Merge branch 'ps/ci-rust' into dk/ci-rust-fix

* ps/ci-rust:
  rust: support for Windows
  ci: verify minimum supported Rust version
  ci: check for common Rust mistakes via Clippy
  rust/varint: add safety comments
  ci: check formatting of our Rust code
  ci: deduplicate calls to `apt-get update`
  t8020: fix test failure due to indeterministic tag sorting
  gitlab-ci: upload Meson test logs as JUnit reports
  gitlab-ci: drop workaround for Python certificate store on Windows
  gitlab-ci: ignore failures to disable realtime monitoring
  gitlab-ci: dedup instructions to disable realtime monitoring
  ci: enable Rust for breaking-changes jobs
  ci: convert "pedantic" job into full build with breaking changes
  BreakingChanges: announce Rust becoming mandatory
  varint: reimplement as test balloon for Rust
  varint: use explicit width for integers
  help: report on whether or not Rust is enabled
  Makefile: introduce infrastructure to build internal Rust library
  Makefile: reorder sources after includes
  meson: add infrastructure to build internal Rust library

Author: gitster

.github/workflows/main.yml

@@ -379,6 +379,8 @@ jobs:
         - jobname: linux-breaking-changes
           cc: gcc
           image: ubuntu:rolling
+        - jobname: fedora-breaking-changes-meson
+          image: fedora:latest
         - jobname: linux-leaks
           image: ubuntu:rolling
           cc: gcc
@@ -396,8 +398,6 @@ jobs:
         # Supported until 2025-04-02.
         - jobname: linux32
           image: i386/ubuntu:focal
-        - jobname: pedantic
-          image: fedora:latest
         # A RHEL 8 compatible distro.  Supported until 2029-05-31.
         - jobname: almalinux-8
           image: almalinux:8
@@ -458,6 +458,21 @@ jobs:
     - run: ci/install-dependencies.sh
     - run: ci/run-static-analysis.sh
     - run: ci/check-directional-formatting.bash
+  rust-analysis:
+    needs: ci-config
+    if: needs.ci-config.outputs.enabled == 'yes'
+    env:
+      jobname: RustAnalysis
+      CI_JOB_IMAGE: ubuntu:rolling
+    runs-on: ubuntu-latest
+    container: ubuntu:rolling
+    concurrency:
+      group: rust-analysis-${{ github.ref }}
+      cancel-in-progress: ${{ needs.ci-config.outputs.skip_concurrent == 'yes' }}
+    steps:
+    - uses: actions/checkout@v4
+    - run: ci/install-dependencies.sh
+    - run: ci/run-rust-checks.sh
   sparse:
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'

.gitignore

@@ -1,4 +1,6 @@
 /fuzz_corpora
+/target/
+/Cargo.lock
 /GIT-BUILD-DIR
 /GIT-BUILD-OPTIONS
 /GIT-CFLAGS

.gitlab-ci.yml

@@ -45,6 +45,8 @@ test:linux:
       - jobname: linux-breaking-changes
         image: ubuntu:20.04
         CC: gcc
+      - jobname: fedora-breaking-changes-meson
+        image: fedora:latest
       - jobname: linux-TEST-vars
         image: ubuntu:20.04
         CC: gcc
@@ -58,8 +60,6 @@ test:linux:
       - jobname: linux-asan-ubsan
         image: ubuntu:rolling
         CC: clang
-      - jobname: pedantic
-        image: fedora:latest
       - jobname: linux-musl-meson
         image: alpine:latest
       - jobname: linux32
@@ -70,6 +70,8 @@ test:linux:
   artifacts:
     paths:
       - t/failed-test-artifacts
+    reports:
+      junit: build/meson-logs/testlog.junit.xml
     when: on_failure
 
 test:osx:
@@ -110,16 +112,24 @@ test:osx:
   artifacts:
     paths:
       - t/failed-test-artifacts
+    reports:
+      junit: build/meson-logs/testlog.junit.xml
     when: on_failure
 
