playing w/ GCC warnings

[Thien-Thi Nguyen]

What do people do to make experimentation w/ GCC warnings easy?

In Guile-PG's configure.in, there is:
|## If we're using GCC, ask for aggressive warnings.
|if test x"$GCC" = xyes ; then
|  AGGRESSIVE_WARNINGS="-std=gnu99 -pedantic"
|  for x in all extra float-equal declaration-after-statement \
|           undef shadow pointer-arith cast-qual cast-align aggregate-return \
|           old-style-definition no-missing-field-initializers \
|           nested-externs inline volatile-register-var disabled-optimization
|    do AGGRESSIVE_WARNINGS="$AGGRESSIVE_WARNINGS -W$x"
|  done
|fi
|AC_SUBST([AGGRESSIVE_WARNINGS])

and in the src/Makefile.am:
| AM_CFLAGS = $(AGGRESSIVE_WARNINGS) $(MORE_AGGRESSIVE_WARNINGS)

I do this in order to not touch CFLAGS.  I wonder if this is
contra-indicated somehow, and if not, if the result can be
achieved in a better (more idiomatic, more "standard") way.

thi