Where does semantic_type, sic, YYSTYPE get defined

[Arthur Schwarz]

The following example code:
1: Defines YYSTYPE as semantic_type,
2: Does not define semantic_type, 
3: Generates C output files instead of C++.

Section 3.4.2 of Bison 3.0 and Bison 2.7 manual says:
 "o let Bison compute the union type from the tags you assign to symbols"


What am I missing?



/*  > bison -d --no-lines --warnings=all --language=c++ multipleTypes */

%language "C++"
%token <float> B
%token <char>  D
%token <int>   E
%type  <int>   a
%type  <int>   c

%start a

%%
a : B c { $$ = 1; }
  ;
c : D E { $$ = 2; }
  ;