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harbour-core/harbour/doc/compiler.txt
2000-03-23 01:41:28 +00:00

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/*
* $Id$
*/
/* $DOC$
* $FUNCNAME$
* Compiler Options
* $CATEGORY$
* Document
* $ONELINER$
* Compiler Options
* $DESCRIPTION$
*
* Invoking the Harbour compiler: </par>
* ============================== </par>
*
* harbour <file[.prg]> [options] </par>
* or </par>
* harbour [options] <file[.prg]> </par>
* or </par>
* harbour [options] <file[.prg]> [options] </par>
*
*
* The command line options have to be separated by at least one space.
* The option can start with either '/' character or '-' character. </par>
*
* The Harbour command line options: </par>
* ================================= </par>
*
* /a automatic memvar declaration </par>
* ----------------- </par>
* This causes all variables declared by PARAMETER, PRIVATE or PUBLIC
* statements to be automatically declared as MEMVAR variables. </par>
*
* /b debug info </par>
* ----------------- </par>
* The compiler generates all information required for debugging </par>
*
* /d<id>[=<val>] #define <id> </par>
* ----------------- </par>
*
* /es[<level>] set exit severity </par>
* ----------------- </par>
*
* /es or /es0 - all warnings are ignored and exit code returned by
* the compiler (accessed by DOS ERRORLEVEL command)
* is equal to 0 if there are no errors in compiled
* source file. </par>
* /es1 - any warnings generate a non-zero exit code, but
* output is still created. </par>
* /es2 - all warnings are treated as errors and no output
* file is created. The exit code is set to a non-zero
* value. </par>
*
* /g<type> output type generated is <type> </par>
* ----------------- </par>
*
* /gc output type: C source (.c) (default) </par>
* /gf output type: Windows/DOS OBJ32 (.obj) </par>
* /gh output type: Harbour Portable Object (.hrb) </par>
* /gj output type: Java source (.java) </par>
* /gp output type: Pascal source (.pas) </par>
* /gr output type: Windows resource (.rc) </par>
*
* /i<path> add #include file search path </par>
* ----------------- </par>
*
* /l suppress line number information </par>
* ----------------- </par>
* The compiler does not generate the source code line numbers in
* the output file. The PROCLINE() function will return 0 for
* modules compiled using this option. </par>
*
* /m compile current module only </par>
* ----------------- </par>
*
* /n no implicit starting procedure </par>
* ----------------- </par>
* The compiler does not create a procedure with the same name as
* the compiled file. This means that any declarations placed
* before the first PROCEDURE or FUNCTION statement have file-
* wide scope and can be accessed/used in all functions/procedures
* defined in the compiled source file. All executable statements
* placed at the beginning of the file and before the first
* PROCEDURE/FUNCTION statement are ignored. </par>
*
* /o<path> output file drive and/or path </par>
* ----------------- </par>
*
* /p generate pre-processed output (.ppo) file </par>
* ----------------- </par>
* The compiler only creates the file that contains the result of
* pre-processing the source file. </par>
*
* /q quiet </par>
* ----------------- </par>
* The compiler does not print any messages during compiling
* (except the copyright info). </par>
*
* /q0 be really quiet and don't display even the copyright info </par>
*
* /r[<lib>] request linker to search <lib> (or none) </par>
* ----------------- </par>
* Currently not supported in Harbour. </par>
*
* /s syntax check only </par>
* ----------------- </par>
* The compiler checks the syntax only. No output file is generated. </par>
*
* /t<path> path for temp file creation </par>
* ----------------- </par>
* Currently not used in Harbour (the Harbour compiler does not
* create any temporary files). </par>
*
* /u[<file>] use command definition set in <file> (or none) </par>
* ----------------- </par>
* Not supported yet. </par>
*
* /v variables are assumed M-> </par>
* ----------------- </par>
* All undeclared or unaliased variables are assumed MEMVAR
* variables (private or public variables). If this switch is not
* used then the scope of such variables is checked at runtime. </par>
*
* /w[<level>] set warning level number (0..3, default 1) </par>
* ----------------- </par>
*
* /w0 - no warnings </par>
* /w or /w1 - Clipper compatible warnings </par>
* /w2 - some useful warnings missed in Clipper </par>
* /w3 - warnings generated for Harbour language extensions </par>
*
* /x[<prefix>] set symbol init function name prefix (for .c only) </par>
* ----------------- </par>
* Sets the prefix added to the generated symbol init function name
* (in C output currently). This function is generated
* automatically for every PRG module compiled. This additional
* prefix can be used to suppress problems with duplicated symbols
* during linking an application with some third party libraries. </par>
*
* /y trace lex & yacc activity </par>
* ----------------- </par>
* The Harbour compiler uses the FLEX and YACC utilities to parse
* the source code and to generate the required output file. This
* option traces the activity of these utilities. </par>
*
* /z suppress logical shortcutting (.and. & .or.) </par>
* ----------------- </par>
*
* /10 restrict symbol length to 10 characters </par>
* ----------------- </par>
* All variable and function names are cut to maximum 10 characters. </par>
*
*
* Compilation in batch mode. </par>
* ========================== </par>
*
* @<file> compile list of modules in <file> </par>
* ----------------- </par>
* Not supported yet. </par>
*
*
*
* Known incompatibilities between harbour and clipper compilers </par>
* ============================================================= </par>
*
* NOTE: </par>
* If you want a 100% compatible compile and runtime libraries then
* you have to define HARBOUR_STRICT_CLIPPER_COMPATIBILITY. This
* option should be defined in the file include/hbsetup.h (in fact this
* option is placed in a comment by default - you need to remove the
* /* */ characters only). This change has to be done before invoking
* the make utility. </par>
*
*
* Handling of undeclared variables </par>
* -------------------------------- </par>
* When a value is assigned to an undeclared variable and the '-v'
* command line option is not used, then the Clipper compiler assumes
* that the variable is a PRIVATE or a PUBLIC variable and generates
* POPM (pop memvar) opcode. </par>
*
* When the value of an undeclared variable is accessed and the '-v'
* command line option is not used, the Clipper compiler generates PUSHV
* (push variable) opcode that determines the type of variable at runtime.
