From 98fac8bc183c113903403793ffe411358ee40d8a Mon Sep 17 00:00:00 2001
From: Christian Heimes <christian@python.org>
Date: Mon, 6 Dec 2021 14:18:56 +0200
Subject: [PATCH] bpo-44035: Check autoconf files thoroughly (GH-29935)

Check that users don't push changes with outdated or patched autoconf.
The presence of runstatedir option and aclocal 1.16.3 are good markers.

Use my container image to regenerate autoconf files. "Check for changes"
will fail later when any file is regenerated.

Use ccache in check_generated_files to speed up testing.
---
 .github/workflows/build.yml                   | 23 +++++++++++++------
 .gitignore                                    |  2 ++
 .../2021-12-06-09-31-27.bpo-44035.BiO4XC.rst  |  2 ++
 3 files changed, 20 insertions(+), 7 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Build/2021-12-06-09-31-27.bpo-44035.BiO4XC.rst

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index fbf7bb6fe21..99f05f3abec 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -64,6 +64,18 @@ jobs:
       - uses: actions/setup-python@v2
       - name: Install Dependencies
         run: sudo ./.github/workflows/posix-deps-apt.sh
+      - name: Add ccache to PATH
+        run: echo "PATH=/usr/lib/ccache:$PATH" >> $GITHUB_ENV
+      - name: Configure ccache action
+        uses: hendrikmuhs/ccache-action@v1
+      - name: Check Autoconf version 2.69 and aclocal 1.16.3
+        run: |
+          grep "Generated by GNU Autoconf 2.69" configure
+          grep "aclocal 1.16.3" aclocal.m4
+          grep -q "runstatedir" configure
+          grep -q "PKG_PROG_PKG_CONFIG" aclocal.m4
+      - name: Regenerate autoconf files
+        run: docker run --rm -v $(pwd):/src quay.io/tiran/cpython_autoconf:269
       - name: Build CPython
         run: |
           # Build Python with the libpython dynamic library
@@ -75,9 +87,10 @@ jobs:
           git add -u
           changes=$(git status --porcelain)
           # Check for changes in regenerated files
-          if ! test -z "$changes"
-          then
-            echo "Generated files not up to date. Perhaps you forgot to run make regen-all or build.bat --regen ;)"
+          if test -n "$changes"; then
+            echo "Generated files not up to date."
+            echo "Perhaps you forgot to run make regen-all or build.bat --regen. ;)"
+            echo "configure files must be regenerated with a specific, unpatched version of autoconf."
             echo "$changes"
             exit 1
           fi
@@ -85,10 +98,6 @@ jobs:
         run: make smelly
       - name: Check limited ABI symbols
         run: make check-limited-abi
-      - name: Check Autoconf version 2.69
-        run: |
-          grep "Generated by GNU Autoconf 2.69" configure
-          grep "PKG_PROG_PKG_CONFIG" aclocal.m4
 
   build_win32:
     name: 'Windows (x86)'
diff --git a/.gitignore b/.gitignore
index cfd3163cd18..39de8410200 100644
--- a/.gitignore
+++ b/.gitignore
@@ -115,6 +115,8 @@ Tools/unicode/data/
 /config.log
 /config.status
 /config.status.lineno
+# hendrikmuhs/ccache-action@v1
+/.ccache
 /platform
 /profile-clean-stamp
 /profile-run-stamp
diff --git a/Misc/NEWS.d/next/Build/2021-12-06-09-31-27.bpo-44035.BiO4XC.rst b/Misc/NEWS.d/next/Build/2021-12-06-09-31-27.bpo-44035.BiO4XC.rst
new file mode 100644
index 00000000000..7530587b73d
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2021-12-06-09-31-27.bpo-44035.BiO4XC.rst
@@ -0,0 +1,2 @@
+CI now verifies that autoconf files have been regenerated with a current and
+unpatched autoconf package.