Allow merging all libcore/alloc doctests into a single binary by jyn514 · Pull Request #153072 · rust-lang/rust

jyn514 · 2026-02-25T03:13:34Z

This is only the changes needed to allow merging the tests. This doesn't actually turn doctest merging on in bootstrap. I think that might be a useful follow-up, since it makes them much faster to run, but it's not without downsides because it means we'll no longer be testing that doctests have all necessary feature() attributes.

The motivation for this change is to run the tests with -C instrument-coverage and then generate a coverage report from the output. Currently, this is very expensive because it requires parsing DWARF for each doctest binary. Merging the binaries decreases the time taken from several hours to ~30 seconds.

There are several parts to this change, most of which are independent and I'm happy to split out into other PRs.

Upgrade process spawning logging from debug->info so it's easier to see, including in a rustdoc built without debug symbols.
Core doctests now support being run with -C panic=abort. Ferrocene needs this downstream for complicated reasons; it's a one-line change so I figured it's not a big deal.
Downgrade errors about duplicate features from a hard error to a warning. The meaning is clear here, and doctest merging often creates duplicate features since it lifts them all to the crate root. This involves changes to the compiler but generally I expect this to be low-impact.
- Enable this new warning, as well as several related feature lints, in rustdoc. By default rustdoc doesn't lint on anything except the lints it manually adds.
Rustdoc now treats allow(incomplete_features) as a crate-level attribute, just like internal_features. Without this, it's possible to get hard errors if rustdoc lifts features to the crate level but not allows.
Core doctests now support being built with --merge-doctests=yes. In particular, I removed a few $crate usages and explicitly marked a few doctests as standalone_crate.

rustbot · 2026-02-25T03:13:37Z

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

rustbot · 2026-02-25T03:13:39Z

r? @jdonszelmann

rustbot has assigned @jdonszelmann.
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
compiler expanded to 68 candidates
Random selection from 13 candidates

bjorn3 · 2026-02-25T07:38:00Z

Merging doctest would mean that we did no longer test that the set of features in doc tests are accurate, right? Those are visible to the user.

jyn514 · 2026-02-25T12:54:56Z

Yes. That’s why this doesn’t actually switch on merging, as mentioned in the description.

compiler/rustc_lint_defs/src/builtin.rs

tests/rustdoc-ui/rustc-check-passes.rs

rustbot · 2026-03-09T11:12:48Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

jyn514 · 2026-03-09T11:29:59Z

... CI flake probably?

##[error]The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.

jyn514 · 2026-03-09T11:31:16Z

@rustbot ready

jdonszelmann · 2026-03-09T11:38:11Z

@bors r+ rollup

rust-bors · 2026-03-09T11:38:14Z

📌 Commit b2229d2 has been approved by jdonszelmann

It is now in the queue for this repository.

jdonszelmann · 2026-03-09T11:39:17Z

@bors rollup=iffy
(rustdoc tests might fail, might be hard to test locally so jyn suggested to maybe even use never)

jdonszelmann · 2026-03-09T11:39:36Z

@bors r-

jdonszelmann · 2026-03-09T11:42:23Z

let's just rerun PR CI quickly to make sure, r=me afterwards

rust-log-analyzer · 2026-03-09T16:11:27Z

The job aarch64-gnu-llvm-20-1 failed! Check out the build log: (web) (plain enhanced) (plain)

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

/dev/sda15       98M  6.4M   92M   7% /boot/efi
tmpfs           1.6G   16K  1.6G   1% /run/user/1001
================================================================================

Sufficient disk space available (120898892KB >= 52428800KB). Skipping cleanup.
##[group]Run echo "[CI_PR_NUMBER=$num]"
echo "[CI_PR_NUMBER=$num]"
shell: /usr/bin/bash --noprofile --norc -e -o pipefail {0}
---
set -ex

# Run a subset of tests. Used to run tests in parallel in multiple jobs.

# When this job partition is run as part of PR CI, skip tidy to allow revealing more failures. The
# dedicated `tidy` job failing won't block other PR CI jobs from completing, and so tidy failures
# shouldn't inhibit revealing other failures in PR CI jobs.
if [ "$PR_CI_JOB" == "1" ]; then
  echo "PR_CI_JOB set; skipping tidy"
  SKIP_TIDY="--skip tidy"
fi

