2C(1)							      General Commands Manual							     2C(1)

NAME

       2c, 6c, 8c, kc, vc, xc - C compilers

SYNOPSIS

       2c [ option ...	] [ file ...  ]
       6c [ option ...	] [ file ...  ]
       8c [ option ...	] [ file ...  ]
       kc [ option ...	] [ file ...  ]
       vc [ option ...	] [ file ...  ]
       xc [ option ...	] [ file ...  ]

DESCRIPTION

       2c, 6c, 8c, kc, vc, and xc compile the named C files into MC68020, i960, i386, SPARC, MIPS, and ATT3210 object files.  The compilers handle
       most preprocessing directives themselves; a complete preprocessor is available in cpp(1), which must be run separately.

       Let the first letter of the compiler name be O= 2, 6, 8, k, v, or x.  The output object files end in .O.  The letter is also the prefix	of
       related	programs: Oa is the assembler, Ol is the loader.  Associated with each compiler is a string objtype= 68020, 960, 386, sparc, mips,
       or 3210.  Plan 9 conventionally sets the $objtype environment variable to the objtype string appropriate to  the  current  machine's  type.
       Plan  9	also conventionally has /objtype directories, which contain among other things: include, for machine-dependent include files; lib,
       for public object code libraries; bin, for public programs; and mkfile, for preconditioning mk(1).

       The compiler options are:

       -o obj	 Place output in file obj (allowed only if there is just one input file).  Default is to take the last element of the  input  file
		 name, strip any trailing .c, and append .O.

       -w	 Print warning messages about unused variables, etc.

       -B	 Accept  functions  without  a	new-style  ANSI  C  function prototype.  By default, the compilers reject functions used without a
		 defined prototype, although ANSI C permits them.

       -Dname=def
       -Dname	 Define the name to the preprocessor, as if by If no definition is given, the name is defined as

       -Idir	 An file whose name does not begin with slash or is enclosed in double quotes is always sought first in the directory of the  file
		 argument.   If  this  fails,  or  the	name  is  enclosed  in	<>,  it is then sought in directories named in -I options, then in
		 /sys/include, and finally in /$objtype/include.

       -N	 Suppress automatic registerization and optimization.

       -S	 Print an assembly language version of the object code on standard output as well as generating the .O file.

       -a	 Instead of compiling, print on standard output acid functions (see acid(1)) for  examining  structures  declared  in  the  source
		 files.

       -aa	 Like -a except suppress information about structures declared in included header files.

       The compilers support several extensions to ANSI C:

       -      A structure or union may contain unnamed substructures and subunions.  The fields of the substructures or subunions can then be used
	      as if they were members of the parent structure or union (the resolution of a name conflict is unspecified).  When a pointer to  the
	      outer  structure	or  union is used in a context that is only legal for the unnamed substructure, the compiler promotes the type and
	      adjusts the pointer value to point at the substructure.  If the unnamed structure or union is of a type with a tag name specified by
	      a typedef statement, the unnamed structure or union can be explicitly referenced by <struct variable>.<tagname>.

       -      A structure value can be formed with an expression such as
		  (struct S){v1, v2, v3}
	      where the list elements are values for the fields of struct S.

       -      Array initializers can specify the indices of the array in square brackets, as
		  int a[] = { [3] 1, [10] 5 };
	      which initializes the third and tenth elements of the eleven-element array a.

       -      Structure initializers can specify the structure element by using the name following a period, as
		  int struct { int x; int y; } s = { .y 1, .x 5 };
	      which initializes elements y and then x of the structure s.

       -      A global variable can be dedicated to a register by declaring it extern register in all modules and libraries.

       -      A #pragma of the form
		  #pragma lib "libbio.a"
	      records  that the program needs to be loaded with file /$objtype/lib/libbio.a; such lines, typically placed in library header files,
	      obviate the -l option of the loaders.  To help identify files in non-standard directories, within the file names in the #pragmas the
	      string $M represents the name of the architecture (e.g., mips) and $O represents its identifying character (e.g., v).

       -      The C++ comment (// to end of line) is accepted as well as the normal convention of /* */.

       -      The compilers accept long long variables as a 64-bit type.  The standard header typedefs this to vlong.  The vlong runtime is slow.

EXAMPLE

       For the 68020, produce a program prog from C files main.c and sub.c:

	      2c -w main.c sub.c
	      2l -o prog main.2 sub.2

FILES

       /sys/include
	      system area for machine-independent #include directives.

       /$objtype/include
	      system area for machine-dependent #include directives.

SOURCE

       /sys/src/cmd/cc
	      machine-independent part

       /sys/src/cmd/2c, etc.
	      machine-dependent part

SEE ALSO

       2a(1), 2l(1), cpp(1), mk(1), nm(1), pcc(1), db(1), acid(1),

       Rob Pike, ``How to Use the Plan 9 C Compiler''

BUGS

       The i960 compiler has been used only to program one I/O controller and is certainly buggy.

       The preprocessor only handles and For a full ANSI preprocessor, use cpp(1) on the files first.

																	     2C(1)