Am Sonntag, den 01.08.2021, 14:26 -0400 schrieb will wray via Liaison:
> Relaxing Restrictions on Arrays, P1997 (https://wg21.link/p1997)
> proposes C array copy semantics, in initialization and assignment.
>
> E.g. P1997 makes 0..4 below well-formed copy operations:
>
> int f()[2] // *#0*
> {
> int a[2] = {1,2};
> int b[2] = a; // *#1*
> a = {3,4}; // *#2*
> b = a; // *#3*
> return {0,1}; // *#0*
> }
> int c[] = f(); // *#4*
>
> *error 0: *'*f*' declared as function returning an array
> *error 1:* array initializer must be an initializer list
> *error 2: *assigning to an array from an initializer list
> *error 3: *invalid array assignment
> *error 4: *c.f. errors 0 and 1
>
> My question:
> Does anyone foresee issues once arrays appear in initializer lists?
> Potential breakages, other change in behaviour, challenges in the
> specification, and its required wording, or the implementation
> (initializer lists seem a dark corner where implementers fear to tread)?

Would the following example change behavior?

void foo(void)
{
  void* b[3];
  void* a[1][3] = { b };
}


Martin


> The one existing case where C and C++ admit array copy semantics
> is character array initialization from string literal:
>
> char hi[] = "hi"; char ho[] = {"ho"};
> typedef struct Hi {char str[3];} Hi;
> Hi yo = {"yo"};
> Hi eh = {{"eh"}};
>
> Hi no = {hi}; // *#a*
>
> *error: *initialization of '*char*' from '*char **' makes integer
> from pointer without a cast [-Werror=int-conversion]
>
> Here, we want *#a* to have the same semantics as Hi yo = {"yo"};
> with an array value accepted in place of a string literal char array.
>
> C appears more lenient than C++ in what is currently accepted here
> (*#a* is accepted with a warning in gcc and clang, without e.g. -pedantic).
>
> Specifically, can we specify the desired no-decay and array copy for *#a *?
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