RegularExpression: Remove redundant overloads

This also makes RegexMatchResult::start/end to reliably report npos
for failed matches. Note that start/end of individual capture groups
might still contain data even if the match has failed overall.

Issue: cmake/cmake#26629

RegularExpression.hxx.in

@@ -42,11 +42,9 @@ public:
   bool isValid() const;
   void clear();
 
-  std::string::size_type start() const;
-  std::string::size_type end() const;
-  std::string::size_type start(int n) const;
-  std::string::size_type end(int n) const;
-  std::string match(int n) const;
+  std::string::size_type start(int n = 0) const;
+  std::string::size_type end(int n = 0) const;
+  std::string match(int n = 0) const;
 
   enum
   {
@@ -99,22 +97,6 @@ inline void RegularExpressionMatch::clear()
   searchstring = nullptr;
 }
 
-/**
- * \brief Returns the start index of the full match.
- */
-inline std::string::size_type RegularExpressionMatch::start() const
-{
-  return static_cast<std::string::size_type>(this->startp[0] - searchstring);
-}
-
-/**
- * \brief Returns the end index of the full match.
- */
-inline std::string::size_type RegularExpressionMatch::end() const
-{
-  return static_cast<std::string::size_type>(this->endp[0] - searchstring);
-}
-
 /**
  * \brief Returns the start index of nth submatch.
  *        start(0) is the start of the full match.
@@ -363,15 +345,13 @@ public:
    * Match indices
    */
   inline RegularExpressionMatch const& regMatch() const;
-  inline std::string::size_type start() const;
-  inline std::string::size_type end() const;
-  inline std::string::size_type start(int n) const;
-  inline std::string::size_type end(int n) const;
+  inline std::string::size_type start(int n = 0) const;
+  inline std::string::size_type end(int n = 0) const;
 
   /**
    * Match strings
    */
-  inline std::string match(int n) const;
+  inline std::string match(int n = 0) const;
 
   /**
    * Copy the given regular expression.
@@ -505,22 +485,6 @@ inline RegularExpressionMatch const& RegularExpression::regMatch() const
   return this->regmatch;
 }
 
-/**
- * Returns the start index of the full match.
- */
-inline std::string::size_type RegularExpression::start() const
-{
-  return regmatch.start();
-}
-
-/**
- * Returns the end index of the full match.
- */
-inline std::string::size_type RegularExpression::end() const
-{
-  return regmatch.end();
-}
-
 /**
  * Return start index of nth submatch. start(0) is the start of the full match.
  */