[ralfj]

> it met one common definition of "memory safety", which was essentially "have a garbage collector"

This is the first time I hear that being suggested as ever having been the definition of memory safety. Do you have a source for this?

Given that except for Go every single language gets this right (to my knowledge), I am kind of doubtful that this is a consequence of the term changing its meaning.

[phire]

True, "have a garbage collector" was never the formal definition, it was more "automatic memory management". But this predates the work on Rust's ownership system and while there were theories of static automatic memory management, all practical examples of automatic memory management were some form of garbage collection.

If you go to the original 2009 announcement presentation for Go [1], not only is "memory-safety" listed as a primary goal, but Pike provides the definition of memory-safe that they are using, which is:

"The program should not be able to derive a bad address and just use it"

Which Go mostly achieves with a combination of garbage collection and not allowing pointer arithmetic.

The source of Go's failure is concurrency, which has a knock-on effect that invalidates memory safety. Note that stated goal from 2009 is "good support for concurrency", not "concurrent-safe".

[1] https://youtu.be/rKnDgT73v8s?t=463

[ralfj]

Thanks! I added a reference to that in the blog post.

Interestingly, in 2012 Rob Pike explicitly said that Go is "not purely memory safe" because "sharing is legal": https://go.dev/talks/2012/splash.slide#49. However it is not entirely clear what he means by that (I was not able to find a recording of the talk), but it seems likely he's referring to this very issue.

> "The program should not be able to derive a bad address and just use it"

My example does exactly that, so -- as you say, Go mostly achieves this, but not entirely.

> Note that stated goal from 2009 is "good support for concurrency", not "concurrent-safe".

My argument is that being concurrency-unsafe implies being memory-unsafe, for the reasons laid down in the blog post. I understand that that is a somewhat controversial opinion. :)