Race condition between Makefile.Debug and Makefile.Release when using debug_and_release on Mac

Take this example .pro file:

1. dogwalk.pro
   TEMPLATE = lib
   TARGET = dogwalk
   CONFIG += debug_and_release build_all
   SOURCES += dogwalk.cpp
   CONFIG(debug, debug|release) {
   DESTDIR = Debug
   } else {
   DESTDIR = Release
   }

This generates these rules in the separate debug and release makefiles:

1. Makefile.Release
   Release/$(TARGET): $(OBJECTS) $(SUBLIBS) $(OBJCOMP)
   @$(CHK_DIR_EXISTS) Release/ || $(MKDIR) Release/
   -$(DEL_FILE) $(TARGET) $(TARGET0) $(TARGET1) $(TARGET2)
   $(LINK) $(LFLAGS) -o $(TARGET) $(OBJECTS) $(LIBS) $(OBJCOMP)
   -ln -s $(TARGET) $(TARGET0)
   -ln -s $(TARGET) $(TARGET1)
   -ln -s $(TARGET) $(TARGET2)
   -$(DEL_FILE) Release/$(TARGET)
   -$(DEL_FILE) Release/$(TARGET0)
   -$(DEL_FILE) Release/$(TARGET1)
   -$(DEL_FILE) Release/$(TARGET2)
   -$(MOVE) $(TARGET) $(TARGET0) $(TARGET1) $(TARGET2) Release/

1. Makefile.Debug
   Debug/$(TARGET): $(OBJECTS) $(SUBLIBS) $(OBJCOMP)
   @$(CHK_DIR_EXISTS) Debug/ || $(MKDIR) Debug/
   -$(DEL_FILE) $(TARGET) $(TARGET0) $(TARGET1) $(TARGET2)
   $(LINK) $(LFLAGS) -o $(TARGET) $(OBJECTS) $(LIBS) $(OBJCOMP)
   -ln -s $(TARGET) $(TARGET0)
   -ln -s $(TARGET) $(TARGET1)
   -ln -s $(TARGET) $(TARGET2)
   -$(DEL_FILE) Debug/$(TARGET)
   -$(DEL_FILE) Debug/$(TARGET0)
   -$(DEL_FILE) Debug/$(TARGET1)
   -$(DEL_FILE) Debug/$(TARGET2)
   -$(MOVE) $(TARGET) $(TARGET0) $(TARGET1) $(TARGET2) Debug/

Each rule ends up putting $(TARGET) under Release or Debug directories, as requested. However, at the line `$(LINK) $(LFLAGS) -o $(TARGET) ...' and following ln commands, both of the makefiles are using $(TARGET), $(TARGET0) etc in the current directory as intermediate files.

Therefore, if a `make' is done on the top Makefile with any `-j', the two rules race with each other. Symptoms may include:

• everything works OK
• one of the Debug or Release directories ends up with broken symbolic links
• the Debug directory ends up with the library built in release mode or vice versa

The bug is compounded by the fact that errors in the ln, rm and mv commands are all ignored so the build claims to be successful.