tonic_build-based build.rs crashes

[soenkehahn]

I tried to use rustc_codegen_cranelift in a project that has a build.rs file using the tonic_build crate. It seems that the compiled build.rs executable is crashing. I put up a repo that reproduces this here: https://github.com/soenkehahn/cranelift-bug. In that repo, cargo build works successfully, but path_to_rustc_codegen_cranelift/build/cargo build does not. I get the following error:

error: failed to run custom build command for `foo v0.0.1 (/home/shahn/cranelift-bug)`

Caused by:
  process didn't exit successfully: `/home/shahn/cranelift-bug/target/debug/build/foo-39185742e3e011c8/build-script-build` (signal: 6, SIGABRT: process abort signal)

Passing in -vvv to get a more informative error message does not yield anything more interesting, as far as I can tell.

I'm using rustc_codegen_cranelift from commit e9eac6bd on linux.

[bjorn3]

Duplicate of https://github.com/bjorn3/rustc_codegen_cranelift/issues/1101

tl;dr: tonic_build uses proc_macro2 which checks if it runs inside a proc_macro by calling a proc_macro function that panics if it is called outside of a proc macro. cg_clif doesn't yet support catching panics and as such aborts.

You could try adding proc_macro2 as build-dependency and then calling proc_macro2::fallback::force() before tonic_build inside the build script. This will force it to assume that it isn't running inside a proc macro.

[soenkehahn]

I see. Thanks for the explanation. proc_macro2::fallback::force() does the trick. Unfortunately the real project that I was trying to use rustc_codegen_cranelift in, also depends on cssparser, which fails for the same reason (as described in #1101).