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diagnostics: avoid mismatch between variance index and hir generic #116045
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@@ -1755,20 +1755,41 @@ fn check_variances_for_type_defn<'tcx>( | |||||||||||||||||||||||||||||||||
.collect::<FxHashSet<_>>() | ||||||||||||||||||||||||||||||||||
}); | ||||||||||||||||||||||||||||||||||
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let ty_generics = tcx.generics_of(item.owner_id); | ||||||||||||||||||||||||||||||||||
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for (index, _) in variances.iter().enumerate() { | ||||||||||||||||||||||||||||||||||
let parameter = Parameter(index as u32); | ||||||||||||||||||||||||||||||||||
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if constrained_parameters.contains(¶meter) { | ||||||||||||||||||||||||||||||||||
continue; | ||||||||||||||||||||||||||||||||||
} | ||||||||||||||||||||||||||||||||||
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let param = &hir_generics.params[index]; | ||||||||||||||||||||||||||||||||||
let ty_param = &ty_generics.params[index]; | ||||||||||||||||||||||||||||||||||
let mut hir_param = &hir_generics.params[index]; | ||||||||||||||||||||||||||||||||||
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if ty_param.name != hir_param.name.ident().name { | ||||||||||||||||||||||||||||||||||
// valid programs always have lifetimes before types in the generic parameter list | ||||||||||||||||||||||||||||||||||
// ty_generics are normalized to be in this required order, and variances are built | ||||||||||||||||||||||||||||||||||
// from ty generics, not from hir generics. but we need hir generics to get | ||||||||||||||||||||||||||||||||||
// a span out | ||||||||||||||||||||||||||||||||||
// | ||||||||||||||||||||||||||||||||||
// if they aren't in the same order, then the user has written invalid code, and already | ||||||||||||||||||||||||||||||||||
// got an error about it (or I'm wrong about this) | ||||||||||||||||||||||||||||||||||
tcx.sess | ||||||||||||||||||||||||||||||||||
.delay_span_bug(hir_param.span, "hir generics and ty generics in different order"); | ||||||||||||||||||||||||||||||||||
for hp in hir_generics.params { | ||||||||||||||||||||||||||||||||||
if hp.name.ident().name == ty_param.name { | ||||||||||||||||||||||||||||||||||
hir_param = hp; | ||||||||||||||||||||||||||||||||||
break; | ||||||||||||||||||||||||||||||||||
} | ||||||||||||||||||||||||||||||||||
} | ||||||||||||||||||||||||||||||||||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Should we just silence the error? The program is invalid anyway, and we check that by delaying a bug.
Suggested change
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Yeah, that seems reasonable. There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more.
Suggested change
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} | ||||||||||||||||||||||||||||||||||
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match param.name { | ||||||||||||||||||||||||||||||||||
match hir_param.name { | ||||||||||||||||||||||||||||||||||
hir::ParamName::Error => {} | ||||||||||||||||||||||||||||||||||
_ => { | ||||||||||||||||||||||||||||||||||
let has_explicit_bounds = explicitly_bounded_params.contains(¶meter); | ||||||||||||||||||||||||||||||||||
report_bivariance(tcx, param, has_explicit_bounds); | ||||||||||||||||||||||||||||||||||
report_bivariance(tcx, hir_param, has_explicit_bounds); | ||||||||||||||||||||||||||||||||||
} | ||||||||||||||||||||||||||||||||||
} | ||||||||||||||||||||||||||||||||||
} | ||||||||||||||||||||||||||||||||||
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@@ -0,0 +1,5 @@ | ||
struct Foo<T, 'a>(&'a ()); | ||
//~^ ERROR lifetime parameters must be declared prior to | ||
//~| ERROR parameter `T` is never used | ||
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fn main() {} |
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@@ -0,0 +1,18 @@ | ||
error: lifetime parameters must be declared prior to type and const parameters | ||
--> $DIR/issue-83556.rs:1:15 | ||
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LL | struct Foo<T, 'a>(&'a ()); | ||
| ----^^- help: reorder the parameters: lifetimes, then consts and types: `<'a, T>` | ||
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error[E0392]: parameter `T` is never used | ||
--> $DIR/issue-83556.rs:1:12 | ||
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LL | struct Foo<T, 'a>(&'a ()); | ||
| ^ unused parameter | ||
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= help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData` | ||
= help: if you intended `T` to be a const parameter, use `const T: usize` instead | ||
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error: aborting due to 2 previous errors | ||
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For more information about this error, try `rustc --explain E0392`. |
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Working with def_ids is always more robust.
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Good catch.