Use configure_file to optimize incremental builds for git-describe.h

library/.gitignore

@@ -0,0 +1 @@
+git-describe.cmake

library/CMakeLists.txt

@@ -322,25 +322,18 @@ IF(DFHACK_PRERELEASE)
     )
 ENDIF()
 
-# always re-run git-describe if cmake is re-run (e.g. if build ID or version changes)
-EXECUTE_PROCESS(COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_SOURCE_DIR}/git-describe.cmake)
+configure_file(git-describe.cmake.in ${CMAKE_CURRENT_SOURCE_DIR}/git-describe.cmake @ONLY)
 if (EXISTS ${CMAKE_SOURCE_DIR}/.git/index AND EXISTS ${CMAKE_SOURCE_DIR}/.git/modules/library/xml/index)
-    ADD_CUSTOM_COMMAND(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/git-describe.h
+    ADD_CUSTOM_COMMAND(OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/include/git-describe.h
       COMMAND ${CMAKE_COMMAND}
           -D dfhack_SOURCE_DIR:STRING=${dfhack_SOURCE_DIR}
-          -D git_describe_tmp_h:STRING=${CMAKE_CURRENT_BINARY_DIR}/git-describe.h
           -D GIT_EXECUTABLE:STRING=${GIT_EXECUTABLE}
-          -D DFHACK_BUILD_ID:STRING=${DFHACK_BUILD_ID}
           -P ${CMAKE_CURRENT_SOURCE_DIR}/git-describe.cmake
       COMMENT "Obtaining git commit information"
       DEPENDS ${CMAKE_SOURCE_DIR}/.git/index
           ${CMAKE_SOURCE_DIR}/.git/modules/library/xml/index
           ${CMAKE_CURRENT_SOURCE_DIR}/git-describe.cmake
-    )
-    ADD_CUSTOM_COMMAND(OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/include/git-describe.h
-        DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/git-describe.h
-        COMMAND ${CMAKE_COMMAND} -E copy_if_different ${CMAKE_CURRENT_BINARY_DIR}/git-describe.h ${CMAKE_CURRENT_SOURCE_DIR}/include/git-describe.h
-        COMMENT "Copy include/git-describe.h"
+          include/git-describe.h.in
     )
 endif ()
 

library/git-describe.cmake

@@ -1,37 +0,0 @@
-execute_process(COMMAND ${GIT_EXECUTABLE} describe --tags --abbrev=8 --long
-    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}"
-    OUTPUT_VARIABLE DFHACK_GIT_DESCRIPTION)
-execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse HEAD
-    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}"
-    OUTPUT_VARIABLE DFHACK_GIT_COMMIT)
-execute_process(COMMAND ${GIT_EXECUTABLE} describe --tags --abbrev=8 --exact-match
-    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}"
-    RESULT_VARIABLE DFHACK_GIT_TAGGED_RESULT
-    OUTPUT_QUIET ERROR_QUIET)
-
-# Check library/xml for matching commits
-execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse HEAD:library/xml
-    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}"
-    OUTPUT_VARIABLE DFHACK_GIT_XML_EXPECTED_COMMIT)
-execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse HEAD
-    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}/library/xml"
-    OUTPUT_VARIABLE DFHACK_GIT_XML_COMMIT)
-
-file(WRITE ${git_describe_tmp_h} "")
-
-macro(git_describe_definition var)
-    string(STRIP "${${var}}" GIT_DEF_VALUE)
-    file(APPEND ${git_describe_tmp_h} "#define ${var} \"${GIT_DEF_VALUE}\"\n")
-endmacro()
-
-git_describe_definition(DFHACK_GIT_DESCRIPTION)
-git_describe_definition(DFHACK_GIT_COMMIT)
-git_describe_definition(DFHACK_GIT_XML_EXPECTED_COMMIT)
-git_describe_definition(DFHACK_GIT_XML_COMMIT)
-git_describe_definition(DFHACK_BUILD_ID)
-if(${DFHACK_GIT_TAGGED_RESULT} EQUAL 0)
-    file(APPEND ${git_describe_tmp_h} "#define DFHACK_GIT_TAGGED\n")
-endif()
-if(${DFHACK_GIT_XML_COMMIT} STREQUAL ${DFHACK_GIT_XML_EXPECTED_COMMIT})
-    file(APPEND ${git_describe_tmp_h} "#define DFHACK_GIT_XML_MATCH\n")
-endif()

library/git-describe.cmake.in

@@ -0,0 +1,33 @@
+# Generated from git-describe.cmake.in
+set(DFHACK_BUILD_ID "@DFHACK_BUILD_ID@")
+
+execute_process(COMMAND ${GIT_EXECUTABLE} describe --tags --abbrev=8 --long
+    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}"
+    OUTPUT_VARIABLE DFHACK_GIT_DESCRIPTION
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse HEAD
+    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}"
+    OUTPUT_VARIABLE DFHACK_GIT_COMMIT
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+execute_process(COMMAND ${GIT_EXECUTABLE} describe --tags --abbrev=8 --exact-match
+    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}"
+    RESULT_VARIABLE DFHACK_GIT_TAGGED
+    OUTPUT_QUIET ERROR_QUIET)
+
+# Check library/xml for matching commits
+execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse HEAD:library/xml
+    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}"
+    OUTPUT_VARIABLE DFHACK_GIT_XML_EXPECTED_COMMIT
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse HEAD
+    WORKING_DIRECTORY "${dfhack_SOURCE_DIR}/library/xml"
+    OUTPUT_VARIABLE DFHACK_GIT_XML_COMMIT
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+if(${DFHACK_GIT_XML_COMMIT} STREQUAL ${DFHACK_GIT_XML_EXPECTED_COMMIT})
+    set(DFHACK_GIT_XML_MATCH TRUE)
+else()
+    set(DFHACK_GIT_XML_MATCH FALSE)
+endif()
+
+configure_file(${dfhack_SOURCE_DIR}/library/include/git-describe.h.in ${dfhack_SOURCE_DIR}/library/include/git-describe.h)

library/include/.gitignore

@@ -1 +1 @@
-git-describe.*
+git-describe.h

library/include/git-describe.h.in

@@ -0,0 +1,7 @@
+#cmakedefine DFHACK_GIT_DESCRIPTION "@DFHACK_GIT_DESCRIPTION@"
+#cmakedefine DFHACK_GIT_COMMIT "@DFHACK_GIT_COMMIT@"
+#cmakedefine DFHACK_GIT_XML_EXPECTED_COMMIT "@DFHACK_GIT_XML_EXPECTED_COMMIT@"
+#cmakedefine DFHACK_GIT_XML_COMMIT "@DFHACK_GIT_XML_COMMIT@"
+#define DFHACK_BUILD_ID "@DFHACK_BUILD_ID@"
+#cmakedefine DFHACK_GIT_TAGGED
+#cmakedefine DFHACK_GIT_XML_MATCH