Make gaudi_add_compile_test also work for succeeding tests

Fix `gaudi_add_compile_test` such that it also allows to add tests
that require a successful compilation.

cmake/GaudiProjectConfig.cmake

@@ -2621,7 +2621,8 @@ endfunction()
 #
 # Declare a compilation test (typically to test for compilation failure):
 #  ERRORS - List of errors (regex allowed) that are all required in the output
-#           in order for the test to succeed(!)
+#           in order for the test to succeed(!). If not specified, test result is
+#           the same as compilation success/failure.
 #---------------------------------------------------------------------------------------------------
 function(gaudi_add_compile_test executable)
   CMAKE_PARSE_ARGUMENTS(ARG ""
@@ -2636,17 +2637,18 @@ function(gaudi_add_compile_test executable)
   set_target_properties(${executable} PROPERTIES EXCLUDE_FROM_ALL TRUE
                                                  EXCLUDE_FROM_DEFAULT_BUILD TRUE)
 
-  # Concatenate errors into multiline regex
   if(ARG_ERRORS)
+    # Concatenate errors into multiline regex
     string(REPLACE ";" ".*[\\n\\r]*.*" regex "${ARG_ERRORS}")
+    gaudi_add_test(${executable}
+       COMMAND ${CMAKE_COMMAND} --build . --target ${executable}
+       LABELS ${ARG_LABELS}
+       PASSREGEX ${regex})
   else()
-    set(regex ".*")
+    gaudi_add_test(${executable}
+       COMMAND ${CMAKE_COMMAND} --build . --target ${executable}
+       LABELS ${ARG_LABELS})
   endif()
-
-  gaudi_add_test(${executable}
-                 COMMAND ${CMAKE_COMMAND} --build . --target ${executable}
-                 LABELS ${ARG_LABELS}
-                 PASSREGEX ${regex})
 endfunction()
 
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