[m-rev.] diff: avoid a warning from gcc

[Julien Fischer]

Estimated hours taken: 0.5
Branches: main

Avoid a warning about lvalue casts being deprecated in non .gc grades.

compiler/mercury_deep_copy.c:
	When assigning to MR_hp do so through MR_hp_word, rather
	than via MR_hp (which shouldn't be used as an lvalue).

Julien.

Index: mercury_deep_copy.c
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/mercury_deep_copy.c,v
retrieving revision 1.35
diff -u -r1.35 mercury_deep_copy.c
--- mercury_deep_copy.c	13 Sep 2005 08:25:38 -0000	1.35
+++ mercury_deep_copy.c	20 Jan 2006 06:21:20 -0000
@@ -141,6 +141,19 @@
 		(val2) = swap_tmp;	\
 	} while (0)

+/*
+** The above macro won't suffice when we want to swap the pointers to the
+** heap and the global heap since it will cause gcc to emit warnings about
+** lvalue casts being deprecated.  In that case we use the following macro.
+*/
+#define SWAP_HEAP_AND_GLOBAL_HEAP			\
+	do {						\
+		MR_Word *swap_tmp;			\
+		swap_tmp = MR_hp;			\
+		MR_hp_word = (MR_Word) MR_global_hp; 	\
+		MR_global_hp = swap_tmp;		\
+	} while (0)
+
 #ifdef MR_MIGHT_RECLAIM_HP_ON_FAILURE

 /*
@@ -163,8 +176,8 @@
 	/* temporarily swap the heap with the global heap */
 	SWAP(MR_ENGINE(MR_eng_heap_zone), MR_ENGINE(MR_eng_global_heap_zone),
 		MR_MemoryZone *);
-	SWAP(MR_hp, MR_global_hp, MR_Word *);
-
+	SWAP_HEAP_AND_GLOBAL_HEAP;
+
 	/* copy values from the heap to the global heap */
 	MR_save_transient_hp();
 	result = MR_deep_copy(term, type_info, lower_limit,
@@ -174,8 +187,8 @@
 	/* swap the heap and global heap back again */
 	SWAP(MR_ENGINE(MR_eng_heap_zone), MR_ENGINE(MR_eng_global_heap_zone),
 		MR_MemoryZone *);
-	SWAP(MR_hp, MR_global_hp, MR_Word *);
-
+	SWAP_HEAP_AND_GLOBAL_HEAP;
+
 	MR_save_transient_hp();	/* Because we played with MR_hp */

 	return result;

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