Compaq C
Compaq C
User's Guide for OpenVMS Systems
1.3.1.1 Including Header Files
Header files are pieces of source code that typically contain
declarations shared among C programs. A header file often declares a
set of related functions, as well as defining any types and macros
needed for their use.
To make the contents of a header file available to your program,
include the header file using the
#include
preprocessor directive.
The
#include
directive has three forms. Two of the forms are defined by the ISO C
standard and are portable:
- Inclusion using angle brackets to delimit the file to be included:
- Inclusion using quotation marks to delimit the file to be included:
The third form is the text-module form. It is specific to
OpenVMS systems and is not portable. See Section 5.2.3 for
more information on the text-module form of inclusion.
The form of the
#include
directive used determines where the compiler will look to find the file
to be included. Generally, the compiler looks in the following places,
in the order listed:
- Places named on the command line with the /INCLUDE_DIRECTORY
qualifier or the /LIBRARY qualifier
- Places identified through logical names, such as DECC$USER_INCLUDE,
DECC$SYSTEM_INCLUDE, DECC$LIBRARY_INCLUDE, and DECC$TEXT_LIBRARY
- System-defined places such as the SYS$COMMON:[DECC$LIB.INCLUDE.*]
directory and the SYS$LIBRARY:DECC$RTLDEF.TLB and
SYS$LIBRARY:SYS$STARLET_C.TLB text libraries
You can use the UNUSED message group described in the
#pragma message
description in Section 5.4.13 to enable messages that report apparently
unnecessary
#include
files (and CDD records). Unlike any other messages, these messages must
be enabled on the command line (/WARNINGS=ENABLE=UNUSED), rather than
with
#pragma message
, to be effective.
The Compaq C preprocessor is usually able to determine if a
particular
#include
file that has already been processed once was guarded by the
conventional sequence:
#ifndef FILE_SEEN, #define FILE_SEEN, #endif
.
When the compiler detects this pattern of use the first time a
particular file is included, it remembers that fact as well as the name
of the macro. The next time the same file is included, the compiler
checks to see if the "FILE_SEEN" macro is still defined and, if so, it
does not reopen and reread the file. Note that if the initial test is
in the form
#if !defined
instead of
#ifndef
, then the pattern is not recognized. In a listing file,
#include
directives that are skipped because of this processing are marked with
an "X" just as if the
#include
line itself were excluded.
See the /INCLUDE_DIRECTORY qualifier in Section 1.3.4 for a more
complete description of the search-order rules that Compaq C uses
to locate included files.
See the Compaq C Run-Time Library Reference Manual for OpenVMS Systems for information on the
header files required to use Compaq C Run-Time Library (RTL) functions and macros.
1.3.1.2 Listing Header Files
To list the names of system header files, use the following commands:
$ LIBRARY/LIST SYS$LIBRARY:SYS$STARLET_C.TLB
(OpenVMS Alpha and OpenVMS VAX Version 7.1 and higher)
$ LIBRARY/LIST SYS$LIBRARY:DECC$RTLDEF.TLB
$ DIR SYS$COMMON:[DECC$LIB.REFERENCE.SYS$STARLET_C]*.H;
$ DIR SYS$COMMON:[DECC$LIB.REFERENCE.DECC$RTLDEF]*.H;
$ DIR SYS$LIBRARY:*.H;
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These commands list, respectively:
- The names of the text-module header files for the OpenVMS
system interfaces
- The names of the text-module header files for the Compaq C
language interfaces
- *.h header files for the OpenVMS system interfaces
- *.h header files for the Compaq C language interfaces
- *.h header files for layered products and other applications
Note
The SYS$COMMON:[DECC$LIB.REFERENCE.DECC$RTLDEF] and
SYS$COMMON:[DECC$LIB.REFERENCE.SYS$STARLET_C] directories are only
reference areas for your viewing. They are created during the compiler
installation from the content of the text libraries. By default, the
compiler searches only the text library files for headers; it does not
search these reference directories.
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Be aware that OpenVMS VAX operating systems prior to Version
7.1 do not have a file named SYS$LIBRARY:SYS$STARLET_C.TLB. For these
older versions of the operating system, the STARLET header files are
generated during Compaq C installation and placed in
SYS$LIBRARY:DECC$RTLDEF.TLB and also in both
SYS$COMMON:[DECC$LIB.REFERENCE.DECC$RTLDEF] and
SYS$COMMON:[DECC$LIB.REFERENCE.SYS$STARLET_C].
