"Fix" bug 1189. Basically, allowing multiple references to subgraphs

is dangerous, since it leads to cycles in the subgraph graph. Trying to
support this would be a headache, so we are moving to forbidding this
in DOT. At present, we give a severe warning.

diff --git a/lib/graph/lexer.c b/lib/graph/lexer.c
index f86afd1580fe4232253876cbef3c73e0e51ed33d..2e3c76a097d470c1065f0c9d972422af605d0c06 100644 (file)
--- a/lib/graph/lexer.c
+++ b/lib/graph/lexer.c
@@ -33,7 +33,7 @@ static int LineBufSize;
 static uchar In_comment;
 static uchar Comment_start;
 static uchar Start_html_string;
-static int Line_number;
+int Line_number;
 static char *InputFile;
 static gets_f Lexer_gets;
 
@@ -45,6 +45,11 @@ void agreadline(int n)
     Line_number = n - 1;
 }
 
+int aglinenumber ()
+{
+    return Line_number;
+}
+
   /* (Re)set file:
    */
 void agsetfile(char *f)

diff --git a/lib/graph/libgraph.h b/lib/graph/libgraph.h
index 609a80612c5b37a18e95fc194633ba0210905b36..5d411f1e09a53b4f1171e085d57f1476e130eaf5 100644 (file)
--- a/lib/graph/libgraph.h
+++ b/lib/graph/libgraph.h
@@ -167,6 +167,7 @@ extern "C" {
     void agpushproto(Agraph_t *);
     char *agstrdup_html(char *s);
     int agtoken(char *);
+    int aglinenumber ();
     void agwredge(Agraph_t *, FILE *, Agedge_t *, int);
     void agwrnode(Agraph_t *, FILE *, Agnode_t *, int, int);
     extern Dtdisc_t agNamedisc, agNodedisc, agOutdisc, agIndisc,

diff --git a/lib/graph/parser.y b/lib/graph/parser.y
index 40d0fdf3c78a42a7c862afae76fa88a28d8e4b46..0f9ebcbbea9c71a892118f01833abe5d5dbe17fe 100644 (file)
--- a/lib/graph/parser.y
+++ b/lib/graph/parser.y
@@ -34,6 +34,14 @@ static objstack_t    *SP;
 static Agraph_t                *Gstack[32];
 static int                     GSP;
 
+static void subgraph_warn ()
+{
+    agerr (AGWARN, "The use of \"subgraph %s\", line %d, without a body is deprecated.\n",
+       G->name, aglinenumber());
+    agerr (AGPREV, "This may cause unexpected behavior or crash the program.\n");
+    agerr (AGPREV, "Please use a single definition of the subgraph within the context of its parent graph \"%s\"\n", Gstack[GSP-2]->name);
+}
+
 static void push_subg(Agraph_t *g)
 {
        G = Gstack[GSP++] = g;
@@ -452,7 +460,7 @@ edgeRHS             :       T_edgeop node_id {mid_edgestmt($2);}
 subg_stmt      :       subg_hdr '{' stmt_list '}'%prec '{' {$$ = pop_gobj();}
                |       T_subgraph '{' { anonsubg(); } stmt_list '}' {$$ = pop_gobj();}
                |       '{' { anonsubg(); } stmt_list '}' {$$ = pop_gobj();}
-               |       subg_hdr %prec T_subgraph {$$ = pop_gobj();}
+               |       subg_hdr %prec T_subgraph {subgraph_warn(); $$ = pop_gobj();}
                ;
 
 subg_hdr       :       T_subgraph symbol