Update C Extensions docs for support in latest C++

	* doc/extend.texi (Long Long, Hex Floats): Document support for
	long long and hex floats in more recent versions of ISO C++.

From-SVN: r264076

gcc/ChangeLog

+2018-09-04  Jonathan Wakely  <jwakely@redhat.com>
+
+	* doc/extend.texi (Long Long, Hex Floats): Document support for
+	long long and hex floats in more recent versions of ISO C++.
+
 2018-09-03  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/87177

gcc/doc/extend.texi

@@ -843,8 +843,8 @@ for targets with @code{long long} integer less than 128 bits wide.
 @cindex @code{LL} integer suffix
 @cindex @code{ULL} integer suffix
 
-ISO C99 supports data types for integers that are at least 64 bits wide,
-and as an extension GCC supports them in C90 mode and in C++.
+ISO C99 and ISO C++11 support data types for integers that are at least
+64 bits wide, and as an extension GCC supports them in C90 and C++98 modes.
 Simply write @code{long long int} for a signed integer, or
 @code{unsigned long long int} for an unsigned integer.  To make an
 integer constant of type @code{long long int}, add the suffix @samp{LL}
@@ -1121,11 +1121,11 @@ are supported by the DWARF debug information format.
 @section Hex Floats
 @cindex hex floats
 
-ISO C99 supports floating-point numbers written not only in the usual
-decimal notation, such as @code{1.55e1}, but also numbers such as
+ISO C99 and ISO C++17 support floating-point numbers written not only in
+the usual decimal notation, such as @code{1.55e1}, but also numbers such as
 @code{0x1.fp3} written in hexadecimal format.  As a GNU extension, GCC
 supports this in C90 mode (except in some cases when strictly
-conforming) and in C++.  In that format the
+conforming) and in C++98, C++11 and C++14 modes.  In that format the
 @samp{0x} hex introducer and the @samp{p} or @samp{P} exponent field are
 mandatory.  The exponent is a decimal number that indicates the power of
 2 by which the significant part is multiplied.  Thus @samp{0x1.f} is