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Dana Jansens
6c6552ce57
Currently if the first operand contains an error, we will return error, even though the second operands contains a runtime, and it has a stronger priority (the phase always goes up if possible). Import is only allowed on instructions with compile-time values, so we crash if we ever try to import a runtime value. Importable instructions must diagnose unexpected runtime values and produce errors in the semir from which they would be imported so that runtime values are never imported by another semir. If we had an instruction where you had an error value from the first operand, and runtime from the second, and we imported it: - Before https://github.com/carbon-language/carbon-lang/pull/5728 we would crash in import, but only because we treated errors as runtime - After https://github.com/carbon-language/carbon-lang/pull/5728 we would import ErrorInst because we propagate errors. This is desirable for cases with compile-time values and errors present only. - After this PR, we would crash again, cuz you're importing a runtime thing. This change means that instructions containing an `InstConstantKind::Never` instruction like`ValueParam` will consistently evaluate to a runtime value, even if there are errors present. This is visible in the `BindName` instructions changing in the semir, where they became constant `ErrorInst` values previously but no longer do.