Linker error: "no memory region specified for section '.ARM.extab'"

[phil-opp]

I'm working with generators and async/await. I tried to move some more complex function into a generator, but I got the following linker error when compiling in debug mode:

rust-lld: error: no memory region specified for section '.ARM.extab'

I looked for other mentions of .ARM.extab on GitHub and found this PR from 2014: hackndev/zinc#238. It seems like this section is used for unwinding and can be discarded. When I compile in release mode with LTO the error disappears, so it really seems like the section isn't needed.

I think we could fix this problem by either discarding or including .ARM.extab in link.x.in.

My rust version is: rustc 1.32.0-nightly (edaac35d6 2018-11-24).

[thejpster]

If you run against a fork of cortex-m-rt and hack the link.x.in to discard the .ARM.extab section, does your debug build then work?

[phil-opp]

@thejpster Sorry for the delay! I tried it again with a modified link.x.in, but the same error occurs. Not sure why…

[phil-opp]

@thejpster Turns out a dependency was still using the crates.io version of cortex-m-rt. When I override the crate in all dependencies with through a patch section, it compiles again. I opened #169 with this fix.

Edit: I was compiling with some code commented out. Sorry for the noise.

[phil-opp]

@thejpster Ok, I did some more investigation and was able to fix this by discarding *(.ARM.extab.*); instead of *(.ARM.extab);. I also made sure that no code is commented out this time :).

I opened a new PR in #170.