1.3.2 Compilation Modes
Compaq C has two complementary qualifiers that control which
dialect of C is to be recognized by the compiler, and which messages
are generated:
- The /STANDARD qualifier controls what language features and
extensions are recognized by the compiler.
- The /[NO]WARNINGS qualifier enables or disables the generation of
warning and/or informational messages.
The /STANDARD qualifier causes the compiler to issue only those
warnings appropriate for the dialect of C being compiled. For example,
VAX C compatibility mode (/STANDARD=VAXC) does not issue warnings
against VAX C extensions, while ANSI C mode does.
To generate a list of all messages that are in effect at the start of
compilation, specify /LIST/SHOW=MESSAGES. For each message, the
identifier, severity, and message text are shown. To also show the
message description and user action for each message listed, specify
/LIST/SHOW=MESSAGES/WARN=VERBOSE.
The Compaq C compiler for OpenVMS systems provides
several dialects of C, which are controlled by the /STANDARD qualifier:
-
Strict ANSI C: Only the ANSI C Standard 89 (C89) language dialect is
recognized. This mode is enabled by specifying /STANDARD=ANSI89 on the
CC command line.
/STANDARD=ANSI89 issues all diagnostics required
by the ANSI C standard as well as a number of optional diagnostics that
help detect source code constructs that are not portable under the C89
standard. Digraph recognition from the 1994 Amendment is also supported
in this mode.
You can use /STANDARD=ANSI89 with /[NO]WARNINGS to
control issuance of informational or warning messages. However, since
the compiler does not recognize many VAX C or common C extensions when
in strict ANSI mode (for example, VAX C keywords not beginning with two
underscores), many of the messages normally associated with flagging
VAX C and common C extensions are not produced.
-
Strict C99 (ALPHA ONLY): Only the ISO C99 dialect is recognized. This
mode is enabled by specifying /STANDARD=C99 on the CC command line.
/STANDARD=C99 accepts just the C99 language without extensions, and
diagnoses violations of the C99 standard. Because C99 is a superset of
Amendment 1 to the C89 standard, and the default mode of RELAXED_ANSI89
is a superset of C99, the __STDC_VERSION__ macro is now defined with the
C99-specified value of 199901L. Only when the ISOC94 keyword is added
to the strict ANSI89, MIA, or COMMON modes does the macro take on the
Amendment 1 value of 199409L (In the absence of the ISOC94 keyword, the
ANSI89, MIA, and COMMON modes do not define the macro at all.)
Note
/STANDARD=C99 is not fully supported on VAX systems. Specifying
/STANDARD=C99 on OpenVMS VAX systems produces a warning and puts the
compiler into /STANDARD=RELAXED_ANSI mode.
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- Relaxed ANSI C:
This is the default mode on OpenVMS systems, and is specified
by /NOSTANDARD or /STANDARD=RELAXED_ANSI89 on the CC command line. The
/STANDARD=RELAXED mode accepts ANSI/ISO C Standard C89 and C99
features, as well as nearly all language extensions (such as additional
Compaq C keywords and predefined macros that do not begin with an
underscore). It excludes only K&R (COMMON mode), VAX C, and
Microsoft features that conflict with standard C. The purpose of the
/STANDARD=RELAXED mode is to support everything from the most current
ISO C standard, in addition to all extensions that do not specify
different semantics for the same constructs.
-
Microsoft compatibility: This mode interprets source programs according
to certain language rules followed by the C compiler provided with the
Microsoft Visual C++ compiler product. This mode is enabled by
specifying /STANDARD=MS on the CC command line. See Section 1.3.3 for
more information about Microsoft compatibility mode.
- ISO C 94:
This mode is enabled by specifying /STANDARD=ISOC94. It can be
specified alone or with any other /STANDARD option except VAXC. If it
is specified alone, the default major mode is RELAXED_ANSI89.
Specifying /STANDARD=ISOC94 enables digraph processing
and defines the predefined macro
__STDC_VERSION__=199409L
,
as specified by Amendment 1 to the C89 standard.
-
VAX C compatibility: This mode is enabled by specifying /STANDARD=VAXC.
It allows the same language as the ANSI C language, but also supports
VAX C extensions that are incompatible with the ANSI C Standard and
that change the language semantics. This mode provides compatibility
for programs that depend on old VAX C behavior.
-
Portable: This mode is enabled by specifying /STANDARD=PORTABLE. It
places the compiler in RELAXED_ANSI89 mode and enables the issuance of
diagnostics that warn about any nonportable usages encountered.
/STANDARD=PORTABLE is supported for VAX C compatibility only. It is
equivalent to the recommended combination of qualifiers
/STANDARD=RELAXED_ANSI89/WARNINGS=ENABLE=PORTABLE.
