[bjorn3]

The first half of this PR is preparations for being able to create multiple incr comp sessions for a single crate. This will become important to store the post-ThinLTO incr comp artifacts once -Zno-link/-Zlink-only will run ThinLTO in a separate rustc session, thus requiring the main incr comp session to be finished before ThinLTO runs. The second half of this PR is a bunch of minor cleanups to load_dep_graph.

Part of rust-lang/compiler-team#908

[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? @Enselic

rustbot has assigned @Enselic.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

• Owners of files modified in this PR: compiler, incremental
• compiler, incremental expanded to 77 candidates
• Random selection from 22 candidates

[Enselic]

@rustbot reroll

[rustbot]

miri is developed in its own repository. If the Miri part of this change can be broken out, consider making this change to rust-lang/miri instead. However, if Miri needs adjusting for rustc changes, just ignore this message.

cc @rust-lang/miri

[rust-log-analyzer]

The job test-aarch64-gnu-llvm-22-1 failed! Check out the build log: (web) (plain enhanced) (plain)

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

failures:

---- [ui] tests/ui-fulldeps/codegen-backend/hotplug.rs#dep stdout ----

error in revision `dep`: auxiliary build of /checkout/tests/ui-fulldeps/codegen-backend/auxiliary/the_backend.rs failed to compile: 
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui-fulldeps/codegen-backend/auxiliary/the_backend.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--cfg" "dep" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui-fulldeps/codegen-backend/hotplug.dep/auxiliary" "-Znext-solver=coherence" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "--edition=2021" "--crate-type" "dylib" "-L" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui-fulldeps/codegen-backend/hotplug.dep/auxiliary"
stdout: none
--- stderr -------------------------------
error[E0432]: unresolved import `rustc_session::IncrCompSession`
##[error]  --> /checkout/tests/ui-fulldeps/codegen-backend/auxiliary/the_backend.rs:21:21
   |
---

---- [ui] tests/ui-fulldeps/codegen-backend/hotplug.rs#dep stdout end ----
---- [ui] tests/ui-fulldeps/codegen-backend/hotplug.rs#bindep stdout ----

error in revision `bindep`: auxiliary build of /checkout/tests/ui-fulldeps/codegen-backend/auxiliary/the_backend.rs failed to compile: 
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui-fulldeps/codegen-backend/auxiliary/the_backend.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--cfg" "bindep" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui-fulldeps/codegen-backend/hotplug.bindep/auxiliary" "-Znext-solver=coherence" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "--edition=2021" "--crate-type" "dylib" "-L" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui-fulldeps/codegen-backend/hotplug.bindep/auxiliary"
stdout: none
--- stderr -------------------------------
error[E0432]: unresolved import `rustc_session::IncrCompSession`
##[error]  --> /checkout/tests/ui-fulldeps/codegen-backend/auxiliary/the_backend.rs:21:21
   |
---

---- [ui] tests/ui-fulldeps/codegen-backend/hotplug.rs#bindep stdout end ----
---- [ui] tests/ui-fulldeps/codegen-backend/hotplug.rs#normal stdout ----

error in revision `normal`: auxiliary build of /checkout/tests/ui-fulldeps/codegen-backend/auxiliary/the_backend.rs failed to compile: 
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui-fulldeps/codegen-backend/auxiliary/the_backend.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--cfg" "normal" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui-fulldeps/codegen-backend/hotplug.normal/auxiliary" "-Znext-solver=coherence" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "--edition=2021" "--crate-type" "dylib" "-L" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui-fulldeps/codegen-backend/hotplug.normal/auxiliary"
stdout: none
--- stderr -------------------------------
error[E0432]: unresolved import `rustc_session::IncrCompSession`
##[error]  --> /checkout/tests/ui-fulldeps/codegen-backend/auxiliary/the_backend.rs:21:21
   |