Fix version calculation script

Author: christofmuc

cmake/calc_version.cmake

@@ -1,12 +1,31 @@
 # Get the version from our sub cmakefile
 execute_process(
     COMMAND ${CMAKE_COMMAND} -P "${CMAKE_CURRENT_LIST_DIR}/gitversion.cmake"
-    ERROR_VARIABLE PROJECT_VERSION
+    OUTPUT_VARIABLE PROJECT_VERSION
+    ERROR_VARIABLE PROJECT_VERSION_ERROR
+    RESULT_VARIABLE PROJECT_VERSION_RESULT
+    OUTPUT_STRIP_TRAILING_WHITESPACE
     ERROR_STRIP_TRAILING_WHITESPACE
 )
 
-# Cleanup output
+if(NOT PROJECT_VERSION_RESULT EQUAL 0)
+    if(PROJECT_VERSION_ERROR)
+        message(FATAL_ERROR "Version calculation failed: ${PROJECT_VERSION_ERROR}")
+    else()
+        message(FATAL_ERROR "Version calculation failed with exit code ${PROJECT_VERSION_RESULT}")
+    endif()
+endif()
+
+# Strip CMake's status prefix and surrounding whitespace
+string(REGEX REPLACE "^--[ \t]*" "" PROJECT_VERSION "${PROJECT_VERSION}")
 string(REGEX REPLACE "^[[:space:]]+|[[:space:]]+$" "" PROJECT_VERSION "${PROJECT_VERSION}")
-string(REGEX REPLACE "\n$" "" PROJECT_VERSION "${PROJECT_VERSION}")
-message("${PROJECT_VERSION}")
+
+if(PROJECT_VERSION STREQUAL "")
+    message(FATAL_ERROR "Version calculation returned an empty string")
+endif()
+
+# Emit plain text so shell captures are clean
+execute_process(
+    COMMAND ${CMAKE_COMMAND} -E echo "${PROJECT_VERSION}"
+)