[m-rev.] for review: disallow `#if' in C `pragma foreign_type'

[Fergus Henderson]

Estimated hours taken: 0.75
Branches: main

Document that C preprocessor directives are not permitted in C
`pragma foreign_type' declarations.

doc/reference_manual.texi:
	Document that C preprocessor directives are not permitted in
	C `pragma foreign_type' declarations.  This is needed because we
	generate uses of foreign types inside macro invocations, e.g.
	MR_MAYBE_BOX_FOREIGN_TYPE(), and the ISO C standard does not
	permit preprocessor directives inside macro invocations.

	(It would be nicer for the compiler to generate a C typedef,
	and then generate references to the typedef name inside
	MR_MAYBE_BOX_FOREIGN_TYPE() rather than copying the user's type
	definition directly.  But it's not very important, and this
	is an easier fix.)

	Also, some minor clarifications to the documentation for
	C and Java `foreign_type' pragmas.

Workspace: /home/jupiter/fjh/ws-jupiter/mercury
Index: doc/reference_manual.texi
===================================================================
RCS file: /home/mercury1/repository/mercury/doc/reference_manual.texi,v
retrieving revision 1.285
diff -u -d -r1.285 reference_manual.texi
--- doc/reference_manual.texi	23 Dec 2003 02:53:09 -0000	1.285
+++ doc/reference_manual.texi	30 Dec 2003 10:27:49 -0000
@@ -6019,7 +6019,13 @@
 A C @samp{pragma foreign_type} declaration has the form:
 
 @example
-:- pragma foreign_type("C", @var{MercuryTypeName}, @var{CForeignType}).
+:- pragma foreign_type("C", @var{MercuryTypeName}, "@var{CForeignType}").
+ at end example
+
+For example,
+
+ at example
+:- pragma foreign_type("C", long_double, "long double").
 @end example
 
 The @var{CForeignType} can be any C type name that obeys the following
@@ -6031,6 +6037,9 @@
 @samp{void (*)(void)}.  However, it would be OK to use a typedef name
 which was defined as a function pointer type.)
 
+C preprocessor directives (such as @samp{#if}) may not be used in
+ at var{CForeignType}.
+
 @strong{With @samp{--gc accurate}, foreign_types which are C pointer types
 must not point to the Mercury heap.}
 
@@ -6316,7 +6325,7 @@
 A Java @samp{pragma foreign_type} declaration has the form:
 
 @example
-:- pragma foreign_type("Java", @var{MercuryTypeName}, @var{JavaType}).
+:- pragma foreign_type("Java", @var{MercuryTypeName}, "@var{JavaType}").
 @end example
 
 The @var{JavaType} can be any accessible Java type.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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