E.1.13 Preprocessing Directives (G.3.13)

E.1.13.1 (6.8.1) Whether the value of a single-character character constant in a constant expression that controls conditional inclusion matches the value of the same character constant in the execution character set:

A character constant within a preprocessing directive has the same numeric value as it has within any other expression.

(6.8.1) Whether such a character constant may have a negative value:

Character constants in this context may have negative values (SPARC) (x86).

(6.8.2) The method for locating includable source files:

A file whose name is delimited by < > is searched for first in the directories named by the -I option, and then in the standard directory. The standard directory is /usr/include, unless the -YI option is used to specify a different default location.

A file whose name is delimited by quotes is searched for first in the directory of the source file that contains the #include, then in directories named by the -I option, and last in the standard directory.

If a file name enclosed in < > or double quotes begins with a / character, the file name is interpreted as a path name beginning in the root directory. The search for this file begins in the root directory only.

(6.8.2) The support of quoted names for includable source files:

Quoted file names in include directives are supported.

(6.8.2) The mapping of source file character sequences:

Source file characters are mapped to their corresponding ASCII values.

(6.8.6) The behavior on each recognized #pragma directive:

The following pragmas are supported. See 2.8 Pragmas for more information.

• align integer (variable[, variable])

• does_not_read_global_data (funcname [, funcname])

• does_not_return (funcname[, funcname])

• does_not_write_global_data (funcname[, funcname])

• error_messages (on|off|default, tag1[ tag2... tagn])

• fini (f1[, f2..., fn])

• ident string

• init (f1[, f2..., fn])

• inline (funcname[, funcname])

• int_to_unsigned (funcname)

• MP serial_loop

• MP serial_loop_nested

• MP taskloop

• no_inline (funcname[, funcname])

• nomemorydepend

• no_side_effect (funcname[, funcname])

• opt_level (funcname[, funcname])

• pack(n)

• pipeloop(n)

• rarely_called (funcname[, funcname])

• redefine_extname old_extname new_extname

• returns_new_memory (funcname[, funcname])

• unknown_control_flow (name[, name])

• unroll (unroll_factor)

• weak (symbol1 [= symbol2])

(6.8.8) The definitions for __DATE__ and __TIME__ when, respectively, the date and time of translation are not available:

These macros are always available from the environment.