fix(cmake): go back to ALIAS target

Signed-off-by: Henry Schreiner <[email protected]>

CMakeLists.txt

@@ -229,8 +229,7 @@ if(NOT TARGET pybind11_headers)
   # (long name used here to keep this from clashing in subdirectory mode)
   add_library(pybind11_headers INTERFACE)
   add_library(pybind11::pybind11_headers ALIAS pybind11_headers) # to match exported target
-  add_library(pybind11::headers IMPORTED INTERFACE)
-  set_target_properties(pybind11::headers PROPERTIES INTERFACE_LINK_LIBRARIES pybind11_headers)
+  add_library(pybind11::headers ALIAS pybind11_headers)
 
   target_include_directories(
     pybind11_headers ${pybind11_system} INTERFACE $<BUILD_INTERFACE:${pybind11_INCLUDE_DIR}>

tools/pybind11Common.cmake

@@ -79,14 +79,25 @@ if(CMAKE_SYSTEM_NAME MATCHES Emscripten AND NOT _pybind11_no_exceptions)
   if(CMAKE_VERSION VERSION_LESS 3.13)
     message(WARNING "CMake 3.13+ is required to build for Emscripten. Some flags will be missing")
   else()
-    set_property(
-      TARGET pybind11::headers
-      APPEND
-      PROPERTY INTERFACE_LINK_OPTIONS -fexceptions)
-    set_property(
-      TARGET pybind11::headers
-      APPEND
-      PROPERTY INTERFACE_COMPILE_OPTIONS -fexceptions)
+    if(_pybind11_is_config)
+      set_property(
+        TARGET pybind11::pybind11_headers
+        APPEND
+        PROPERTY INTERFACE_LINK_OPTIONS -fexceptions)
+      set_property(
+        TARGET pybind11::pybind11_headers
+        APPEND
+        PROPERTY INTERFACE_COMPILE_OPTIONS -fexceptions)
+    else()
+      set_property(
+        TARGET pybind11_headers
+        APPEND
+        PROPERTY INTERFACE_LINK_OPTIONS -fexceptions)
+      set_property(
+        TARGET pybind11_headers
+        APPEND
+        PROPERTY INTERFACE_COMPILE_OPTIONS -fexceptions)
+    endif()
   endif()
 endif()