.\"	$OpenBSD: tradcpp.1,v 1.4 2016/12/28 22:47:11 schwarze Exp $
.\"
.\" Copyright (c) 2013 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by David A. Holland.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
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.Dd $Mdocdate: December 28 2016 $
.Dt TRADCPP 1
.Os
.Sh NAME
.Nm tradcpp
.Nd traditional (K&R-style) C macro preprocessor
.Sh SYNOPSIS
.Nm tradcpp
.Op Fl options
.Op Ar input-file Op Ar output-file
.Sh DESCRIPTION
The
.Nm
command provides a traditional K&R-style C macro preprocessor.
It is intended to be suitable for historical Unix uses of the
preprocessor, such as
.Sy imake ,
particularly those that depend on preservation of whitespace.
.Pp
The chief ways in which traditional cpp differs from
Standard C are:
.Bl -bullet -offset indent
.It
Macro arguments are expanded within quoted strings.
There is no stringize operator.
.It
There is no token pasting operator; tokens can be concatenated by
placing comments between them.
This process is also not limited to valid C language tokens.
.It
Whitespace is preserved, and in particular tabs are not expanded into
spaces.
Furthermore, additional whitespace is not injected.
.El
.Sh OPTIONS
.Nm
has many options, many of which are defined for compatibility with
.Xr gcc 1
or other compilers.
Many of the options are not yet implemented.
.\" The option lists have been sorted in what I hope is a sensible
.\" order. Please don't arbitrarily alphabetize them.
.Ss Common Options
.Bl -tag -width bubblebabble
.It Fl C
Retain comments in output.
.It Fl Dmacro[=expansion]
Provide a definition for the named macro.
If no expansion is provided, the value
.Dq 1
is used.
Note that like many Unix compilers,
.Nm
does not accept a space between the
.Dq D
and the macro name.
.It Fl Ipath
Add the specified path to the main list of include directories.
Note that like many Unix compilers,
.Nm
does not accept a space between the
.Dq I
and the directory name.
.It Fl nostdinc
Do not search the standard system include directories.
.It Fl P
Suppress line number information in the output.
Currently line number information is not generated at all and this
option has no effect.
.It Fl Umacro
Remove any existing definition for the named macro.
Note that like many Unix compilers,
.Nm
does not accept a space between the
.Dq U
and the macro name.
.It Fl undef
Remove all predefined macros.
.El
.Ss Warning Options
Warning options can be disabled or enabled by inserting, or not, the
string
.Dq no-
between the
.Dq W
and the warning name.
Herein the
.Dq Fl Wno-
form is shown for options that are enabled by default.
.Bl -tag -width bubblebabble
.It Fl Wall
Turn on all warnings.
The option
.Fl Wno-all
disables only the warnings that are disabled by default.
.It Fl w
Turn off all warnings.
.It Fl Werror
Make warnings into fatal errors.
.It Fl Wcomment
Warn about nested comments.
.It Fl Wno-endif-labels
Don't warn about symbols attached to #endif directives.
(The warning is currently not implemented.)
.It Fl Wundef
Warn about undefined symbols appearing in #if and #elif expressions.
.It Fl Wunused-macros
Warn about macros that are defined and never used.
Not implemented.
.El
.Ss Depend Options
.Bl -tag -width bubblebabble
.It Fl M
Generate dependency information for
.Xr make 1
on the standard output, instead of preprocessing.
Not implemented.
.It Fl MD
Like
.Fl M
but skip system headers.
Not implemented.
.It Fl MM
Like
.Fl M
but write the dependency information to a file named after the input
file with extension
.Pa \.d
and preprocess normally to standard output.
Not implemented.
.It Fl MMD
Like
.Fl MM
but skip system headers.
Not implemented.
.It Fl MF Ar file
Send dependency output to the named file instead of the default
location.
Not implemented.
.It Fl MG
When generating dependency information, assume that missing files are
generated instead of failing.
Not implemented.
.It Fl MP
Issue dummy rules for all include files.
This prevents
.Xr make 1
from choking if an include file is removed.
Not implemented.
.It Fl MQ Ar target
Same as
.Fl MT
except that any
.Xr make 1
metacharacters appearing in the target are escaped.
