clifton_r@verifone.com (11/13/90)
The following contains the changes to my draft V7 C spec since its last
posting, in the form of a GNU diff with context. I am posting only diffs
to hold down the volume of the posting. I will mail the current spec to
any individual requesting it.
-- Clifton
--------------------------- c u t -- h e r e ---->8------------------------
*** v7spec.o24 Thu Oct 25 14:36:12 1990
--- v7spec.n08 Thu Nov 08 17:03:06 1990
***************
*** 1,3 ****
UNIX V7 C Language Specification
! Revision A.1. 24 October 1990
--- 1,3 ----
UNIX V7 C Language Specification
! Revision A.2. 08 November 1990
***************
*** 9,12 ****
! Tel: +1 808 623-2911
! FAX: +1 808 623-3201
--- 9,12 ----
! Tel: +1 808 623 2911
! FAX: +1 808 623 3201
***************
*** 15,16 ****
--- 15,21 ----
+ Modification history:
+ Rev A.1. 90/10/24 - first stable version of document
+ Rev A.2. 90/11/08 - deleted refs to "signed", added info on diff's
+ between Ritchie V7 C compiler and later PCC-based compilers.
+
0. INTRODUCTION
***************
*** 52,55 ****
! To summarize the usual V7 C extensions, this implementation of the C
! language supports:
o the "enum" declaration for enumerated types [3];
--- 57,60 ----
! To summarize the usual V7 C extensions, this dialect of the C language
! supports:
o the "enum" declaration for enumerated types [3];
***************
*** 60,68 ****
o the "void" data type (but not the "void *" of ANSI C);
! o the "signed char" type;
! o the "unsigned char", "unsigned short", and "unsigned long" types;
! o and calling of function pointers without an explicit dereference.
! o conditional assignment of structures and unions via "a?b:c";
! It also supports the following C features which are considered archaic
! or traditional, and are not supported in the most recent C compilers:
o "Old-fashioned" initializers, such as "int i 3;";
--- 65,89 ----
o the "void" data type (but not the "void *" of ANSI C);
! o separate member name spaces for structure and union types;
! o the "unsigned char", "unsigned short", and "unsigned long" types.
!
! NOTE: The original Ritchie C compiler distributed with UNIX Version 7
! supported only those features flagged with reference [3] above. It did
! not support the "void" data type, the additional "unsigned" types, or
! the separate name spaces for union/structure types.
!
! Steven Johnson's PCC was the first to implement these features, and the
! writers of most other V7 compilers followed his lead. A V7 C compiler which
! fails to support the "void" type, or the additional "unsigned" types, or
! which follows the Ritchie name-space rules for structure and union members,
! should preferably document the fact.
!
! Many V7 C compilers support the following additional extensions:
! o calling of function pointers without an explicit dereference;
! o conditional assignment of structures and unions via "a?b:c".
!
! These features should be specifically documented if supported.
! V7 C compilers also generally support the following C features which
! are considered archaic or traditional, and are not supported in the most
! recent C compilers:
o "Old-fashioned" initializers, such as "int i 3;";
***************
*** 72,73 ****
--- 93,95 ----
+
1. Introduction
***************
*** 79,86 ****
describe the functionality of, and the language implemented by the majority
! of C compilers released with UNIX Version 7. That is, it intends to
! describe the C dialect generally classed as "UNIX Version 7" C or V7 C. In
! some areas, a single behavior or feature set will be specified; in other
! areas, a range of behaviors will be described, any one of which may be
! considered acceptable or normal in a given implementation.
2. Lexical conventions
--- 101,111 ----
describe the functionality of, and the language implemented by the majority
! of C compilers released with UNIX Version 7, and by a number of subsequent
! compilers modeled on the Bell Labs C Compilers. That is, it intends to
! describe the C dialect generally classed as "UNIX Version 7" C or V7 C.
+ In some areas, a single behavior or feature set will be specified; in
+ other areas, a range of behaviors will be described, any one of which may be
+ considered acceptable or normal in a given implementation. Some historical
+ background will be given where appropriate.
