Auto merge of #74468 - Manishearth:rollup-5nhvz80, r=Manishearth

Rollup of 11 pull requests

Successful merges:

 - #72414 ( Add lazy initialization primitives to std)
 - #74069 (Compare tagged/niche-filling layout and pick the best one)
 - #74418 (ci: Set `shell: bash` as a default, remove duplicates)
 - #74441 (bootstrap.py: patch RPATH on NixOS to handle the new zlib dependency.)
 - #74444 (Add regression test for #69414)
 - #74448 (improper_ctypes_definitions: allow `Box`)
 - #74449 (Test codegen of compare_exchange operations)
 - #74450 (Fix `Safety` docs for `from_raw_parts_mut`)
 - #74453 (Use intra-doc links in `str` and `BTreeSet`)
 - #74457 (rustbuild: drop tool::should_install)
 - #74464 (Use pathdiff crate)

Failed merges:

r? @ghost

1 files changed, 4 insertions, 32 deletions

diff --git a/src/ci/github-actions/ci.yml b/src/ci/github-actions/ci.yml
index 0b3b77f217d..5573d87aa2e 100644
--- a/src/ci/github-actions/ci.yml
+++ b/src/ci/github-actions/ci.yml
@@ -79,7 +79,6 @@ x--expand-yaml-anchors--remove:
     steps:
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
-        shell: bash
 
       - name: checkout the source code
         uses: actions/checkout@v1
@@ -95,7 +94,6 @@ x--expand-yaml-anchors--remove:
 
       - name: add extra environment variables
         run: src/ci/scripts/setup-environment.sh
-        shell: bash
         env:
           # Since it's not possible to merge `${{ matrix.env }}` with the other
           # variables in `job.<name>.env`, the variables defined in the matrix
@@ -106,67 +104,54 @@ x--expand-yaml-anchors--remove:
 
       - name: decide whether to skip this job
         run: src/ci/scripts/should-skip-this.sh
-        shell: bash
         <<: *step
 
       - name: collect CPU statistics
         run: src/ci/scripts/collect-cpu-stats.sh
-        shell: bash
         <<: *step
 
       - name: show the current environment
         run: src/ci/scripts/dump-environment.sh
-        shell: bash
         <<: *step
 
       - name: install awscli
         run: src/ci/scripts/install-awscli.sh
-        shell: bash
         <<: *step
 
       - name: install sccache
         run: src/ci/scripts/install-sccache.sh
-        shell: bash
         <<: *step
 
       - name: install clang
         run: src/ci/scripts/install-clang.sh
-        shell: bash
         <<: *step
 
       - name: install WIX
         run: src/ci/scripts/install-wix.sh
-        shell: bash
         <<: *step
 
       - name: ensure the build happens on a partition with enough space
         run: src/ci/scripts/symlink-build-dir.sh
-        shell: bash
         <<: *step
 
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         <<: *step
 
       - name: install MSYS2
         run: src/ci/scripts/install-msys2.sh
-        shell: bash
         <<: *step
 
       - name: install MinGW
         run: src/ci/scripts/install-mingw.sh
-        shell: bash
         <<: *step
 
       - name: install ninja
         run: src/ci/scripts/install-ninja.sh
-        shell: bash
         <<: *step
 
       - name: enable ipv6 on Docker
         run: src/ci/scripts/enable-docker-ipv6.sh
-        shell: bash
         <<: *step
 
       # Disable automatic line ending conversion (again). On Windows, when we're
@@ -176,22 +161,18 @@ x--expand-yaml-anchors--remove:
       # appropriate line endings.
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         <<: *step
 
       - name: checkout submodules
         run: src/ci/scripts/checkout-submodules.sh
-        shell: bash
         <<: *step
 
       - name: ensure line endings are correct
         run: src/ci/scripts/verify-line-endings.sh
-        shell: bash
         <<: *step
 
       - name: run the build
         run: src/ci/scripts/run-build-from-ci.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: ${{ env.CACHES_AWS_ACCESS_KEY_ID }}
           AWS_SECRET_ACCESS_KEY: ${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.CACHES_AWS_ACCESS_KEY_ID)] }}
@@ -200,7 +181,6 @@ x--expand-yaml-anchors--remove:
 
       - name: upload artifacts to S3
         run: src/ci/scripts/upload-artifacts.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: ${{ env.ARTIFACTS_AWS_ACCESS_KEY_ID }}
           AWS_SECRET_ACCESS_KEY: ${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.ARTIFACTS_AWS_ACCESS_KEY_ID)] }}
@@ -250,18 +230,10 @@ on:
 
 defaults:
   run:
-    # While on Linux and macOS builders it just forwards the arguments to the
-    # system bash, this wrapper allows switching from the host's bash.exe to
-    # the one we install along with MSYS2 mid-build on Windows.
-    #
-    # Once the step to install MSYS2 is executed, the CI_OVERRIDE_SHELL
-    # environment variable is set pointing to our MSYS2's bash.exe. From that
-    # moment the host's bash.exe will not be called anymore.
-    #
-    # This is needed because we can't launch our own bash.exe from the host
-    # bash.exe, as that would load two different cygwin1.dll in memory, causing
-    # "cygwin heap mismatch" errors.
-    shell: python src/ci/exec-with-shell.py {0}
+    # On Linux, macOS, and Windows, use the system-provided bash as the default
+    # shell. (This should only make a difference on Windows, where the default
+    # shell is PowerShell.)
+    shell: bash
 
 jobs:
   pr: