169 NEW: Compiler
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     With Clipper 5.0, a completely new compiler has been supplied.
     This compiler is considerably more complex than the Summer '87
     compiler with many more options and some new behaviors.  The
     following is a list of some of the major changes this compiler
     represents over the Summer '87 compiler:

     1. Preprocessor:  The Clipper 5.0 compiler includes a built-in
        preprocessor that automatically runs each time a program (.prg)
        file is compiled.  Its basic function is similar to that of a C
        compiler preprocessor: it scans the text of the program you are
        compiling, searching and replacing text according to rules
        defined by preprocessor directives.  Refer to the list of
        directives above.

     2. Commands:  All commands in Clipper 5.0 are defined by the
        preprocessor directives #command and #translate.

     3. Standard Commands:  All Clipper 5.0 standard commands are
        defined in the header file STD.CH.

     4. Command-line options:  All compiler options can be specified
        prefaced by the backslash (/) character as well as the dash (-)
        character.

     5. Options:  All new (and modified) compiler options are
        summarized below:

        Table: New and Changed Compiler Options
        -----------------------------------------------------------------
        Option    Meaning
        -----------------------------------------------------------------
        /A        Automatic MEMVAR declaration
        /B        Include debugging information in object file
        /CREDIT   Display the Clipper 5.0 credits
        /D        Define an identifier to the pre-processor
        /I        Specify an #include file search path
        /N        Specify no implicit starting procedure
        /P        In previous releases, this option allowed you to load
                  the compiler and switch disks.  This feature is no
                  longer supported.  The /P option is now used to
                  generate a pre-processed output (.ppo) file.
        /R        Request linker to search named library
        /U        Specify a user-defined standard header file
        /V        Assume references to undeclared or unaliased variable
                  names are public or private variables
        /W        Enable warning messages for undeclared variables, etc.
        -----------------------------------------------------------------

     6. Environment variables:  In addition to command-line options,
        the Clipper 5.0 compiler can now use environment variables to
        control compiler operations as follows:

        Table: Compiler Environment Variables
        -----------------------------------------------------------------
        Variable     Meaning
        -----------------------------------------------------------------
        CLIPPERCMD   Defines default compiler command-line options
        INCLUDE      Specifies a path list to search for header files
        TMP          Specifies a directory for creating temporary files
        -----------------------------------------------------------------

     7. (.clp) files:  There are two changes that have been made to
        compiler (.clp) script files.  First, files specified in a
        (.clp) file can include a drive and path spec.  Second, files
        specified in a (.clp) file can optionally include an extension.

     8. Pickiness:  As a general principle, the Clipper 5.0 compiler
        provides a high degree of compatibility with the Summer '87
        compiler.  However, it adheres to a more rigorously defined
        semantic model and, therefore, is pickier in some cases about
        syntax that was accepted by the Summer '87 compiler.

     9. Optimization:  The Clipper 5.0 compiler performs several types
        of optimization including:

        .  Shortcutting
        .  Constant folding
        .  Dead code removal

        Refer to Release Note #4 for more details on this subject.