../x.py --stage 2 test \
  ${SKIP_TIDY:+$SKIP_TIDY} \
  --skip compiler \
  --skip src
#!/bin/bash

set -ex

# Run a subset of tests. Used to run tests in parallel in multiple jobs.

# When this job partition is run as part of PR CI, skip tidy to allow revealing more failures. The
# dedicated `tidy` job failing won't block other PR CI jobs from completing, and so tidy failures
# shouldn't inhibit revealing other failures in PR CI jobs.
if [ "$PR_CI_JOB" == "1" ]; then
  echo "PR_CI_JOB set; skipping tidy"
  SKIP_TIDY="--skip tidy"
fi

../x.py --stage 2 test \
  ${SKIP_TIDY:+$SKIP_TIDY} \
  --skip tests \
  --skip coverage-map \
  --skip coverage-run \
  --skip library \
  --skip tidyselftest
---
Executing "/scripts/stage_2_test_set1.sh"
+ /scripts/stage_2_test_set1.sh
PR_CI_JOB set; skipping tidy
+ '[' 1 == 1 ']'
+ echo 'PR_CI_JOB set; skipping tidy'
+ SKIP_TIDY='--skip tidy'
+ ../x.py --stage 2 test --skip tidy --skip compiler --skip src
##[group]Building bootstrap
    Finished `dev` profile [unoptimized] target(s) in 0.04s
##[endgroup]
downloading https://static.rust-lang.org/dist/2026-03-05/rustfmt-nightly-aarch64-unknown-linux-gnu.tar.xz
---
test [ui] tests/ui/abi/abi-sysv64-register-usage.rs ... ignored, ignored when the architecture is aarch64
test [ui] tests/ui/abi/abi-typo-unstable.rs#feature_enabled ... ok
test [ui] tests/ui/abi/abi-typo-unstable.rs#feature_disabled ... ok
test [ui] tests/ui/abi/anon-extern-mod.rs ... ok
test [ui] tests/ui/abi/avr-sram.rs#disable_sram ... ok
test [ui] tests/ui/abi/arm-unadjusted-intrinsic.rs#aarch64 ... ok
test [ui] tests/ui/abi/avr-sram.rs#has_sram ... ok
test [ui] tests/ui/abi/avr-sram.rs#no_sram ... ok
test [ui] tests/ui/abi/arm-unadjusted-intrinsic.rs#arm ... ok
test [ui] tests/ui/abi/bad-custom.rs ... ok
test [ui] tests/ui/abi/c-stack-as-value.rs ... ok
test [ui] tests/ui/abi/c-zst.rs#aarch64-darwin ... ok
test [ui] tests/ui/abi/c-zst.rs#powerpc-linux ... ok
---
test [ui] tests/ui/asm/aarch64/ttbr0_el2.rs ... ok
test [ui] tests/ui/asm/aarch64/type-check-2-2.rs ... ok
test [ui] tests/ui/asm/aarch64/type-check-3.rs ... ok
test [ui] tests/ui/asm/aarch64/type-f16.rs ... ok
test [ui] tests/ui/asm/aarch64v8r.rs#hf ... ok
test [ui] tests/ui/asm/aarch64v8r.rs#r82 ... ok
test [ui] tests/ui/asm/aarch64/sym.rs ... ok
test [ui] tests/ui/asm/aarch64v8r.rs#sf ... ok
test [ui] tests/ui/asm/arm-low-dreg.rs ... ok
test [ui] tests/ui/asm/binary_asm_labels.rs ... ignored, only executed when the architecture is x86_64
test [ui] tests/ui/asm/asm-with-nested-closure.rs ... ok
test [ui] tests/ui/asm/cfg-parse-error.rs ... ok
test [ui] tests/ui/asm/cfg.rs#reva ... ignored, only executed when the architecture is x86_64
---
test [ui] tests/ui/const-generics/occurs-check/unused-substs-1.rs ... ok
test [ui] tests/ui/const-generics/occurs-check/unused-substs-3.rs ... ok
test [ui] tests/ui/const-generics/occurs-check/unused-substs-4.rs ... ok
test [ui] tests/ui/const-generics/occurs-check/unused-substs-5.rs ... ok
test [ui] tests/ui/const-generics/ogca/basic-fail.rs ... ok
test [ui] tests/ui/const-generics/ogca/basic.rs ... ok
test [ui] tests/ui/const-generics/ogca/generic-param-rhs.rs ... ok
test [ui] tests/ui/const-generics/ogca/rhs-but-not-root.rs ... ok
test [ui] tests/ui/const-generics/ogca/coherence-ambiguous.rs ... ok
