feat: add uninstall target for CMake (#2265)

* add uninstall target for cmake

* only add target when built as master project
Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>
Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

.gitignore

@@ -32,7 +32,6 @@ MANIFEST
 .DS_Store
 /dist
 /build
-/cmake/
 .cache/
 sosize-*.txt
 pybind11Config*.cmake

CMakeLists.txt

@@ -246,3 +246,12 @@ if(PYBIND11_INSTALL)
     NAMESPACE "pybind11::"
     DESTINATION ${PYBIND11_CMAKECONFIG_INSTALL_DIR})
 endif()
+
+# Uninstall target
+if(PYBIND11_MASTER_PROJECT)
+  configure_file("${CMAKE_CURRENT_SOURCE_DIR}/cmake/cmake_uninstall.cmake.in"
+                 "${CMAKE_CURRENT_BINARY_DIR}/cmake_uninstall.cmake" IMMEDIATE @ONLY)
+
+  add_custom_target(uninstall COMMAND ${CMAKE_COMMAND} -P
+                                      ${CMAKE_CURRENT_BINARY_DIR}/cmake_uninstall.cmake)
+endif()

cmake/cmake_uninstall.cmake.in

+# Source: https://gitlab.kitware.com/cmake/community/-/wikis/FAQ#can-i-do-make-uninstall-with-cmake
+
+if(NOT EXISTS "@CMAKE_BINARY_DIR@/install_manifest.txt")
+  message(FATAL_ERROR "Cannot find install manifest: @CMAKE_BINARY_DIR@/install_manifest.txt")
+endif()
+
+file(READ "@CMAKE_BINARY_DIR@/install_manifest.txt" files)
+string(REGEX REPLACE "\n" ";" files "${files}")
+foreach(file ${files})
+  message(STATUS "Uninstalling $ENV{DESTDIR}${file}")
+  if(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+    exec_program(
+      "@CMAKE_COMMAND@" ARGS "-E remove \"$ENV{DESTDIR}${file}\""
+      OUTPUT_VARIABLE rm_out
+      RETURN_VALUE rm_retval
+      )
+    if(NOT "${rm_retval}" STREQUAL 0)
+      message(FATAL_ERROR "Problem when removing $ENV{DESTDIR}${file}")
+    endif()
+  else(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+    message(STATUS "File $ENV{DESTDIR}${file} does not exist.")
+  endif()
+endforeach()