Add ExternDecl and ExternType for extern classes. #3893
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Depends on #3891 |
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| case CARBON_KIND(SemIR::ClassType class_type): { | ||
| prev_class_id = class_type.class_id; | ||
| break; | ||
| } |
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When does this case happen? I'm cautious here because I don't think we want any previous name that names a class type to be merged. Eg, if the previous declaration was an ImportRef naming alias C = OtherClass;, then that shouldn't merge with class C even though it was a class type. But if I'm reading ResolvePrevInstForMerge correctly, you'll get a ClassType in both the case of an imported class declaration and in the case of any other imported declaration that constant-evaluates to a class type.
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Theoretically I agree, but I'd say what you're mentioning (with alias) is not supported right now.
Bear in mind an ImportRef only has the constant value to point at the instruction in the current IR. This is all we have to work with, without a major refactoring. Which maybe should occur, and I have already have spots I'm thinking about this, but that's very much out-of-scope.
This expands `extern` handling for most cases.
This expands `extern` handling for most cases.
This expands
externhandling for most cases.