thread 'rustc' panicked at 'failed to open bitcode file'

[aurexav]

thread 'rustc' panicked at 'failed to open bitcode file `/Users/xavier/Documents/program/darwinia-network/common/target/debug/wbuild/target/wasm32-unknown-unknown/release/incremental/darwinia_eth_relay-14z60xegabart/s-fn86imq5gn-oskx2p-working/2kbbxxydsp0pt75g.pre-lto.bc`: No such file or directory (os error 2)', /rustc/a08c47310c7d49cbdc5d7afb38408ba519967ecd/src/libstd/macros.rs:16:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.45.0-nightly (a08c47310 2020-05-07) running on x86_64-apple-darwin

note: compiler flags: -C opt-level=3 -C panic=abort -C linker-plugin-lto -C incremental -C link-arg=--export-table -C link-arg=--export=__heap_base -C link-arg=--import-memory --crate-type lib

note: some of the compiler flags provided by cargo are hidden

error: could not compile `darwinia-eth-relay`.

To learn more, run the command again with --verbose.

First compile is ok, after I modify some contents. It failed. I've to cargo clean. Then works.

[aurexav]

I don't know how to setup a minimal env to reproduce this. But I'd love to provide any info you needed.

[ehuss]

cc @alexcrichton Is this maybe related to #71754? (Although this sounds like the opposite of that, where it is missing the bit code.)

[alexcrichton]

Some digging shows that this is a preexisting bug in rustc:

$ touch foo.rs 
$ rustc +stable foo.rs -C incremental=inc -O --crate-type rlib -C linker-plugin-lto
$ rustc +stable foo.rs -C incremental=inc -O --crate-type rlib -C linker-plugin-lto
thread 'rustc' panicked at 'failed to open bitcode file `/home/alex/code/rust3/lol/inc/foo-2274d9nt8ooh9/s-fn8iukgg9j-10g2qx1-working/2yck3ogdpf9mjtsp.pre-lto.bc`: No such file or directory (os error 2)', <::std::macros::panic macros>:5:6
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.43.1 (8d69840ab 2020-05-04) running on x86_64-unknown-linux-gnu

note: compiler flags: -C incremental -C linker-plugin-lto -C save-temps --crate-type rlib

I believe that this is only showing up now because Cargo is only just now passing -Clinker-plugin-lto

[alexcrichton]

I've posted a fix for this at #72020