-
Common usage C: This mode is enabled by specifying /STANDARD=COMMON. It
enforces K & R programming style; that is, compatibility with older
UNIX compilers such as
pcc
and
gcc
. This mode is close to a subset of /STANDARD=VAXC mode.
-
MIA conformance: This mode is enabled by specifying /STANDARD=MIA. This
is strict ANSI C with some differences required by the Multivendor
Integration Architecture (MIA) standard. Compiling a program with
/STANDARD=MIA sets the
__MIA
predefined macro to 1.
With one exception, the /STANDARD qualifier options are mutually
exclusive. Do not combine them. The exception is that you can specify
/STANDARD=ISOC94 with any other option except VAXC.
Compaq C modules compiled in different modes can be linked and
executed together.
The /STANDARD qualifier is further described in Section 1.3.4.
Also see the
__HIDE_FORBIDDEN_NAMES
predefined macro ( Section 6.1.7).
1.3.3 Microsoft Compatibility Compilation Mode
The /STANDARD=MS qualifier instructs the Compaq C compiler to
interpret your source code according to certain language rules followed
by the C compiler provided with the Microsoft Visual C++ compiler
product. However, compatibility with this implementation is not
complete. The following sections describe the compatibility situations
that Compaq C recognizes. In most cases, these situations consist
of relaxing a standard behavior and suppressing a diagnostic message.
1.3.3.1 Unnamed Nested struct or union Members
Allow a declaration of a structure with no name within another
structure. You can reference all members of the inner structure as
members of the named outer structure. This is similar to the C++
treatment of nested unions lacking a name, but extended to both
structures and unions. A similar capability is provided by the VAX C
variant_struct
and
variant_union
types.
For example:
struct{
struct{
int a;
int b;
}; /*No name here */
int c;
}d; /* d.a, d.b, and d.c are valid member names. */
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1.3.3.2 Block Scope Declaration of static Functions
Allow a
static
function declaration in block scope (that is, inside another function).
For example:
f(){
static int a(int b);
}
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1.3.3.3 Treat &* as Having No Effect
ANSI C does not allow the
&
operator to produce an lvalue expression. The Microsoft relaxation
allows
&
to produce an lvalue in certain cases.
For example:
int *a, *b;
f() {
&*a=b;
}
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1.3.3.4 Integer and Pointer Comparisons without a Cast
Allow integers and pointers to be compared without a cast.
For example:
int *a,b;
f(){
if (a==b)
b=1;
}
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1.3.3.5 char is Not Treated as a Unique Type
Treat the
char
type as either
signed char
or
unsigned char
, depending on the default in effect.
For example, a pointer to
char
can be assigned to a pointer to
signed char
, assuming the command-line default of /NOUNSIGNED_CHAR:
signed char *a;
char *b;
f() {
b=a;
}
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1.3.3.6 Double Semicolons in Declarations
Suppress warning messages for declarations that contain two semicolons.
(That is, allow completely empty declarations at file scope.)
For example:
1.3.3.7 Declaration without a Type
Suppress warning messages for declarations that contain a variable name
but no type.
For example:
1.3.3.8 Enumerators in an Enumeration Declaration
Ignore any extra comma at the end of the last enumerator in an
enumeration declaration.
For example:
enum E {a, b, c,}; /* Ignore the comma after "c". /*
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1.3.3.9 Useless Typedefs
Allow
typedef
s that have a type specifier but no identifier name declaring the new
type.
For example:
typedef struct { int a; };
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1.3.3.10 Unrecognized Pragmas Accepted
Suppress warning messages when one of the following unsupported
Microsoft pragmas is encountered:
#pragma code_seg
#pragma optimize
#pragma warning
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1.3.4 CC Command Qualifiers
The following list shows all the command qualifiers and their defaults
available with the CC command. A description of each qualifier follows
the list.
