std.cfg: Added support for std::clamp() (danmar#7154)

Reference: https://en.cppreference.com/w/cpp/algorithm/clamp

Author: orbitcowboy

cfg/std.cfg

@@ -69,7 +69,7 @@
     <noreturn>true</noreturn>
   </function>
   <!--              void unexpected(); (until C++11)          -->
-  <!-- [[noreturn]] void unexpected(); (since C++11)          --> 
+  <!-- [[noreturn]] void unexpected(); (since C++11)          -->
   <!-- (deprecated)(removed in C++17)                         -->
   <function name="std::unexpected">
     <noreturn>true</noreturn>
@@ -6363,6 +6363,28 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
     <arg nr="1" direction="in"/>
     <leak-ignore/>
   </function>
+  <!-- template< class T >                constexpr const T& std::clamp( const T& v, const T& lo, const T& hi);                (since C++17) -->
+  <!-- template< class T, class Compare > constexpr const T& std::clamp( const T& v, const T& lo, const T& hi, Compare comp ); (since C++17) -->
+  <!-- https://en.cppreference.com/w/cpp/algorithm/clamp -->
+  <function name="clamp,std::clamp">
+    <use-retval/>
+    <noreturn>false</noreturn>
+    <leak-ignore/>
+    <pure/>
+    <returnValue>arg1&lt;arg2?arg2:arg1&gt;arg3?arg3:arg1</returnValue>
+    <arg nr="1" direction="in">
+      <not-uninit/>
+    </arg>
+    <arg nr="2" direction="in">
+      <not-uninit/>
+    </arg>
+    <arg nr="3" direction="in">
+      <not-uninit/>
+    </arg>
+    <arg nr="4" direction="in" default="">
+      <not-uninit/>
+    </arg>
+  </function>
   <!-- template <class T> const T& min(const T& a, const T& b); -->
   <function name="min,std::min">
     <use-retval/>

test/cfg/std.cpp

@@ -73,6 +73,25 @@ void unreachableCode_std_unexpected(int &x)
 }
 #endif
 
+#ifdef __cpp_lib_clamp
+int ignoredReturnValue_std_clamp(const int x)
+{
+    // cppcheck-suppress ignoredReturnValue
+    std::clamp(x, 1, -1);
+    return std::clamp(x, 1, -1);
+}
+void knownConditionTrueFalse_std_clamp(const int x)
+{
+    // cppcheck-suppress knownConditionTrueFalse
+    if(std::clamp(-2, -1, 1) == -1){}
+    // cppcheck-suppress knownConditionTrueFalse
+    if(std::clamp(2, -1, 1) == 1){}
+    // cppcheck-suppress knownConditionTrueFalse
+    if(std::clamp(0, -1, 1) == 0){}
+    if(std::clamp(x, 0, 2)){}
+}
+#endif // __cpp_lib_clamp
+
 void unreachableCode_std_terminate(int &x)
 {
     std::terminate();