.It Fl MT Ar target
Set the name of the
.Xr make 1
target appearing in the generated dependency information.
The default is the name of the input file with its suffix replaced
with the suffix for object files, normally
.Pa .o .
.\" If this option is given more than once, all named targets will
.\" be emitted.
.\" (The current operating mode framework doesn't support that.)
.El
.Ss More Include Path Options
.Bl -tag -width bubblebabble
.It Fl idirafter Ar path
Add the specified path to the
.Dq afterwards
include path.
This path is searched after all directories specified with
.Fl I
and the standard system directories.
Directories on this path are treated as containing system include
files.
.It Fl imacros Ar file
Read in
.Ar file
prior to reading the main input file, and preprocess it, but throw
away the output and retain only the macro definitions.
.It Fl include Ar file
Read in and preprocess
.Ar file
prior to reading the main input file.
.It Fl iprefix Ar prefix
Set the path prefix used with the
.Fl iwithprefix
option.
.It Fl iquote Ar path
Add
.Ar path
to the list of directories searched for include directives written
with quotes.
This list is not searched for include directives written with angle
brackets.
.It Fl iremap Ar string:replacement
Substitute
.Ar replacement
for
.Ar string
in the
.Dv __FILE__
built-in macro.
Not supported.
.It Fl isysroot Ar path
Use
.Ar path
as the
.Dq system root ,
that is, the directory under which the standard system paths are found.
.It Fl isystem Ar path
Add
.Ar path
to the list of system include directories.
This list is searched after the list given with
.Ar I .
Files found on this path are treated as system headers.
.It Fl iwithprefix Ar dir
Splice
.Ar dir
onto the prefix given with
.Fl iprefix
and add this directory as if it were specified with
.Fl idirafter .
.It Fl iwithprefixbefore Ar dir
Like
.Fl iwithprefix
but adds the result as if it were specified with
.Fl I .
.El
.Ss Diagnostic Options
.Bl -tag -width bubblebabble
.It Fl dD
Dump all macro definitions, except for the predefined macros, after
the normal preprocessing output.
Not implemented.
.It Fl dI
Dump all include directives along with the normal preprocessing
output.
Not implemented.
.It Fl dM
Dump all macro definitions instead of the normal preprocessing
output.
Not implemented.
.It Fl dN
Like
.Fl dD
but emits only macro names and not the expansions.
Not implemented.
.It Fl H
Output a trace of the include tree as it gets processed.
Not implemented.
.El
.Ss Other Options
.Bl -tag -width bubblebabble
.It Fl CC
Retain comments in output.
Same as
.Fl C ,
accepted for compatibility with
.Xr gcc 1 .
.It Fl fdollars-in-identifiers , Fl fno-dollars-in-identifiers
Enable
.Pq or disable, respectively
the use of the dollar sign in identifiers.
Not implemented.
.It Fl ftabstop=num
Set the tab width to the specified value, for reporting column
positions in diagnostics.
The default is 8.
Not implemented.
.It Fl std=standard
Ask
.Nm
to conform to the named standard.
The default, and the only supported value, is
.Dq krc .
.It Fl traditional
This option is accepted for compatibility with
.Xr gcc 1
and ignored.
.It Fl x Ar lang
Adjust the preprocessor for the given language.
The only values accepted for
.Ar lang
are
.Dq assembler-with-cpp
and
.Dq c ,
neither of which have any effect on the behavior of
.Nm .
.El
.Sh FILES
The default list of directories searched for include files is:
.Bl -item -offset indent -compact
.It
.Pa /usr/local/include
.It
.Pa /usr/include
.El
.Sh SEE ALSO
.Xr cc 1 ,
.Xr cpp 1 ,
.Xr make 1
.Sh STANDARDS
None.
The whole point of a traditional cpp is that it reflects practices
in pre-standardization implementations of C.
Some information is available from the first edition of Kernighan and
Ritchie.
Much of the rest of the behavior is based on lore, pragmatism,
material encountered in the wild, and comparison to other
implementations.
.Sh HISTORY
The original version of
.Nm
was written one evening in late 2010.
This version had some problems and was put aside.
The first working version was released in June 2013.
.\" .Sh AUTHORS
.\" .An David A. Holland
.Sh BUGS
Probably plenty.