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let trivial_noop take ownership of self

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This commit is contained in:
Niko Matsakis 2018-06-06 09:57:13 -04:00
parent 8147d17d8e
commit f998628e5c
2 changed files with 29 additions and 27 deletions
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27
src/librustc_mir/borrow_check/nll/type_check/mod.rs
View File

@ -736,20 +736,21 @@ fn fully_perform_op<R>(
describe_op: impl Fn() -> String,
op: impl TypeOp<'gcx, 'tcx, Output = R>,
) -> Result<R, TypeError<'tcx>> {
if let Some(r) = op.trivial_noop() {
return Ok(r);
match op.trivial_noop() {
Ok(r) => Ok(r),
Err(op) => {
let (r, opt_data) = self.fully_perform_op_and_get_region_constraint_data(
|| format!("{} at {:?}", describe_op(), locations),
op,
)?;
if let Some(data) = opt_data {
self.push_region_constraints(locations, data);
}
Ok(r)
}
}
let (r, opt_data) = self.fully_perform_op_and_get_region_constraint_data(
|| format!("{} at {:?}", describe_op(), locations),
op,
)?;
if let Some(data) = opt_data {
self.push_region_constraints(locations, data);
}
Ok(r)
}
fn push_region_constraints(

29
src/librustc_mir/borrow_check/nll/type_check/type_op.rs
View File

@ -13,11 +13,12 @@
use rustc::traits::{Obligation, ObligationCause, PredicateObligation};
use rustc::ty::{ParamEnv, Predicate, Ty};
pub(super) trait TypeOp<'gcx, 'tcx> {
pub(super) trait TypeOp<'gcx, 'tcx>: Sized {
type Output;
/// Micro-optimization point: true if this is trivially true.
fn trivial_noop(&self) -> Option<Self::Output>;
/// Micro-optimization: returns `Ok(x)` if we can trivially
/// produce the output, else returns `Err(self)` back.
fn trivial_noop(self) -> Result<Self::Output, Self>;
/// Produce a description of the operation for the debug logs.
fn perform(
@ -45,8 +46,8 @@ impl<'gcx, 'tcx, F, R> TypeOp<'gcx, 'tcx> for CustomTypeOp<F>
{
type Output = R;
fn trivial_noop(&self) -> Option<Self::Output> {
None
fn trivial_noop(self) -> Result<Self::Output, Self> {
Err(self)
}
fn perform(self, type_checker: &mut TypeChecker<'_, 'gcx, 'tcx>) -> InferResult<'tcx, R> {
@ -68,11 +69,11 @@ pub(super) fn new(sub: Ty<'tcx>, sup: Ty<'tcx>) -> Self {
impl<'gcx, 'tcx> TypeOp<'gcx, 'tcx> for Subtype<'tcx> {
type Output = ();
fn trivial_noop(&self) -> Option<Self::Output> {
fn trivial_noop(self) -> Result<Self::Output, Self> {
if self.sub == self.sup {
Some(())
Ok(())
} else {
None
Err(self)
}
}
@ -101,11 +102,11 @@ pub(super) fn new(a: Ty<'tcx>, b: Ty<'tcx>) -> Self {
impl<'gcx, 'tcx> TypeOp<'gcx, 'tcx> for Eq<'tcx> {
type Output = ();
fn trivial_noop(&self) -> Option<Self::Output> {
fn trivial_noop(self) -> Result<Self::Output, Self> {
if self.a == self.b {
Some(())
Ok(())
} else {
None
Err(self)
}
}
@ -141,11 +142,11 @@ pub(super) fn new(
impl<'gcx, 'tcx> TypeOp<'gcx, 'tcx> for ProvePredicates<'tcx> {
type Output = ();
fn trivial_noop(&self) -> Option<Self::Output> {
fn trivial_noop(self) -> Result<Self::Output, Self> {
if self.obligations.is_empty() {
Some(())
Ok(())
} else {
None
Err(self)
}
}