[3.11] Add CI step to check changes in the exported ABI (#92442)

.github/workflows/build.yml

@@ -56,6 +56,28 @@ jobs:
             git diff --name-only origin/$GITHUB_BASE_REF.. | grep -qE '(ssl|hashlib|hmac|^.github)' && echo '::set-output name=run_ssl_tests::true' || true
           fi
 
+  check_abi:
+    name: 'Check if the ABI has changed'
+    runs-on: ubuntu-20.04
+    needs: check_source
+    if: needs.check_source.outputs.run_tests == 'true'
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+      - name: Install Dependencies
+        run: |
+            sudo ./.github/workflows/posix-deps-apt.sh
+            sudo apt-get install -yq abigail-tools
+      - name: Build CPython
+        env:
+          CFLAGS: -g3 -O0
+        run: |
+          # Build Python with the libpython dynamic library
+          ./configure --enable-shared
+          make -j4
+      - name: Check for changes in the ABI
+        run: make check-abidump
+
   check_generated_files:
     name: 'Check if generated files are up to date'
     runs-on: ubuntu-latest

Makefile.pre.in

@@ -1198,6 +1198,14 @@ regen-global-objects: $(srcdir)/Tools/scripts/generate_global_objects.py
 ############################################################################
 # ABI
 
+regen-abidump: all
+	@$(MKDIR_P) $(srcdir)/Doc/data/
+	abidw "libpython$(LDVERSION).so" --no-architecture --out-file $(srcdir)/Doc/data/python$(LDVERSION).abi.new
+	@$(UPDATE_FILE) $(srcdir)/Doc/data/python$(LDVERSION).abi $(srcdir)/Doc/data/python$(LDVERSION).abi.new
+
+check-abidump: all
+		abidiff $(srcdir)/Doc/data/python$(LDVERSION).abi "libpython$(LDVERSION).so" --drop-private-types --no-architecture --no-added-syms
+
 regen-limited-abi: all
 	$(RUNSHARED) ./$(BUILDPYTHON) $(srcdir)/Tools/scripts/stable_abi.py --generate-all $(srcdir)/Misc/stable_abi.toml