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Merged
folkertdev merged 2 commits into from
Mar 12, 2025
Merged

support or-patterns #2

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b4cba1f
refactor pattern logic to its own function
folkertdev Mar 12, 2025
c63e01e
implement or-patterns
folkertdev Mar 12, 2025
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97 changes: 67 additions & 30 deletions compiler/rustc_mir_build/src/builder/expr/into.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ use rustc_middle::thir::*;
use rustc_middle::ty::CanonicalUserTypeAnnotation;
use rustc_middle::ty::util::Discr;
use rustc_pattern_analysis::constructor::Constructor;
use rustc_pattern_analysis::rustc::DeconstructedPat;
use rustc_pattern_analysis::rustc::RustcPatCtxt;
use rustc_span::source_map::Spanned;
use tracing::{debug, instrument};
Expand Down Expand Up @@ -319,39 +320,25 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let mut arm_blocks = Vec::with_capacity(arms.len());
for &arm in arms {
let pat = &this.thir[arm].pattern;
let deconstructed_pat = cx.lower_pat(pat);

match deconstructed_pat.ctor() {
Constructor::Variant(variant_index) => {
let PatKind::Variant { adt_def, .. } = pat.kind else {
unreachable!()
};

let discr = adt_def
.discriminant_for_variant(this.tcx, *variant_index);

let block = this.cfg.start_new_block();
arm_blocks.push((*variant_index, discr, block, arm))
}
Constructor::IntRange(int_range) => {
assert!(int_range.is_singleton());

let bits = state_ty.primitive_size(this.tcx).bits();
let value = int_range.lo.as_finite_int(bits).unwrap();

let discr =
Discr { val: value, ty: **deconstructed_pat.ty() };

let block = this.cfg.start_new_block();
arm_blocks.push((VariantIdx::ZERO, discr, block, arm))
}
Constructor::Wildcard => {
otherwise = Some((this.cfg.start_new_block(), arm));
}
other => todo!("{:?}", other),
}
this.loop_match_patterns(
arm,
&cx.lower_pat(pat),
None,
&mut arm_blocks,
&mut otherwise,
);
}

// handle patterns like `None | None` or two different arms that
// have the same pattern.
//
// NOTE: why this works is a bit subtle: we always want to pick the
// first arm for a pattern, and because this is a stable sort that
// works out.
arm_blocks.sort_by_key(|(_, discr, _, _)| discr.val);
arm_blocks.dedup_by_key(|(_, discr, _, _)| discr.val);

// if we're matching on an enum, the discriminant order in the `SwitchInt`
// targets should match the order yielded by `AdtDef::discriminants`.
if state_ty.is_enum() {
Expand Down Expand Up @@ -400,6 +387,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
.chain(otherwise);

for (mut block, arm) in it {
if this.cfg.block_data(block).terminator.is_some() {
continue; // this can occur with or-patterns
}

let empty_place = this.get_unit_temp();
unpack!(
block = this.expr_into_dest(
Expand Down Expand Up @@ -842,4 +833,50 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
_ => false,
}
}

fn loop_match_patterns(
&mut self,
arm_id: ArmId,
pat: &DeconstructedPat<'_, 'tcx>,
current_block: Option<BasicBlock>,
result: &mut Vec<(VariantIdx, Discr<'tcx>, BasicBlock, ArmId)>,
otherwise: &mut Option<(BasicBlock, ArmId)>,
) {
match pat.ctor() {
Constructor::Variant(variant_index) => {
let PatKind::Variant { adt_def, .. } = pat.data().kind else { unreachable!() };

let discr = adt_def.discriminant_for_variant(self.tcx, *variant_index);

let block = current_block.unwrap_or_else(|| self.cfg.start_new_block());
result.push((*variant_index, discr, block, arm_id));
}
Constructor::IntRange(int_range) => {
assert!(int_range.is_singleton());

let bits = pat.ty().primitive_size(self.tcx).bits();
let value = int_range.lo.as_finite_int(bits).unwrap();

let discr = Discr { val: value, ty: **pat.ty() };

let block = current_block.unwrap_or_else(|| self.cfg.start_new_block());
result.push((VariantIdx::ZERO, discr, block, arm_id));
}
Constructor::Wildcard => {
// the first wildcard wins
if otherwise.is_none() {
let block = current_block.unwrap_or_else(|| self.cfg.start_new_block());
*otherwise = Some((block, arm_id))
}
}
Constructor::Or => {
let block = current_block.unwrap_or_else(|| self.cfg.start_new_block());

for indexed in pat.iter_fields() {
self.loop_match_patterns(arm_id, &indexed.pat, Some(block), result, otherwise);
}
}
other => todo!("{:?}", other),
}
}
}
41 changes: 41 additions & 0 deletions tests/ui/match/loop-match-or-pattern.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,41 @@
//@ run-pass

#![feature(loop_match)]

enum State {
A,
B,
C,
D,
}

fn main() {
let mut state = State::A;
#[loop_match]
'a: loop {
state = 'blk: {
match state {
State::A => {
if true {
#[const_continue]
break 'blk State::B;
} else {
#[const_continue]
break 'blk State::D;
}
}
State::B | State::D => {
if true {
#[const_continue]
break 'blk State::C;
} else {
// No drops allowed at this point
#[const_continue]
break 'blk State::A;
}
}
State::C => break 'a,
}
}
}
}
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