multiple rlib candidates for tokio_02 found

[djmarcin]

I'm looking into converting a project to use bazel. It depends on tokio 0.3 as well as tokio 0.2 via the tokio_compat_02 library. When compiling tokio_compat_02 this error occurs:

INFO: From Compiling Rust lib tokio_compat_02 v0.1.2 (4 files):
error[E0465]: multiple rlib candidates for `tokio_02` found
  --> external/raze__tokio_compat_02__0_1_2/src/lib.rs:88:5
   |
88 | use tokio_02::runtime::{Handle, Runtime};
   |     ^^^^^^^^
   |
note: candidate #1: /home/vagrant/.cache/bazel/_bazel_vagrant/71ed060a30795ab0736b520a305b19cd/execroot/__main__/bazel-out/k8-fastbuild/bin/external/raze__tokio__0_2_22/libtokio-1162538576.rlib
  --> external/raze__tokio_compat_02__0_1_2/src/lib.rs:88:5
   |
88 | use tokio_02::runtime::{Handle, Runtime};
   |     ^^^^^^^^
note: candidate #2: /home/vagrant/.cache/bazel/_bazel_vagrant/71ed060a30795ab0736b520a305b19cd/execroot/__main__/bazel-out/k8-fastbuild/bin/external/raze__tokio__0_3_3/libtokio--1544283644.rlib
  --> external/raze__tokio_compat_02__0_1_2/src/lib.rs:88:5
   |
88 | use tokio_02::runtime::{Handle, Runtime};
   |     ^^^^^^^^

I've tried manually renaming the target in BUILD.tokio-0.2.22.bazel to tokio_02 as well as all the crates that depend on it, but the same error occurs. I'm not sure where to go from here.

[djmarcin]

The problem appears to be that the generated BUILD.tokio_compat_02-0.1.2.bazel contains the following:

    aliases = {
        "@raze__tokio__0_2_22//:tokio": "tokio_02",
        "@raze__tokio__0_3_3//:tokio": "tokio_02",
    },

Manually changing this to the folloiwng appears to fix the problem.

    aliases = {
        "@raze__tokio__0_2_22//:tokio": "tokio_02",
        "@raze__tokio__0_3_3//:tokio": "tokio",
    },

It looks like this is generated here, but it's not clear to me how to override these.

cargo-raze/impl/src/rendering/templates/partials/common_attrs.template

Lines 3 to 12 in 2e7f0d8

	aliases = {
	{%- for alias in crate.default_deps.aliased_dependencies %}
	"{{alias.target}}": "{{alias.alias}}",
	{%- endfor %}
	{%- for dep in crate.targeted_deps %}
	{%- for alias in dep.deps.aliased_dependencies %}
	"{{alias.target}}": "{{alias.alias}}",
	{%- endfor %}
	{%- endfor %}
	},

[djmarcin]

For this specific issue, it looks like there is a hacky workaround:

[package.metadata.raze.crates.tokio-compat-02.'*']
skipped_deps = [
  "tokio-0.3.3",
]
additional_deps = [
  "@raze__tokio__0_3_3//:tokio"
]

This results in deleting the tokio-0.3.3 dep which removes the alias, but then manually adds the dep back so that the build works. It would be nice to figure out why this erroneous alias was created in the first place though.

[UebelAndre]

At a quick glance. It seems like #282 might address this

[djmarcin]

I also hit this issue with the oauth2 package just now, and the common thread seems to be that they use the package specifier inside the Cargo.toml dependency line to alias things. I see that sort of aliasing mentioned in that issue so 🤞 that it will solve it soon. For now, I can manually edit the generated files as a workaround (not all can be solved by simply removing/re-adding the dependency).

[GregBowyer]

Almost certainly fixed by #282, is there a Cargo.toml I can test with?