+
2. Lexical conventions
***************
*** 126,130 ****
! The words "signed", "void", "enum", and possibly "asm" are reserved as
! keywords. The words "entry" and "fortran" are not reserved.
2.4. Constants
--- 151,160 ----
! The words "void", "enum", and possibly "asm" are reserved as keywords.
!
! The words "entry" and "fortran" are not reserved.
+ NOTE: "void" was not implemented in the original Ritchie V7 C compiler.
+ A very few V7 compilers may therefore fail to support it, but those
+ compilers should preferably document that it is not supported.
+
2.4. Constants
***************
*** 154,155 ****
--- 184,189 ----
+ NOTE: "unsigned long" was not implemented in the original Ritchie V7 C
+ compiler. A very few V7 compilers may therefore fail to support it, but
+ those compilers should preferably document that it is not supported.
+
2.4.2. Explicit long constants
***************
*** 172,173 ****
--- 206,211 ----
+ NOTE: "unsigned long" was not implemented in the original Ritchie V7 C
+ compiler. A very few V7 compilers may therefore fail to support it, but
+ those compilers should preferably document that it is not supported.
+
2.4.3 Character constants
***************
*** 225,229 ****
! The "signed" attribute may be used to modify an integral type
! declaration. Since this is the default attribute for "int"s, "short"s, and
! "long"s, this is primarily useful for "char" declarations.
--- 263,267 ----
! NOTE: "void" was not implemented in the original Ritchie V7 C compiler.
! A very few V7 compilers may therefore fail to support it, but those
! compilers should preferably document that it is not supported.
***************
*** 230,233 ****
The "char" type may be either signed or unsigned by default. A "char"
! type declaration may be explicitly declared as either "signed" or
! "unsigned".
--- 268,270 ----
The "char" type may be either signed or unsigned by default. A "char"
! type declaration may be explicitly declared as "unsigned".
***************
*** 241,242 ****
--- 278,284 ----
+ NOTE: "unsigned char" and "unsigned long" were not implemented in the
+ original Ritchie V7 C compiler. A very few V7 compilers may therefore
+ fail to support them, but those compilers should preferably document
+ that they are not supported.
+
5. Objects and lvalues
***************
*** 254,257 ****
The "char" type may be either signed or unsigned by default. A "char"
! type declaration may be explicitly declared as either "signed" or
! "unsigned".
--- 296,298 ----
The "char" type may be either signed or unsigned by default. A "char"
! type declaration may be explicitly declared as "unsigned".
***************
*** 281,282 ****
--- 322,328 ----
+ NOTE: "unsigned char" and "unsigned long" were not implemented in the
+ original Ritchie V7 C compiler. A very few V7 compilers may therefore
+ fail to support them, but those compilers should preferably document
+ that they are not supported.
+
6.2 Float and double
***************
*** 333,334 ****
--- 379,384 ----
+ NOTE: "void" was not implemented in the original Ritchie V7 C compiler.
+ A very few V7 compilers may therefore fail to support it, but those
+ compilers should preferably document that it is not supported.
+
Note that "++" and "--" are defined by this section to be unary
***************
*** 384,389 ****
! The second and third expressions of the conditional may be structures
! or unions of the same type, in which case the type of the expression is the
! common structure or union type. Not all V7 C compilers accept conditional
! assignment of structures or unions.
--- 434,445 ----
! Some V7 C compilers accept conditional assignment of structures or
! unions. In this case, the second and third expressions of the conditional
! may be structures or unions of the same type, in which case the type of the
! expression is the common structure or union type. Not all V7 C compilers
! accept this construct.
!
! Compilers differ substantially as to the complexity of the expression
! which can appear as the second operand. Some will accept a completely
! general expression (including an assignment expression), while others are
! more restricted.
***************
*** 432,437 ****
NOTE: The syntax given specifically permits the declarator-list to be
! omitted. Therefore "int ;" is a perfectly valid declaration, which declares
! no variables. A compiler may issue a warning for a declaration of this
! form.
8.1. Storage class specifiers
--- 488,498 ----
NOTE: The syntax given specifically permits the declarator-list to be
! omitted. Therefore "int ;" is a perfectly valid declaration, which
! declares no variables. A compiler may issue a warning for a
! declaration of this form.
