1. Command Line Driver Program
   

This document describes the interface to the command line driver. Additional options for recent updates of Comeau C/C++ can be found at http://www.comeaucomputing.com/features.html. The command line driver is invoked by a command of the form

    como [options] ifile

The options follow below. Additional options for recent updates of Comeau C/C++ can be found at http://www.comeaucomputing.com/features.html. Note that whether strict mode (see below) is the default or not depends upon how you installed Comeau C++, at least for UNIX platforms. Under Windows, the default mode is not strict mode, and furthermore is --microsoft, which allows compatibility with the MS header files. For most platforms, when you invoke Comeau C++, it will tell you what mode it is in.

--preprocess
-E Do preprocessing only. Write preprocessed text to the preprocessing output file, with comments removed and with line control information.

-c Compile only. Do not link. Instiantiate only those templates directly "owned" by this file. Do not confuse this with the --c (note two dashes not one) option which specificies C90 mode. So if you want to compile and link a C90 source you'd write: como --c c.c and to compile but not link a C90 source you'd write: como -c --c c.c or como --c -c c.c and so on.

--no_line_commands
-P Do preprocessing only. Write preprocessed text to the preprocessing output file, with comments removed and without line control information.

--comments
-C Keep comments in the preprocessed output. This should be specified after either --preprocess or --no_line_commands; it does not of itself request preprocessing output.

--old_line_commands When generating source output (e.g., with the C-generating back end), put out #line directives in the form used by the Reiser cpp, i.e., "# nnn" instead of "#line nnn".

--dependencies
-M Do preprocessing only. Instead of the normal preprocessing output, generate on the preprocessing output file a list of dependency lines suitable for input to the UNIX make program. Note that when implicit inclusion of templates is enabled, the output may indicate false (but safe) dependencies unless --no_preproc_only is also used.

--trace_includes
-H Do preprocessing only. Instead of the normal preprocessing output, generate on the preprocessing output file a list of the names of files #included.

--define_macro name [ = def ]
-D name [ = def ] Define macro name as def. If "= def " is omitted, define name as 1.

--undefine_macro name
-Uname Remove any initial definition of the macro name. --undefine_macro options are processed after all --define_macro options in the command line have been processed.

--include_directory dir
-Idir Add dir to the list of directories searched for #includes. Files whose names are not absolute pathnames and that are enclosed in "..." will be searched for in the following directories, in the order listed:

1. The directory containing the current input file (the primary source file or the file containing the #include);
   
2. Any directories specified in --include_directory options (in the order in which they were listed on the command line);
   
3. Any directories on the standard list (this list is selected at the time of installation of the front end; often, it is just the one directory /usr/include or a similar system include directory for C++).
   
   For file names enclosed in <...>, only the directories that are specified using the --include_directory option and those on the standard list are searched. If dir is specified as "-", e.g., "-I-", the option indicates the point in the list of --include_directory options at which the search for file names enclosed in <...> should begin. That is, the search for <...> names should only consider directories named in --include_directory options following the -I-, and the directories of item 3 above. -I- also removes the directory containing the current input file (item 1 above) from the search path for file names enclosed in "...".
   
   

symbol-id name ref-code file-name line-number column-number
is written, where ref-code is D for definition, d for declaration (that is, a declaration that is not a definition), M for modification, A for address taken, U for used, C for changed (but actually meaning "used and modified in a single operation," such as an increment), R for any other kind of reference, or E for an error in which the kind of reference is indeterminate. symbol-id is a unique decimal number for the symbol. The fields of the above line are separated by tab characters.

--list lfile
-Llfile Generate raw listing information in the file lfile. This information is likely to be used to generate a formatted listing. The raw listing file contains raw source lines, information on transitions into and out of include files, and diagnostics generated by the front end. Each line of the listing file begins with a key character that identifies the type of line, as follows:
N: a normal line of source; the rest of the line is the text of the line.

X: the expanded form of a normal line of source; the rest of the line is the text of the line. This line appears following the N line, and only if the line contains non-trivial modifications (comments are considered trivial modifications; macro expansions, line splices, and trigraphs are considered non-trivial modifications).

S: a line of source skipped by an #if or the like; the rest of the line is text. Note that the #else, #elif, or #endif that ends a skip is marked with an N.

L: an indication of a change in source position. The line has a format similar to the # line-identifying directive output by cpp, that is to say

L line-number "file-name" key
where key is 1 for entry into an include file, 2 for exit from an include file, and omitted otherwise. The first line in the raw listing file is always an L line identifying the primary input file. L lines are also output for #line directives (key is omitted). L lines indicate the source position of the following source line in the raw listing file.