test [ui] tests/ui/const-generics/outer-lifetime-in-const-generic-default.rs ... ok
test [ui] tests/ui/const-generics/opaque_types.rs ... ok
test [ui] tests/ui/const-generics/opaque_types2.rs ... ok
test [ui] tests/ui/const-generics/overlapping_impls.rs ... ok
test [ui] tests/ui/const-generics/params-in-ct-in-ty-param-lazy-norm.rs#full ... ok
---
test [ui] tests/ui/extern/issue-64655-extern-rust-must-allow-unwind.rs#fat2 ... ok
test [ui] tests/ui/extern/issue-64655-extern-rust-must-allow-unwind.rs#fat3 ... ok
test [ui] tests/ui/extern/issue-80074.rs ... ok
test [ui] tests/ui/extern/issue-95829.rs ... ok
test [ui] tests/ui/extern/lgamma-linkage.rs ... ok
test [ui] tests/ui/extern/issue-64655-extern-rust-must-allow-unwind.rs#thin1 ... ok
test [ui] tests/ui/extern/no-mangle-associated-fn.rs ... ok
test [ui] tests/ui/extern/not-in-block.rs ... ok
test [ui] tests/ui/extern/unsized-extern-derefmove.rs ... ok
test [ui] tests/ui/feature-gates/allow-features-empty.rs ... ok
---
test [ui] tests/ui/feature-gates/feature-gate-macro-derive.rs ... ok
test [ui] tests/ui/feature-gates/feature-gate-macro-metavar-expr-concat.rs ... ok
test [ui] tests/ui/feature-gates/feature-gate-marker_trait_attr.rs ... ok
test [ui] tests/ui/feature-gates/feature-gate-may-dangle.rs ... ok
test [ui] tests/ui/feature-gates/feature-gate-mgca-type-const-syntax.rs ... ok
test [ui] tests/ui/feature-gates/feature-gate-min-generic-const-args.rs ... ok
test [ui] tests/ui/feature-gates/feature-gate-movrs_target_feature.rs ... ignored, only executed when the architecture is x86_64
test [ui] tests/ui/feature-gates/feature-gate-more-maybe-bounds.rs ... ok
test [ui] tests/ui/feature-gates/feature-gate-min_const_fn.rs ... ok
test [ui] tests/ui/feature-gates/feature-gate-naked_functions_rustic_abi.rs ... ignored, only executed when the architecture is x86_64
---
test [ui] tests/ui/imports/ambiguous-9.rs ... ok
test [ui] tests/ui/imports/ambiguous-import-visibility-module.rs ... ok
test [ui] tests/ui/imports/ambiguous-glob-vs-expanded-extern.rs ... ok
test [ui] tests/ui/imports/ambiguous-8.rs ... ok
test [ui] tests/ui/imports/ambiguous-panic-glob-vs-multiouter.rs ... ok
test [ui] tests/ui/imports/ambiguous-panic-globvsglob.rs ... ok
test [ui] tests/ui/imports/ambiguous-panic-no-implicit-prelude.rs ... ok
test [ui] tests/ui/imports/ambiguous-panic-non-prelude-core-glob.rs ... ok
test [ui] tests/ui/imports/ambiguous-panic-non-prelude-std-glob.rs ... ok
test [ui] tests/ui/imports/ambiguous-panic-pick-core.rs ... ok
test [ui] tests/ui/imports/ambiguous-panic-pick-std.rs ... ok
---
test [ui] tests/ui/layout/null-pointer-optimization-sizes.rs ... ok
test [ui] tests/ui/layout/post-mono-layout-cycle.rs ... ok
test [ui] tests/ui/layout/randomize.rs#normal ... ok
test [ui] tests/ui/layout/randomize.rs#randomize-layout ... ok
test [ui] tests/ui/layout/rigid-alias-due-to-broken-impl.rs ... ok
test [ui] tests/ui/layout/null-pointer-optimization.rs ... ok
test [ui] tests/ui/layout/size-of-val-raw-too-big.rs ... ignored, only executed when the pointer width is 32bit (Layout computation rejects this layout for different reasons on 64-bit.)
test [ui] tests/ui/layout/reprc-power-alignment.rs ... ok
test [ui] tests/ui/layout/struct.rs ... ok
test [ui] tests/ui/layout/rust-call-abi-not-a-tuple-ice-81974.rs ... ok
---
---- [ui] tests/ui/feature-gates/duplicate-features.rs stdout ----

