fix lints in rust tests (#6743)

Co-authored-by: Casper Neo <cneo@google.com>

samples/sample_binary.rs

@@ -33,7 +33,7 @@ pub use monster_generated::my_game::sample::{Color, Equipment,
 fn main() {
   // Build up a serialized buffer algorithmically.
   // Initialize it with a capacity of 1024 bytes.
-  let mut builder = flatbuffers::FlatBufferBuilder::new_with_capacity(1024);
+  let mut builder = flatbuffers::FlatBufferBuilder::with_capacity(1024);
 
   // Serialize some weapons for the Monster: A 'sword' and an 'axe'.
   let weapon_one_name = builder.create_string("Sword");

src/idl_gen_rust.cpp

@@ -2589,6 +2589,7 @@ class RustGenerator : public BaseGenerator {
       // Setter.
       if (IsStruct(field.value.type)) {
         code_.SetValue("FIELD_SIZE", NumToString(InlineSize(field.value.type)));
+        code_ += " #[allow(clippy::identity_op)]";  // If FIELD_OFFSET=0.
         code_ += "  pub fn set_{{FIELD_NAME}}(&mut self, x: &{{FIELD_TYPE}}) {";
         code_ +=
             "    self.0[{{FIELD_OFFSET}}..{{FIELD_OFFSET}} + {{FIELD_SIZE}}]"

tests/monster_test_generated.rs

@@ -1341,6 +1341,7 @@ impl<'a> Vec3 {
     unsafe { &*(self.0[26..].as_ptr() as *const Test) }
   }
 
+ #[allow(clippy::identity_op)]
   pub fn set_test3(&mut self, x: &Test) {
     self.0[26..26 + 4].copy_from_slice(&x.0)
   }
@@ -1626,6 +1627,7 @@ impl<'a> StructOfStructs {
     unsafe { &*(self.0[0..].as_ptr() as *const Ability) }
   }
 
+ #[allow(clippy::identity_op)]
   pub fn set_a(&mut self, x: &Ability) {
     self.0[0..0 + 8].copy_from_slice(&x.0)
   }
@@ -1634,6 +1636,7 @@ impl<'a> StructOfStructs {
     unsafe { &*(self.0[8..].as_ptr() as *const Test) }
   }
 
+ #[allow(clippy::identity_op)]
   pub fn set_b(&mut self, x: &Test) {
     self.0[8..8 + 4].copy_from_slice(&x.0)
   }
@@ -1642,6 +1645,7 @@ impl<'a> StructOfStructs {
     unsafe { &*(self.0[12..].as_ptr() as *const Ability) }
   }
 
+ #[allow(clippy::identity_op)]
   pub fn set_c(&mut self, x: &Ability) {
     self.0[12..12 + 8].copy_from_slice(&x.0)
   }

tests/rust_usage_test/tests/flexbuffers_tests/qc_serious.rs

@@ -1,7 +1,6 @@
 use super::rwyw::NonNullString;
 use flexbuffers::*;
 use quickcheck::{Arbitrary, Gen};
-use serde::{Deserialize, Serialize};
 use std::collections::BTreeMap;
 
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]

tests/rust_usage_test/tests/integration_test.rs

@@ -364,7 +364,7 @@ fn test_object_api_reads_correctly() -> Result<(), &'static str>{
 #[should_panic]
 #[test]
 fn builder_abort_with_greater_than_maximum_buffer_size() {
-    flatbuffers::FlatBufferBuilder::new_with_capacity(flatbuffers::FLATBUFFERS_MAX_BUFFER_SIZE+1);
+    flatbuffers::FlatBufferBuilder::with_capacity(flatbuffers::FLATBUFFERS_MAX_BUFFER_SIZE+1);
 }
 
 #[test]
@@ -2605,7 +2605,7 @@ mod byte_layouts {
 
     #[test]
     fn layout_03b_11xbyte_vector_matches_builder_size() {
-        let mut b = flatbuffers::FlatBufferBuilder::new_with_capacity(12);
+        let mut b = flatbuffers::FlatBufferBuilder::with_capacity(12);
         b.start_vector::<u8>(8);
 
         let mut gold = vec![0u8; 0];