From: erg <devnull@localhost>
Date: Thu, 6 Sep 2007 20:16:19 +0000 (+0000)
Subject: "Fix" bug 1189. Basically, allowing multiple references to subgraphs
X-Git-Tag: LAST_LIBGRAPH~32^2~5290
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=7dd6aee78774cd18f9bb31c348a41a4cab19eadd;p=graphviz

"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 f86afd158..2e3c76a09 100644
--- 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 609a80612..5d411f1e0 100644
--- 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 40d0fdf3c..0f9ebcbbe 100644
--- 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