* If a field with the requested name exists in the current workarea then
* its value is used. If there is no field then a PRIVATE or a PUBLIC
* variable is used (if exists). </par>
*
* The Harbour compiler generates an opcode to determine the type of
* variable at runtime (POPVARIABLE or PUSHVARIABLE) in both cases
* (assignment and access). </par>
*
* The difference can be checked by the following code: </par>
* <fixed>
* PROCEDURE MAIN()
* PRIVATE myname
*
* DBCREATE( "TEST", { { "MYNAME", "C", 10, 0} } )
* USE test NEW
* SELECT test
* APPEND BLANK
*
* FIELD->myname := "FIELD"
* MEMVAR->myname := "MEMVAR"
*
* myname := myname + " assigned"
*
* // In Clipper: "FIELD", In Harbour: "FIELD assigned"
* ? FIELD->myname
*
* // In Clipper: "MEMVAR assigned", In Harbour: "MEMVAR"
* ? MEMVAR->myname
*
* USE
*
* RETURN
* </fixed>
*
* Passing an undeclared variable by the reference </par>
* ----------------------------------------------- </par>
* The Clipper compiler uses the special opcode PUSHP to pass a
* reference to an undeclared variable ( '@' operator ). The type of
* passed variable is checked at runtime (field or memvar). However,
* field variables cannot be passed by reference. This means that
* Clipper checks the memvar variable only and doesn't look for a field.
* This is the reason why the Harbour compiler uses the usual
* PUSHMEMVARREF opcode in such cases. Notice that the runtime behavior
* is the same in Clipper and in Harbour - only the generated opcodes
* are different. </par>
*
*
* Handling of object messages </par>
* --------------------------- </par>
* The HARBOUR_STRICT_CLIPPER_COMPATIBILITY setting determines
* the way chained send messages are handled. </par>
*
* For example, the following code: </par>
*
* a:b( COUNT() ):c += 1 </par>
*
* will be handled as: </par>
*
* a:b( COUNT() ):c := a:b( COUNT() ):c + 1 </par>
*
* in strict Clipper compatibility mode and </par>
*
* temp := a:b( COUNT() ), temp:c += 1 </par>
*
* in non-strict mode. </par>
*
* In practice, Clipper will call the COUNT() function two times:
* the first time before addition and the second one after addition.
* In Harbour, COUNT() will be called only once, before addition. </par>
*
* The Harbour (non-strict) method is: </par>
* 1) faster </par>
* 2) it guarantees that the same instance variable of the same object
* will be changed </par>
*
* (See also: source/compiler/expropt.c) </par>
*
* Initialization of static variables </par>
* ---------------------------------- </par>
*
* There is a difference in the initialization of static
* variables that are initialized with a codeblock that refers to
* a local variable. For example: </par>
* <fixed>
* PROCEDURE TEST()
* LOCAL MyLocalVar
* STATIC MyStaticVar := {|| MyLocalVar }
*
* MyLocalVar :=0
* ? EVAL( MyStaticVar )
*
* RETURN
* </fixed>
* The above code compiles fine in Clipper, but it generates a
* runtime error Error/BASE 1132 Bound error: array access
* Called form (b)STATICS$(0) </par>
*
* In Harbour this code generates a compile time error:
* Error E0009 Illegal variable (b) initializer: 'MyLocalVar' </par>
*
* Both Clipper and Harbour are handling all local variables used in a
* codeblock in a special way: they are detached from the local stack
* of function/procedure where they are declared. This allows access to
* these variables after the exit from a function/procedure. However,
* all static variables are initialized in a separate procedure
* ('STATICS$' in Clipper and '(_INITSTATICS)' in Harbour) before the
* main procedure and before all INIT procedures. The local variables
* don't exist on the eval stack when static variables are initialized,
* so they cannot be detached. </par>
*
* $END$
*/