DIP 1025--Dynamic Arrays Only Shrink, Never Grow--Community Review Round 1

Jab jab_293 at gmall.com
Tue Nov 12 17:25:06 UTC 2019

On Tuesday, 12 November 2019 at 15:54:22 UTC, John Colvin wrote:
> *The author should explain what previously impossible/unsafe 
> code can now be made possible/safe given the proposed change.*

Looking at the examples again, do they even show memory 

This would be a memory leak, not memory corruption:

   int[] slice = cast(int*)malloc(10 * int.sizeof)[0 .. 10];
   slice ~= 1;
   free(slice.ptr); // Oops!

This doesn't show memory corruption either, its a potential logic 
bug as it doesn't consider a side effect of array concatenation.

   enum { dead, alive }
   int[] cat = new int[6];
   cat[5] = alive;
   int[] b = cat;
   b ~= 1;      // may or may not move b to new location
   b[5] = dead; // indeterminate whether cat[5] is dead or alive

Neither of these examples are pertinent to @safe, which is aimed 
at reducing/removing memory corruption.

This would be a more relevant problem for @safe:

   int[] slice = cast(int*)malloc(10 * int.sizeof)[0 .. 10];
   slice ~= 1;       // use after free

As far as I'm aware none of the current previous DIPs resolve 
this do they?

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