From the article:
> Even in a release build, the compiler has not optimized out the stack. As we execute more and more operations, the stack gets deeper and deeper until it inevitably overflows.
> Even in a release build, the compiler has not optimized out the stack. As we execute more and more operations, the stack gets deeper and deeper until it inevitably overflows.
Having a way to guarantee TCO/TCE is essential for some cases, yes. GP's question, though, was why a keyword specifically and not a hypothetical attribute that effectively does the same thing.
One of the things I forget to give thanks to the Rust designers for is the default of immutability. I remember my days in a Java environment where policy was "everything needs to be declared final" (so "final" got spattered all over the place) with zero nostalgia. Requiring TCE callees to explicitly represent themselves as TCE-friendly would be the same sort of abomination.