--- ci.yml	2021-04-21 12:38:06.075756040 -0700
+++ ci_sh_def.yml	2021-04-21 12:38:47.155420465 -0700
@@ -1,4 +1,15 @@
-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
+#
+# Thanks a lot to @rhaschke for PR #2930!
+
+name: "CI-SH-DEF"
 
 on:
   workflow_dispatch:
@@ -100,6 +111,7 @@
         -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
@@ -127,6 +139,7 @@
         -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 }}
 
@@ -283,6 +296,7 @@
         -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
@@ -312,7 +326,8 @@
       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
@@ -392,7 +407,7 @@
         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
@@ -451,6 +466,7 @@
         -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
@@ -506,6 +522,7 @@
         -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)")
 
@@ -538,6 +555,7 @@
         -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)")
 
@@ -597,6 +615,7 @@
         -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
@@ -647,6 +666,7 @@
         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
 
@@ -742,6 +762,7 @@
         -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
@@ -788,6 +809,7 @@
         -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
@@ -808,12 +830,13 @@
           - 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