Why Does the Runtime Main Function Have an Infinite Loop and a Nil Pointer Assignment?

Debugging Unusual Behavior in the Runtime Main Function

In the main function of src/runtime/proc.go, you may have noticed an infinite for loop that initially appears to be unnecessary. This loop's purpose is to handle unexpected runtime issues.

When the program attempts to exit using the exit(0) call, the loop acts as a safety measure. If the exit call fails, it indicates that something has gone seriously wrong within the runtime, including issues with panic or other critical system functions.

In such cases, the infinite for loop prevents the program from continuing execution. By design, it is intended to stop the program and prevent further undefined behavior or potential damage.

The loop also features an assignment to a nil pointer, which triggers a segmentation fault in systems with memory protection units. This is another failsafe to halt the program if other methods fail.

It's important to note that this loop is typically considered unreachable code. However, its inclusion serves as a critical debugging tool, allowing developers to catch potential problems during testing and development of new ports.

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