[Pkg-rust-maintainers] Bug#1149708: rust-ethnum-intrinsics - autopkgtest failure with rustc 1.96.1

[Peter Green]

Package: rust-ethnum-intrinsics
Version: 1.2.0-1
Severity: serious

The autopkgtest for rust-ethnum-intrinsics is failing with rustc
1.96.1 (passes with rustc 1.95.0)

https://ci.debian.net/packages/r/rust-ethnum-intrinsics/testing/amd64/76287058/#S7

>  87s [ethnum-intrinsics 1.2.0] cargo:warning=/tmp/tmp.jt05ShXuiT/target/x86_64-unknown-linux-gnu/debug/build/ethnum-intrinsics-34a87cfafd80ec4e/out/intrinsics.ll:255:43: error: unterminated attribute group
>  87s [ethnum-intrinsics 1.2.0] cargo:warning=  255 | attributes #3 = { mustprogress nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none) }
>  87s [ethnum-intrinsics 1.2.0] cargo:warning=      |                                           ^
>  87s [ethnum-intrinsics 1.2.0] cargo:warning=1 error generated.
>  87s [ethnum-intrinsics 1.2.0] Error: Error { kind: ToolExecError, message: "command did not execute successfully (status code exit status: 1): LC_ALL=\"C\" \"clang\" \"-O3\" \"-ffunction-sections\" \"-fdata-sections\" \"-fPIC\" \"-g\" \"-gdwarf-4\" \"-fno-omit-frame-pointer\" \"-m64\" \"--target=x86_64-unknown-linux-gnu\" \"-g\" \"-O2\" \"-Werror=implicit-function-declaration\" \"-ffile-prefix-map=/usr/share/cargo/registry/ethnum-intrinsics-1.2.0=.\" \"-fstack-protector-strong\" \"-fstack-clash-protection\" \"-Wformat\" \"-Werror=format-security\" \"-fcf-protection\" \"-o\" \"/tmp/tmp.jt05ShXuiT/target/x86_64-unknown-linux-gnu/debug/build/ethnum-intrinsics-34a87cfafd80ec4e/out/2d6e53ea640327d5-intrinsics.o\" \"-c\" \"/tmp/tmp.jt05ShXuiT/target/x86_64-unknown-linux-gnu/debug/build/ethnum-intrinsics-34a87cfafd80ec4e/out/intrinsics.ll\"" }
>  87s warning: ethnum-intrinsics at 1.2.0: /tmp/tmp.jt05ShXuiT/target/x86_64-unknown-linux-gnu/debug/build/ethnum-intrinsics-34a87cfafd80ec4e/out/intrinsics.ll:255:43: error: unterminated attribute group
>  87s warning: ethnum-intrinsics at 1.2.0:   255 | attributes #3 = { mustprogress nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none) }
>  87s warning: ethnum-intrinsics at 1.2.0:       |                                           ^
>  87s warning: ethnum-intrinsics at 1.2.0: 1 error generated.
>  87s error: failed to run custom build command for `ethnum-intrinsics v1.2.0 (/usr/share/cargo/registry/ethnum-intrinsics-1.2.0)`

I'd guess that this is caused by a llvm version mismatch betwen rustc and clang,
but I don't know what the best way to fix it is.