Compiler error when using profile-with-tracing with wgpu-core

[Shfty]

wgpu-core uses profiling for instrumentation, and fails to compile if a downstream crate enables the profile-with-tracing feature on a local profiling dependency.

Repro steps

• cargo init wgpu-error
• Add a wgpu-core = "0.8.1" dependency to Cargo.toml
• Add a profiling = { version = "1.0.1", features = ["profile-with-tracing"] } dependency to Cargo.toml
• cargo build

This results in a lengthy set of compiler errors, the most prominent of which is failed to resolve: use of undeclared crate or module 'tracing' on each invocation of the profiling::scope macro, and expected type parameter 'B', found struct 'profiling::tracing::level_filters::LevelFilter' where the macro is invoked in a generic context.

The other feature flags don't exhibit this issue. Adding a tracing dependency to the wgpu-error binary crate causes the same outcome, as does using version = "1" for profiling to match its entry in the wgpu-core Cargo.toml, so this doesn't appear to be a local dependency or version mismatch issue.

Given that the tracing dependency is present in profiling as a re-export, and that its presence in wgpu-error makes no difference, I suspect that $crate is actually resolving to the nonexistent wgpu-core::tracing due to some quirk with macro expansion.

Relevant wgpu-core issue:
gfx-rs/wgpu#1477

[aclysma]

Published as 1.0.2