[derive] Rename is_c_like -> is_fieldless #804
Merged
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The implementation of this method checks for the presence of fields. While this is /similar/ to the concept of a C-like enum, it's not the same. Fieldless enums are exactly as described: none of their variants has fields. C-like enums, on the other hand, are more recently referred to as "unit-only" because their variants are not permitted to contain parentheses or curly braces. E.g., the following is a fieldless enum, but is not a C-like/unit-only enum:
This distinction is important specifically when it comes to discriminants. The syntax
Foo::A as u8
computes the discriminant value of theA
variant. However,Foo::B
is a type constructor, and thus is a function. As a result,Foo::B as u8
computes the address of the functionFoo::B
.