Re: Bison bugs (memory leaks) found by valgrind in GLR-related tests

[Paul Eggert]

"Joel E. Denny" <address@hidden> writes:

> Unfortunately, I don't have a linux box set up, and I'm pretty sure
> valgrind requires the kernel.  I've been meaning to set one up
> specifically for valgrind, but it won't be any time soon.

OK.  Perhaps you don't need valgrind, since I can tell you its results.
valgrind reports that cxx-type.at contains test cases that leak memory,
and if you look at the test cases it's pretty obvious that they do.
Unfortunately when I tried to close the leaks (see below) I ended up
freeing storage more than once, and I suspect it's due to a GLR bug
(one that perhaps you're already fixing).

If you install this patch to tests/cxx-type.at, the test case should
fail nicely even if you're not using valgrind.  I think the problem is
that error handling doesn't do free right.

By the way, should the action for "error ';'" free ($1)?


--- cxx-type.at 2005-07-24 00:24:22.000000000 -0700
+++ /home/eggert/junk/cxx-type.at       2005-12-07 22:38:01.000000000 -0800
@@ -39,7 +39,7 @@ $1
 [ static YYSTYPE stmtMerge (YYSTYPE x0, YYSTYPE x1);])[
   #define YYINITDEPTH 10
   #define YYSTACKEXPANDABLE 1
-  static char *format (char const *, ...);
+  static char *format (char const *, char *, char *);
   struct YYLTYPE;
 #if YYPURE
 # if YYLSP_NEEDED
@@ -77,12 +77,13 @@ prog :
                             @2.first_line, @2.first_column,
                             @2.last_line, @2.last_column);])[
                        printf ("%s\n", ]$[2);
+                       free (]$[2);
                   }
      ;
 
 stmt : expr ';'  $2    { $$ = ]$[1; }
      | decl      $3
-     | error ';'       { static char error_msg[] = "<error>"; $$ = error_msg; }
+     | error ';'       { $$ = format ("<error>", 0, 0); }
      | '@'             { YYACCEPT; }
      ;
 
@@ -95,7 +96,8 @@ expr : ID
 decl : TYPENAME declarator ';'
                        { $$ = format ("<declare>(%s,%s)", ]$[1, ]$[2); }
      | TYPENAME declarator '=' expr ';'
-                       { $$ = format ("<init-declare>(%s,%s,%s)", ]$[1, ]$[2, 
]$[4); }
+                       { $$ = format ("<init-declare>(%s,%s)", ]$[1,
+                                      format ("%s,%s", ]$[2, ]$[4)); }
      ;
 
 declarator : ID
@@ -205,13 +207,12 @@ yyerror (ERROR_PARAMETERS)
 
 
 static char *
-format (char const *form, ...)
+format (char const *form, char *arg1, char *arg2)
 {
    char buffer[1024];
-   va_list args;
-   va_start (args, form);
-   vsprintf (buffer, form, args);
-   va_end (args);
+   sprintf (buffer, form, arg1, arg2);
+   free (arg1);
+   free (arg2);
    return strcpy ((char *) malloc (strlen (buffer) + 1), buffer);
 }