Disallow struct layout changes #735
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Lots of indents have changed, best view the diff by https://github.com/ffi/ffi/pull/735/files?w=1 |
headius
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Jan 8, 2020
This seems like not only an odd feature, but a bad/dangerous one. When the layout has been used for any existing objects, changing it will produce very difficult-to-diagnose bugs (at least) or potentially memory violations if the layout is re-retrieved from the class and used for previous pointers. It was heavily used in the specs to overwrite one and the same class multiple times to change the layout immediatelly before the test. However this use case is specific to testing and should not be used anyway. Fixes ffi#734
This is a follow-up to the previous commit. The benchmarks also made use of the redefinition feature of struct layouts. Namespacing avoids redefinition, but uses separate classes for all structs.
Since raising an exception is an API change but it doesn't justify a major version bump, just warn in that case.
larskanis
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Warning looks good to me. |
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This seems like not only an odd feature, but a bad/dangerous one.
When the layout has been used for any existing objects, changing it will produce
very difficult-to-diagnose bugs (at least) or potentially memory violations
if the layout is re-retrieved from the class and used for previous pointers.
It was heavily used in the specs to overwrite one and the same class multiple times to change the layout immediatelly before the test.
However this use case is specific to testing and should not be used anyway.
Fixes #734