What is the best command-line tool to clean up code?

Question

When I'm writing C - code I solely use an editor and gcc. I was wondering if anyone could suggest a good and simple tool that will find unused variables, function declarations and possibly make some optimisations.

Does anybody know a good tool?

Answer 1

As Dan Fego pointed out, GCC can catch unused variables and unused static functions. It won't normally find unused extern functions as it normally works one source file at a time.

GCC (v4.3.2) has hundreds if not thousands of options. One that might help is '--combine' to combine source files (as long as you're not in the habit of putting the same function or variable names inside different source files).

The option '--help' tells you more; the options '--help=optimizers' and '--help=warnings' each give you a couple hundred lines of output. The warnings include:

-Wunused                    This switch lacks documentation -Wunused-function           Warn when a function is unused -Wunused-label              This switch lacks documentation -Wunused-macros             Warn about macros defined in the main file that                             are not used -Wunused-parameter          Warn when a function parameter is unused -Wunused-value              Warn when an expression value is unused -Wunused-variable           Warn when a variable is unused 

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Added: this is a script called glint that I use to sanitize my code. It is quite old so it doesn't use the '#!/bin/sh' notation for the first line and it says '$*' instead of '"$@"', both of which should be fixed, but neither needs to be fixed urgently. Note that even though GCC 4.x no longer supports the '-fwriteable-strings' option, it still supports the '-Wwrite-strings' option and that has value.

This script demonstrates that you can get a lot of mileage out of existing tools with just a small amount of work. You can configure just about every option it uses - albeit mainly via the environment rather than the command line. Of course, you can add extra warning options to the command line; what you can't do is remove predetermined options except via the environment. But that's OK; they're chosen by default for good reasons. These days, I'd probably set 'GLINT_ANSI=-std=c99' or fix the script; I've not been using it much of late since I code fairly closely to the standard that glint enforces. (Note that the '-o /dev/null' means that you can only do one file at a time; hack to fix!)

:   "@(#)$Id: glint.sh,v 1.5 2002/08/09 21:40:52 jleffler Exp jleffler $" # #   Use GCC as excruciatingly pedantic lint #   Not a complete replacement for lint -- it doesn't do inter-file checking. #   Now configurable via the environment. #   Use GLINT_EXTRA_FLAGS to set extra flags via the environment. #   NB: much Solaris code won't work with -undef enabled.  : ${GLINT_GCC:='gcc'}  : ${GLINT_ANSI='-ansi'} : ${GLINT_FNO_COMMON='-fno-common'} : ${GLINT_FSHORT_ENUMS='-fshort-enums'} : ${GLINT_PEDANTIC='-pedantic'} : ${GLINT_UNDEF='-undef'} : ${GLINT_W='-W'} : ${GLINT_WAGGREGATE_RETURN='-Waggregate-return'} : ${GLINT_WALL='-Wall'} : ${GLINT_WCAST_ALIGN='-Wcast-align'} : ${GLINT_WCAST_QUAL='-Wcast-qual'} : ${GLINT_WCONVERSION='-Wconversion'} : ${GLINT_WMISSING_DECLARATIONS='-Wmissing-declarations'} : ${GLINT_WREDUNDANT_DECLS='-Wredundant-decls'} : ${GLINT_WMISSING_PROTOTYPES='-Wmissing-prototypes'} : ${GLINT_WNESTED_EXTERNS='-Wnested-externs'} : ${GLINT_WPOINTER_ARITH='-Wpointer-arith'} : ${GLINT_WSHADOW='-Wshadow'} : ${GLINT_WSTRICT_PROTOTYPES='-Wstrict-prototypes'} : # ${GLINT_WTRADITIONAL='-Wtraditional'} : ${GLINT_WWRITE_STRINGS='-Wwrite-strings'}  exec ${GLINT_GCC} \     ${GLINT_ANSI} \     ${GLINT_FNO_COMMON} \     ${GLINT_FSHORT_ENUMS} \     ${GLINT_PEDANTIC} \     ${GLINT_UNDEF} \     ${GLINT_WAGGREGATE_RETURN} \     ${GLINT_WALL} \     ${GLINT_WCAST_ALIGN} \     ${GLINT_WCAST_QUAL} \     ${GLINT_WCONVERSION} \     ${GLINT_WMISSING_DECLARATIONS} \     ${GLINT_WREDUNDANT_DECLS} \     ${GLINT_WMISSING_PROTOTYPES} \     ${GLINT_WNESTED_EXTERNS} \     ${GLINT_WPOINTER_ARITH} \     ${GLINT_WSHADOW} \     ${GLINT_WSTRICT_PROTOTYPES} \     ${GLINT_WTRADITIONAL} \     ${GLINT_WWRITE_STRINGS} \     ${GLINT_W} \     ${GLINT_EXTRA_FLAGS} \     -o /dev/null -O4 -g -c $*