Merge pull request #2733 from jamessan/nan-decimal

Only format Unexpected::Float with decimal point if it is finite

serde/src/de/mod.rs

@@ -2312,13 +2312,17 @@ impl Display for WithDecimalPoint {
             }
         }
 
-        let mut writer = LookForDecimalPoint {
-            formatter,
-            has_decimal_point: false,
-        };
-        tri!(write!(writer, "{}", self.0));
-        if !writer.has_decimal_point {
-            tri!(formatter.write_str(".0"));
+        if self.0.is_finite() {
+            let mut writer = LookForDecimalPoint {
+                formatter,
+                has_decimal_point: false,
+            };
+            tri!(write!(writer, "{}", self.0));
+            if !writer.has_decimal_point {
+                tri!(formatter.write_str(".0"));
+            }
+        } else {
+            tri!(write!(formatter, "{}", self.0));
         }
         Ok(())
     }

test_suite/tests/test_de_error.rs

@@ -1438,6 +1438,14 @@ fn test_integer_from_float() {
     );
 }
 
+#[test]
+fn test_nan_no_decimal_point() {
+    assert_de_tokens_error::<isize>(
+        &[Token::F32(f32::NAN)],
+        "invalid type: floating point `NaN`, expected isize",
+    );
+}
+
 #[test]
 fn test_unit_struct_from_seq() {
     assert_de_tokens_error::<UnitStruct>(