🚀 go-pugleaf

In article <1992Nov5.184831.16328@newshost.lanl.gov> jlg@cochiti.lanl.gov (J. Giles) writes:
>C has actually committed two sins against array users - both as a
>result of this coercion to pointer.  First, it is not notationally
>convenient in C to program procedures which handle variable sized
>conformable arrays.  Second, the coercion to pointer makes it 
>impossible for the C compiler to *locally* determine whether 
>incoming pointers are aliased.  If the user were offered a choice,
>then he could declare the incoming arguments as pointers if he
>wanted to *allow* aliasing, and he could declare them as arrays
>(with or without variable dimensions) when he wanted to disallow
>aliasing.

I don't think either of these sins is related to its array->pointer
coercion feature.

The problem with variable-sized multidimensional arrays is due to the fact
that C includes interior array dimensions as part of the static type of an
array.  Note that GCC provides variable-sized arrays as an extension, using
the intuitive notation.

And it's possible to have aliasing without pointer variables.  Fortran has
this problem because parameters are passed by reference -- their solution
was simply to legislate that programs are not permitted to pass array
parameters (or is it all parameters) in such a fashion that such aliases
would occur.  It's not possible to detect this statically in the general
case.


-- 
Barry Margolin
System Manager, Thinking Machines Corp.

barmar@think.com          {uunet,harvard}!think!barmar