* doc/bison.texinfo (Calc++ Parser): Fix memory leak reported by

Sander Brandenburg in
<http://lists.gnu.org/archive/html/bug-bison/2006-09/msg00002.html>.
Also, fix minor white space and comment issues.

doc/bison.texinfo

@@ -7423,8 +7423,8 @@ factor both as follows.
 
 @comment file: calc++-driver.hh
 @example
-// Announce to Flex the prototype we want for lexing function, ...
-# define YY_DECL					\
+// Tell Flex the lexer's prototype ...
+# define YY_DECL                                        \
   yy::calcxx_parser::token_type                         \
   yylex (yy::calcxx_parser::semantic_type* yylval,      \
          yy::calcxx_parser::location_type* yylloc,      \
@@ -7675,7 +7675,9 @@ unit: assignments exp  @{ driver.result = $2; @};
 assignments: assignments assignment @{@}
            | /* Nothing.  */        @{@};
 
-assignment: "identifier" ":=" exp @{ driver.variables[*$1] = $3; @};
+assignment:
+     "identifier" ":=" exp
+       @{ driver.variables[*$1] = $3; delete $1; @};
 
 %left '+' '-';
 %left '*' '/';
@@ -7683,7 +7685,7 @@ exp: exp '+' exp   @{ $$ = $1 + $3; @}
    | exp '-' exp   @{ $$ = $1 - $3; @}
    | exp '*' exp   @{ $$ = $1 * $3; @}
    | exp '/' exp   @{ $$ = $1 / $3; @}
-   | "identifier"  @{ $$ = driver.variables[*$1]; @}
+   | "identifier"  @{ $$ = driver.variables[*$1]; delete $1; @}
    | "number"      @{ $$ = $1; @};
 %%
 @end example
@@ -7844,8 +7846,8 @@ main (int argc, char *argv[])
       driver.trace_scanning = true;
     else
       @{
-	driver.parse (*argv);
-	std::cout << driver.result << std::endl;
+        driver.parse (*argv);
+        std::cout << driver.result << std::endl;
       @}
 @}
 @end example