+ NOTE: "unsigned char" and "unsigned long" were not implemented in the
+ original Ritchie V7 C compiler. A very few V7 compilers may therefore
+ fail to support them, but those compilers should preferably document
+ that they are not supported.
+
8.1. Storage class specifiers
***************
*** 444,447 ****
! "void" and "signed" must be added to the list of possible type-
! specifiers.
--- 505,511 ----
! "void" must be added to the list of possible type-specifiers.
!
! NOTE: "void" was not implemented in the original Ritchie V7 C compiler.
! A very few V7 compilers may therefore fail to support it, but those
! compilers should preferably document that it is not supported.
***************
*** 450,455 ****
! The word "signed" may be thought of as an additional adjective which
! may be applied to an integral type specifier; moreover, "unsigned" may be
! used in combination with "char", "short", and "long". This means the
! following additional combinations are acceptable:
--- 514,519 ----
! The word "unsigned" may be thought of as an adjective which may be
! applied to an integral type specifier; it may be used in combination with
! "char", "short", and "long". This means the following additional
! combinations are acceptable:
***************
*** 458,469 ****
unsigned long (or) unsigned long int
- signed char
- signed short (or) signed short int
- signed (or) signed int
- signed long (or) signed long int
! The keywords "signed", "unsigned", and "short" may not be applied to
! "float" or "double." The type "long double" is not supported.
! A V7 C compiler should always support the "void" type and "enum" types.
8.3 Declarators
--- 522,535 ----
unsigned long (or) unsigned long int
! The keywords "unsigned" and "short" may not be applied to "float" or
! "double." The type "long double" is not supported.
! NOTE: "unsigned char" and "unsigned long" were not implemented in the
! original Ritchie V7 C compiler. A very few V7 compilers may therefore
! fail to support them, but those compilers should preferably document
! that they are not supported.
+ A V7 C compiler must support the "enum" types, and should preferably
+ also support the "void" type.
+
8.3 Declarators
***************
*** 484,489 ****
different components. In Ritchie, component names for all structures were
! drawn from a single name space, and components of different structures could
! have the same name only if they had the identical type and identical offset
! (relative position) within the structure. A V7 C compiler should not
! enforce this restriction.
--- 550,560 ----
different components. In Ritchie, component names for all structures were
! drawn from a single name space, and components of different structure types
! could have the same name only if they had the identical type and identical
! offset (relative position) within the structure. A V7 C compiler should
! generally not enforce this restriction.
!
! NOTE: Separate name spaces for distinct structure and union types were
! not implemented in the original Ritchie V7 C compiler. A very few V7
! compilers may therefore fail to support them, but those compilers
! should preferably document that they are not supported.
***************
*** 698,700 ****
that block. The compiler documentation should describe which scope rule is
! followed in this case.
--- 769,771 ----
that block. The compiler documentation should describe which scope rule is
! followed for in this case.
***************
*** 831,837 ****
! A function pointer followed by a parenthesized parameter list is
! interpreted as a dereference of the function pointer, followed by a call of
! the function; thus following the declaration "int (*funcp)();" the two
! statements "(*funcp)();" and "funcp();" are equivalent.
14.3 Conditional compilation
--- 902,912 ----
! Some V7 C compilers will automatically dereference a function pointer
! in the context of a function call. That is, the use of the pointer,
! followed by a parenthesized parameter list, is interpreted as a dereference
! of the function pointer, followed by a call of the function; thus following
! the declaration "int (*funcp)();" the two statements "(*funcp)();" and
! "funcp();" are equivalent.
+ Not all V7 C compilers accept this usage.
+
14.3 Conditional compilation
***************
*** 889,891 ****
! Add "signed" and "void" to the type-specifier list.
--- 964,970 ----
! Add "void" to the type-specifier list.
!
! NOTE: "void" was not implemented in the original Ritchie V7 C compiler.
! A very few V7 compilers may therefore fail to support it, but those
! compilers should preferably document that it is not supported.
-------------------------------------------------------------------------------
clifton_r@zon.verifone.com