C[XX]FLAGS convention

[Jeffrey Walton]

Hi All,

I have a makefile which sets up CXXFLAGS (and does not use CFLAGS).
The recipe for *.cpp looks similar to:

.cpp.o:
        $(CXX) $(CXXFLAGS) -c $< -o $@

(1) Should the recipe include $(CFLAGS) by convention?

If a user wants a specific warning or setting, he/she can invoke make
similar to `make CXXFLAGS=-Winline`. This overrides our stock
settings.

(2) Should one normally honor the user's setting, or is it OK to use
override and merge flags? Ie,

    # GNUMakefile
    override CXXFLAGS += -Wall -Wextra -Wformat=2 -Wformat-security

Jeff