* tests/cxx-type.at: Construct a tree, count the parents of shared

nodes, and free each node once and only once.  Previously, the memory
for semantic values was leaked instead.

tests/cxx-type.at

@@ -34,12 +34,33 @@ $1
 
 %{
   #include <stdio.h>
-  #define YYSTYPE char *
+  union Node {
+    struct {
+      int type;
+      int parents;
+    } node_info;
+    struct {
+      int type; /* 1 */
+      int parents;
+      char const *form;
+      union Node *children[3];
+    } nterm;
+    struct {
+      int type; /* 0 */
+      int parents;
+      char *text;
+    } term;
+  };
+  typedef union Node Node;
+  static Node *new_nterm (char const *, Node *, Node *, Node *);
+  static Node *new_term (char *);
+  static void free_node (Node *);
+  static char *node_to_string (Node *);
+  #define YYSTYPE Node *
 ]m4_bmatch([$2], [stmtMerge],
 [ static YYSTYPE stmtMerge (YYSTYPE x0, YYSTYPE x1);])[
   #define YYINITDEPTH 10
   #define YYSTACKEXPANDABLE 1
-  static char *format (char const *, ...);
   struct YYLTYPE;
 #if YYPURE
 # if YYLSP_NEEDED
@@ -66,36 +87,41 @@ $1
 
 %glr-parser
 
-%destructor { free ($$); } TYPENAME ID
+%destructor { free_node ($$); } stmt expr decl declarator TYPENAME ID
 
 %%
 
 prog :
      | prog stmt   {
-]AT_LOCATION_IF([
+                       char *output;]AT_LOCATION_IF([
 			printf ("%d.%d-%d.%d: ",
 			     @2.first_line, @2.first_column,
 			     @2.last_line, @2.last_column);])[
-			printf ("%s\n", ]$[2);
+                       output = node_to_string (]$[2);
+                       printf ("%s\n", output);
+                       free (output);
+                       free_node (]$[2);
 		   }
      ;
 
 stmt : expr ';'  $2	{ $$ = ]$[1; }
      | decl      $3
-     | error ';'	{ static char error_msg[] = "<error>"; $$ = error_msg; }
+     | error ';'       { $$ = new_nterm ("<error>", 0, 0, 0); }
      | '@'		{ YYACCEPT; }
      ;
 
 expr : ID
-     | TYPENAME '(' expr ')'  { $$ = format ("<cast>(%s,%s)", ]$[3, ]$[1); }
-     | expr '+' expr	      { $$ = format ("+(%s,%s)", ]$[1, ]$[3); }
-     | expr '=' expr          { $$ = format ("=(%s,%s)", ]$[1, ]$[3); }
+     | TYPENAME '(' expr ')'
+                       { $$ = new_nterm ("<cast>(%s,%s)", ]$[3, ]$[1, 0); }
+     | expr '+' expr   { $$ = new_nterm ("+(%s,%s)", ]$[1, ]$[3, 0); }
+     | expr '=' expr    { $$ = new_nterm ("=(%s,%s)", ]$[1, ]$[3, 0); }
      ;
 
 decl : TYPENAME declarator ';'
-			{ $$ = format ("<declare>(%s,%s)", ]$[1, ]$[2); }
+                       { $$ = new_nterm ("<declare>(%s,%s)", ]$[1, ]$[2, 0); }
      | TYPENAME declarator '=' expr ';'
-			{ $$ = format ("<init-declare>(%s,%s,%s)", ]$[1, ]$[2, ]$[4); }
+                       { $$ = new_nterm ("<init-declare>(%s,%s,%s)", ]$[1,
+                                         ]$[2, ]$[4); }
      ;
 
 declarator : ID
@@ -174,14 +200,13 @@ yylex (LEX_PARAMETERS)
 		ungetc (c, stdin);
 		buffer[i++] = 0;
 		tok = isupper ((unsigned char) buffer[0]) ? TYPENAME : ID;
-		yylval = strcpy ((char *) malloc (i), buffer);
+               yylval = new_term (strcpy ((char *) malloc (i), buffer));
 	      }
 	    else
 	      {
-		static char empty_string[] = "";
 		colNum += 1;
 		tok = c;
-		yylval = empty_string;
+               yylval = 0;
 	      }
 #if YYLSP_NEEDED
 	    yylloc.last_column = colNum-1;
@@ -203,16 +228,82 @@ yyerror (ERROR_PARAMETERS)
   fprintf (stderr, "%s\n", s);
 }
 
+static Node *
+new_nterm (char const *form, Node *child0, Node *child1, Node *child2)
+{
+  Node *node = malloc (sizeof (Node));
+  node->nterm.type = 1;
+  node->nterm.parents = 0;
+  node->nterm.form = form;
+  node->nterm.children[0] = child0;
+  if (child0)
+    child0->node_info.parents += 1;
+  node->nterm.children[1] = child1;
+  if (child1)
+    child1->node_info.parents += 1;
+  node->nterm.children[2] = child2;
+  if (child2)
+    child2->node_info.parents += 1;
+  return node;
+}
+
+static Node *
+new_term (char *text)
+{
+  Node *node = malloc (sizeof (Node));
+  node->term.type = 0;
+  node->term.parents = 0;
+  node->term.text = text;
+  return node;
+}
+
+static void
+free_node (Node *node)
+{
+  if (!node)
+    return;
+  node->node_info.parents -= 1;
+  /* Free only if 0 (last parent) or -1 (no parents).  */
+  if (node->node_info.parents > 0)
+    return;
+  if (node->node_info.type == 1)
+    {
+      free_node (node->nterm.children[0]);
+      free_node (node->nterm.children[1]);
+      free_node (node->nterm.children[2]);
+    }
+  else
+    free (node->term.text);
+  free (node);
+}
 
 static char *
-format (char const *form, ...)
+node_to_string (Node *node)
 {
-   char buffer[1024];
-   va_list args;
-   va_start (args, form);
-   vsprintf (buffer, form, args);
-   va_end (args);
-   return strcpy ((char *) malloc (strlen (buffer) + 1), buffer);
+  char *child0;
+  char *child1;
+  char *child2;
+  char *buffer;
+  if (!node)
+    {
+      buffer = malloc (1);
+      buffer[0] = 0;
+    }
+  else if (node->node_info.type == 1)
+    {
+      child0 = node_to_string (node->nterm.children[0]);
+      child1 = node_to_string (node->nterm.children[1]);
+      child2 = node_to_string (node->nterm.children[2]);
+      buffer = malloc (strlen (node->nterm.form) + strlen (child0)
+                      + strlen (child1) + strlen (child2) + 1);
+      sprintf (buffer, node->nterm.form, child0, child1, child2);
+      free (child0);
+      free (child1);
+      free (child2);
+    }
+  else
+    buffer = strdup (node->term.text);
+  return buffer;
 }
 
 ]]
@@ -220,7 +311,7 @@ m4_bmatch([$2], [stmtMerge],
 [[static YYSTYPE
 stmtMerge (YYSTYPE x0, YYSTYPE x1)
 {
-  return format ("<OR>(%s,%s)", x0, x1);
+  return new_nterm ("<OR>(%s,%s)", x0, x1, 0);
 }
 ]])
 )