You can place command qualifiers either on the CC command line itself
or on individual file specifications (with the exception of the
/LIBRARY qualifier). If placed on a file specification, the qualifier
affects only the compilation of the specified source file and all
subsequent source files in the compilation unit. If placed on the CC
command line, the qualifier affects all source files in all compilation
units unless it is overridden by a qualifier on an individual file
specification.
| Command Qualifiers |
Default |
|
/ACCEPT=(option[,option])
|
See text.
|
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/[NO]ANALYSIS_DATA[=file-spec]
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/NOANALYSIS_DATA
|
|
/[NO]ANNOTATIONS[=(option,...)]
|
/NOANNOTATIONS
|
|
/[NO]ANSI_ALIAS (ALPHA ONLY)
|
See text.
|
|
/ARCHITECTURE=option (ALPHA ONLY)
|
/ARCHITECTURE=GENERIC
|
|
/ASSUME=(option[,...])
|
See text.
|
|
/[NO]CHECK[=(option,...)] (ALPHA ONLY)
|
/NOCHECK
|
|
/[NO]COMMENTS=option
|
See text.
|
|
/[NO]CROSS_REFERENCE
|
/NOCROSS_REFERENCE
|
|
/[NO]DEBUG[=(option[,...])]
|
/DEBUG=(TRACEBACK,
|
|
|
NOSYMBOLS) (ALPHA ONLY)
|
|
|
/DEBUG=(TRACEBACK,NOINLINE,
|
|
|
NOSYMBOLS) (VAX ONLY)
|
|
/DECC
|
See text.
|
|
/[NO]DEFINE=(identifier[=definition][,...])
|
/NODEFINE
|
|
/[NO]DIAGNOSTICS[=file-spec]
|
/NODIAGNOSTICS
|
|
/ENDIAN=option (ALPHA ONLY)
|
/ENDIAN=LITTLE
|
|
/[NO]ERROR_LIMIT[=n]
|
/ERROR_LIMIT=30
|
|
/EXTERN_MODEL=option
|
/EXTERN_MODEL=RELAXED_REFDEF
|
|
/[NO]FIRST_INCLUDE=(file[,...]) (ALPHA ONLY)
|
/NOFIRST_INCLUDE
|
|
/FLOAT=option
|
/FLOAT=G_FLOAT (ALPHA ONLY)
|
|
|
/FLOAT=D_FLOAT (VAX ONLY)
|
|
/[NO]G_FLOAT
|
/G_FLOAT (ALPHA ONLY)
|
|
|
/NOG_FLOAT (VAX ONLY)
|
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/GRANULARITY=option (ALPHA ONLY)
|
/GRANULARITY=QUADWORD
|
|
/[NO]INCLUDE_DIRECTORY=(pathname[,...])
|
/NOINCLUDE_DIRECTORY
|
|
/IEEE_MODE=option (ALPHA ONLY)
|
IEEE_MODE=FAST
|
|
/INSTRUCTION_SET=[NO]FLOATING_POINT (ALPHA ONLY)
|
/INSTRUCTION_SET=FLOATING_POINT
|
|
/L_DOUBLE_SIZE=option (ALPHA ONLY)
|
/L_DOUBLE_SIZE=128
|
|
/LIBRARY
|
See text.
|
|
/[NO]LINE_DIRECTIVES
|
/LINE_DIRECTIVES
|
|
/[NO]LIST[=file-spec]
|
/NOLIST (interactive mode)
|
|
|
/LIST (batch mode)
|
|
/[NO]MACHINE_CODE[=option]
|
/NOMACHINE_CODE
|
|
/[NO]MEMBER_ALIGNMENT
|
/MEMBER_ALIGNMENT (ALPHA ONLY)
|
|
|
/NOMEMBER_ALIGNMENT (VAX ONLY)
|
|
/[NO]MMS_DEPENDENCIES=option
|
/NOMMS_DEPENDENCIES
|
|
/NAMES=option
|
/NAMES=UPPERCASE
|
|
/NESTED_INCLUDE_DIRECTORY[=option]
|
/NESTED_INCLUDE_DIRECTORY
|
|
|
=INCLUDE_FILE
|
|
/[NO]OBJECT[=file-spec]
|
/OBJECT
|
|
/[NO]OPTIMIZE[=(option[,...])]
|
/OPTIMIZE
|
|
/PDSC_MASK=option (ALPHA ONLY)
|
See text.
|
|
/[NO]PLUS_LIST_OPTIMIZE (ALPHA ONLY)
|
/NOPLUS_LIST_OPTIMIZE
|
|
/[NO]POINTER_SIZE=option (ALPHA ONLY)
|
/NOPOINTER_SIZE
|
|
/PRECISION[=option]
|
See text.
|
|
/[NO]PREFIX_LIBRARY_ENTRIES
|
|
|
[=(option[,...])]
|
See text.
|
|
/[NO]PREPROCESS_ONLY[=filename]
|
/NOPREPROCESS_ONLY
|
|
/[NO]PROTOTYPES[=(option[,...])]
