fix(cmake): upgrade maximum supported CMake version to 3.27 (#4786)

* Upgrade maximum supported CMake version to 3.27 to fix warning with CMP0148 policy (#4785)

* Update `macos_brew_install_llvm` pipeline to use expected Python installation

* Fix `Python_EXECUTABLE` Cmake variable typo

* Apply suggestions from code review

* fix: use FindPython for CMake 3.18+ by default for pybind11's tests

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* tests: fix issues with finding Python

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* tests: also set executable on subdir tests

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* fix(cmake): correct logic for FindPython

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* Update ci.yml

* Revert "Update ci.yml"

This reverts commit 33798adf3f3892ac4b78da8d3d91d3b27611bbe5.

---------

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>
Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

13 files changed, 76 insertions, 35 deletions

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7611cf6e..eca64311 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -973,7 +973,10 @@ jobs:
     - 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 -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON -S . -B build
+      run: >-
+        cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=11 -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON
+        -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
+        -S . -B build
 
     - name: Build C++11
       run: cmake --build build -j 2
@@ -991,7 +994,10 @@ jobs:
       run: git clean -fdx
 
     - name: Configure C++14
-      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=14 -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON -S . -B build2
+      run: >-
+        cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=14 -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON
+        -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
+        -S . -B build2
 
     - name: Build C++14
       run: cmake --build build2 -j 2
@@ -1009,7 +1015,10 @@ jobs:
       run: git clean -fdx
 
     - name: Configure C++17
-      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=17 -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON -S . -B build3
+      run: >-
+        cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=17 -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON
+        -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
+        -S . -B build3
 
     - name: Build C++17
       run: cmake --build build3 -j 2
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7a1199dd..1e75e99e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,13 +12,13 @@ endif()
 
 cmake_minimum_required(VERSION 3.5)
 
-# The `cmake_minimum_required(VERSION 3.5...3.26)` syntax does not work with
+# The `cmake_minimum_required(VERSION 3.5...3.27)` syntax does not work with
 # some versions of VS that have a patched CMake 3.11. This forces us to emulate
 # the behavior using the following workaround:
-if(${CMAKE_VERSION} VERSION_LESS 3.26)
+if(${CMAKE_VERSION} VERSION_LESS 3.27)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
 else()
-  cmake_policy(VERSION 3.26)
+  cmake_policy(VERSION 3.27)
 endif()
 
 if(_pybind11_cmp0148)
@@ -92,9 +92,15 @@ if(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
   set(pybind11_system "")
 
   set_property(GLOBAL PROPERTY USE_FOLDERS ON)
+  if(CMAKE_VERSION VERSION_LESS "3.18")
+    set(_pybind11_findpython_default OFF)
+  else()
+    set(_pybind11_findpython_default ON)
+  endif()
 else()
   set(PYBIND11_MASTER_PROJECT OFF)
   set(pybind11_system SYSTEM)
+  set(_pybind11_findpython_default OFF)
 endif()
 
 # Options
@@ -116,9 +122,18 @@ cmake_dependent_option(
   "Install pybind11 headers in Python include directory instead of default installation prefix"
   OFF "PYBIND11_INSTALL" OFF)
 
-cmake_dependent_option(PYBIND11_FINDPYTHON "Force new FindPython" OFF
+cmake_dependent_option(PYBIND11_FINDPYTHON "Force new FindPython" ${_pybind11_findpython_default}
                        "NOT CMAKE_VERSION VERSION_LESS 3.12" OFF)
 
