Tail call elimination often is part of the language semantics though, for the reason others in this thread have described. E.g. Scheme specifies when a conformant implementation is required to eliminate tail calls: https://conservatory.scheme.org/schemers/Documents/Standards...
replyIf you wrote a correct binary search algorithm and you observed that, under one language implementation, the time complexity scaled linearly with the size of the input instead of logarithmically, you would think the semantics of the program were changed.
replyIf you used an in-place sort algorithm and observed memory requirements that scale super-linearly with the size of the input, you would think the semantics of the program were changed.
In languages with such tail call guarantees, tail recursion _is_ a loop. It semantically encodes constant space complexity.
Programming language semantics as in https://en.wikipedia.org/wiki/Semantics_(programming_languag... is usually decoupled from space complexity. An interpreter or emulator is considered to preserve language semantics even if it changes time or space complexity.
replyWe're talking about the same thing. I disagree. Such interpreter or emulator would preserve _some_ language semantics, but not all.
replyThe specification allows implementations to have limits on maximum call stack depth and all sorts of other things. It's absolutely semantically meaningful in C to allocate a new stack frame.
replyThe details of how a stack is managed isn't normally part of programming language semantics.
replyNo, but "this action consumes a potentially exhaustible resource and could therefore fail" is normally part of programming language semantics
reply