From 726ff5ed31d609ea63a2fa8dccf8c1ea14b1b938 Mon Sep 17 00:00:00 2001
From: Jethro Beekman <jethro@fortanix.com>
Date: Fri, 3 Jan 2020 10:40:19 +0100
Subject: [PATCH] impl Serializer for &mut fmt::Formatter

---
 serde/src/ser/impls.rs | 125 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 124 insertions(+), 1 deletion(-)

diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index 803c739e..a1346bfa 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -1,6 +1,6 @@
 use lib::*;
 
-use ser::{Error, Serialize, SerializeTuple, Serializer};
+use ser::{Error, Impossible, Serialize, SerializeTuple, Serializer};
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -881,3 +881,126 @@ atomic_impl! {
 atomic_impl! {
     AtomicI64 AtomicU64
 }
+
+////////////////////////////////////////////////////////////////////////////////
+
+impl Error for fmt::Error {
+    fn custom<T: fmt::Display>(_msg: T) -> Self {
+        fmt::Error
+    }
+}
+
+macro_rules! fmt_primitives {
+    ($($f:ident: $t:ty, )*) => {$(
+        fn $f(self, v: $t) -> fmt::Result {
+            write!(self, "{}", v)
+        }
+    )*}
+}
+
+impl<'a, 'b> Serializer for &'a mut fmt::Formatter<'b> {
+    type Ok = ();
+    type Error = fmt::Error;
+    type SerializeSeq = Impossible<(), fmt::Error>;
+    type SerializeTuple = Impossible<(), fmt::Error>;
+    type SerializeTupleStruct = Impossible<(), fmt::Error>;
+    type SerializeTupleVariant = Impossible<(), fmt::Error>;
+    type SerializeMap = Impossible<(), fmt::Error>;
+    type SerializeStruct = Impossible<(), fmt::Error>;
+    type SerializeStructVariant = Impossible<(), fmt::Error>;
+
+    fmt_primitives!(
+        serialize_str: &str,
+        serialize_bool: bool,
+        serialize_i8: i8,
+        serialize_i16: i16,
+        serialize_i32: i32,
+        serialize_i64: i64,
+        serialize_u8: u8,
+        serialize_u16: u16,
+        serialize_u32: u32,
+        serialize_u64: u64,
+        serialize_f32: f32,
+        serialize_f64: f64,
+        serialize_char: char,
+        serialize_unit_struct: &'static str,
+    );
+    fn serialize_unit(self) -> fmt::Result {
+        Ok(())
+    }
+    fn serialize_unit_variant(self, _: &'static str, _: u32, v: &'static str) -> fmt::Result {
+        write!(self, "{}", v)
+    }
+
+    fn serialize_bytes(self, _v: &[u8]) -> fmt::Result {
+        Err(fmt::Error)
+    }
+    fn serialize_none(self) -> fmt::Result {
+        Err(fmt::Error)
+    }
+    fn serialize_some<T: ?Sized>(self, _value: &T) -> fmt::Result
+    where
+        T: Serialize,
+    {
+        Err(fmt::Error)
+    }
+    fn serialize_newtype_struct<T: ?Sized>(self, _name: &'static str, _value: &T) -> fmt::Result
+    where
+        T: Serialize,
+    {
+        Err(fmt::Error)
+    }
+    fn serialize_newtype_variant<T: ?Sized>(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _value: &T,
+    ) -> fmt::Result
+    where
+        T: Serialize,
+    {
+        Err(fmt::Error)
+    }
+    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq, fmt::Error> {
+        Err(fmt::Error)
+    }
+    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple, fmt::Error> {
+        Err(fmt::Error)
+    }
+    fn serialize_tuple_struct(
+        self,
+        _name: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeTupleStruct, fmt::Error> {
+        Err(fmt::Error)
+    }
+    fn serialize_tuple_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeTupleVariant, fmt::Error> {
+        Err(fmt::Error)
+    }
+    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap, fmt::Error> {
+        Err(fmt::Error)
+    }
+    fn serialize_struct(
+        self,
+        _name: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeStruct, fmt::Error> {
+        Err(fmt::Error)
+    }
+    fn serialize_struct_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeStructVariant, fmt::Error> {
+        Err(fmt::Error)
+    }
+}