Merge pull request rust-lang#19126 from lnicola/sync-from-rust

minor: Sync from downstream

Author: lnicola

.github/workflows/ci.yml

@@ -62,9 +62,6 @@ jobs:
     name: ${{ matrix.full_name }}
     needs: [ calculate_matrix ]
     runs-on: "${{ matrix.os }}"
-    defaults:
-      run:
-        shell: ${{ contains(matrix.os, 'windows') && 'msys2 {0}' || 'bash' }}
     timeout-minutes: 360
     env:
       CI_JOB_NAME: ${{ matrix.name }}
@@ -80,22 +77,6 @@ jobs:
         # Check the `calculate_matrix` job to see how is the matrix defined.
         include: ${{ fromJSON(needs.calculate_matrix.outputs.jobs) }}
     steps:
-      - if: contains(matrix.os, 'windows')
-        uses: msys2/setup-msys2@v2.22.0
-        with:
-          # i686 jobs use mingw32. x86_64 and cross-compile jobs use mingw64.
-          msystem: ${{ contains(matrix.name, 'i686') && 'mingw32' || 'mingw64' }}
-          # don't try to download updates for already installed packages
-          update: false
-          # don't try to use the msys that comes built-in to the github runner,
-          # so we can control what is installed (i.e. not python)
-          release: true
-          # Inherit the full path from the Windows environment, with MSYS2's */bin/
-          # dirs placed in front. This lets us run Windows-native Python etc.
-          path-type: inherit
-          install: >
-            make
-
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
 
@@ -109,7 +90,7 @@ jobs:
       # intensive jobs to run on free runners, which however also have
       # less disk space.
       - name: free up disk space
-        uses: jlumbroso/free-disk-space@54081f138730dfa15788a46383842cd2f914a1be
+        run: src/ci/scripts/free-disk-space.sh
         if: matrix.free_disk
 
       # Rust Log Analyzer can't currently detect the PR number of a GitHub

.gitignore

@@ -83,6 +83,7 @@ __pycache__/
 node_modules
 package-lock.json
 package.json
+/src/doc/rustc-dev-guide/mermaid.min.js
 
 ## Rustdoc GUI tests
 tests/rustdoc-gui/src/**.lock

CONTRIBUTING.md

@@ -12,6 +12,15 @@ Documentation for contributing to the compiler or tooling is located in the [Gui
 Development][rustc-dev-guide], commonly known as the [rustc-dev-guide]. Documentation for the
 standard library in the [Standard library developers Guide][std-dev-guide], commonly known as the [std-dev-guide].
 
+## Making changes to subtrees and submodules
+
+For submodules, changes need to be made against the repository corresponding the
+submodule, and not the main `rust-lang/rust` repository.
+
+For subtrees, prefer sending a PR against the subtree's repository if it does
+not need to be made against the main `rust-lang/rust` repostory (e.g. a
+rustc-dev-guide change that does not accompany a compiler change).
+
 ## About the [rustc-dev-guide]
 
 The [rustc-dev-guide] is meant to help document how rustc –the Rust compiler– works,