Auto merge of #12204 - rust-lang:revert-12181-which-channel-backport,…

… r=epage

Revert "chore: detect the channel a PR wants to merge into"

Reverts #12181

GitHub Action expression `success()` will look into the chain of dependent jobs. On master CI passed but on a backport it still failed <#12200 (comment)>

This isn't worth pursuing at this moment either. To fix it, it's unavoidable to write something like below for bors job

```yaml
    if: "always()
      && !(contains(needs.*.result, 'cancelled')
        || contains(needs.*.result, 'skipped')
        || contains(needs.*.result, 'failure')
      )
      && github.event_name == 'push'
      && github.ref == 'refs/heads/auto-cargo'
    "
```

I don't think that's good in long-term.

r? ehuss

.github/workflows/main.yml

@@ -16,20 +16,6 @@ env:
   CARGO_REGISTRIES_CRATES_IO_PROTOCOL: sparse
 
 jobs:
-  # Determine which channel will be merged into.
-  channel:
-    runs-on: ubuntu-latest
-    outputs:
-      CHANNEL: ${{ steps.channel.outputs.CHANNEL }}
-    env:
-      BASE_SHA: ${{ github.event.pull_request.base.sha }}
-    steps:
-    - uses: actions/checkout@v3
-      with:
-        fetch-depth: 0 # fetch all branches
-    - id: channel
-      run: ci/which-channel.sh
-
   # Check Code style quickly by running `rustfmt` over all code
   rustfmt:
     runs-on: ubuntu-latest
@@ -77,42 +63,8 @@ jobs:
       - run: rustup update stable && rustup default stable
       - run: ci/validate-version-bump.sh
 
-  # Generate strategy matrix for different platforms and channels
-  # (see ci/matrix.json)
-  matrix:
-    runs-on: ubuntu-latest
-    needs:
-    - channel
-    outputs:
-      matrix: ${{ steps.matrix.outputs.matrix }}
-    steps:
-    - uses: actions/checkout@v3
-    - name: Generate strategy matrix
-      id: matrix
-      run: |
-        CHANNEL=${{ needs.channel.outputs.CHANNEL }}
-
-        # This reads ci/matrix.json and then filters the environment we want to
-        # build on, based on the channel this PR want to merge into.
-        #
-        # * For stable, we build only on stable toolchain.
-        # * For beta, we build on stable and beta.
-        # * For nightly, we build on stable, beta, and nightly.
-        MATRIX=$(
-          jq --arg C "$CHANNEL" 'map (. | 
-            if ($C == "beta") then select(.rust | startswith("nightly") | not)
-            elif ($C == "stable") then select(.rust | startswith("stable"))
-            else . end)' ci/matrix.json
-        )
-        echo "$MATRIX"
-
-        # Outputs as Job's outputs for other jobs to reuse.
-        echo "MATRIX={\"include\":$(echo $MATRIX)}" >> "$GITHUB_OUTPUT"
-
   test:
     runs-on: ${{ matrix.os }}
-    needs:
-    - matrix
     env:
       CARGO_PROFILE_DEV_DEBUG: 1
       CARGO_PROFILE_TEST_DEBUG: 1
@@ -121,7 +73,36 @@ jobs:
       # Deny warnings on CI to avoid warnings getting into the codebase.
       RUSTFLAGS: -D warnings
     strategy:
-      matrix: ${{ fromJSON(needs.matrix.outputs.MATRIX) }}
+      matrix:
+        include:
+        - name: Linux x86_64 stable
+          os: ubuntu-latest
+          rust: stable
+          other: i686-unknown-linux-gnu
+        - name: Linux x86_64 beta
+          os: ubuntu-latest
+          rust: beta
+          other: i686-unknown-linux-gnu
+        - name: Linux x86_64 nightly
+          os: ubuntu-latest
+          rust: nightly
+          other: i686-unknown-linux-gnu
+        - name: macOS x86_64 stable
+          os: macos-latest
+          rust: stable
+          other: x86_64-apple-ios
+        - name: macOS x86_64 nightly
+          os: macos-latest
+          rust: nightly
+          other: x86_64-apple-ios
+        - name: Windows x86_64 MSVC stable
+          os: windows-latest
+          rust: stable-msvc
+          other: i686-pc-windows-msvc
+        - name: Windows x86_64 gnu nightly # runs out of space while trying to link the test suite
+          os: windows-latest
+          rust: nightly-gnu
+          other: i686-pc-windows-gnu
     name: Tests ${{ matrix.name }}
     steps:
     - uses: actions/checkout@v3
@@ -199,9 +180,6 @@ jobs:
 
   build_std:
     runs-on: ubuntu-latest
-    needs:
-    - channel
-    if: needs.channel.outputs.CHANNEL == 'master'
     steps:
     - uses: actions/checkout@v3
     - run: rustup update nightly && rustup default nightly
@@ -212,8 +190,6 @@ jobs:
         CARGO_RUN_BUILD_STD_TESTS: 1
   docs:
     runs-on: ubuntu-latest
-    needs:
-    - channel
     steps:
     - uses: actions/checkout@v3
     - run: rustup update nightly && rustup default nightly
@@ -235,36 +211,22 @@ jobs:
     - run: cd src/doc && mdbook build --dest-dir ../../target/doc
     - name: Run linkchecker.sh
       run: |
-        BRANCH=${{ needs.channel.outputs.CHANNEL }}
         cd target
-        curl -sSLO "https://raw.githubusercontent.com/rust-lang/rust/$BRANCH/src/tools/linkchecker/linkcheck.sh"
+        curl -sSLO https://raw.githubusercontent.com/rust-lang/rust/master/src/tools/linkchecker/linkcheck.sh
         sh linkcheck.sh --all --path ../src/doc cargo
 
-  # Jobs that may be skipped if they aren't going to merge into master (nightly).
-  #
-  # This is needed because GitHub Actions treats success() as false if a job is
-  # skipped, and the bors success/failure jobs below need to ignore skipped jobs.
-  z-nightly-jobs:
-    needs:
-    - channel
-    - build_std
-    if: "(needs.channel.outputs.CHANNEL != 'master' && !failure()) || success()"
-    runs-on: ubuntu-latest
-    steps:
-    - run: exit 0
-
   success:
     permissions:
       contents: none
     name: bors build finished
     needs:
+    - build_std
     - docs
     - lockfile
     - resolver
     - rustfmt
     - test
     - test_gitoxide
-    - z-nightly-jobs
     runs-on: ubuntu-latest
     if: "success() && github.event_name == 'push' && github.ref == 'refs/heads/auto-cargo'"
     steps:
@@ -274,13 +236,13 @@ jobs:
       contents: none
     name: bors build finished
     needs:
+    - build_std
     - docs
     - lockfile
     - resolver
     - rustfmt
     - test
     - test_gitoxide
-    - z-nightly-jobs
     runs-on: ubuntu-latest
     if: "!success() && github.event_name == 'push' && github.ref == 'refs/heads/auto-cargo'"
     steps: