[BeeOnRope]

Why is that a problem? Inlining and optimization aren't minor aspects of compiling to native code, they are responsible for order-of-magnitude speedups.

My point is that it is easy to say "don't remove my code" while looking at a simple single-function example, but in actual compilation huge portions of a function are "dead" after inlining, constant propagation and other optimizations: not talking anything about C-specific UB or other shenanigans. You don't want to throw that out.

[somat]

Apologies for the flippant one liner, You made a good point and deserve more than that.

On the one hand, having the optimizer save you from your own bad code is a huge draw, this is my desperate hope with SQL, I can write garbage queries and the optimizer will save me from myself.

But... Someone put that code there, spent time and effort to get that machinery into place with the expectation that it is doing something. and when the optimizer takes that away with no hint. That does not feel right either. Especially when the program now behaves differently when "optimized" vs unoptimized.

[BeeOnRope]

What I mean is that we look at a function in isolation and see that it doesn't have any "dead code", e.g.,:

  int factorial(int x) {
    if (x < 0) throw invalid_input();
    // compute factorial ...
  }

This doesn't have any dead code in a static examination: at compilation-time, however, this function may be compiled multiple times, e.g., as factorial(5) or factorial(x) where x is known to be non-negative by range analysis. In this case, the `if (x < 0)` is simply pruned away as "dead code", and you definitely want this! It's not a minor thing, it's a core component of an optimizing compiler.

This same pruning is also responsible for the objectionable pruning away of dead code in the examples of compilers working at cross-purposes to programmers, but it's not easy to have the former behavior without the latter, and that's also why something like -Wdead-code is hard to implement in a way which wouldn't give constant false-positives.

[rurban]

Removing unused inlined functions or false constexpr's is trivial to see. We already have -Winline. We care about removed branches, exprs and stmts due to some optimizer logic.

I'm talking about the optimizer, not the linker, which thanksfully does a lot of pruning.