Consistently avoid '?' throughout serde crate

This makes it easy to redefine a 'try' macro to compare compile-time
between `$expr?` and `match $expr { Ok=>v, Err=>return }`.

serde/src/de/ignored_any.rs

@@ -228,7 +228,7 @@ impl<'de> Visitor<'de> for IgnoredAny {
     where
         A: EnumAccess<'de>,
     {
-        data.variant::<IgnoredAny>()?.1.newtype_variant()
+        try!(data.variant::<IgnoredAny>()).1.newtype_variant()
     }
 }
 

serde/src/de/impls.rs

@@ -2268,14 +2268,14 @@ where
     where
         D: Deserializer<'de>,
     {
-        let (start, end) = deserializer.deserialize_struct(
+        let (start, end) = try!(deserializer.deserialize_struct(
             "Range",
             range::FIELDS,
             range::RangeVisitor {
                 expecting: "struct Range",
                 phantom: PhantomData,
             },
-        )?;
+        ));
         Ok(start..end)
     }
 }
@@ -2289,14 +2289,14 @@ where
     where
         D: Deserializer<'de>,
     {
-        let (start, end) = deserializer.deserialize_struct(
+        let (start, end) = try!(deserializer.deserialize_struct(
             "RangeInclusive",
             range::FIELDS,
             range::RangeVisitor {
                 expecting: "struct RangeInclusive",
                 phantom: PhantomData,
             },
-        )?;
+        ));
         Ok(RangeInclusive::new(start, end))
     }
 }

serde/src/de/mod.rs

@@ -565,7 +565,7 @@ pub trait Deserialize<'de>: Sized {
         D: Deserializer<'de>,
     {
         // Default implementation just delegates to `deserialize` impl.
-        *place = Deserialize::deserialize(deserializer)?;
+        *place = try!(Deserialize::deserialize(deserializer));
         Ok(())
     }
 }

serde/src/de/value.rs

@@ -1501,7 +1501,7 @@ where
     where
         T: de::DeserializeSeed<'de>,
     {
-        match self.map.next_key_seed(seed)? {
+        match try!(self.map.next_key_seed(seed)) {
             Some(key) => Ok((key, private::map_as_enum(self.map))),
             None => Err(de::Error::invalid_type(de::Unexpected::Map, &"enum")),
         }

serde/src/ser/impls.rs

@@ -614,9 +614,10 @@ impl Serialize for SystemTime {
         S: Serializer,
     {
         use super::SerializeStruct;
-        let duration_since_epoch = self
-            .duration_since(UNIX_EPOCH)
-            .map_err(|_| S::Error::custom("SystemTime must be later than UNIX_EPOCH"))?;
+        let duration_since_epoch = match self.duration_since(UNIX_EPOCH) {
+            Ok(duration_since_epoch) => duration_since_epoch,
+            Err(_) => return Err(S::Error::custom("SystemTime must be later than UNIX_EPOCH")),
+        };
         let mut state = try!(serializer.serialize_struct("SystemTime", 2));
         try!(state.serialize_field("secs_since_epoch", &duration_since_epoch.as_secs()));
         try!(state.serialize_field("nanos_since_epoch", &duration_since_epoch.subsec_nanos()));