Unfortunate. There isn't ever a good reason to have an infinite loop so concerned compilers could have just diagnosed this as a warning.

▲ echoangle 11 hours ago | parent | next [-]

The article mentions a use case for that:

> What I found is that this is common in embedded and kernel code as a halt-on-error pattern. When a fatal error occurs and there’s no operating system to exit to, you simply stop:

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pdonis 10 hours ago | parent | next [-]

If this is a genuine use case, I wonder why the language can't just introduce a built-in function for it. For example, std::get_stuck_here(). Then the compiler would know not to optimize this away. The implementation under the hood could still be an infinite loop, but the compiler would not have to guess why it's there.

	▲	gpderetta 4 hours ago \| parent \| next [-]
		one could already add loads off a volatile and portably prevent the loop from being optimized. But there was already a lot of existing embedded code that had this sort of loop, (and more will be written as it is an existing idiom) which the committee wanted to un-break.
	▲	sigbottle 8 hours ago \| parent \| prev [-]
		__asm__ __volatile("hlt"); when doing quick and hacky debugging could work

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account42 10 hours ago | parent | prev [-]

Low level code can and should use assembly to get the precise effect they desire in these cases.

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echoangle 10 hours ago | parent | next [-]

Why not just allow infinite loops instead of having me write assembly for it though?

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account42 10 hours ago | parent [-]

Because a compiler being allowed to assume that a loop always terminates gives it more room to optimize the 99% of loops that aren't supposed to run until the heat death of the universe.

	▲	echoangle 10 hours ago \| parent [-]
		Or you could just detect while loops with constant condition (like the C standard) and not touch any programs that don't exhibit UB while allowing infinite loops for other use cases at zero runtime cost and negligible compile cost.

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mdspan 10 hours ago | parent | prev | next [-]

That would be pretty cumbersome though. If you're targeting N different architectures, you would have to write N different assembly blocks.

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rcxdude 10 hours ago | parent | prev [-]

I shouldn't need to drop to assembly to get an infinite loop that works!

▲ sumtechguy 10 hours ago | parent | prev | next [-]

> There isn't ever a good reason to have an infinite loop

That seems to be a very broad statement. For example in a system where interrupts mostly control things this sort of 'do not close the program' could be useful.

A guy I worked with had one I never would think of because I do not work in that field.

But yeah a warning would probably be useful.

▲ not_the_fda 10 hours ago | parent | prev | next [-]

Interrupt driven super loops are very common on bare metal systems.

▲ mdspan 10 hours ago | parent | prev | next [-]

Compilers can still diagnose something as a warning even if it's not UB.

	▲	cppcppcpp 8 hours ago \| parent [-]
		Can, yes. Must, no.

▲ weinzierl 10 hours ago | parent | prev [-]

For Rust the infinite loop is important enough to have its own keyword.

	▲	kibwen 9 hours ago \| parent [-]
		The reason for this is interesting. Loop constructs that you're guaranteed to enter have implications for control flow (in every language, not just Rust). It means that the following program is valid in Rust: `let x; // declared, but uninitialized variable loop { // control flow is guaranteed to enter this loop if some_condition() { x = 42; // initialize x break; } } foo(x); // Rust knows that x is initialized as of here in all possible paths` In contrast, while loops check their condition before entering, which means the entire loop body might be skipped. Languages which guarantee initialization-before-use might special-case certain conditions for while loops as a hint to the control flow analysis (e.g. Java special-cases `while(true)`), but obviously this doesn't generalize to arbitrary conditions. Interestingly, this all suggest that, in C-like languages, the more natural implementation of an infinite loop should not be `while(true)` nor `for(;;)`, but rather `do {} while(true)`, because do-while are also guaranteed to enter their body (and note that Rust doesn't feature do-while loops).