+# Allow PYTHON_EXECUTABLE if in FINDPYTHON mode and building pybind11's tests
+# (makes transition easier while we support both modes).
+if(PYBIND11_MASTER_PROJECT
+   AND PYBIND11_FINDPYTHON
+   AND DEFINED PYTHON_EXECUTABLE
+   AND NOT DEFINED Python_EXECUTABLE)
+  set(Python_EXECUTABLE "${PYTHON_EXECUTABLE}")
+endif()
+
 # NB: when adding a header don't forget to also add it to setup.py
 set(PYBIND11_HEADERS
     include/pybind11/detail/class.h
diff --git a/docs/advanced/embedding.rst b/docs/advanced/embedding.rst
index e6a1686f..4cb6ebc6 100644
--- a/docs/advanced/embedding.rst
+++ b/docs/advanced/embedding.rst
@@ -18,7 +18,7 @@ information, see :doc:`/compiling`.
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.5...3.26)
+    cmake_minimum_required(VERSION 3.5...3.27)
     project(example)
 
     find_package(pybind11 REQUIRED)  # or `add_subdirectory(pybind11)`
diff --git a/docs/compiling.rst b/docs/compiling.rst
index 9d53904c..f6a21691 100644
--- a/docs/compiling.rst
+++ b/docs/compiling.rst
@@ -241,7 +241,7 @@ extension module can be created with just a few lines of code:
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.5...3.26)
+    cmake_minimum_required(VERSION 3.5...3.27)
     project(example LANGUAGES CXX)
 
     add_subdirectory(pybind11)
@@ -498,7 +498,7 @@ You can use these targets to build complex applications. For example, the
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.5...3.26)
+    cmake_minimum_required(VERSION 3.5...3.27)
     project(example LANGUAGES CXX)
 
     find_package(pybind11 REQUIRED)  # or add_subdirectory(pybind11)
@@ -556,7 +556,7 @@ information about usage in C++, see :doc:`/advanced/embedding`.
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.5...3.26)
+    cmake_minimum_required(VERSION 3.5...3.27)
     project(example LANGUAGES CXX)
 
     find_package(pybind11 REQUIRED)  # or add_subdirectory(pybind11)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index d68067df..6ad729aa 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -7,13 +7,13 @@
 
 cmake_minimum_required(VERSION 3.5)
 
-# The `cmake_minimum_required(VERSION 3.5...3.26)` syntax does not work with
+# The `cmake_minimum_required(VERSION 3.5...3.27)` syntax does not work with
 # some versions of VS that have a patched CMake 3.11. This forces us to emulate
 # the behavior using the following workaround:
-if(${CMAKE_VERSION} VERSION_LESS 3.26)
+if(${CMAKE_VERSION} VERSION_LESS 3.27)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
 else()
-  cmake_policy(VERSION 3.26)
+  cmake_policy(VERSION 3.27)
 endif()
 
 # Filter out items; print an optional message if any items filtered. This ignores extensions.
diff --git a/tests/test_cmake_build/CMakeLists.txt b/tests/test_cmake_build/CMakeLists.txt
index e5aa975c..f28bde08 100644
--- a/tests/test_cmake_build/CMakeLists.txt
+++ b/tests/test_cmake_build/CMakeLists.txt
@@ -5,9 +5,8 @@ function(pybind11_add_build_test name)
 
   set(build_options "-DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}")
 
+  list(APPEND build_options "-DPYBIND11_FINDPYTHON=${PYBIND11_FINDPYTHON}")
   if(PYBIND11_FINDPYTHON)
-    list(APPEND build_options "-DPYBIND11_FINDPYTHON=${PYBIND11_FINDPYTHON}")
-
     if(DEFINED Python_ROOT_DIR)
       list(APPEND build_options "-DPython_ROOT_DIR=${Python_ROOT_DIR}")
     endif()
diff --git a/tests/test_cmake_build/installed_embed/CMakeLists.txt b/tests/test_cmake_build/installed_embed/CMakeLists.txt
index d9dcb45e..89207a36 100644
--- a/tests/test_cmake_build/installed_embed/CMakeLists.txt
+++ b/tests/test_cmake_build/installed_embed/CMakeLists.txt
@@ -1,12 +1,12 @@
 cmake_minimum_required(VERSION 3.5)
 
