How do I step into a function called in a return value when debugging with rust-gdb?

Question

In the following code:

match fnA(size) {
    Some(arr) => SomeBlock::new(size, &arr, false).as_ptr().add(1) as *mut c_void,
    None => ptr::null::<c_void>() as *mut c_void,
}

I want to use rust-gdb to step into SomeBlock::new(size, &arr, false) . When I run it normally, I am able to step into fnA , but if I try to step when I'm on the line with Some(arr) , gdb just ends up running the rest of the program and exiting.

I know I can directly insert a breakpoint at SomeBlock::new , but I was curious if there was a cleaner way of doing it.

Answer 1

According to the GDB documentation on Rust :

The Rust expression evaluator does not support “statement-like” expressions such as if or match , or lambda expressions.

It seems that you cannot step into anything that is inside a match expression. Note that you can step into fnA as it is evaluated before its output gets matched inside the match block.