--- ci.yml	2021-10-11 13:18:34.061740320 -0700
+++ ci_sh_def.yml	2021-10-11 13:20:02.319713610 -0700
@@ -1,4 +1,16 @@
-name: CI-SH-AVL
+# PLEASE KEEP THIS GROUP OF FILES IN SYNC AT ALL TIMES:
+#     ci.yml
+#     ci_sh_def.yml
+#     ci_sh_def.yml.patch
+# To import changes made to ci.yml *** ESPECIALLY AFTER `git merge master` ***:
+#     patch -i ci_sh_def.yml.patch -o ci_sh_def.yml
+# To update the patch file after making changes to ci_sh.yml:
+#     diff -u ci.yml ci_sh_def.yml > ci_sh_def.yml.patch
+#     git commit -a -m 'Tracking ci.yml changes from master.'
+#
+# Thanks a lot to @rhaschke for PR #2930!
+
+name: "CI-SH-DEF"
 
 on:
   workflow_dispatch:
@@ -104,6 +116,7 @@
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
         -DCMAKE_CXX_STANDARD=11
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT ${{runner.os == 'Windows' && '/GR /EHsc' || ''}}"
         ${{ matrix.args }}
 
     - name: Build C++11
@@ -131,6 +144,7 @@
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
         -DCMAKE_CXX_STANDARD=17
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT ${{runner.os == 'Windows' && '/GR /EHsc' || ''}}"
         ${{ matrix.args }}
         ${{ matrix.args2 }}
 
@@ -153,6 +167,7 @@
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
         -DCMAKE_CXX_STANDARD=17
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT ${{runner.os == 'Windows' && '/GR /EHsc' || ''}}"
         -DPYBIND11_INTERNALS_VERSION=10000000
         "-DPYBIND11_TEST_OVERRIDE=test_call_policies.cpp;test_gil_scoped.cpp;test_thread.cpp"
         ${{ matrix.args }}
@@ -251,6 +266,7 @@
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
         -DCMAKE_CXX_STANDARD=17
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
 
     - name: Build
       run: cmake --build build -j 2
@@ -305,6 +321,7 @@
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DCMAKE_CXX_STANDARD=${{ matrix.std }}
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
         -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
     - name: Build
@@ -334,7 +351,8 @@
       run: apt-get update && DEBIAN_FRONTEND="noninteractive" apt-get install -y cmake git python3-dev python3-pytest python3-numpy
 
     - name: Configure
-      run: cmake -S . -B build -DPYBIND11_CUDA_TESTS=ON -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON
+      run: cmake -S . -B build -DPYBIND11_CUDA_TESTS=ON -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
+
 
     - name: Build
       run: cmake --build build -j2 --verbose
@@ -414,7 +432,7 @@
         cmake3 -S . -B build -DDOWNLOAD_CATCH=ON \
                             -DCMAKE_CXX_STANDARD=11 \
                             -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)") \
-                            -DCMAKE_CXX_FLAGS="-Wc,--pending_instantiations=0" \
+                            -DCMAKE_CXX_FLAGS="-Wc,--pending_instantiations=0 -DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" \
                             -DPYBIND11_TEST_FILTER="test_smart_ptr.cpp;test_virtual_functions.cpp"
 
     # Building before installing Pip should produce a warning but not an error
@@ -473,6 +491,7 @@
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DCMAKE_CXX_STANDARD=${{ matrix.std }}
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
         -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
     - name: Build
@@ -528,6 +547,7 @@
         -DDOWNLOAD_CATCH=ON     \
         -DDOWNLOAD_EIGEN=OFF    \
         -DCMAKE_CXX_STANDARD=11             \
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"  \
         -DCMAKE_CXX_COMPILER=$(which icpc)  \
         -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
@@ -560,6 +580,7 @@
         -DDOWNLOAD_CATCH=ON     \
         -DDOWNLOAD_EIGEN=OFF    \
         -DCMAKE_CXX_STANDARD=17             \
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"  \
         -DCMAKE_CXX_COMPILER=$(which icpc)  \
         -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
@@ -631,6 +652,7 @@
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
         -DCMAKE_CXX_STANDARD=11
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
         -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
     - name: Build
@@ -681,6 +703,7 @@
         cmake ../pybind11-tests
         -DDOWNLOAD_CATCH=ON
         -DPYBIND11_WERROR=ON
+        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
         -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
       working-directory: /build-tests
 
@@ -776,6 +799,7 @@
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DCMAKE_CXX_FLAGS="/GR /EHsc /DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
         ${{ matrix.args }}
     - name: Build C++11
       run: cmake --build build -j 2
@@ -822,6 +846,7 @@
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DCMAKE_CXX_FLAGS="/GR /EHsc /DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
 
     - name: Build C++14
       run: cmake --build build -j 2
@@ -842,12 +867,13 @@
           - 3.7
         std:
           - 14
+        args: [ -DCMAKE_CXX_FLAGS="/GR /EHsc /DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" ]
 
         include:
           - python: 2.7
             std: 17
             args: >
-              -DCMAKE_CXX_FLAGS="/permissive- /EHsc /GR"
+              -DCMAKE_CXX_FLAGS="/permissive- /EHsc /GR /DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
 
     steps:
     - uses: actions/checkout@v2
@@ -914,7 +940,7 @@
     - name: Configure C++11
       # LTO leads to many undefined reference like
       # `pybind11::detail::function_call::function_call(pybind11::detail::function_call&&)
-      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=11 -S . -B build
+      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=11 -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" -S . -B build
 
     - name: Build C++11
       run: cmake --build build -j 2
@@ -932,7 +958,7 @@
       run: git clean -fdx
 
     - name: Configure C++14
-      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=14 -S . -B build2
+      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=14 -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" -S . -B build2
 
     - name: Build C++14
       run: cmake --build build2 -j 2
@@ -950,7 +976,7 @@
       run: git clean -fdx
 
     - name: Configure C++17
-      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=17 -S . -B build3
+      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" -S . -B build3
 
     - name: Build C++17
       run: cmake --build build3 -j 2