bjoernager/rust
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Auto merge of #60280 - varkor:const-param-invariance, r=eddyb

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Fix indexing issue for const parameter invariance

We were previously not taking account of the parent parameters.

r? @eddyb
cc @Zoxc
This commit is contained in:
bors 2019-05-01 03:06:13 +00:00
commit 834bd1959c
1 changed files with 17 additions and 5 deletions
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22
src/librustc_typeck/variance/solve.rs
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@ -78,6 +78,22 @@ impl<'a, 'tcx> SolveContext<'a, 'tcx> {
} }
} }
fn enforce_const_invariance(&self, generics: &ty::Generics, variances: &mut Vec<ty::Variance>) {
let tcx = self.terms_cx.tcx;
// Make all const parameters invariant.
for param in generics.params.iter() {
if let ty::GenericParamDefKind::Const = param.kind {
variances[param.index as usize] = ty::Invariant;
}
}
// Make all the const parameters in the parent invariant (recursively).
if let Some(def_id) = generics.parent {
self.enforce_const_invariance(tcx.generics_of(def_id), variances);
}
}
fn create_map(&self) -> FxHashMap<DefId, Lrc<Vec<ty::Variance>>> { fn create_map(&self) -> FxHashMap<DefId, Lrc<Vec<ty::Variance>>> {
let tcx = self.terms_cx.tcx; let tcx = self.terms_cx.tcx;
@ -91,11 +107,7 @@ impl<'a, 'tcx> SolveContext<'a, 'tcx> {
debug!("id={} variances={:?}", id, variances); debug!("id={} variances={:?}", id, variances);
// Const parameters are always invariant. // Const parameters are always invariant.
for (idx, param) in generics.params.iter().enumerate() { self.enforce_const_invariance(generics, &mut variances);
if let ty::GenericParamDefKind::Const = param.kind {
variances[idx] = ty::Invariant;
}
}
// Functions are permitted to have unused generic parameters: make those invariant. // Functions are permitted to have unused generic parameters: make those invariant.
if let ty::FnDef(..) = tcx.type_of(def_id).sty { if let ty::FnDef(..) = tcx.type_of(def_id).sty {