Update (diff) to draft of V7 C description

clifton_r at verifone.com clifton_r at verifone.com
Tue Nov 13 15:24:22 AEST 1990


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.

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