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The Myth of Smart Pointers
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this post was submitted on 30 Nov 2023
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This blog post writes a dissertation about garbage collection, heap memory management, the absolute need to take courses on assembly language, and other contrived and absurd tangents.
Looking at the code, the guy gets a double-free because he instantiates two
std::unique_ptrfrom the same raw pointer.I'm sure the author felt very clever to pull up all these topics to write a blog post about, but in the end all they're doing is writing buggy code based on their misconception of a topic.
Yeah, unless I'm missing something the author would have the same outcome with regular pointers if he'd freed them at the same time (one at the end of the anon scope and one at the end of fun1). This is nothing to do with garbage collection and is simply a result of, as you mention, pointing to the same memory with two pointers and freeing both.
His issue seems to be with the implementation of malloc, which is pretty funny because he's basically claiming C itself has unpredictable garbage collection. I almost can't believe it's legit, it seems like such a basic, fundamental misunderstanding of concepts it's like chatGPT output.
That's basically it. The way the blogger wrote
fun1means the pointer is freed once the function exits, because they explicitly added thestd::unique_ptrto take over its lifetime. Afterwards they are surprised by the fact that it really took over its lifetime.The weird part is that the blogger had to go way out of its way to write that bug.
I agree. It almost sounds like one of those coding exercises recruiters throw candidates in preliminary hiring rounds to weed out the bottom 5% that have no idea what they are doing.