LLVM debuginfo assertion "overlapping or duplicate fragments" fails with ridiculous MIR inlining

[saethlin]

I compile a toolchain locally and cargo install utilities with it, using some ridiculous flags intended to get more mileage out of assertions in the toolchain.

The compiler for this is built with:

./configure --set profile=compiler --set llvm.assertions=true --set llvm.download-ci-llvm=true --set rust.debug=true --set rust.incremental=false
RUSTFLAGS_NOT_BOOTSTRAP="-Zmir-opt-level=4 -Zmir-enable-passes=-DataflowConstProp -Zcross-crate-inline-threshold=yes" x build library

Then installing some crates with this will fail, the one I've been minimizing (yes really, this is somewhat minimized) the set of flags is tokei:

RUSTFLAGS="-Copt-level=1 -Zinline-mir -Zmir-opt-level=1 -Cdebuginfo=2 -Zcross-crate-inline-threshold=yes -Zinline-mir-hint-threshold=1000 -Zinline-mir-threshold=1000" cargo +master-stage1 install tokei --force --target=x86_64-unknown-linux-gnu

Compilation will eventually fail with this error:

rustc: /checkout/src/llvm-project/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp:722: void llvm::DwarfExpression::addFragmentOffset(const DIExpression *): Assertion `FragmentOffset >= OffsetInBits && "overlapping or duplicate fragments"' failed.

This is NOT caused by #128861. The assertion can be hit on the commit directly before that one.