Implement an alternative way of handling generated lex files in CVS. This

should solve the "updating cvs when .l files change give me conflict markers
that break my build" issue.

llvm-svn: 26160

Makefile.rules

@@ -1204,6 +1204,8 @@ ifneq ($(LexFiles),)
 %.c: %.l
 %.cpp: %.l
 
+all:: $(LexFiles:%.l=$(PROJ_SRC_DIR)/%.cpp.cvs)
+
 # Note the extra sed filtering here, used to cut down on the warnings emited 
 # by GCC.  The last line is a gross hack to work around flex aparently not 
 # being able to resize the buffer on a large token input.  Currently, for 
@@ -1217,10 +1219,18 @@ $(PROJ_SRC_DIR)/%.cpp: $(PROJ_SRC_DIR)/%.l
 	$(SED) 's/void \*yy_flex_realloc/inline void *yy_flex_realloc/' | \
 	$(SED) 's/#define YY_BUF_SIZE 16384/#define YY_BUF_SIZE (16384*64)/' \
 	  > $(PROJ_SRC_DIR)/$*.cpp
-	$(Echo) "*** DON'T FORGET TO CHECK IN $*.cpp (generated file)"
+    
+# IFF the .l file has changed since it was last checked into CVS, copy the .l
+# file to .l.cvs and the generated .cpp file to .cpp.cvs.  We use this mechanism
+# so that people without flex can build LLVM by copying the .cvs files to the 
+# source location and building them.
+$(LexFiles:%.l=$(PROJ_SRC_DIR)/%.cpp.cvs): \
+$(PROJ_SRC_DIR)/%.cpp.cvs: $(PROJ_SRC_DIR)/%.cpp
+	$(Verb) $(CMP) -s $@ $< || \
+      ($(CP) $< $@; $(CP) $(PROJ_SRC_DIR)/$*.l $(PROJ_SRC_DIR)/$*.l.cvs)
 
-LexObjs := $(patsubst %.l,$(ObjDir)/%.o,$(LexFiles))
-$(LexObjs): $(ObjDir)/%.o : $(PROJ_SRC_DIR)/%.cpp
+$(LexFiles:%.l=$(ObjDir)/%.o) : \
+$(ObjDir)/%.o : $(PROJ_SRC_DIR)/%.cpp
 
 clean-local::
 	-$(Verb) $(RM) -f $(LexOutput)
@@ -1323,7 +1333,7 @@ ifneq ($strip($(filter-out clean clean-local dist-clean,$(MAKECMDGOALS))),)
 
 # Get the list of dependency files
 DependFiles := $(basename $(filter %.cpp %.c %.cc, $(Sources)))
-DependFiles := $(patsubst %,$(PROJ_OBJ_DIR)/$(BuildMode)/%.d,$(DependFiles))
+DependFiles := $(DependFiles:%=$(PROJ_OBJ_DIR)/$(BuildMode)/%.d)
 
 -include /dev/null $(DependFiles)