+.windows_before_script: &windows_before_script
+  # Disabling realtime monitoring fails on some of the runners, but it
+  # significantly speeds up test execution in the case where it works. We thus
+  # try our luck, but ignore any failures.
+  - Set-MpPreference -DisableRealtimeMonitoring $true; $true
+
 build:mingw64:
   stage: build
   tags:
     - saas-windows-medium-amd64
   variables:
     NO_PERL: 1
   before_script:
-    - Set-MpPreference -DisableRealtimeMonitoring $true
+    - *windows_before_script
     - ./ci/install-sdk.ps1 -directory "git-sdk"
   script:
     - git-sdk/usr/bin/bash.exe -l -c 'ci/make-test-artifacts.sh artifacts'
@@ -136,7 +146,7 @@ test:mingw64:
     - job: "build:mingw64"
       artifacts: true
   before_script:
-    - Set-MpPreference -DisableRealtimeMonitoring $true
+    - *windows_before_script
     - git-sdk/usr/bin/bash.exe -l -c 'tar xf artifacts/artifacts.tar.gz'
     - New-Item -Path .git/info -ItemType Directory
     - New-Item .git/info/exclude -ItemType File -Value "/git-sdk"
@@ -150,18 +160,10 @@ test:mingw64:
   tags:
     - saas-windows-medium-amd64
   before_script:
-    - Set-MpPreference -DisableRealtimeMonitoring $true
-    - choco install -y git meson ninja openssl
+    - *windows_before_script
+    - choco install -y git meson ninja rust-ms
     - Import-Module $env:ChocolateyInstall\helpers\chocolateyProfile.psm1
     - refreshenv
-    # The certificate store for Python on Windows is broken and fails to fetch
-    # certificates, see https://bugs.python.org/issue36011. This seems to
-    # mostly be an issue with how the GitLab image is set up as it is a
-    # non-issue on GitHub Actions. Work around the issue by importing
-    # cetrificates manually.
-    - Invoke-WebRequest https://curl.haxx.se/ca/cacert.pem -OutFile cacert.pem
-    - openssl pkcs12 -export -nokeys -in cacert.pem -out certs.pfx -passout "pass:"
-    - Import-PfxCertificate -CertStoreLocation Cert:\LocalMachine\Root -FilePath certs.pfx
 
 build:msvc-meson:
   extends: .msvc-meson
@@ -183,6 +185,9 @@ test:msvc-meson:
   script:
     - meson test -C build --no-rebuild --print-errorlogs --slice $Env:CI_NODE_INDEX/$Env:CI_NODE_TOTAL
   parallel: 10
+  artifacts:
+    reports:
+      junit: build/meson-logs/testlog.junit.xml
 
 test:fuzz-smoke-tests:
   image: ubuntu:latest
@@ -207,6 +212,17 @@ static-analysis:
     - ./ci/run-static-analysis.sh
     - ./ci/check-directional-formatting.bash
 
+rust-analysis:
+  image: ubuntu:rolling
+  stage: analyze
+  needs: [ ]
+  variables:
+    jobname: RustAnalysis
+  before_script:
+    - ./ci/install-dependencies.sh
+  script:
+    - ./ci/run-rust-checks.sh
+
 check-whitespace:
   image: ubuntu:latest
   stage: analyze

Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "gitcore"
+version = "0.1.0"
+edition = "2018"
+rust-version = "1.49.0"
+
+[lib]
+crate-type = ["staticlib"]
+
+[dependencies]

Documentation/BreakingChanges.adoc

@@ -171,6 +171,51 @@ JGit, libgit2 and Gitoxide need to support it.
   matches the default branch name used in new repositories by many of the
   big Git forges.
 
+* Git will require Rust as a mandatory part of the build process. While Git
+  already started to adopt Rust in Git 2.49, all parts written in Rust are
+  optional for the time being. This includes:
++
+  ** The Rust wrapper around libgit.a that is part of "contrib/" and which has
+     been introduced in Git 2.49.
+  ** Subsystems that have an alternative implementation in Rust to test
+     interoperability between our C and Rust codebase.
+  ** Newly written features that are not mission critical for a fully functional
+     Git client.
++
+These changes are meant as test balloons to allow distributors of Git to prepare
+for Rust becoming a mandatory part of the build process. There will be multiple
+milestones for the introduction of Rust:
++
+--
+1. Initially, with Git 2.52, support for Rust will be auto-detected by Meson and
+   disabled in our Makefile so that the project can sort out the initial
+   infrastructure.
+2. In Git 2.53, both build systems will default-enable support for Rust.
+   Consequently, builds will break by default if Rust is not available on the
+   build host. The use of Rust can still be explicitly disabled via build
+   flags.
+3. In Git 3.0, the build options will be removed and support for Rust is
+   mandatory.
+--
++
+You can explicitly ask both Meson and our Makefile-based system to enable Rust
+by saying `meson configure -Drust=enabled` and `make WITH_RUST=YesPlease`,
+respectively.
++
+The Git project will declare the last version before Git 3.0 to be a long-term
+support release. This long-term release will receive important bug fixes for at
+least four release cycles and security fixes for six release cycles. The Git
+project will hand over maintainership of the long-term release to distributors
+in case they need to extend the life of that long-term release even further.
+Details of how this long-term release will be handed over to the community will
+be discussed once the Git project decides to stop officially supporting it.
++
+We will evaluate the impact on downstream distributions before making Rust
+mandatory in Git 3.0. If we see that the impact on downstream distributions
+would be significant, we may decide to defer this change to a subsequent minor
+release. This evaluation will also take into account our own experience with
+how painful it is to keep Rust an optional component.
+
 === Removals
 
 * Support for grafting commits has long been superseded by git-replace(1).