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Remove contraction. The contraction rules predated the notion of an

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empty region, and they complicate region inference to no particular end.
They also lead in some cases to spurious errors like #29048 (though in
some cases these errors are helpful in tracking down missing
constraints).
This commit is contained in:
Niko Matsakis 2015-10-16 20:19:25 -04:00
parent 60ab57e56d
commit 41bca6dd76
4 changed files with 58 additions and 312 deletions
Download patch file Download diff file Expand all files Collapse all files

24
src/librustc_driver/test.rs
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@ -351,6 +351,11 @@ impl<'a, 'tcx> Env<'a, 'tcx> {
self.tcx().types.isize)
}
pub fn t_rptr_empty(&self) -> Ty<'tcx> {
self.infcx.tcx.mk_imm_ref(self.infcx.tcx.mk_region(ty::ReEmpty),
self.tcx().types.isize)
}
pub fn dummy_type_trace(&self) -> infer::TypeTrace<'tcx> {
infer::TypeTrace::dummy(self.tcx())
}
@ -593,16 +598,15 @@ fn lub_free_free() {
#[test]
fn lub_returning_scope() {
test_env(EMPTY_SOURCE_STR,
errors(&["cannot infer an appropriate lifetime"]), |env| {
env.create_simple_region_hierarchy();
let t_rptr_scope10 = env.t_rptr_scope(10);
let t_rptr_scope11 = env.t_rptr_scope(11);
// this should generate an error when regions are resolved
env.make_lub_ty(env.t_fn(&[], t_rptr_scope10),
env.t_fn(&[], t_rptr_scope11));
})
test_env(EMPTY_SOURCE_STR, errors(&[]), |env| {
env.create_simple_region_hierarchy();
let t_rptr_scope10 = env.t_rptr_scope(10);
let t_rptr_scope11 = env.t_rptr_scope(11);
let t_rptr_empty = env.t_rptr_empty();
env.check_lub(env.t_fn(&[t_rptr_scope10], env.tcx().types.isize),
env.t_fn(&[t_rptr_scope11], env.tcx().types.isize),
env.t_fn(&[t_rptr_empty], env.tcx().types.isize));
});
}
#[test]