-# The `cmake_minimum_required(VERSION 3.5...3.26)` syntax does not work with
+# The `cmake_minimum_required(VERSION 3.5...3.27)` syntax does not work with
 # some versions of VS that have a patched CMake 3.11. This forces us to emulate
 # the behavior using the following workaround:
-if(${CMAKE_VERSION} VERSION_LESS 3.26)
+if(${CMAKE_VERSION} VERSION_LESS 3.27)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
 else()
-  cmake_policy(VERSION 3.26)
+  cmake_policy(VERSION 3.27)
 endif()
 
 project(test_installed_embed CXX)
diff --git a/tests/test_cmake_build/installed_function/CMakeLists.txt b/tests/test_cmake_build/installed_function/CMakeLists.txt
index 2f4f6427..e752494e 100644
--- a/tests/test_cmake_build/installed_function/CMakeLists.txt
+++ b/tests/test_cmake_build/installed_function/CMakeLists.txt
@@ -1,13 +1,13 @@
 cmake_minimum_required(VERSION 3.5)
 project(test_installed_module CXX)
 
-# The `cmake_minimum_required(VERSION 3.5...3.26)` syntax does not work with
+# The `cmake_minimum_required(VERSION 3.5...3.27)` syntax does not work with
 # some versions of VS that have a patched CMake 3.11. This forces us to emulate
 # the behavior using the following workaround:
-if(${CMAKE_VERSION} VERSION_LESS 3.26)
+if(${CMAKE_VERSION} VERSION_LESS 3.27)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
 else()
-  cmake_policy(VERSION 3.26)
+  cmake_policy(VERSION 3.27)
 endif()
 
 project(test_installed_function CXX)
diff --git a/tests/test_cmake_build/installed_target/CMakeLists.txt b/tests/test_cmake_build/installed_target/CMakeLists.txt
index a981e236..3f7eb514 100644
--- a/tests/test_cmake_build/installed_target/CMakeLists.txt
+++ b/tests/test_cmake_build/installed_target/CMakeLists.txt
@@ -1,12 +1,12 @@
 cmake_minimum_required(VERSION 3.5)
 
-# The `cmake_minimum_required(VERSION 3.5...3.26)` syntax does not work with
+# The `cmake_minimum_required(VERSION 3.5...3.27)` syntax does not work with
 # some versions of VS that have a patched CMake 3.11. This forces us to emulate
 # the behavior using the following workaround:
-if(${CMAKE_VERSION} VERSION_LESS 3.26)
+if(${CMAKE_VERSION} VERSION_LESS 3.27)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
 else()
-  cmake_policy(VERSION 3.26)
+  cmake_policy(VERSION 3.27)
 endif()
 
 project(test_installed_target CXX)
diff --git a/tests/test_cmake_build/subdirectory_embed/CMakeLists.txt b/tests/test_cmake_build/subdirectory_embed/CMakeLists.txt
index f286746b..7e713343 100644
--- a/tests/test_cmake_build/subdirectory_embed/CMakeLists.txt
+++ b/tests/test_cmake_build/subdirectory_embed/CMakeLists.txt
@@ -1,12 +1,12 @@
 cmake_minimum_required(VERSION 3.5)
 
-# The `cmake_minimum_required(VERSION 3.5...3.26)` syntax does not work with
+# The `cmake_minimum_required(VERSION 3.5...3.27)` syntax does not work with
 # some versions of VS that have a patched CMake 3.11. This forces us to emulate
 # the behavior using the following workaround:
-if(${CMAKE_VERSION} VERSION_LESS 3.26)
+if(${CMAKE_VERSION} VERSION_LESS 3.27)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
 else()
-  cmake_policy(VERSION 3.26)
+  cmake_policy(VERSION 3.27)
 endif()
 
 project(test_subdirectory_embed CXX)
@@ -16,6 +16,12 @@ set(PYBIND11_INSTALL
     CACHE BOOL "")
 set(PYBIND11_EXPORT_NAME test_export)
 
+# Allow PYTHON_EXECUTABLE if in FINDPYTHON mode and building pybind11's tests
+# (makes transition easier while we support both modes).
+if(DEFINED PYTHON_EXECUTABLE AND NOT DEFINED Python_EXECUTABLE)
+  set(Python_EXECUTABLE "${PYTHON_EXECUTABLE}")
+endif()
+
 add_subdirectory("${pybind11_SOURCE_DIR}" pybind11)
 
