building rustc with autodiff and debug enabled fails.

[ZuseZ4]

I tried this code:

./configure --enable-llvm-link-shared --enable-llvm-plugins --enable-llvm-enzyme --release-channel=nightly --enable-llvm-assertions --enable-clang --enable-lld --enable-option-checking --enable-ninja --disable-docs --enable-debug
./x.py build --stage 1 library

I expected to see this happen: builds rustc

Instead, this happened:

thread 'rustc' panicked at compiler/rustc_codegen_ssa/src/codegen_attrs.rs:57:9:
unexpected `def_kind` in `codegen_fn_attrs`: GlobalAsm

[...]

query stack during panic:
#0 [codegen_fn_attrs] computing codegen attributes of `probestack::{global_asm#0}`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
... and 1 other queries... use `env RUST_BACKTRACE=1` to see the full query stack
error: could not compile `compiler_builtins` (lib)

Meta

rustc --version --verbose:

build from source

I know that debug builds used to work a few months ago.
So one could try to debug this by looking at the code. A much simpler solution probably is just
to do some binary search by building some older PR from the tracking issue with debug=true until finding one that builds. From there it should be easy to figure out which PR introduced the bug. Once that's clear it is hopefully easier to understand which change introduced the bug, and either directly fix it, or ask for help here or in the zulip channel. I'm marking it as easy, since it takes a bit of time to test multiple PRs but it isn't overly complex, and we had support for it and didn't introduce overly complex code changes in the last months. So the fix is likely also comparably simple.

This bug prevents us from enabling autodiff in CI and thus nightly, so any help would be appreciated!

Backtrace

<backtrace>

[Shourya742]

@rustbot claim

[ZuseZ4]

@Shourya742 Since you still have the other open issue and I had some time today, I looked into it.
I could reproduce the bug starting with #133429, together with the error message it was easy from there to find the one-line fix. We want to prevent source functions to be inlined before autodiff, however we were incorrectly also checking for the other two MonoItem types, Static and GlobalAsm. Marking them as no-inline wouldn't be sensible.