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No longer return value_constructors for all_constructors

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varkor 2018-05-29 12:47:39 +01:00
parent d27c21c016
commit 07064de9a7
1 changed files with 15 additions and 18 deletions
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33
src/librustc_mir/hair/pattern/_match.rs
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@ -426,11 +426,10 @@ impl<'tcx> Witness<'tcx> {
/// Option<!> we do not include Some(_) in the returned list of constructors.
fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
pcx: PatternContext<'tcx>)
-> (Vec<Constructor<'tcx>>, bool)
-> Vec<Constructor<'tcx>>
{
debug!("all_constructors({:?})", pcx.ty);
let exhaustive_integer_patterns = cx.tcx.features().exhaustive_integer_patterns;
let mut value_constructors = false;
let ctors = match pcx.ty.sty {
ty::TyBool => {
[true, false].iter().map(|&b| {
@ -461,7 +460,6 @@ fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
.collect()
}
ty::TyChar if exhaustive_integer_patterns => {
value_constructors = true;
let endpoint = |c: char| {
let ty = ty::ParamEnv::empty().and(cx.tcx.types.char);
ty::Const::from_bits(cx.tcx, c as u128, ty)
@ -473,7 +471,6 @@ fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
]
}
ty::TyInt(ity) if exhaustive_integer_patterns => {
value_constructors = true;
// FIXME(49937): refactor these bit manipulations into interpret.
let bits = Integer::from_attr(cx.tcx, SignedInt(ity)).size().bits() as u128;
let min = 1u128 << (bits - 1);
@ -484,7 +481,6 @@ fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
RangeEnd::Included)]
}
ty::TyUint(uty) if exhaustive_integer_patterns => {
value_constructors = true;
// FIXME(49937): refactor these bit manipulations into interpret.
let bits = Integer::from_attr(cx.tcx, UnsignedInt(uty)).size().bits() as u128;
let max = !0u128 >> (128 - bits);
@ -501,7 +497,7 @@ fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
}
}
};
(ctors, value_constructors)
ctors
}
fn max_slice_length<'p, 'a: 'p, 'tcx: 'a, I>(
@ -810,22 +806,23 @@ pub fn is_useful<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
debug!("used_ctors = {:#?}", used_ctors);
// `all_ctors` are all the constructors for the given type, which
// should all be represented (or caught with the wild pattern `_`).
// `value_constructors` is true if we may exhaustively consider all
// the possible values (e.g. integers) of a type as its constructors.
let (all_ctors, value_constructors) = all_constructors(cx, pcx);
let all_ctors = all_constructors(cx, pcx);
debug!("all_ctors = {:#?}", all_ctors);
// The only constructor patterns for which it is valid to
// treat the values as constructors are ranges (see
// `all_constructors` for details).
let exhaustive_integer_patterns = cx.tcx.features().exhaustive_integer_patterns;
let consider_value_constructors = exhaustive_integer_patterns
&& all_ctors.iter().all(|ctor| match ctor {
ConstantRange(..) => true,
_ => false,
});
// `missing_ctors` are those that should have appeared
// as patterns in the `match` expression, but did not.
let mut missing_ctors = vec![];
for req_ctor in &all_ctors {
// The only constructor patterns for which it is valid to
// treat the values as constructors are ranges (see
// `all_constructors` for details).
let consider_value_constructors = value_constructors && match req_ctor {
ConstantRange(..) => true,
_ => false,
};
if consider_value_constructors {
let mut refined_ctors = vec![req_ctor.clone()];
for used_ctor in &used_ctors {
@ -886,7 +883,7 @@ pub fn is_useful<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
let is_non_exhaustive = is_privately_empty || is_declared_nonexhaustive;
if missing_ctors.is_empty() && !is_non_exhaustive {
if value_constructors {
if consider_value_constructors {
// If we've successfully matched every value
// of the type, then we're done.
NotUseful
@ -962,7 +959,7 @@ pub fn is_useful<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
witness
}).collect()
} else {
if value_constructors {
if consider_value_constructors {
// If we've been trying to exhaustively match
// over the domain of values for a type,
// then we can provide better diagnostics