 # Test basic target functionality
diff --git a/tests/test_cmake_build/subdirectory_function/CMakeLists.txt b/tests/test_cmake_build/subdirectory_function/CMakeLists.txt
index 275a75c0..56b8b3d9 100644
--- a/tests/test_cmake_build/subdirectory_function/CMakeLists.txt
+++ b/tests/test_cmake_build/subdirectory_function/CMakeLists.txt
@@ -1,16 +1,22 @@
 cmake_minimum_required(VERSION 3.5)
 
-# The `cmake_minimum_required(VERSION 3.5...3.26)` syntax does not work with
+# The `cmake_minimum_required(VERSION 3.5...3.27)` syntax does not work with
 # some versions of VS that have a patched CMake 3.11. This forces us to emulate
 # the behavior using the following workaround:
-if(${CMAKE_VERSION} VERSION_LESS 3.26)
+if(${CMAKE_VERSION} VERSION_LESS 3.27)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
 else()
-  cmake_policy(VERSION 3.26)
+  cmake_policy(VERSION 3.27)
 endif()
 
 project(test_subdirectory_function CXX)
 
+# Allow PYTHON_EXECUTABLE if in FINDPYTHON mode and building pybind11's tests
+# (makes transition easier while we support both modes).
+if(DEFINED PYTHON_EXECUTABLE AND NOT DEFINED Python_EXECUTABLE)
+  set(Python_EXECUTABLE "${PYTHON_EXECUTABLE}")
+endif()
+
 add_subdirectory("${pybind11_SOURCE_DIR}" pybind11)
 pybind11_add_module(test_subdirectory_function ../main.cpp)
 set_target_properties(test_subdirectory_function PROPERTIES OUTPUT_NAME test_cmake_build)
diff --git a/tests/test_cmake_build/subdirectory_target/CMakeLists.txt b/tests/test_cmake_build/subdirectory_target/CMakeLists.txt
index 37bb2c56..72d880b3 100644
--- a/tests/test_cmake_build/subdirectory_target/CMakeLists.txt
+++ b/tests/test_cmake_build/subdirectory_target/CMakeLists.txt
@@ -1,16 +1,22 @@
 cmake_minimum_required(VERSION 3.5)
 
-# The `cmake_minimum_required(VERSION 3.5...3.26)` syntax does not work with
+# The `cmake_minimum_required(VERSION 3.5...3.27)` syntax does not work with
 # some versions of VS that have a patched CMake 3.11. This forces us to emulate
 # the behavior using the following workaround:
-if(${CMAKE_VERSION} VERSION_LESS 3.26)
+if(${CMAKE_VERSION} VERSION_LESS 3.27)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
 else()
-  cmake_policy(VERSION 3.26)
+  cmake_policy(VERSION 3.27)
 endif()
 
 project(test_subdirectory_target CXX)
 
+# Allow PYTHON_EXECUTABLE if in FINDPYTHON mode and building pybind11's tests
+# (makes transition easier while we support both modes).
+if(DEFINED PYTHON_EXECUTABLE AND NOT DEFINED Python_EXECUTABLE)
+  set(Python_EXECUTABLE "${PYTHON_EXECUTABLE}")
+endif()
+
 add_subdirectory("${pybind11_SOURCE_DIR}" pybind11)
 
 add_library(test_subdirectory_target MODULE ../main.cpp)
diff --git a/tools/pybind11NewTools.cmake b/tools/pybind11NewTools.cmake
index 4b694863..cd88a645 100644
--- a/tools/pybind11NewTools.cmake
+++ b/tools/pybind11NewTools.cmake
@@ -54,7 +54,7 @@ if(NOT Python_FOUND AND NOT Python3_FOUND)
   # If we are in submodule mode, export the Python targets to global targets.
   # If this behavior is not desired, FindPython _before_ pybind11.
   if(NOT is_config
-     AND NOT Python_ARTIFACTS_INTERACTIVE
+     AND Python_ARTIFACTS_INTERACTIVE
      AND _pybind11_global_keyword STREQUAL "")
     if(TARGET Python::Python)
       set_property(TARGET Python::Python PROPERTY IMPORTED_GLOBAL TRUE)