|
/NOPROTOTYPES
|
|
/PSECT_MODEL=[NO]MULTILANGUAGE (ALPHA ONLY)
|
/NOMULTILANGUAGE
|
|
/REENTRANCY=option (ALPHA ONLY)
|
/REENTRANCY=TOLERANT
|
|
/REPOSITORY=option
|
/See text.
|
|
/ROUNDING_MODE=option (ALPHA ONLY)
|
/ROUNDING_MODE=NEAREST
|
|
/[NO]SHARE_GLOBALS
|
/NOSHARE_GLOBALS
|
|
/SHOW[=(option[,...])]
|
/SHOW=(NOBRIEF,
|
|
|
NOCROSS_REFERENCE,
|
|
|
NODICTIONARY,
|
|
|
NOEXPANSION,
|
|
|
NOINCLUDE,
|
|
|
NOINTERMEDIATE,
|
|
|
NOMESSAGE,
|
|
|
NOSTATISTICS,
|
|
|
NOSYMBOLS,
|
|
|
NOTRANSLATION,
|
|
|
SOURCE,
|
|
|
TERMINAL)
|
|
/[NO]STANDARD[=(option[,...])]
|
/NOSTANDARD (equivalent to
|
|
|
/STANDARD=RELAXED_ANSI89 )
|
|
/[NO]TIE (ALPHA ONLY)
|
/NOTIE
|
|
/[NO]UNDEFINE=(identifier[,...])
|
/NOUNDEFINE
|
|
/[NO]UNSIGNED_CHAR
|
/NOUNSIGNED_CHAR
|
|
/VAXC (VAX ONLY)
|
See text.
|
|
/[NO]VERSION
|
/NOVERSION
|
|
/[NO]WARNINGS[=(option[,...])]
|
/WARNINGS
|
/ACCEPT=(option[,option])
Allows the compiler to accept C language syntax that it might not
normally accept.
Compaq C accepts slightly different syntax depending upon the
compilation mode specified with the /STANDARD qualifier. The /ACCEPT
qualifier can fine tune the language syntax accepted by each /STANDARD
mode.
The following qualifier options can be specified:
Table 1-1 /ACCEPT Qualifier Options
| Option |
Usage |
|
[NO]C99_KEYWORDS
|
Controls whether or not the C99 Standard keywords
inline
and
restrict
(which are are in the C89 namespace for user identifiers) are accepted
without double leading underscores. The spelling with two leading
underscores (
__inline
,
__restrict
) is in the namespace reserved to the compiler implementation and is
always recognized as a keyword regardless of this option.
|
|
[NO]GCCINLINE
|
The gcc compiler implements an
inline
function qualifier for functions with external linkage that gives
similar capabilites as the C99
extern inline
feature for functions, but the usage details are somewhat different:
the combination of
extern
and
inline
keywords makes an inline definition, instead of the exlusive use of the
inline
keyword without the
extern
keyword. This option controls which variation of the feature is
implemented.
|
|
[NO]RESTRICT_KEYWORD
|
Controls whether or not the compiler recognizes the C99 standard
restrict
keyword regardless of the /STANDARD mode used.
This only affects recognition of the spelling of the keyword as
proposed for inclusion in the C99 standard. The spelling with two
leading underscores,
__restrict
, is in the namespace reserved to the compiler implementation and is
always recognized as a keyword regardless of this option.
Note that [NO]RESTRICT_KEYWORD is a subset of [NO]C99_KEYWORDS. They
have the same compiler-mode defaults.
|
|
[NO]VAXC_KEYWORDS
|
Controls whether or not the compiler recognizes the VAX C keywords
(such as "readonly") regardless of the /STANDARD mode used.
|
The default values are based upon the settings of the /STANDARD
qualifier:
- For /STANDARD=RELAXED_ANSI89, the default is:
/ACCEPT=(VAXC_KEYWORDS,C99_KEYWORDS,NOGCCINLINE)
- For /STANDARD=VAXC, the default is:
/ACCEPT=(VAXC_KEYWORDS,NOC99_KEYWORDS,NOGCCINLINE)
- In all other modes, the default is:
/ACCEPT=(NOVAXC_KEYWORDS,NOC99_KEYWORDS,NOGCCINLINE)
/[NO]ANALYSIS_DATA[=file-spec]
Generates a file of source-code analysis information. The default file
name is the file name of the primary source file; the default file type
is .ANA. The .ANA file is reserved for use with Compaq layered
products. The default is /NOANALYSIS_DATA. For more information, see
Appendix C.
/[NO]ANNOTATIONS[=option]
Controls whether or not the source listing file is annotated with
indications of specific optimizations performed or, in some cases, not
performed. These annotations can be helpful in understanding the
optimization process.
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