Type-check require declarations
#6286
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danakj
requested review from
dwblaikie and
zygoloid
and removed request for
a team and
dwblaikie
| // CHECK:STDERR: ^~~~~~~ | ||
| interface Z(T:! type) { | ||
| // Self can not appear in a requirement. It can appear in the self-type or in | ||
| // an interface parameter. |
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Is this a rule? I don't recall this one. Do you know why this is disallowed?
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This is #6285, which needs some discussion. There is a TODO in the code where the diagnostic is generated.
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I have removed this restriction and diagnostic.
| // CHECK:STDERR: require T impls Z(Self); | ||
| // CHECK:STDERR: ^~~~~~~ | ||
| // CHECK:STDERR: | ||
| require T impls Z(Self); |
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I guess eventually the error we want here is that Z is not identified (if I remember correctly). Maybe worth a TODO?
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Josh says IIUC we want to be able to require itself, and it should just mean it uses all the require statements that were written above. When there's none then that doesn't work though.
| context.decl_introducer_state_stack().Push<Lex::TokenKind::Require>(); | ||
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| auto scope_id = context.scope_stack().PeekNameScopeId(); | ||
| auto scope_inst_id = context.name_scopes().Get(scope_id).inst_id(); |
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Is this inst id always valid (eg, in a scope nested within a function scope)?
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I believe so, yes.
In this:
interface Y {}
fn F() {
interface Z {
require impls Y;
}
}
The scope inst is the Z decl.
If you meant:
fn F() {
require impls Y;
}
Then that's a parse error.
toolchain/check/handle_require.cpp
Outdated
| } | ||
| for (auto self_impls : facet_type_info.self_impls_constraints) { | ||
| type_iter.Add(self_impls); | ||
| } |
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Should we be checking all of these interfaces mention Self, not just that any of them do? Eg require i32 impls X(Self) & Y should probably be invalid.
2 participants
They don't get stored anywhere yet, but this type checks the declarations and diagnoses errors in their form, such as not placing a facet type after
implsor a type before it.