--- a/src/lex.l	Wed Dec 22 22:11:51 1999 +0000
+++ b/src/lex.l	Wed Dec 22 23:36:14 1999 +0000
@@ -165,6 +165,8 @@
 
 static bool Vwarn_separator_insert = false;
 
+static bool Vwarn_single_quote_string = false;
+
 // Forward declarations for functions defined at the bottom of this
 // file.
 
@@ -189,6 +191,7 @@
 static yum_yum eat_whitespace (void);
 static yum_yum eat_continuation (void);
 static void maybe_warn_separator_insert (char sep);
+static void gripe_single_quote_string (void);
 
 %}
 
@@ -1755,6 +1758,10 @@
 
 		  yylval.tok_val = new token (s);
 		  token_stack.push (yylval.tok_val);
+
+		  if (delim == '\'')
+		    gripe_single_quote_string ();
+
 		  return TEXT;
 		}
 	    }
@@ -2217,6 +2224,22 @@
     }
 }
 
+static void
+gripe_single_quote_string (void)
+{
+  string nm = curr_fcn_file_full_name;
+
+  if (Vwarn_single_quote_string)
+    {
+      if (nm.empty ())
+	warning ("single quote delimited string near line %d",
+		 input_line_number);
+      else
+	warning ("single quote delimited string near line %d of file %s",
+		 input_line_number, nm.c_str ());
+    }
+}
+
 static int
 warn_separator_insert (void)
 {
@@ -2226,6 +2249,14 @@
 }
 
 static int
+warn_single_quote_string (void)
+{
+  Vwarn_single_quote_string = check_preference ("warn_single_quote_string");
+
+  return 0;
+}
+
+static int
 whitespace_in_literal_matrix (void)
 {
   int pref = 0;
@@ -2252,6 +2283,10 @@
     "print warning if commas or semicolons that might be inserted\n\
 automatically in literal matrices");
 
+  DEFVAR (warn_single_quote_string, 0.0, warn_single_quote_string,
+    "print warning if a signle quote character is used to introduce a\n\
+ string constant");
+
   DEFVAR (whitespace_in_literal_matrix, "", whitespace_in_literal_matrix,
     "control auto-insertion of commas and semicolons in literal matrices");
 }