The second field of an option record can specify any of the following properties. When an option takes an argument, it is enclosed in parentheses following the option property name. The parser that handles option files is quite simplistic, and will be tricked by any nested parentheses within the argument text itself; in this case, the entire option argument can be wrapped in curly braces within the parentheses to demarcate it, e.g.:
The option is available for all languages and targets.
The option is available for all languages but is target-specific.
The option is handled by the compiler driver using code not shared with the compilers proper (cc1 etc.).
The option is available when compiling for the given language.
It is possible to specify several different languages for the same
option. Each language must have been declared by an earlier
Language record. See Option file format.
The option is only handled by the compilers proper (cc1 etc.) and should not be accepted by the driver.
The option does not have a “no-” form. All options beginning with “f”, “W” or “m” are assumed to have a “no-” form unless this property is used.
The option will turn off another option othername, which is
the option name with the leading “-” removed. This chain action will
propagate through the
Negative property of the option to be
As a consequence, if you have a group of mutually-exclusive
Negative properties should form a circular chain.
For example, if options -a, -b and
-c are mutually exclusive, their respective
properties should be ‘Negative(b)’, ‘Negative(c)’
The option takes a mandatory argument.
that the option and argument can be included in the same
entry (as with
-mflush-func=name, for example).
Separate indicates that the option and argument can be
argv entries (as with
-o). An option is
allowed to have both of these properties.
The option takes an optional argument. If the argument is given,
it will be part of the same
argv entry as the option itself.
This property cannot be used alongside
For an option marked
Separate, the message
message will be used as an error message if the mandatory
argument is missing; for options without
generic error message is used. message should contain a single
‘%qs’ format, which will be used to format the name of the option
For an option marked
Separate, indicate that it takes n
arguments. The default is 1.
The option’s argument is a non-negative integer. The option parser
will check and convert the argument before passing it to the relevant
UInteger should also be used on options like
-falign-loops where both
-falign-loops=n are supported to make sure the saved
options are given a full integer.
The option’s argument should be converted to lowercase as part of
putting it in canonical form, and before comparing with the strings
indicated by any
For an option marked
Separate, the option only takes an
argument in the compiler proper, not in the driver. This is for
compatibility with existing options that are used both directly and
via -Wp,; new options should not have this property.
The state of this option should be stored in variable var
(actually a macro for
The way that the state is stored depends on the type of option:
InverseMaskproperties, var is the integer variable that contains the mask.
UIntegerproperty, var is an integer variable that stores the value of the argument.
Enumproperty, var is a variable (type given in the
Typeproperty of the ‘Enum’ record whose
Nameproperty has the same argument as the
Enumproperty of this option) that stores the value of the argument.
Deferproperty, var is a pointer to a
VEC(cl_deferred_option,heap)that stores the option for later processing. (var is declared with type
void *and needs to be cast to
The option-processing script will usually zero-initialize var.
You can modify this behavior using
The option controls an integer variable var and is active when
var equals set. The option parser will set var to
set when the positive form of the option is used and
when the “no-” form is used.
var is declared in the same way as for the single-argument form described above.
The variable specified by the
Var property should be statically
initialized to value. If more than one option using the same
Init, all must specify the same initializer.
The option is associated with a bit in the
variable (see Run-time Target) and is active when that bit is set.
You may also specify
Var to select a variable other than
The options-processing script will automatically allocate a unique bit
for the option. If the option is attached to ‘target_flags’,
the script will set the macro
MASK_name to the appropriate
bitmask. It will also declare a
TARGET_name macro that has
the value 1 when the option is active and 0 otherwise. If you use
to attach the option to a different variable, the bitmask macro with be
The option is the inverse of another option that has the
Mask(othername) property. If thisname is given,
the options-processing script will declare a
macro that is 1 when the option is active and 0 otherwise.
The option’s argument is a string from the set of strings associated with the corresponding ‘Enum’ record. The string is checked and converted to the integer specified in the corresponding ‘EnumValue’ record before being passed to option handlers.
