Exclude dependencies of `std` for diagnostics

Currently crates in the sysroot can show up in diagnostic suggestions, such as in rust-lang#135232. To prevent this, introduce a query `visible_crates` that excludes crates marked `is_private_dep` and use this query in user-facing areas of code.

Setting `#![feature(rustc_private)]` overrides this to just use all crates, since `rustc_private` enables use of `std`'s private dependencies.

Notably, this changes `all_traits` to use `.visible_crates(())` rather than `.crates(())`. This is not strictly required and filtering could happen later as-needed; however, I cannot think of any cases where traits from private dependencies should be relevant in trait selection or diagnostics, so filtering at this earlier point seems more likely to avoid similar issues in the future.

This may be reviewed per-commit.

Fixes: rust-lang#135232

The change between 0.1.143 and 0.1.144 includes refactoring that was in
compiler-builtins before, but had to be reverted before landing in
rust-lang/rust because the traits were leaking into diagnostics [1].
Recently a fix for this issue was merged [2] so the cleanup is reapplied
here.

This also acts as a regression test for [2].

[1]: rust-lang#128691 (comment)
[2]: rust-lang#135278

`compiler_builtins` is always available as an injected dependency,
introduced in AST as `extern crate compiler_builtins as _`. This makes
it indistinguishable from any other user-specified `extern crate`,
meaning `is_private_dep` does not see it as a dependency that should be
marked private; this is the reason that `compiler_builtins` sometimes
leaks into diagnostics, and has slightly different behavior from other
stdlib dependencies tested in [1].

There is no easy way to know that an instance of `extern crate
compiler_builtins` was the injected version; however,
`compiler_builtins`

To get around this, always mark `compiler_builtins` private. The items
in this crate are never used directly, and this is the most

[1]: rust-lang#135278

The change between 0.1.143 and 0.1.144 includes refactoring that was in
compiler-builtins before, but had to be reverted before landing in
rust-lang/rust because the traits were leaking into diagnostics [1].
Recently a fix for this issue was merged [2] so the cleanup is reapplied
here.

This also acts as a regression test for [2].

[1]: rust-lang#128691 (comment)
[2]: rust-lang#135278

The change between 0.1.143 and 0.1.144 includes refactoring that was in
compiler-builtins before, but had to be reverted before landing in
rust-lang/rust because the traits were leaking into diagnostics [1].
Recently a fix for this issue was merged [2] so the cleanup is reapplied
here.

This also acts as a regression test for [2].

[1]: rust-lang#128691 (comment)
[2]: rust-lang#135278

The change between 0.1.143 and 0.1.144 includes refactoring that was in
compiler-builtins before, but had to be reverted before landing in
rust-lang/rust because the traits were leaking into diagnostics [1].
Recently a fix for this issue was merged [2] so the cleanup is reapplied
here.

This also acts as a regression test for [2].

[1]: rust-lang#128691 (comment)
[2]: rust-lang#135278

The change between 0.1.143 and 0.1.144 includes refactoring that was in
compiler-builtins before, but had to be reverted before landing in
rust-lang/rust because the traits were leaking into diagnostics [1].
Recently a fix for this issue was merged [2] so the cleanup is reapplied
here.

This also acts as a regression test for [2].

[1]: rust-lang#128691 (comment)
[2]: rust-lang#135278

The change between 0.1.143 and 0.1.144 includes refactoring that was in
compiler-builtins before, but had to be reverted before landing in
rust-lang/rust because the traits were leaking into diagnostics [1].
Recently a fix for this issue was merged [2] so the cleanup is reapplied
here.

This also acts as a regression test for [2].

[1]: rust-lang#128691 (comment)
[2]: rust-lang#135278

The change between 0.1.143 and 0.1.144 includes refactoring that was in
compiler-builtins before, but had to be reverted before landing in
rust-lang/rust because the traits were leaking into diagnostics [1].
Recently a fix for this issue was merged [2] so the cleanup is reapplied
here.

This also acts as a regression test for [2].

[1]: rust-lang#128691 (comment)
[2]: rust-lang#135278

…, r=<try>

Resolve `compiler_builtins` not being treated as private; clean up rust-lang#135278

Follow up of rust-lang#135278

Do the following (one per commit):

* Do not make dependencies of `std` private by default
* Update remaining sysroot crates to use `public-dependencies`
* Force `compiler_builtins` to be private, since it is an injected `extern crate`
* Ensure that marking a dependency private makes its dependents private by default as well
* Do the `compiler_builtins` update that has been blocked on this

Based on top of rust-lang#136226 so there are a few preceding commits.

try-job: test-various
try-job: x86_64-msvc-1

The change between 0.1.143 and 0.1.144 includes refactoring that was in
compiler-builtins before, but had to be reverted before landing in
rust-lang/rust because the traits were leaking into diagnostics [1].
Recently a fix for this issue was merged [2] so the cleanup is reapplied
here.

