get rid of warning C4800 under VS2010

chacha21 · chacha21 · commit aa1b0312743c · 2017-03-02T16:56:20.000+01:00
the "std::basic_ios::operator bool" differs between C++98 and C++11. The
"double not" syntax is portable and covers both cases with equivalent
meaning
diff --git a/modules/core/src/persistence.cpp b/modules/core/src/persistence.cpp
@@ -7697,7 +7697,7 @@ std::string base64::make_base64_header(const char * dt)
 bool base64::read_base64_header(std::vector<char> const & header, std::string & dt)
 {
     std::istringstream iss(header.data());
-    return static_cast<bool>(iss >> dt);
+    return !!(iss >> dt);//the "std::basic_ios::operator bool" differs between C++98 and C++11. The "double not" syntax is portable and covers both cases with equivalent meaning
 }
 
 /****************************************************************************

Original file line number	Diff line number	Diff line change
`@@ -7697,7 +7697,7 @@ std::string base64::make_base64_header(const char * dt)`
`7697`	`7697`	`bool base64::read_base64_header(std::vector<char> const & header, std::string & dt)`
`7698`	`7698`	`{`
`7699`	`7699`	`std::istringstream iss(header.data());`
`7700`		`- return static_cast<bool>(iss >> dt);`
	`7700`	`+ return !!(iss >> dt);//the "std::basic_ios::operator bool" differs between C++98 and C++11. The "double not" syntax is portable and covers both cases with equivalent meaning`
`7701`	`7701`	`}`
`7702`	`7702`
`7703`	`7703`	`/****************************************************************************`