[Issue 18849] New: std.allocator: AllocatorList uses deallocate and ignores return value in deallocateAll

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18849

          Issue ID: 18849
           Summary: std.allocator: AllocatorList uses deallocate and
                    ignores return value in deallocateAll
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody at puremagic.com
          Reporter: dlang-bugzilla at thecybershadow.net

AllocatorList's deallocateAll has the code:

        if (special)
        {
            special.deallocate(allocators);
        }

This has the issues:

- The return value is ignored. If the deallocation failed, the failure should
be communicated to the caller. Currently, this causes a silent memory leak.

- Some allocators, such as Region, can deallocateAll, but cannot deallocate.
Ideally the complete inability to deallocate() should be detected at
compile-time, and such combinations rejected.

- The documentation of AllocatorList has two examples of using it with Region,
which will not work (leak memory) due to the above.

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