This also acts as a regression test for [2].

[1]: rust-lang#128691 (comment)
[2]: rust-lang#135278

…, r=<try>

Resolve `compiler_builtins` not being treated as private; clean up rust-lang#135278

Follow up of rust-lang#135278

Do the following (one per commit):

* Do not make dependencies of `std` private by default
* Update remaining sysroot crates to use `public-dependencies`
* Ensure that marking a dependency private makes its dependents private by default as well
* Do the `compiler_builtins` update that has been blocked on this

Based on top of rust-lang#136226 so there are a few preceding commits.

try-job: test-various
try-job: x86_64-msvc-1

Replace `public_test_dep!` by placing optionally public items into new
modules, then controlling what is exported with the `public-test-deps`
feature.

This is nicer for automatic formatting and diagnostics.

This is a reland of 2e2a925 ("Eliminate the use of
`public_test_dep!`"), which was reverted in 47e50fd ('Revert "Eliminate
the use of..."') due to a bug exposed at [1]. This was fixed in [2], so
the cleanup should be able to be applied again.

[1]: rust-lang/rust#128691
[2]: rust-lang/rust#135278

(cherry picked from commit d4abaf4)

…, r=<try>

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw

…, r=<try>

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2
try-job: i686-mingw-3

…, r=<try>

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

Replace `public_test_dep!` by placing optionally public items into new
modules, then controlling what is exported with the `public-test-deps`
feature.

This is nicer for automatic formatting and diagnostics.

This is a reland of 2e2a925 ("Eliminate the use of
`public_test_dep!`"), which was reverted in 47e50fd ('Revert "Eliminate
the use of..."') due to a bug exposed at [1]. This was fixed in [2], so
the cleanup should be able to be applied again.

[1]: rust-lang/rust#128691
[2]: rust-lang/rust#135278

(cherry picked from commit d4abaf4)

…, r=<try>

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

…te, r=bjorn3

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

…te, r=bjorn3

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

…te, r=bjorn3

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

…te, r=bjorn3

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

Rollup merge of rust-lang#135501 - tgross35:stdlib-dependencies-private, r=bjorn3

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

Replace `public_test_dep!` by placing optionally public items into new
modules, then controlling what is exported with the `public-test-deps`
feature.

This is nicer for automatic formatting and diagnostics.

This is a reland of 2e2a925 ("Eliminate the use of
`public_test_dep!`"), which was reverted in 47e50fd ('Revert "Eliminate
the use of..."') due to a bug exposed at [1], reapplied in d4abaf4
because the issue should have been fixed in [2], then reverted again in
f6eef07 because [2] did not actually fix the issue.

[3] has landed in rust-lang/rust since then, which should resolve the
last problem remaining after [2]. So, apply this change for what is
hopefully the final time.

[1]: rust-lang/rust#128691
[2]: rust-lang/rust#135278
[3]: rust-lang/rust#135501

Replace `public_test_dep!` by placing optionally public items into new
modules, then controlling what is exported with the `public-test-deps`
feature.

This is nicer for automatic formatting and diagnostics.

This is a reland of 2e2a925 ("Eliminate the use of
`public_test_dep!`"), which was reverted in 47e50fd ('Revert "Eliminate
the use of..."') due to a bug exposed at [1], reapplied in d4abaf4
because the issue should have been fixed in [2], then reverted again in
f6eef07 because [2] did not actually fix the issue.

[3] has landed in rust-lang/rust since then, which should resolve the
last problem remaining after [2]. So, apply this change for what is
hopefully the final time.

[1]: rust-lang/rust#128691
[2]: rust-lang/rust#135278
[3]: rust-lang/rust#135501

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang/rust#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in #135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang/rust#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang/rust#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in #135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang/rust#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang/rust#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in #135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang/rust#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

…te, r=bjorn3

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2

…te, r=bjorn3

Inject `compiler_builtins` during postprocessing and ensure it is made private

Follow up of rust-lang#135278

Do the following:

* Inject `compiler_builtins` during postprocessing, rather than injecting `extern crate compiler_builtins as _` into the AST
* Do not make dependencies of `std` private by default (this was added in rust-lang#135278)
* Make sure sysroot crates correctly mark their dependencies private/public
* Ensure that marking a dependency private makes its dependents private by default as well, unless otherwise specified
* Do the `compiler_builtins` update that has been blocked on this

There is more detail in the commit messages. This includes the changes I was working on in rust-lang#136226.

try-job: test-various
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: i686-mingw-1
try-job: i686-mingw-2