This feature would IMO violate the contract that C allows you to specify memory layout of objects, to some level of detail (I am being a little vague about the “level of detail”).
Supporting closures, more or less, requires design decisions that are equivalent to choosing a specific layout for objects in an object-oriented language. C, as it is, makes none of these assumptions and you can translate a lot of different language ABIs into some C code (that may be clumsy). Keeping the abstraction that function pointers = pointers to entry points for functions, well, that’s frustrating for C programmers writing C programs, but extremely useful for interoperability.
At the moment we can not call nested functions or other things from other language from C, which is a pretty big hole in our interoperability story. I do not see why we need to make any design decision to specify object layout, we simply need a code pointer and static chain pair, which would then be sufficient to call arbitrary entities from other languages.
This is why I want to have such a feature in C. It would be extremely useful for language interoperability.
But because ISA was mentioned, x86 does indeed even have native support for this: https://devblogs.microsoft.com/oldnewthing/20231211-00/?p=10... These instructions are not too useful though and I do not think anybody uses them.
This feature would IMO violate the contract that C allows you to specify memory layout of objects, to some level of detail (I am being a little vague about the “level of detail”).
Supporting closures, more or less, requires design decisions that are equivalent to choosing a specific layout for objects in an object-oriented language. C, as it is, makes none of these assumptions and you can translate a lot of different language ABIs into some C code (that may be clumsy). Keeping the abstraction that function pointers = pointers to entry points for functions, well, that’s frustrating for C programmers writing C programs, but extremely useful for interoperability.
At the moment we can not call nested functions or other things from other language from C, which is a pretty big hole in our interoperability story. I do not see why we need to make any design decision to specify object layout, we simply need a code pointer and static chain pair, which would then be sufficient to call arbitrary entities from other languages.
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