Split IncrCompSession out of Session

[bjorn3]

This will allow introducing a separate incr comp session dir for the post LTO artifacts in the future. In addition it statically encodes the lifetime of the incr comp session rather than requiring an enum behind a mutex stored in the Session.

Based on #159000

[rustbot]

rustc_codegen_gcc is developed in its own repository. If possible, consider making this change to rust-lang/rustc_codegen_gcc instead.

cc @antoyo, @GuillaumeGomez

[rustbot]

r? @jackh726

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[rust-log-analyzer]

The job pr-check-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

error[E0308]: mismatched types
   --> src/librustdoc/doctest.rs:262:9
    |
261 |     } = match result {
    |               ------ this expression has type `(Result<Option<CreateRunnableDocTests>, String>, Option<...>)`
262 |         Ok(Some(collector)) => collector,
    |         ^^^^^^^^^^^^^^^^^^^ expected `(Result<Option<...>, ...>, ...)`, found `Result<_, _>`
    |
    = note: expected tuple `(std::result::Result<std::option::Option<CreateRunnableDocTests>, std::string::String>, std::option::Option<IncrCompSession>)`
                found enum `std::result::Result<_, _>`
    = note: the full name for the type has been written to '/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-tools/x86_64-unknown-linux-gnu/release/build/rustdoc/e2ade74941381a74/out/rustdoc-e2ade74941381a74.long-type-5211659539069302315.txt'
    = note: consider using `--verbose` to print the full type name to the console

error[E0308]: mismatched types
   --> src/librustdoc/doctest.rs:263:9
    |
261 |     } = match result {
    |               ------ this expression has type `(Result<Option<CreateRunnableDocTests>, String>, Option<...>)`
262 |         Ok(Some(collector)) => collector,
263 |         Ok(None) => return,
    |         ^^^^^^^^ expected `(Result<Option<...>, ...>, ...)`, found `Result<_, _>`
    |
    = note: expected tuple `(std::result::Result<std::option::Option<CreateRunnableDocTests>, std::string::String>, std::option::Option<IncrCompSession>)`
                found enum `std::result::Result<_, _>`
    = note: the full name for the type has been written to '/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-tools/x86_64-unknown-linux-gnu/release/build/rustdoc/e2ade74941381a74/out/rustdoc-e2ade74941381a74.long-type-5211659539069302315.txt'
    = note: consider using `--verbose` to print the full type name to the console

error[E0308]: mismatched types
   --> src/librustdoc/doctest.rs:264:9
    |
261 |     } = match result {
    |               ------ this expression has type `(Result<Option<CreateRunnableDocTests>, String>, Option<...>)`
...
264 |         Err(error) => {
    |         ^^^^^^^^^^ expected `(Result<Option<...>, ...>, ...)`, found `Result<_, _>`
    |
    = note: expected tuple `(std::result::Result<std::option::Option<CreateRunnableDocTests>, std::string::String>, std::option::Option<IncrCompSession>)`
                found enum `std::result::Result<_, _>`
    = note: the full name for the type has been written to '/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-tools/x86_64-unknown-linux-gnu/release/build/rustdoc/e2ade74941381a74/out/rustdoc-e2ade74941381a74.long-type-5211659539069302315.txt'
    = note: consider using `--verbose` to print the full type name to the console

error[E0277]: the `?` operator can only be used in a closure that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> src/librustdoc/lib.rs:858:27
    |
852 |                 interface::run_compiler(config, |compiler| {
    |                                                 ---------- this function should return `Result` or `Option` to accept `?`
...
858 |                         })?;
    |                           ^ cannot use the `?` operator in a closure that returns `(std::result::Result<(), _>, std::option::Option<IncrCompSession>)`

error[E0308]: mismatched types
   --> src/librustdoc/lib.rs:852:17
    |
850 |               return wrap_return(
    |                      ----------- arguments to this function are incorrect
851 |                   dcx,
852 | /                 interface::run_compiler(config, |compiler| {
853 | |                     // construct a phony "crate" without actually running the parser
854 | |                     // allows us to use other compiler infrastructure like dep-info
855 | |                     let file =
...   |
886 | |                     })
887 | |                 }),
    | |__________________^ expected `Result<(), String>`, found `(Result<(), _>, Option<IncrCompSession>)`
    |
    = note: expected enum `std::result::Result<(), std::string::String>`
              found tuple `(std::result::Result<(), _>, std::option::Option<IncrCompSession>)`
note: function defined here
   --> src/librustdoc/lib.rs:720:15
    |
720 | pub(crate) fn wrap_return(dcx: DiagCtxtHandle<'_>, res: Result<(), String>) {
    |               ^^^^^^^^^^^                          -----------------------

error[E0308]: mismatched types
   --> src/librustdoc/lib.rs:930:9
    |
930 | /         rustc_interface::create_and_enter_global_ctxt(compiler, krate, |tcx| {
931 | |             if sess.dcx().has_errors().is_some() {
932 | |                 sess.dcx().fatal("Compilation failed, aborting rustdoc");
...   |
995 | |         })
    | |          ^- help: consider using a semicolon here: `;`
    | |__________|
    |            expected `()`, found `((), Option<IncrCompSession>)`
    |
    = note: expected unit type `()`
                   found tuple `((), std::option::Option<IncrCompSession>)`
note: return type inferred to be `()` here
   --> src/librustdoc/lib.rs:926:13
    |
926 |             return;
    |             ^^^^^^