map(|field| FieldPat {
field: self.typeck_results.field_index(field.hir_id),
pattern: self.lower_pattern(field.pat),
})
.collect();
self.lower_variant_or_leaf(res, pat.hir_id, pat.span, ty, subpatterns)
}
hir::PatKind::Or(pats) => PatKind::Or { pats: self.lower_patterns(pats) },
hir::PatKind::Err(guar) => PatKind::Error(guar),
};
Box::new(Pat { span, ty, kind })
}
fn lower_tuple_subpats(
&mut self,
pats: &'tcx [hir::Pat<'tcx>],
expected_len: usize,
gap_pos: hir::DotDotPos,
) -> Vec<FieldPat<'tcx>> {
pats.iter()
.enumerate_and_adjust(expected_len, gap_pos)
.map(|(i, subpattern)| FieldPat {
field: FieldIdx::new(i),
pattern: self.lower_pattern(subpattern),
})
.collect()
}
fn lower_patterns(&mut self, pats: &'tcx [hir::Pat<'tcx>]) -> Box<[Box<Pat<'tcx>>]> {
pats.iter().map(|p| self.lower_pattern(p)).collect()
}
fn lower_opt_pattern(&mut self, pat: Option<&'tcx hir::Pat<'tcx>>) -> Option<Box<Pat<'tcx>>> {
pat.map(|p| self.lower_pattern(p))
}
fn slice_or_array_pattern(
&mut self,
span: Span,
ty: Ty<'tcx>,
prefix: &'tcx [hir::Pat<'tcx>],
slice: Option<&'tcx hir::Pat<'tcx>>,
suffix: &'tcx [hir::Pat<'tcx>],
) -> PatKind<'tcx> {
let prefix = self.lower_patterns(prefix);
let slice = self.lower_opt_pattern(slice);
let suffix = self.lower_patterns(suffix);
match ty.kind() {
ty::Slice(..) => PatKind::Slice { prefix, slice, suffix },
ty::Array(_, len) => {
let len = len
.try_to_target_usize(self.tcx)
.expect("expected len of array pat to be definite");
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) => {
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::Covariant },
};
}
kind
}
#[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![])),
};
let args = self.typeck_results.node_args(id);
let c = ty::Const::new_unevaluated(self.tcx, ty::UnevaluatedConst { def: def_id, args });
let pattern = self.const_to_pat(c, ty, 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,
variance: ty::Contravariant,
},
},
ty,
})
} else {
pattern
}
}
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);
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(c, ty, id, span).kind,
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;
debug_assert!(!args.has_free_regions());
let ct = ty::UnevaluatedConst { def: def_id.to_def_id(), args };
let subpattern = self.const_to_pat(ty::Const::new_unevaluated(self.tcx, ct), ty, id, span);
PatKind::InlineConstant { subpattern, def: def_id }
}
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 ct_ty = self.typeck_results.expr_ty(expr);
let lit_input = LitToConstInput { lit: &lit.node, ty: ct_ty, neg };
match self.tcx.at(expr.span).lit_to_const(lit_input) {
Ok(constant) => self.const_to_pat(constant, ct_ty, 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
}
}