rustbuild builds docs for too many crates

[ollie27]

The Makefiles only build the docs for:

std
alloc
collections
core
libc
rustc_unicode

I assume alloc, collections and rustc_unicode are included mostly so the src links in std work. I'm not sure why libc is included though...

Anyway, with rustbuild it builds all of these:

core
compiler_builtins
rand
libc
rustc_unicode
alloc
unwind
panic_abort
alloc_system
panic_unwind
collections
std
std_shim

getopts
term
test
test_shim

Most of these are implementation details of std so shouldn't be included. The test docs are a big problem because of the same issue as #34800, generating them means the search index will get overridden.

[steveklabnik]

I'd say it's a bit more complex than that: we do want the ability to build these docs, but don't currently include them in the releases.

[alexcrichton]

I'm going to preemptively tag this as a regression as it'll soon become one. I suspect we can fix this by just disabling rustdoc in Cargo.toml for a bunch of crates. Should be an easy thing to knock out!

[bluss]

Nightly docs may show effect of this? Search index only contains getopts, term, test crates. See example: https://doc.rust-lang.org/nightly/std/index.html?search=Vec

[ollie27]

Yeah, I figured that might happen. I've submitted a small PR to fix that: #38398.