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Cppfront command line options

Cppfront is invoked using

cppfront [options] file ...

where

  • options is optional, and can include options described on this page

  • file ... is a list of one or more .cpp2 filenames to be compiled

Command line options are spelled starting with - or / followed by the option name. For example, -help prints help.

For convenience, you can shorten the name to any unique prefix not shared with another option. For example:

  • -help can be equivalently written as -hel, -he, or -h, because no other option starts with h.
  • -import-std and -include-std can be shortened to -im and -in respectively, but not -i which would be ambiguous with each other.

Basic command line options

-help, -h, -?

Prints an abbreviated version of this documentation page.

-import-std, -im

Makes the entire C++ standard library (namespace std::) available via a module import std.compat; (which implies import std;).

When you use either -import-std or -include-std, your .cpp2 program will not need to explicitly import any C++ standard library module or #include any C++ standard library header (it can still do that, but it would be redundant).

This option is implicitly set if -pure-cpp2 is selected.

This option is ignored if -include-std is selected. If your Cpp1 compiler does not yet support standard library modules std and std.compat, this option automatically uses -include-std instead as a fallback.

-include-std, -in

Makes the entire C++ standard library (namespace std::) available via an '#include" of every standard header.

This option should always work with all standard headers, including draft-standard C++26 headers that are not yet in a published standard, because it tracks new headers as they are added and uses feature tests to not include headers that are not yet available on your Cpp1 implementation.

-pure-cpp2, -p

Allow Cpp2 syntax only.

This option also sets -import-std.

-version, -vers

Print version, build, copyright, and license information.

Additional dynamic safety check controls

-no-comparison-checks, -no-c

Disable mixed-sign comparison safety checks. If not disabled, mixed-sign comparisons are diagnosed by default.

-no-div-zero-checks, -no-d

Disable integer division by zero checks. If not disabled, integer division by zero checks are performed by default when both the numerator and denominator are integer types.

-no-null-checks, -no-n

Disable null safety checks. If not disabled, null dereference checks are performed by default.

-no-subscript-checks, -no-s

Disable subscript bounds safety checks. If not disabled, subscript bounds safety checks are performed by default.

Support for constrained target environments

-fno-exceptions, -fno-e

Disable C++ exception handling. This should be used only if you must run in an environment that bans C++ exception handling, and so you are already using a similar command line option for your Cpp1 compiler.

If this option is selected, a failed as for std::variant will assert.

-fno-rtti, -fno-r

Disable C++ run-time type information (RTTI). This should be used only if you must run in an environment that bans C++ RTTI, and so you are already using a similar command line option for your Cpp1 compiler.

If this option is selected, trying to using as for * (raw pointers) or std::any will assert.

Cpp1 file content options

-clean-cpp1, -cl

Emit clean .cpp files without #line directives and other extra information that cppfront normally emits in the .cpp to light up C++ tools (e.g., to let IDEs integrate cppfront error message output, debuggers step to the right lines in Cpp2 source code, and so forth). In normal use, you won't need -c.

-emit-cppfront-info, -e

Emit cppfront version and build in the .cpp file.

-line-paths, -l

Emit absolute paths in #line directives.

Cppfront output options

-cwd path, -cw path

Changes the current working directory to 'path'. Can be useful in build scripts to control where generated Cpp1 files are places; see also -output.

-debug, -d

Emit compiler debug output. This is only useful when debugging cppfront itself.

-format-colon-errors, -fo

Emit cppfront diagnostics using :line:col: format for line and column numbers, if that is the format better recognized by your IDE, so that it will pick up cppfront messages and integrate them in its normal error message output location. If not set, by default cppfront diagnostics use (line,col) format.

-output filename, -o filename

Output to 'filename' (can be 'stdout'). If not set, the default output filename for is the same as the input filename without the 2 (e.g., compiling hello.cpp2 by default writes its output to hello.cpp, and header.h2 to header.h).

-quiet, -q

Print no console output unless there are errors to report.

-verbose, -verb

Print verbose statistics and -debug output.