1 files changed, 19 insertions, 9 deletions
diff --git a/src/ser/value.rs b/src/ser/value.rs
index d29390a..47a17a3 100644
--- a/src/ser/value.rs
+++ b/src/ser/value.rs
@@ -60,10 +60,10 @@ impl serde::ser::Serializer for ValueSerializer {
     type SerializeSeq = super::SerializeValueArray;
     type SerializeTuple = super::SerializeValueArray;
     type SerializeTupleStruct = super::SerializeValueArray;
-    type SerializeTupleVariant = super::SerializeValueArray;
+    type SerializeTupleVariant = super::SerializeTupleVariant;
     type SerializeMap = super::SerializeMap;
     type SerializeStruct = super::SerializeMap;
-    type SerializeStructVariant = serde::ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeStructVariant = super::SerializeStructVariant;
 
     fn serialize_bool(self, v: bool) -> Result<Self::Ok, Self::Error> {
         Ok(v.into())
@@ -108,7 +108,17 @@ impl serde::ser::Serializer for ValueSerializer {
         self.serialize_f64(v as f64)
     }
 
-    fn serialize_f64(self, v: f64) -> Result<Self::Ok, Self::Error> {
+    fn serialize_f64(self, mut v: f64) -> Result<Self::Ok, Self::Error> {
+        // Discard sign of NaN when serialized using Serde.
+        //
+        // In all likelihood the sign of NaNs is not meaningful in the user's
+        // program. Ending up with `-nan` in the TOML document would usually be
+        // surprising and undesirable, when the sign of the NaN was not
+        // intentionally controlled by the caller, or may even be
+        // nondeterministic if it comes from arithmetic operations or a cast.
+        if v.is_nan() {
+            v = v.copysign(1.0);
+        }
         Ok(v.into())
     }
 
@@ -205,10 +215,10 @@ impl serde::ser::Serializer for ValueSerializer {
         self,
         _name: &'static str,
         _variant_index: u32,
-        _variant: &'static str,
+        variant: &'static str,
         len: usize,
     ) -> Result<Self::SerializeTupleVariant, Self::Error> {
-        self.serialize_seq(Some(len))
+        Ok(super::SerializeTupleVariant::tuple(variant, len))
     }
 
     fn serialize_map(self, len: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
@@ -233,11 +243,11 @@ impl serde::ser::Serializer for ValueSerializer {
 
     fn serialize_struct_variant(
         self,
-        name: &'static str,
+        _name: &'static str,
         _variant_index: u32,
-        _variant: &'static str,
-        _len: usize,
+        variant: &'static str,
+        len: usize,
     ) -> Result<Self::SerializeStructVariant, Self::Error> {
-        Err(Error::UnsupportedType(Some(name)))
+        Ok(super::SerializeStructVariant::struct_(variant, len))
     }
 }