diff --git a/.github/workflows/ci_sh_def.yml b/.github/workflows/ci_sh_def.yml
index 4b583b826e..0ec1d80d60 100644
--- a/.github/workflows/ci_sh_def.yml
+++ b/.github/workflows/ci_sh_def.yml
@@ -49,6 +49,7 @@ jobs:
         - '3.9'
         - '3.10'
         - '3.11'
+        - '3.12'
         - 'pypy-3.7'
         - 'pypy-3.8'
         - 'pypy-3.9'
@@ -87,6 +88,7 @@ jobs:
       uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python }}
+        allow-prereleases: true
 
     - name: Setup Boost (Linux)
       # Can't use boost + define _
@@ -474,16 +476,16 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - { gcc: 7, std: 11, container_suffix: "" }
-          - { gcc: 7, std: 17, container_suffix: "" }
-          - { gcc: 8, std: 14, container_suffix: "" }
-          - { gcc: 8, std: 17, container_suffix: "" }
-          - { gcc: 10, std: 17, container_suffix: "-bullseye" }
-          - { gcc: 11, std: 20, container_suffix: "" }
-          - { gcc: 12, std: 20, container_suffix: "" }
+          - { gcc: 7, std: 11 }
+          - { gcc: 7, std: 17 }
+          - { gcc: 8, std: 14 }
+          - { gcc: 8, std: 17 }
+          - { gcc: 10, std: 17 }
+          - { gcc: 11, std: 20 }
+          - { gcc: 12, std: 20 }
 
     name: "🐍 3 • GCC ${{ matrix.gcc }} • C++${{ matrix.std }}• x64"
-    container: "gcc:${{ matrix.gcc }}${{ matrix.container_suffix }}"
+    container: "gcc:${{ matrix.gcc }}"
 
     steps:
     - uses: actions/checkout@v3
diff --git a/.github/workflows/ci_sh_def.yml.patch b/.github/workflows/ci_sh_def.yml.patch
index 5c3b62fc56..3e30cd28f0 100644
--- a/.github/workflows/ci_sh_def.yml.patch
+++ b/.github/workflows/ci_sh_def.yml.patch
@@ -1,5 +1,5 @@
---- ci.yml	2023-06-17 07:10:16.997113344 -0700
-+++ ci_sh_def.yml	2023-06-17 07:15:45.148706667 -0700
+--- ci.yml	2023-06-27 15:11:06.976142533 -0700
++++ ci_sh_def.yml	2023-06-27 15:11:46.760090228 -0700
 @@ -1,4 +1,16 @@
 -name: CI
 +# PLEASE KEEP THIS GROUP OF FILES IN SYNC AT ALL TIMES:
@@ -27,7 +27,7 @@
    cancel-in-progress: true
  
  env:
-@@ -117,6 +129,7 @@
+@@ -119,6 +131,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=11
@@ -35,7 +35,7 @@
          ${{ matrix.args }}
  
      - name: Build C++11
-@@ -146,6 +159,7 @@
+@@ -148,6 +161,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=17
@@ -43,7 +43,7 @@
          ${{ matrix.args }}
  
      - name: Build
-@@ -167,6 +181,7 @@
+@@ -169,6 +183,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=17
@@ -51,7 +51,7 @@
          -DPYBIND11_INTERNALS_VERSION=10000000
          ${{ matrix.args }}
  
-@@ -253,6 +268,7 @@
+@@ -255,6 +270,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=17
@@ -59,7 +59,7 @@
  
      - name: Build
        run: cmake --build build -j 2
-@@ -318,6 +334,7 @@
+@@ -320,6 +336,7 @@
          -DPYBIND11_WERROR=ON
          -DDOWNLOAD_CATCH=ON
          -DCMAKE_CXX_STANDARD=${{ matrix.std }}
@@ -67,7 +67,7 @@
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
  
      - name: Build
-@@ -347,7 +364,7 @@
+@@ -349,7 +366,7 @@
        run: apt-get update && DEBIAN_FRONTEND="noninteractive" apt-get install -y cmake git python3-dev python3-pytest python3-numpy
  
      - name: Configure
@@ -76,7 +76,7 @@
  
      - name: Build
        run: cmake --build build -j2 --verbose
-@@ -428,7 +445,7 @@
+@@ -430,7 +447,7 @@
          cmake3 -S . -B build -DDOWNLOAD_CATCH=ON \
                              -DCMAKE_CXX_STANDARD=11 \
                              -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)") \
@@ -85,7 +85,7 @@
                              -DPYBIND11_TEST_FILTER="test_smart_ptr.cpp"
  
      # Building before installing Pip should produce a warning but not an error
-@@ -487,6 +504,7 @@
+@@ -489,6 +506,7 @@
          -DPYBIND11_WERROR=ON
          -DDOWNLOAD_CATCH=ON
          -DCMAKE_CXX_STANDARD=${{ matrix.std }}
@@ -93,7 +93,7 @@
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
  
