Remove unused `PExpr::is_the_same()`

The last user of the `PExpr::is_the_same()` method was removed in commit
37b60a4c52 ("Clean up interface of the PWire class").

Remove the method.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

PExpr.cc

@@ -53,11 +53,6 @@ bool PExpr::has_aa_term(Design*, NetScope*) const
       return false;
 }
 
-bool PExpr::is_the_same(const PExpr*that) const
-{
-      return typeid(this) == typeid(that);
-}
-
 NetNet* PExpr::elaborate_lnet(Design*, NetScope*) const
 {
       cerr << get_fileline() << ": error: "
@@ -514,15 +509,6 @@ const verinum& PENumber::value() const
       return *value_;
 }
 
-bool PENumber::is_the_same(const PExpr*that) const
-{
-      const PENumber*obj = dynamic_cast<const PENumber*>(that);
-      if (obj == 0)
-	    return false;
-
-      return *value_ == *obj->value_;
-}
-
 PEString::PEString(char*s)
 : text_(s)
 {

PExpr.h

@@ -180,11 +180,6 @@ class PExpr : public LineInfo {
       virtual bool is_collapsible_net(Design*des, NetScope*scope,
                                       NetNet::PortType port_type) const;
 
-	// This method returns true if that expression is the same as
-	// this expression. This method is used for comparing
-	// expressions that must be structurally "identical".
-      virtual bool is_the_same(const PExpr*that) const;
-
     protected:
       unsigned fix_width_(width_mode_t mode);
 
@@ -639,8 +634,6 @@ class PENumber : public PExpr {
 					 bool is_cassign,
 					 bool is_force) const;
 
-      virtual bool is_the_same(const PExpr*that) const;
-
     private:
       verinum*const value_;
 };