Fixed zerodiv FN for '1/std::erf(0)'

cfg/std.cfg

@@ -1258,7 +1258,7 @@
   <function name="erf,std::erf">
     <use-retval/>
     <pure/>
-    <returnValue type="double"/>
+    <returnValue type="double">erf(arg1)</returnValue>
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1" direction="in">
@@ -1269,7 +1269,7 @@
   <function name="erff,std::erff">
     <use-retval/>
     <pure/>
-    <returnValue type="float"/>
+    <returnValue type="float">erf(arg1)</returnValue>
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1" direction="in">
@@ -1280,7 +1280,7 @@
   <function name="erfl,std::erfl">
     <use-retval/>
     <pure/>
-    <returnValue type="long double"/>
+    <returnValue type="long double">erf(arg1)</returnValue>
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1" direction="in">

lib/programmemory.cpp

@@ -719,6 +719,17 @@ static std::unordered_map<std::string, BuiltinLibraryFunction> createBuiltinLibr
         v.valueType = ValueFlow::Value::ValueType::FLOAT;
         return v;
     };
+    functions["erf"] = [](const std::vector<ValueFlow::Value>& args) {
+        if (args.size() != 1)
+            return ValueFlow::Value::unknown();
+        ValueFlow::Value v = args[0];
+        if (!v.isFloatValue() && !v.isIntValue())
+            return ValueFlow::Value::unknown();
+        double value = args[0].isFloatValue() ? args[0].floatValue : args[0].intvalue;
+        v.floatValue = std::erf(value);
+        v.valueType = ValueFlow::Value::ValueType::FLOAT;
+        return v;
+    };
     functions["sqrt"] = [](const std::vector<ValueFlow::Value>& args) {
         if (args.size() != 1)
             return ValueFlow::Value::unknown();

test/cfg/std.cpp

@@ -57,6 +57,13 @@ int zerodiv_cbrt()
     return 42 / i;
 }
 
+int zerodiv_erf()
+{
+    int i = std::erf(0);
+    // cppcheck-suppress zerodiv
+    return 42 / i;
+}
+
 int zerodiv_asin()
 {
     int i = std::asin(0);