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From: Bryan@SU-SIERRA.ARPA (Doug Bryan)
Newsgroups: net.lang.ada
Subject: pragmas
Message-ID: <8605100458.AA10347@ucbvax.Berkeley.EDU>
Date: Wed, 7-May-86 00:55:53 EDT
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Posted: Wed May  7 00:55:53 1986
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Sam,

Yes, the language-defined (Appendix B) pragmas need not be "recognized" 
by an implementation, yet all language-defined pragmas must be "supported"
by an implementation.  Here "recognized" means implemented, the semantics
hold; "supported" simply means that the existance of a language-defined
pragma cannot make a compilation unit syntactically invalid.  This is my
interpretation.  Let me tell you why:

2.8(8)	... language-defined pragmas "must be supported by every 
	 implementation."
2.8(11)	"It is recommended (but not required) that implementations issue 
	 warnings for pragmas that are not recognized and therefore ignored."

Par (11) says that an implementation may "ignore" a pragma.  So here in
2.8 we see that there must be a difference between 'not support' and "ignore".

11.7(1)	"The presence of a SUPPRESS pragma give permission to an implementation
	 to omit curtain run-time checks."
11.7(3) "The permission to omit the given check extends ..."
11.7(20) "For curtain implementations, it may be impossible or too costly
	  to suppress curtain checks.  The corresponding SUPPRESS pragma 
	  can be ignored."

6.3.2(1) "The pragma INLINE is used to indicate that inline expansion of the
	  subprogram body is desired for every call to each of the named
	  subprograms."
6.3.2(4) "For each call of the named subprograms, an implementation is free
	  to follow or to ignore the recommendation expressed by the pragma."

It seems clear that the pragmas SUPPRESS and INLINE are optional.
In the explination of other pragmas, for instance SHARED 9.11(9-11),
the word "must" often appears and the reader does not get any indication
that the pragma is optional.  In such cases, one must revert back to 
2.8(11).  In these cases, 2.8(11) has precedence, and thus all pragmas
are optional yet "supported".

doug
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