cmake: more idiomatic header installation

src/CMakeLists.txt

@@ -4,23 +4,27 @@
 #
 
 set(include_directory ${PROJECT_SOURCE_DIR}/include)
+set(public_headers
+    # cmake-format: sort
+    ${include_directory}/mtime_calendar.h
+    ${include_directory}/mtime_calendar360day.h
+    ${include_directory}/mtime_calendar365day.h
+    ${include_directory}/mtime_calendarGregorian.h
+    ${include_directory}/mtime_date.h
+    ${include_directory}/mtime_datetime.h
+    ${include_directory}/mtime_eventHandling.h
+    ${include_directory}/mtime_eventList.h
+    ${include_directory}/mtime_iso8601.h
+    ${include_directory}/mtime_julianDay.h
+    ${include_directory}/mtime_time.h
+    ${include_directory}/mtime_timedelta.h
+    ${include_directory}/mtime_utilities.h
+    ${include_directory}/orbit.h
+)
 
 add_library(
   mtime # cmake-format: sort
-  ${include_directory}/mtime_calendar.h
-  ${include_directory}/mtime_calendar360day.h
-  ${include_directory}/mtime_calendar365day.h
-  ${include_directory}/mtime_calendarGregorian.h
-  ${include_directory}/mtime_date.h
-  ${include_directory}/mtime_datetime.h
-  ${include_directory}/mtime_eventHandling.h
-  ${include_directory}/mtime_eventList.h
-  ${include_directory}/mtime_iso8601.h
-  ${include_directory}/mtime_julianDay.h
-  ${include_directory}/mtime_time.h
-  ${include_directory}/mtime_timedelta.h
-  ${include_directory}/mtime_utilities.h
-  ${include_directory}/orbit.h
+  ${public_headers}
   kepler.c
   libmtime.f90
   mtime_c_bindings.f90
@@ -64,6 +68,7 @@ set_target_properties(
              Fortran_MODULE_DIRECTORY "${Fortran_MODULE_DIRECTORY}"
              C_STANDARD 99
              C_STANDARD_REQUIRED ON
+             PUBLIC_HEADER "${public_headers}"
              EXPORT_NAME mtime::mtime
 )
 
@@ -80,6 +85,4 @@ target_include_directories(
 
 install(TARGETS mtime EXPORT "mtime-targets")
 
-install(
-  DIRECTORY "${Fortran_MODULE_DIRECTORY}/" "${include_directory}/" TYPE INCLUDE
-)
+install(DIRECTORY "${Fortran_MODULE_DIRECTORY}/" TYPE INCLUDE)