[m-rev.] diff: fix #line bug

[Fergus Henderson]

Estimated hours taken: 0.5
Branches: main

compiler/c_util.m:
	Change set_line_num so that if we do not have a valid context,
	it calls reset_line_num.

	Previous it would just not emit any #line directive, but that is wrong,
	because it causes the C compiler to assume that such lines come from
	the next line in the source file after wherever the previous line
	in the C file came from.  This is incorrect and can lead to confusing
	results.

Workspace: /home/ceres/fjh/mercury
Index: compiler/c_util.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/c_util.m,v
retrieving revision 1.12
diff -u -d -r1.12 c_util.m
--- compiler/c_util.m	24 Nov 2002 03:57:22 -0000	1.12
+++ compiler/c_util.m	14 Mar 2003 15:48:44 -0000
@@ -147,16 +147,19 @@
 
 c_util__set_line_num(File, Line) -->
 	globals__io_lookup_bool_option(line_numbers, LineNumbers),
-	(
-		{ Line > 0 },
-		{ File \= "" },
-		{ LineNumbers = yes }
-	->
-		io__write_string("#line "),
-		io__write_int(Line),
-		io__write_string(" """),
-		c_util__output_quoted_string(File),
-		io__write_string("""\n")
+	( { LineNumbers = yes } ->
+		(
+			{ Line > 0 },
+			{ File \= "" }
+		->
+			io__write_string("#line "),
+			io__write_int(Line),
+			io__write_string(" """),
+			c_util__output_quoted_string(File),
+			io__write_string("""\n")
+		;
+			c_util__reset_line_num
+		)
 	;
 		[]
 	).

-- 
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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