>> I’ll cast away the const if needed.

> Undefined behavior[2]

How so? As the page you linked mentions, simply casting 'const T *' to regular 'T *' is well-defined; it's only modifying a const object through the pointer that's UB (C17 6.7.3/7).

> I don't believe assignments are sequence points and only the function call is.

Assigments within expressions don't create sequence points. However, the expression of an expression statement is a full expression (i.e., not a subexpression of another expression), and there is a sequence point between each pair of full expressions (C17 6.8/4). In other words, the semicolons create sequence points.

> #define assert(c) while (!(c)) __builtin_unreachable()

And people keep telling me that nobody uses the C preprocessor to define their own syntax any more!

> > I’ll cast away the const if needed.

> Undefined behavior[2]

To be clear, it's only UB if the object was defined const, which is the case given he wrote:

> One small exception: I still like it as a hint to place static tables in read-only memory closer to the code. I’ll cast away the const if needed.

So you are correct on this point. Funnily enough, such objects are relatively rare IME, so I had to double-check to see that he was advocating it in the rare case where it must not be applied.

> Undefined behavior[2]

Given that this particular undefined behavior usually causes crashes in practice, I expect the author is talking about casting away the const but not actually writing to the pointer. Which is legal.

Or a common situation is mutable -> const -> mutable.

And that is legal.

The legal cases in which he needs to cast away const could be avoided if the arguments to called functions appropriately qualified.

He never said he needs to cast away const to do what he is attempting to do, he just said that he wants to cast away const to reduce clutter, even though the program would have the same semantics as if he kept the const.

If only there were a way to indicate the function argument isn't mutated. </s>

My spidey senses tingle whenever I see const-ness cast away because it almost always means something is wrong. Either a function is missing a qualifier on an argument, or something very unsafe is happening. Why force callers to cast away const-ness in hopes that everything will be fine when you can just write the correct function signature.