Enables GATs iteration in the Element API

.github/workflows/coverage.yml

@@ -23,7 +23,7 @@ jobs:
         with:
           profile: minimal
           # nightly can be very volatile--pin this to a version we know works well...
-          toolchain: nightly-2022-05-01
+          toolchain: nightly-2022-10-12
           override: true
       - name: Cargo Test
         uses: actions-rs/cargo@v1

.github/workflows/rust.yml

@@ -34,7 +34,11 @@ jobs:
         uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: stable
+          # We're temporarily testing against `beta` to have access to GATs. When Rust v1.65 is released in
+          # 2022-11, we should change this back to `stable`.
+          # See: https://github.com/amzn/ion-rust/issues/443
+          toolchain: beta
+          components: rustfmt, clippy
           override: true
       - name: Cargo Build 
         uses: actions-rs/cargo@v1

Cargo.toml

@@ -38,7 +38,6 @@ num-bigint = "0.3"
 num-integer = "0.1.44"
 num-traits = "0.2"
 arrayvec = "0.7"
-hashlink = "0.8.1"
 smallvec = "1.9.0"
 
 [dev-dependencies]

examples/read_all_values.rs

@@ -62,7 +62,7 @@ fn read_all_values<R: RawReader>(reader: &mut R) -> IonResult<usize> {
                 match ion_type {
                     Struct | List | SExpression => reader.step_in()?,
                     String => {
-                        let _text = reader.map_string(|_s| ())?;
+                        reader.map_string(|_s| ())?;
                     }
                     Symbol => {
                         let _symbol_id = reader.read_symbol()?;
@@ -83,10 +83,10 @@ fn read_all_values<R: RawReader>(reader: &mut R) -> IonResult<usize> {
                         let _boolean = reader.read_bool()?;
                     }
                     Blob => {
-                        let _blob = reader.map_blob(|_b| ())?;
+                        reader.map_blob(|_b| ())?;
                     }
                     Clob => {
-                        let _clob = reader.map_clob(|_c| ())?;
+                        reader.map_clob(|_c| ())?;
                     }
                     Null => {}
                 }

src/binary/int.rs

@@ -125,7 +125,7 @@ impl DecodedInt {
         let empty_leading_bytes: u32 = (magnitude.leading_zeros() - 1) >> 3;
         let first_occupied_byte = empty_leading_bytes as usize;
 
-        let mut magnitude_bytes: [u8; mem::size_of::<u64>()] = (magnitude as u64).to_be_bytes();
+        let mut magnitude_bytes: [u8; mem::size_of::<u64>()] = magnitude.to_be_bytes();
         let bytes_to_write: &mut [u8] = &mut magnitude_bytes[first_occupied_byte..];
         if value < 0 {
             bytes_to_write[0] |= 0b1000_0000;

src/binary/non_blocking/raw_binary_reader.rs

@@ -86,7 +86,7 @@ struct EncodedValue {
 impl EncodedValue {
     /// Returns the offset of the current value's type descriptor byte.
     fn header_offset(&self) -> usize {
-        self.header_offset as usize
+        self.header_offset
     }
 
     /// Returns the length of this value's header, including the type descriptor byte and any
@@ -734,7 +734,7 @@ impl<A: AsRef<[u8]>> IonReader for RawBinaryBufferReader<A> {
         let coefficient_size_in_bytes =
             encoded_value.value_length() - exponent_var_int.size_in_bytes();
 
-        let exponent = exponent_var_int.value() as i64;
+        let exponent = exponent_var_int.value();
         let coefficient = buffer.read_int(coefficient_size_in_bytes)?;
 
         if coefficient.is_negative_zero() {

src/binary/raw_binary_reader.rs

@@ -91,7 +91,7 @@ struct EncodedValue {
 impl EncodedValue {
     /// Returns the offset of the current value's type descriptor byte.
     fn header_offset(&self) -> usize {
-        self.header_offset as usize
+        self.header_offset
     }
 
     /// Returns the length of this value's header, including the type descriptor byte and any
@@ -526,7 +526,7 @@ impl<R: IonDataSource> IonReader for RawBinaryReader<R> {
         let coefficient_size_in_bytes =
             self.cursor.value.value_length - exponent_var_int.size_in_bytes();
 
-        let exponent = exponent_var_int.value() as i64;
+        let exponent = exponent_var_int.value();
         let coefficient = self.read_int(coefficient_size_in_bytes)?;
 
         if coefficient.is_negative_zero() {
@@ -938,7 +938,7 @@ where
     #[inline(always)]
     fn read_var_int(&mut self) -> IonResult<VarInt> {
         let var_int = VarInt::read(&mut self.data_source)?;
-        self.cursor.bytes_read += var_int.size_in_bytes() as usize;
+        self.cursor.bytes_read += var_int.size_in_bytes();
         Ok(var_int)
     }
 

src/binary/var_uint.rs

@@ -117,7 +117,7 @@ impl VarUInt {
     /// unsigned integer
     #[inline(always)]
     pub fn size_in_bytes(&self) -> usize {
-        self.size_in_bytes as usize
+        self.size_in_bytes
     }
 }
 

src/symbol_ref.rs

@@ -75,6 +75,21 @@ impl AsSymbolRef for Symbol {
     }
 }
 
+impl AsSymbolRef for &Symbol {
+    fn as_symbol_ref(&self) -> SymbolRef {
+        self.text()
+            .map(SymbolRef::with_text)
+            .unwrap_or_else(SymbolRef::with_unknown_text)
+    }
+}
+
+impl<'borrow, 'data> AsSymbolRef for &'borrow SymbolRef<'data> {
+    fn as_symbol_ref(&self) -> SymbolRef<'data> {
+        // This is essentially free; the only data inside is an Option<&str>
+        (*self).clone()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;