The option should be stored in a vector, specified with
for later processing.
Alias(opt, posarg, negarg)
The option is an alias for -opt (or the negative form
of that option, depending on
NegativeAlias). In the first form,
any argument passed to the alias is considered to be passed to
-opt, and -opt is considered to be
negated if the alias is used in negated form. In the second form, the
alias may not be negated or have an argument, and posarg is
considered to be passed as an argument to -opt. In the
third form, the alias may not have an argument, if the alias is used
in the positive form then posarg is considered to be passed to
-opt, and if the alias is used in the negative form
then negarg is considered to be passed to -opt.
Aliases should not specify
UInteger. Aliases should normally specify the same languages
as the target of the alias; the flags on the target will be used to
determine any diagnostic for use of an option for the wrong language,
while those on the alias will be used to identify what command-line
text is the option and what text is any argument to that option.
Alias definition is used for an option, driver specs do
not need to handle it and no ‘OPT_’ enumeration value is defined
for it; only the canonical form of the option will be seen in those
For an option marked with
Alias(opt), the option is
considered to be an alias for the positive form of -opt
if negated and for the negative form of -opt if not
NegativeAlias may not be used with the forms of
Alias taking more than one argument.
This option is ignored apart from printing any warning specified using
Warn. The option will not be seen by specs and no ‘OPT_’
enumeration value is defined for it.
For an option marked with
Alias, the option only acts as an alias when passed a separate
argument; with a joined argument it acts as a normal option, with an
‘OPT_’ enumeration value. This is for compatibility with the
Java -d option and should not be used for new options.
If this option is used, output the warning message.
message is a format string, either taking a single operand with
a ‘%qs’ format which is the option name, or not taking any
operands, which is passed to the ‘warning’ function. If an alias
Warn, the target of the alias must not also be marked
The state of the option should be printed by -fverbose-asm.
This is a warning option and should be shown as such in --help output. This flag does not currently affect anything other than --help.
This is an optimization option. It should be shown as such in
--help output, and any associated variable named using
Var should be saved and restored when the optimization level is
This is an option that can be overridden on a per-function basis.
PerFunction, but options that do not
affect executable code generation may use this flag instead, so that the
option is not taken into account in ways that might affect executable
The option is deliberately missing documentation and should not be included in the --help output.
The option should only be accepted if preprocessor condition cond is true. Note that any C declarations associated with the option will be present even if cond is false; cond simply controls whether the option is accepted and whether it is printed in the --help output.
cl_target_option structure to hold a copy of the
option, add the functions
cl_target_option_restore to save and restore the options.
The option may also be set by a combined option such as
-ffast-math. This causes the
gcc_options struct to
have a field
is the name of the field holding the value of this option (without the
x_). This gives the front end a way to indicate that
the value has been set explicitly and should not be changed by the
combined option. For example, some front ends use this to prevent
-ffast-math and -fno-fast-math from changing the
value of -fmath-errno for languages that do not use
EnabledBy(opt || opt2)
EnabledBy(opt && opt2)
If not explicitly set, the option is set to the value of
-opt; multiple options can be given, separated by
||. The third form using
&& specifies that the option is
only set if both opt and opt2 are set. The options opt
and opt2 must have the
Common property; otherwise, use
LangEnabledBy(language, opt, posarg, negarg)
When compiling for the given language, the option is set to the value
of -opt, if not explicitly set. opt can be also a list
|| separated options. In the second form, if
opt is used in the positive form then posarg is considered
to be passed to the option, and if opt is used in the negative
form then negarg is considered to be passed to the option. It
is possible to specify several different languages. Each
language must have been declared by an earlier
record. See Option file format.
The option is omitted from the producer string written by -grecord-gcc-switches.
Even if this is a target option, this option will not be recorded / compared to determine if a precompiled header file matches.
The state of this option should be kept in sync with the preprocessor
option var. If this property is set, then properties
Init must be set as well.
This warning option corresponds to
cpplib.h warning reason code
CPP_W_Enum. This should only be used for warning options of the