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  • N2838: Types and sizes: "This changes the specification when the operand of sizeof is not an lvalue of VLA type"???

    From Andrey Tarasevich@andreytarasevich@hotmail.com to comp.std.c on Fri Nov 11 20:49:54 2022
    From Newsgroup: comp.std.c

    https://open-std.org/jtc1/sc22/wg14/www/docs/n2838.htm

    Section "3.2.1. Rationale" of that proposal begins with

    "This changes the specification when the operand of sizeof is *not*
    an lvalue of VLA type [...]"

    Note the "not" in the above sentence: "not an lvalue of VLA type".

    And then it proceeds to demonstrate the proposed change with an example
    in 3.2.2 where the `sizeof` in question (whose behavior will supposedly change) is clearly applied to an lvalue of VLA type!

    So, what is that "not" doing in the initial sentence of 3.2.1? Is this
    just a typo/miswording? Or am I missing something about the intended
    meaning of that sentence?
    --
    Best regards,
    Andrey
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  • From Tim Rentsch@tr.17687@z991.linuxsc.com to comp.std.c on Sun Nov 13 06:42:18 2022
    From Newsgroup: comp.std.c

    Andrey Tarasevich <andreytarasevich@hotmail.com> writes:

    https://open-std.org/jtc1/sc22/wg14/www/docs/n2838.htm

    Section "3.2.1. Rationale" of that proposal begins with

    "This changes the specification when the operand of sizeof is
    *not* an lvalue of VLA type [...]"

    Note the "not" in the above sentence: "not an lvalue of VLA type".

    And then it proceeds to demonstrate the proposed change with an
    example in 3.2.2 where the `sizeof` in question (whose behavior will supposedly change) is clearly applied to an lvalue of VLA type!

    So, what is that "not" doing in the initial sentence of 3.2.1? Is
    this just a typo/miswording? Or am I missing something about the
    intended meaning of that sentence?

    My reading of that statement in 3.2.1 is that it is wrong. The
    change proposed in 3.2 /does/ affect the semantics of sizeof with
    an operand that is an lvalue of VLA type, and also, AFAICT, does
    /not/ affect the semantics of sizeof with any other kind of
    operand. As to what may have caused it, I have nothing new to
    offer.

    <editorial-comment>
    The proposal document is poorly written. The changes proposed
    are either poorly written or poorly thought out, perhaps both.
    Sadly I believe the overall quality of the proposal is indicative
    of what is going on in the ISO C standard more generally.
    </editorial-comment>
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