R, W, E, or C:
an indication of a diagnostic (R for remark, W for warning, E for error, and C for catastrophic error). The line has the form
S "file-name" line-number column-number message-text
where S is R, W, E, or C, as explained above. Errors at the end of file indicate the last line of the primary source file and a column number of zero. Command-line errors are catastrophes with an empty file name ("") and a line and column number of zero. Internal errors are catastrophes with position information as usual, and message-text beginning with (internal error). When a diagnostic displays a list (e.g., all the contending routines when there is ambiguity on an overloaded call), the initial diagnostic line is followed by one or more lines with the same overall format (code letter, file name, line number, column number, and message text), but in which the code letter is the lower case version of the code letter in the initial line. The source position in such lines is the same as that in the corresponding initial line.

--timing
-# Generate compilation timing information. This option causes the compiler to display the amount of CPU time and elapsed time used by each phase of the compilation and a total for the entire compilation.

--pch Automatically use and/or create a precompiled header file - for details, see the "Precompiled Headers" section in this chapter. If --use_pch or --create_pch (manual PCH mode) appears on the command line following this option, its effect is erased.

--create_pch file-name If other conditions are satisfied (see the "Precompiled Headers" section), create a precompiled header file with the specified name. If --pch (automatic PCH mode) or --use_pch appears on the command line following this option, its effect is erased.

--use_pch file-name Use a precompiled header file of the specified name as part of the current compilation. If --pch (automatic PCH mode) or --create_pch appears on the command line following this option, its effect is erased.

--pch_dir directory-name The directory in which to search for and/or create a precompiled header file. This option may be used with automatic PCH mode (--pch) or with manual PCH mode (--create_pch or --use_pch).

--pch_messages
--no_pch_messages Enable or disable the display of a message indicating that a precompiled header file was created or used in the current compilation.

--pch_mem size The number of 1024-byte units of preallocated memory in which to save precompiled-header state (for platforms where we have chosen not to use memory mapping or where it was not reasonably available). Contact us if you feel that you need to use this option.

--restrict
--no_restrict Enable or disable recognition of the restrict keyword.


--long_lifetime_temps
--short_lifetime_temps
Select the lifetime for temporaries: "short" means to end of full expression; "long" means to the earliest of end of scope, end of switch clause, or the next label. "short" is standard C++, and "long" is what cfront uses (the cfront compatibility modes select "long" by default).

--microsoft
--microsoft_16
--no_microsoft Enable or disable recognition of Microsoft extensions, as appropriate and applicable. --microsoft enables 32-bit mode. --microsoft_16 enables 16-bit mode (though only a few Microsoft 16-bit extensions are supported). When Microsoft extensions are recognized, language features that are not recognized by the Microsoft compiler are disabled by default. In most cases these features can then be enabled through use of other command line options (for example, --bool). Note that these options are only recognized under MS-Windows, or if you have a custom port of Comeau C/C++.

--far_data_pointers
--near_data_pointers
--far_code_pointers
--near_code_pointers Set the default size for pointers in 16-bit Microsoft mode, i.e., the memory model. Ignored in other modes.

--wchar_t_keyword
--no_wchar_t_keyword Enable or disable recognition of wchar_t as a keyword. This option is valid only in C++ mode. The front end can be configured to define a preprocessing variable when wchar_t is recognized as a keyword. This preprocessing variable may then be used by the standard header files to determine whether a typedef should be supplied to define wchar_t.

--bool
--no_bool Enable or disable recognition of bool. This option is valid only in C++ mode. The front end can be configured to define a preprocessing variable when bool is recognized. This preprocessing variable may then be used by header files to determine whether a typedef should be supplied to define bool.

--typename
--no_typename Enable or disable recognition of typename. This option is valid only in C++ mode.

--implicit_typename
--no_implicit_typename
Enable or disable implicit determination, from context, whether a template parameter dependent name is a type or nontype. The default value is implicit inclusion and can be changed via a custom porting arrangement. This option is valid only in C++ mode.

--special_subscript_cost
--no_special_subscript_cost
Enable or disable a special nonstandard weighting of the conversion to the integral operand of the [] operator in overload resolution. This is a compatibility feature that may be useful with some existing code. The special cost is enabled by default in cfront 3.0 mode. With this feature enabled, the following code compiles without error:

    struct A {
	A();
	operator int *();
	int operator[](unsigned);
    };
    int main() {
	A a;
	a[0];//Ambiguous,but allowed with this
		//option, operator[] is chosen
        return 0;
    }