      - name: Build
-@@ -509,6 +527,7 @@
+@@ -511,6 +529,7 @@
          -DPYBIND11_WERROR=ON
          -DDOWNLOAD_CATCH=ON
          -DCMAKE_CXX_STANDARD=${{ matrix.std }}
@@ -101,7 +101,7 @@
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
          "-DPYBIND11_TEST_OVERRIDE=test_call_policies.cpp;test_gil_scoped.cpp;test_thread.cpp"
  
-@@ -560,6 +579,7 @@
+@@ -562,6 +581,7 @@
          -DDOWNLOAD_CATCH=ON     \
          -DDOWNLOAD_EIGEN=OFF    \
          -DCMAKE_CXX_STANDARD=11             \
@@ -109,7 +109,7 @@
          -DCMAKE_CXX_COMPILER=$(which icpc)  \
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
  
-@@ -592,6 +612,7 @@
+@@ -594,6 +614,7 @@
          -DDOWNLOAD_CATCH=ON     \
          -DDOWNLOAD_EIGEN=OFF    \
          -DCMAKE_CXX_STANDARD=17             \
@@ -117,7 +117,7 @@
          -DCMAKE_CXX_COMPILER=$(which icpc)  \
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
  
-@@ -659,6 +680,7 @@
+@@ -661,6 +682,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=11
@@ -125,7 +125,7 @@
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
  
      - name: Build
-@@ -709,6 +731,7 @@
+@@ -711,6 +733,7 @@
          cmake ../pybind11-tests
          -DDOWNLOAD_CATCH=ON
          -DPYBIND11_WERROR=ON
@@ -133,7 +133,7 @@
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
        working-directory: /build-tests
  
-@@ -804,6 +827,7 @@
+@@ -806,6 +829,7 @@
          -DPYBIND11_WERROR=ON
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
@@ -141,7 +141,7 @@
          ${{ matrix.args }}
      - name: Build C++11
        run: cmake --build build -j 2
-@@ -858,6 +882,7 @@
+@@ -860,6 +884,7 @@
          -DPYBIND11_WERROR=ON
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
@@ -149,7 +149,7 @@
          ${{ matrix.args }}
      - name: Build C++11
        run: cmake --build build --config Debug -j 2
-@@ -898,6 +923,7 @@
+@@ -900,6 +925,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=20
@@ -157,7 +157,7 @@
  
      - name: Build C++20
        run: cmake --build build -j 2
-@@ -918,6 +944,7 @@
+@@ -920,6 +946,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=20
@@ -165,7 +165,7 @@
          "-DPYBIND11_TEST_OVERRIDE=test_call_policies.cpp;test_gil_scoped.cpp;test_thread.cpp"
  
      - name: Build C++20 - Exercise cmake -DPYBIND11_TEST_OVERRIDE
-@@ -960,7 +987,7 @@
+@@ -962,7 +989,7 @@
      - name: Configure C++11
        # LTO leads to many undefined reference like
        # `pybind11::detail::function_call::function_call(pybind11::detail::function_call&&)
@@ -174,7 +174,7 @@
  
      - name: Build C++11
        run: cmake --build build -j 2
-@@ -978,7 +1005,7 @@
+@@ -980,7 +1007,7 @@
        run: git clean -fdx
  
      - name: Configure C++14
@@ -183,7 +183,7 @@
  
      - name: Build C++14
        run: cmake --build build2 -j 2
-@@ -996,7 +1023,7 @@
+@@ -998,7 +1025,7 @@
        run: git clean -fdx
  
      - name: Configure C++17
@@ -192,7 +192,7 @@
  
      - name: Build C++17
        run: cmake --build build3 -j 2
-@@ -1063,6 +1090,7 @@
+@@ -1065,6 +1092,7 @@
            -DDOWNLOAD_EIGEN=ON
            -DCMAKE_CXX_COMPILER=clang++
            -DCMAKE_CXX_STANDARD=17
@@ -200,7 +200,7 @@
  
        - name: Build
          run: cmake --build . -j 2
-@@ -1128,6 +1156,7 @@
+@@ -1130,6 +1158,7 @@
            -DDOWNLOAD_EIGEN=ON
            -DCMAKE_CXX_COMPILER=clang++
            -DCMAKE_CXX_STANDARD=17
@@ -208,7 +208,7 @@
            -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
  
        - name: Build
-@@ -1151,6 +1180,7 @@
+@@ -1153,6 +1182,7 @@
            -DDOWNLOAD_EIGEN=ON
            -DCMAKE_CXX_COMPILER=clang++
            -DCMAKE_CXX_STANDARD=17