[m-rev.] for review: fix singleton variable warning problem

[Peter Ross]

On Wed, May 29, 2002 at 03:34:23AM +1000, Simon Taylor wrote:
> This isn't an acceptable fix.
> 
How about this.

===================================================================


Estimated hours taken: 4
Branches: main

compiler/make_hlds.m:
    Avoid the problem with a variable with a non anonymous name in a
    Mercury clause is renamed to an anonymous variable name by
    interaction merging in the varset of a pragma foreign_code, and
    hence causes spurious warnings.

tests/valid/Mmakefile:
tests/valid/no_warn_singleton.m:
    A test case.


Index: compiler/make_hlds.m
===================================================================
RCS file: /home/staff/zs/imp/mercury/compiler/make_hlds.m,v
retrieving revision 1.411
diff -u -r1.411 make_hlds.m
--- compiler/make_hlds.m	9 May 2002 16:30:55 -0000	1.411
+++ compiler/make_hlds.m	30 May 2002 16:36:08 -0000
@@ -5644,9 +5644,13 @@
 		io__write_string("  in the argument list.\n"),
 		io__set_exit_status(1)
 	;
-		% merge the varsets of the proc and the new pragma_c_code
+		% Merge the varsets of the proc and the new foreign_proc.
+		% Note that we discard the names of the foreign_proc as
+		% this avoids problems with anonymous variables and
+		% implementations in Mercury.
 		{
-		varset__merge_subst(VarSet0, PVarSet, VarSet1, Subst),
+		varset__merge_subst_without_names(VarSet0,
+				PVarSet, VarSet1, Subst),
 		map__apply_to_list(Args0, Subst, TermArgs),
 		term__term_list_to_var_list(TermArgs, Args),
 
Index: tests/valid/Mmakefile
===================================================================
RCS file: /home/staff/zs/imp/tests/valid/Mmakefile,v
retrieving revision 1.102
diff -u -r1.102 Mmakefile
--- tests/valid/Mmakefile	14 May 2002 14:34:41 -0000	1.102
+++ tests/valid/Mmakefile	30 May 2002 12:49:36 -0000
@@ -135,6 +135,7 @@
 	nasty_func_test.m \
 	nested_mod_type_bug.m \
 	nondet_live.m \
+	no_warn_singleton.m \
 	parsing_bug_main.m \
 	pred_with_no_modes.m \
 	qualified_cons_id.m \
@@ -299,6 +300,7 @@
 MCFLAGS-livevals_seq		= -O5 --opt-space
 MCFLAGS-middle_rec_labels	= --middle-rec --no-follow-vars 
 MCFLAGS-mostly_uniq_mode_inf	= --infer-all
+MCFLAGS-no_warn_singleton	= --halt-at-warn
 MCFLAGS-pred_with_no_modes	= --infer-all
 MCFLAGS-quantifier_warning	= --halt-at-warn
 MCFLAGS-simplify_bug		= -O-1
Index: tests/valid/no_warn_singleton.m
===================================================================
RCS file: tests/valid/no_warn_singleton.m
diff -N tests/valid/no_warn_singleton.m
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ tests/valid/no_warn_singleton.m	30 May 2002 09:20:53 -0000
@@ -0,0 +1,17 @@
+% Check that we don't warn about _IO0 and _IO being used more than once.
+:- module no_warn_singleton.
+
+:- interface.
+
+:- import_module io.
+
+:- pred p(int::out, io::di, io::uo) is det.
+
+:- implementation.
+
+:- pragma foreign_proc("C", p(X::out, _IO0::di, _IO::uo),
+		[will_not_call_mercury, promise_pure], "
+	X = 5;
+").
+
+p(5) --> [].

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