libstdc++: std::stoi etc. do not need C99 <stdlib.h> support [PR110653]

Tested powerpc64le-linux. Pushed to trunk.

-- >8 --

std::stoi, std::stol, std::stoul, and std::stod only depend on C89
functions, so don't need to be guarded by _GLIBCXX_USE_C99_STDLIB

std::stoll and std::stoull don't need C99 strtoll and strtoull if
sizeof(long) == sizeof(long long).

std::stold doesn't need C99 strtold if DBL_MANT_DIG == LDBL_MANT_DIG.

This only applies to the narrow character overloads, the wchar_t
overloads depend on a separate _GLIBCXX_USE_C99_WCHAR macro and none of
them can be implemented in C89 easily.

libstdc++-v3/ChangeLog:

	PR libstdc++/110653
	* include/bits/basic_string.h (stoi, stol, stoul, stod): Do not
	depend on _GLIBCXX_USE_C99_STDLIB.
	[__LONG_WIDTH__ == __LONG_LONG_WIDTH__] (stoll, stoull): Define
	in terms of stol and stoul respectively.
	[__DBL_MANT_DIG__ == __LDBL_MANT_DIG__] (stold): Define in terms
	of stod.

libstdc++-v3/include/bits/basic_string.h

@@ -4108,7 +4108,6 @@ namespace std _GLIBCXX_VISIBILITY(default)
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 _GLIBCXX_BEGIN_NAMESPACE_CXX11
 
-#if _GLIBCXX_USE_C99_STDLIB
   // 21.4 Numeric Conversions [string.conversions].
   inline int
   stoi(const string& __str, size_t* __idx = 0, int __base = 10)
@@ -4125,6 +4124,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
   { return __gnu_cxx::__stoa(&std::strtoul, "stoul", __str.c_str(),
 			     __idx, __base); }
 
+#if _GLIBCXX_USE_C99_STDLIB
   inline long long
   stoll(const string& __str, size_t* __idx = 0, int __base = 10)
   { return __gnu_cxx::__stoa(&std::strtoll, "stoll", __str.c_str(),
@@ -4134,19 +4134,33 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
   stoull(const string& __str, size_t* __idx = 0, int __base = 10)
   { return __gnu_cxx::__stoa(&std::strtoull, "stoull", __str.c_str(),
 			     __idx, __base); }
+#elif __LONG_WIDTH__ == __LONG_LONG_WIDTH__
+  inline long long
+  stoll(const string& __str, size_t* __idx = 0, int __base = 10)
+  { return std::stol(__str, __idx, __base); }
 
-  // NB: strtof vs strtod.
-  inline float
-  stof(const string& __str, size_t* __idx = 0)
-  { return __gnu_cxx::__stoa(&std::strtof, "stof", __str.c_str(), __idx); }
+  inline unsigned long long
+  stoull(const string& __str, size_t* __idx = 0, int __base = 10)
+  { return std::stoul(__str, __idx, __base); }
+#endif
 
   inline double
   stod(const string& __str, size_t* __idx = 0)
   { return __gnu_cxx::__stoa(&std::strtod, "stod", __str.c_str(), __idx); }
 
+#if _GLIBCXX_USE_C99_STDLIB
+  // NB: strtof vs strtod.
+  inline float
+  stof(const string& __str, size_t* __idx = 0)
+  { return __gnu_cxx::__stoa(&std::strtof, "stof", __str.c_str(), __idx); }
+
   inline long double
   stold(const string& __str, size_t* __idx = 0)
   { return __gnu_cxx::__stoa(&std::strtold, "stold", __str.c_str(), __idx); }
+#elif __DBL_MANT_DIG__ == __LDBL_MANT_DIG__
+  inline long double
+  stold(const string& __str, size_t* __idx = 0)
+  { return std::stod(__str, __idx); }
 #endif // _GLIBCXX_USE_C99_STDLIB
 
   // DR 1261. Insufficent overloads for to_string / to_wstring