.\"
.\" Copyright (c) 2013 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by David A. Holland.
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.Dd June 11, 2013
.Dt TRADCPP 1
.Os
.Sh NAME
.Nm tradcpp
.Nd traditional (K&R-style) C macro preprocessor
.Sh SYNOPSIS
.Nm tradcpp
.Op Fl options
.Op Cm input-file Op Cm 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
.Xr imake 1 ,
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 arbirarily 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.
.It Fl -Ipath
Add the specified path to the main list of include directories.
.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 defintion for the named macro.
.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 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.
.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.
.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
.\" David A. Holland
.Sh BUGS
Probably plenty.