error: test compilation failed although it shouldn't!
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/feature-gates/duplicate-features.rs" "-Zthreads=1" "-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" "--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" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/feature-gates/duplicate-features" "-A" "unused" "-W" "unused_attributes" "-A" "internal_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/aarch64-unknown-linux-gnu/native/rust-test-helpers"
stdout: none
--- stderr -------------------------------
error: the feature `if_let` has already been enabled
##[error]  --> /checkout/tests/ui/feature-gates/duplicate-features.rs:9:12
   |
LL | #![feature(if_let)] //~ WARN the feature `if_let` has already been enabled
   |            ^^^^^^
   |
   = note: `#[deny(duplicate_features)]` on by default

error: the feature `rust1` has already been enabled
##[error]  --> /checkout/tests/ui/feature-gates/duplicate-features.rs:6:12
   |
LL | #![feature(rust1)] //~ WARN the feature `rust1` has already been enabled
   |            ^^^^^

error: aborting due to 2 previous errors
------------------------------------------

rustbot assigned jdonszelmann Feb 25, 2026

jyn514 mentioned this pull request Feb 25, 2026

force on doctest merging ferrocene/ferrocene#2180

Draft

This comment has been minimized.

Sign in to view

jyn514 force-pushed the jyn/libcore-doctest-merge branch from 16227c8 to d567da2 Compare February 25, 2026 04:30

rustbot added the T-rustdoc-frontend Relevant to the rustdoc-frontend team, which will review and decide on the web UI/UX output. label Feb 25, 2026

This comment has been minimized.

Sign in to view

jyn514 force-pushed the jyn/libcore-doctest-merge branch from d567da2 to 4254825 Compare February 28, 2026 22:25

This comment has been minimized.

Sign in to view

jdonszelmann requested changes Mar 2, 2026

View reviewed changes

compiler/rustc_lint_defs/src/builtin.rs Outdated Show resolved Hide resolved

tests/rustdoc-ui/rustc-check-passes.rs Outdated Show resolved Hide resolved

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 2, 2026

This comment has been minimized.

Sign in to view

jyn514 force-pushed the jyn/libcore-doctest-merge branch from 4254825 to 952fe7f Compare March 9, 2026 10:39

additional logging for doctest spawning

9bbe2cd

jyn514 force-pushed the jyn/libcore-doctest-merge branch from 952fe7f to b2229d2 Compare March 9, 2026 11:12

This comment has been minimized.

Sign in to view

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 9, 2026

rust-bors bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 9, 2026

rust-bors bot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Mar 9, 2026

jyn514 closed this Mar 9, 2026

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Mar 9, 2026

jyn514 reopened this Mar 9, 2026

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 9, 2026

This comment has been minimized.

Sign in to view

jyn514 added 5 commits March 9, 2026 16:33

downgrade duplicate features from hard-error -> warning

cc6f931

rustdoc moves incomplete_features attr up to the top level

f585415

core doctests support panic=abort

ee4efef

core and alloc doctests support doctest merging

1b54857

Rustdoc lints on duplicate, unused, and stable features

1c7a992

jyn514 force-pushed the jyn/libcore-doctest-merge branch from b2229d2 to 1c7a992 Compare March 9, 2026 15:33

Uh oh!

Conversation

jyn514 commented Feb 25, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rustbot commented Feb 25, 2026

Uh oh!

rustbot commented Feb 25, 2026

Uh oh!

This comment has been minimized.

This comment has been minimized.

bjorn3 commented Feb 25, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

This comment has been minimized.

jyn514 commented Feb 25, 2026

Uh oh!

This comment has been minimized.

Uh oh!

Uh oh!

This comment has been minimized.

rustbot commented Mar 9, 2026

Uh oh!

This comment has been minimized.

jyn514 commented Mar 9, 2026

Uh oh!

jyn514 commented Mar 9, 2026

Uh oh!

jdonszelmann commented Mar 9, 2026

Uh oh!

rust-bors bot commented Mar 9, 2026

Uh oh!

jdonszelmann commented Mar 9, 2026

Uh oh!

jdonszelmann commented Mar 9, 2026

Uh oh!

jdonszelmann commented Mar 9, 2026

Uh oh!

This comment has been minimized.

rust-log-analyzer commented Mar 9, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

jyn514 commented Feb 25, 2026 •

edited by rustbot

Loading

bjorn3 commented Feb 25, 2026 •

edited

Loading