linker error "undefined symbol: __aeabi_uidiv" for target thumbv6m-none-eabi

[starblue]

Beginning with nightly-2019-05-10 I get the following linker error:

error: linking with `rust-lld` failed: exit code: 1
  |
  = note: "rust-lld" "-flavor" "gnu" "-L" "/home/juergen/.rustup/toolchains/nightly-2019-05-10-x86_64-unknown-linux-gnu/lib/rustlib/thumbv6m-none-eabi/lib" "/home/juergen/rust/dust/dust-test/target/thumbv6m-none-eabi/release/deps/test_uart-988eaff94921fb1c.test_uart.67ne5b40-cgu.0.rcgu.o" "-o" "/home/juergen/rust/dust/dust-test/target/thumbv6m-none-eabi/release/deps/test_uart-988eaff94921fb1c" "--gc-sections" "-L" "/home/juergen/rust/dust/dust-test/target/thumbv6m-none-eabi/release/deps" "-L" "/home/juergen/rust/dust/dust-test/target/release/deps" "-L" "/home/juergen/.rustup/toolchains/nightly-2019-05-10-x86_64-unknown-linux-gnu/lib/rustlib/thumbv6m-none-eabi/lib" "--start-group" "--end-group" "-Bstatic" "/home/juergen/.rustup/toolchains/nightly-2019-05-10-x86_64-unknown-linux-gnu/lib/rustlib/thumbv6m-none-eabi/lib/libcompiler_builtins-afe13c5355265d4c.rlib" "-Tldscripts/lpc802m001.ld" "-Lldscripts" "-Map=output/lpc802m001_test-uart.map" "-Bdynamic"
  = note: rust-lld: error: undefined symbol: __aeabi_uidiv
          >>> referenced by num.rs:204 (src/libcore/fmt/num.rs:204)
          >>>               /home/juergen/rust/dust/dust-test/target/thumbv6m-none-eabi/release/deps/test_uart-988eaff94921fb1c.test_uart.67ne5b40-cgu.0.rcgu.o:(core::fmt::num::imp::fmt_u32::h2131a43fb24cc589)

[jonas-schievink]

Please post a way to reproduce this. What code are you trying to build?

[starblue]

This is test-code for microcontrollers using my own framework called dust.
I now uploaded it to https://github.com/starblue/dust .
To reproduce go into the dust-test subdirectory and run make clean && make test-uart with some version of nightly (nightly is needed due to inline assembly). For example, I did

rustup run nightly-2019-05-10-x86_64-unknown-linux-gnu bash -c "make clean && make test-uart"

[hellow554]

Maybe these two are related? #60747
The date matches, I wouldn't be surprised

[jonas-schievink]

(removing regression label since this never built on stable)

[mati865]

#60491 was merged on 2019-05-09 and modifies compiler-builtins.

cc @alexcrichton

EDIT: Related commit rust-lang/compiler-builtins@4bbc838

[alexcrichton]

Thanks for the report @starblue and the cc @mati865, this should be fixed in rust-lang/compiler-builtins#290.