Edit rustc_middle::dep_graph module documentation

[pierwill]

The first commit here moves the content to mod.rs, the second contains edits.

The section I've called "DepNode creation and 'inference'" appears to have some outdated material. (DepConstructor is a struct, not an enum.)

[rust-highfive]

r? @estebank

(rust-highfive has picked a reviewer for you, use r? to override)

[jyn514]

r? @cjgillot

[cjgillot]

You may also want to edit the docs for rustc_query_system::dep_graph::dep_node, which are a copy-paste of those for rustc_middle::dep_graph::dep_node.

[cjgillot]

The define_dep_nodes macro is defined in dep_node.rs.
It defines the DepKind enum, and DepConstructor.
DepNode is defined in rustc_query_system::dep_graph::dep_node.

[cjgillot]

Drive-by: DepConstructor should really just be a mod, since all it does is provide a namespace for functions constructing DepNodes.

[cjgillot]

I am not sure the API is that restricted any more. There is an escape hatch DepNode::new_no_params which is used in non-incremental runs.

[jyn514]

You may also want to edit the docs for rustc_query_system::dep_graph::dep_node, which are a copy-paste of those for rustc_middle::dep_graph::dep_node.

Maybe that module should link to rustc_middle instead? Or use doc = include_str! to make sure they're kept in sync?

[bors]

☔ The latest upstream changes (presumably #78452) made this pull request unmergeable. Please resolve the merge conflicts.

[rust-log-analyzer]

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  SCCACHE_BUCKET: rust-lang-ci-sccache2
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  CACHE_DOMAIN: ci-caches.rust-lang.org
  EXTRA_VARIABLES: {
 "CI_ONLY_WHEN_SUBMODULES_CHANGED": 1
##[endgroup]
adding extra environment variable CI_ONLY_WHEN_SUBMODULES_CHANGED
linux builder detected, using docker to run the build
##[group]Run src/ci/scripts/should-skip-this.sh
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extracting /checkout/obj/build/cache/2020-11-19/rustfmt-nightly-x86_64-unknown-linux-gnu.tar.xz
    Updating crates.io index
    Updating git repository `https://github.com/rust-lang/cargo`
    Updating git repository `https://github.com/rust-lang/rustfmt`
error: the lock file /checkout/Cargo.lock needs to be updated but --locked was passed to prevent this
If you want to try to generate the lock file without accessing the network, use the --offline flag.
Build completed unsuccessfully in 0:00:41
make: *** [prepare] Error 1
Makefile:60: recipe for target 'prepare' failed
Command failed. Attempt 2/5:
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    Updating crates.io index
    Updating git repository `https://github.com/rust-lang/cargo`
    Updating git repository `https://github.com/rust-lang/rustfmt`
error: the lock file /checkout/Cargo.lock needs to be updated but --locked was passed to prevent this
If you want to try to generate the lock file without accessing the network, use the --offline flag.
Build completed unsuccessfully in 0:00:01
make: *** [prepare] Error 1
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Command failed. Attempt 3/5:
    Updating crates.io index
    Updating git repository `https://github.com/rust-lang/cargo`
    Updating git repository `https://github.com/rust-lang/rustfmt`
error: the lock file /checkout/Cargo.lock needs to be updated but --locked was passed to prevent this
If you want to try to generate the lock file without accessing the network, use the --offline flag.
Build completed unsuccessfully in 0:00:00
make: *** [prepare] Error 1
Makefile:60: recipe for target 'prepare' failed
Command failed. Attempt 4/5:
Command failed. Attempt 4/5:
    Updating crates.io index
    Updating git repository `https://github.com/rust-lang/cargo`
    Updating git repository `https://github.com/rust-lang/rustfmt`
error: the lock file /checkout/Cargo.lock needs to be updated but --locked was passed to prevent this
If you want to try to generate the lock file without accessing the network, use the --offline flag.
Build completed unsuccessfully in 0:00:00
make: *** [prepare] Error 1
Makefile:60: recipe for target 'prepare' failed
Command failed. Attempt 5/5:
Command failed. Attempt 5/5:
    Updating crates.io index
    Updating git repository `https://github.com/rust-lang/cargo`
    Updating git repository `https://github.com/rust-lang/rustfmt`
error: the lock file /checkout/Cargo.lock needs to be updated but --locked was passed to prevent this
If you want to try to generate the lock file without accessing the network, use the --offline flag.
Build completed unsuccessfully in 0:00:00
make: *** [prepare] Error 1
Makefile:60: recipe for target 'prepare' failed
The command has failed after 5 attempts.

[pierwill]

Not at all sure I did this rebase correctly... 🤔

[bors]

☔ The latest upstream changes (presumably #81093) made this pull request unmergeable. Please resolve the merge conflicts.