marker_traits: require EvaluatedToOk
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896f058f13
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6 changed files with 93 additions and 3 deletions
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@ -1566,12 +1566,19 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
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// See if we can toss out `victim` based on specialization.
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// This requires us to know *for sure* that the `other` impl applies
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// i.e., `EvaluatedToOk`.
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//
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// FIXME(@lcnr): Using `modulo_regions` here seems kind of scary
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// to me but is required for `std` to compile, so I didn't change it
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// for now.
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let tcx = self.tcx();
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if other.evaluation.must_apply_modulo_regions() {
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let tcx = self.tcx();
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if tcx.specializes((other_def, victim_def)) {
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return true;
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}
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return match tcx.impls_are_allowed_to_overlap(other_def, victim_def) {
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}
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if other.evaluation.must_apply_considering_regions() {
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match tcx.impls_are_allowed_to_overlap(other_def, victim_def) {
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Some(ty::ImplOverlapKind::Permitted { marker: true }) => {
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// Subtle: If the predicate we are evaluating has inference
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// variables, do *not* allow discarding candidates due to
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@ -1616,7 +1623,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
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}
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Some(_) => true,
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None => false,
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};
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}
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} else {
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false
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}
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@ -0,0 +1,9 @@
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// check-pass
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#![feature(marker_trait_attr)]
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#[marker]
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pub trait F {}
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impl<T> F for T where T: Copy {}
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impl<T> F for T where T: 'static {}
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fn main() {}
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8
src/test/ui/marker_trait_attr/region-overlap.rs
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8
src/test/ui/marker_trait_attr/region-overlap.rs
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@ -0,0 +1,8 @@
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#![feature(marker_trait_attr)]
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#[marker]
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trait A {}
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impl<'a> A for (&'static (), &'a ()) {} //~ ERROR type annotations needed
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impl<'a> A for (&'a (), &'static ()) {} //~ ERROR type annotations needed
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fn main() {}
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29
src/test/ui/marker_trait_attr/region-overlap.stderr
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29
src/test/ui/marker_trait_attr/region-overlap.stderr
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@ -0,0 +1,29 @@
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error[E0283]: type annotations needed
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--> $DIR/region-overlap.rs:5:10
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LL | impl<'a> A for (&'static (), &'a ()) {}
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| ^ cannot infer type for tuple `(&'static (), &'a ())`
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= note: cannot satisfy `(&'static (), &'a ()): A`
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note: required by a bound in `A`
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--> $DIR/region-overlap.rs:4:1
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LL | trait A {}
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| ^^^^^^^ required by this bound in `A`
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error[E0283]: type annotations needed
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--> $DIR/region-overlap.rs:6:10
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LL | impl<'a> A for (&'a (), &'static ()) {}
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| ^ cannot infer type for tuple `(&'a (), &'static ())`
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= note: cannot satisfy `(&'a (), &'static ()): A`
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note: required by a bound in `A`
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--> $DIR/region-overlap.rs:4:1
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LL | trait A {}
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| ^^^^^^^ required by this bound in `A`
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0283`.
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25
src/test/ui/marker_trait_attr/unsound-overlap.rs
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25
src/test/ui/marker_trait_attr/unsound-overlap.rs
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@ -0,0 +1,25 @@
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#![feature(marker_trait_attr)]
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#[marker]
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trait A {}
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trait B {}
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impl<T: A> B for T {}
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impl<T: B> A for T {}
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impl A for &str {}
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impl<T: A + B> A for (T,) {}
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trait TraitWithAssoc {
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type Assoc;
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}
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impl<T: A> TraitWithAssoc for T {
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type Assoc = T;
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}
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impl TraitWithAssoc for ((&str,),) {
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//~^ ERROR conflicting implementations
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type Assoc = ((&'static str,),);
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}
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fn main() {}
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12
src/test/ui/marker_trait_attr/unsound-overlap.stderr
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12
src/test/ui/marker_trait_attr/unsound-overlap.stderr
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@ -0,0 +1,12 @@
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error[E0119]: conflicting implementations of trait `TraitWithAssoc` for type `((&str,),)`
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--> $DIR/unsound-overlap.rs:20:1
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LL | impl<T: A> TraitWithAssoc for T {
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| ------------------------------- first implementation here
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...
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LL | impl TraitWithAssoc for ((&str,),) {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `((&str,),)`
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error: aborting due to previous error
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For more information about this error, try `rustc --explain E0119`.
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