makedepend - create dependencies in makefiles
makedepend [ -Dname=def ] [ -Dname ] [
  -Iincludedir ] [ -Yincludedir ]
 [ -a ] [ -fmakefile ] [ -include file
  ] [ -oobjsuffix ]
 [ -pobjprefix ] [ -sstring ] [
  -wwidth ] [ -v ] [ -m ]
 [ -- otheroptions -- ] sourcefile ...
The makedepend program reads each sourcefile in sequence and
  parses it like a C-preprocessor, processing all #include,
  #define, #undef, #ifdef, #ifndef, #endif,
  #if, #elif and #else directives so that it can correctly
  tell which #include, directives would be used in a compilation. Any
  #include, directives can reference files having other #include
  directives, and parsing will occur in these files as well.
Every file that a sourcefile includes, directly or
    indirectly, is what makedepend calls a dependency. These
    dependencies are then written to a makefile in such a way that
    make(1) will know which object files must be recompiled when a
    dependency has changed.
By default, makedepend places its output in the file named
    makefile if it exists, otherwise Makefile. An alternate
    makefile may be specified with the -f option. It first searches the
    makefile for the line
 # DO NOT DELETE THIS LINE -- make depend depends on it.
or one provided with the -s option, as a delimiter for the
    dependency output. If it finds it, it will delete everything following this
    to the end of the makefile and put the output after this line. If it doesn't
    find it, the program will append the string to the end of the makefile and
    place the output following that. For each sourcefile appearing on the
    command line, makedepend puts lines in the makefile of the form
   sourcefile.o: dfile ...
Where sourcefile.o is the name from the command line with
    its suffix replaced with ``.o'', and dfile is a dependency discovered
    in a #include directive while parsing sourcefile or one of the
    files it included.
Normally, makedepend will be used in a makefile target so that typing
  ``make depend'' will bring the dependencies up to date for the makefile. For
  example,
    SRCS = file1.c file2.c ...
    CFLAGS = -O -DHACK -I../foobar -xyz
    depend:
            makedepend -- $(CFLAGS) -- $(SRCS)
The program will ignore any option that it does not understand so that you may
  use the same arguments that you would for cc(1).
  - -Dname=def or -Dname
- Define. This places a definition for name in makedepend's
      symbol table. Without =def the symbol becomes defined as
    ``1''.
- -Iincludedir
- Include directory. This option tells makedepend to prepend
      includedir to its list of directories to search when it encounters
      a #include directive. By default, makedepend only searches
      the standard include directories (usually /usr/include and possibly a
      compiler-dependent directory).
- -Yincludedir
- Replace all of the standard include directories with the single specified
      include directory; you can omit the includedir to simply prevent
      searching the standard include directories.
- -a
- Append the dependencies to the end of the file instead of replacing
    them.
- -fmakefile
- Filename. This allows you to specify an alternate makefile in which
      makedepend can place its output. Specifying ``-'' as the file name
      (i.e., -f-) sends the output to standard output instead of
      modifying an existing file.
- -include file
- Process file as input, and include all the resulting output before
      processing the regular input file. This has the same affect as if the
      specified file is an include statement that appears before the very first
      line of the regular input file.
- -oobjsuffix
- Object file suffix. Some systems may have object files whose suffix is
      something other than ``.o''. This option allows you to specify another
      suffix, such as ``.b'' with -o.b or ``:obj'' with -o:obj and
      so forth.
- -pobjprefix
- Object file prefix. The prefix is prepended to the name of the object
      file. This is usually used to designate a different directory for the
      object file. The default is the empty string.
- -sstring
- Starting string delimiter. This option permits you to specify a different
      string for makedepend to look for in the makefile.
- -wwidth
- Line width. Normally, makedepend will ensure that every output line
      that it writes will be no wider than 78 characters for the sake of
      readability. This option enables you to change this width.
- -v
- Verbose operation. This option causes makedepend to emit the list
      of files included by each input file.
- -m
- Warn about multiple inclusion. This option causes makedepend to
      produce a warning if any input file includes another file more than once.
      In previous versions of makedepend this was the default behavior;
      the default has been changed to better match the behavior of the C
      compiler, which does not consider multiple inclusion to be an error. This
      option is provided for backward compatibility, and to aid in debugging
      problems related to multiple inclusion.
- -- options --
- If makedepend encounters a double hyphen (--) in the argument list,
      then any unrecognized argument following it will be silently ignored; a
      second double hyphen terminates this special treatment. In this way,
      makedepend can be made to safely ignore esoteric compiler arguments
      that might normally be found in a CFLAGS make macro (see the
      EXAMPLE section above). All options that makedepend
      recognizes and appear between the pair of double hyphens are processed
      normally.
The approach used in this program enables it to run an order of magnitude faster
  than any other ``dependency generator'' I have ever seen. Central to this
  performance are two assumptions: that all files compiled by a single makefile
  will be compiled with roughly the same -I and -D options; and
  that most files in a single directory will include largely the same files.Given these assumptions, makedepend expects to be called
    once for each makefile, with all source files that are maintained by the
    makefile appearing on the command line. It parses each source and include
    file exactly once, maintaining an internal symbol table for each. Thus, the
    first file on the command line will take an amount of time proportional to
    the amount of time that a normal C preprocessor takes. But on subsequent
    files, if it encounters an include file that it has already parsed, it does
    not parse it again.
For example, imagine you are compiling two files, file1.c
    and file2.c, they each include the header file header.h, and
    the file header.h in turn includes the files def1.h and
    def2.h. When you run the command
   makedepend file1.c file2.c
makedepend will parse file1.c and consequently,
    header.h and then def1.h and def2.h. It then decides
    that the dependencies for this file are
   file1.o: header.h def1.h def2.h
But when the program parses file2.c and discovers that it,
    too, includes header.h, it does not parse the file, but simply adds
    header.h, def1.h and def2.h to the list of dependencies
    for file2.o.
makedepend parses, but does not currently evaluate, the SVR4
  #predicate(token-list) preprocessor expression; such expressions are simply
  assumed to be true. This may cause the wrong #include directives to be
  evaluated.
Imagine you are parsing two files, say file1.c and
    file2.c, each includes the file def.h. The list of files that
    def.h includes might truly be different when def.h is included
    by file1.c than when it is included by file2.c. But once
    makedepend arrives at a list of dependencies for a file, it is cast
    in concrete.
Todd Brunhoff, Tektronix, Inc. and MIT Project Athena