Log messages from other crates are not visible when running rustdoc

[Aaron1011]

When invoking a locally-built rustc or rustdoc compiled with debug assertions, debug messages can be enabled by setting the environment variable RUST_LOG=debug.

When invoking rustc with RUST_LOG=debug, log message will be displayed from all internal crates (e.g. librustc, libsynax) as expected. However, when invoking rustdoc with RUST_LOG=debug, only messages from librustdoc are displayed, despite many other internal crates being used by rustdoc.

[Mark-Simulacrum]

I suspect the blame lies somewhere within rustc_driver, but I don't know for sure.