rustdoc: error[E0463]: can't find crate for `std`

[GuillaumeGomez]

With the last upstream rust, whenever I build rustdoc (with x.py doc std --stage 1) and try to use it on this code:

pub struct Foo(u8);

I get the following output:

$ ./build/x86_64-unknown-linux-gnu/stage1/bin/rustdoc foo.rs 
error[E0463]: can't find crate for `std`

error: Compilation failed, aborting rustdoc

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0463`.

I tried with stage 2 but got the same error as well. Anyone has an idea what's going on?

[Mark-Simulacrum]

Cc @jyn514

I suspect that this is related to some of the recent changes in this area - it's not clear to me that the command above should put std in the sysroot, but I can see how it might be expected too.

[GuillaumeGomez]

I've been using it for years so it was quite surprising. @jyn514 wrote that to build std sysroot, you now need to run x.py build --stage 1 library/std src/tools/rustdoc.

So the question I guess now is: should x.py doc std put std in the sysroot? Also I'm curious why it was changed.

[jyn514]

So the question I guess now is: should x.py doc std put std in the sysroot? Also I'm curious why it was changed.

This is caused by #95450; it was intentional not to add these to the sysroot because it requires fully building the artifacts instead of only checking them. I don't think doc should add these to the sysroot, no, it's a separate thing conceptually than building the artifacts. The fact that it happened to work for so long is just an accident.

@jyn514 wrote that to build std sysroot, you now need to run x.py build --stage 1 library/std src/tools/rustdoc.

that's the long form - you can also just use x build and it will do the same.

[GuillaumeGomez]

Thanks for the explanations!