Applies all clippy suggestions (wasmi-labs#244)

* Applies all clippy suggestions

In a few cases a clippy annotation was provided to ignore the clippy warning.

* apply rustfmt

* make wasmi compiler under no_std again

* use rustfmt +stable

examples/invoke.rs

@@ -34,11 +34,11 @@ fn main() {
             .entries()
             .iter()
             .find(|entry| func_name == entry.field())
-            .expect(&format!("No export with name {} found", func_name));
+            .unwrap_or_else(|| panic!("No export with name {} found", func_name));
 
         // Function index in the function index space (internally-defined + imported)
         let function_index: usize = match found_entry.internal() {
-            &Internal::Function(index) => index as usize,
+            Internal::Function(index) => *index as usize,
             _ => panic!("Founded export is not a function"),
         };
 
@@ -48,10 +48,7 @@ fn main() {
             Some(import) => import
                 .entries()
                 .iter()
-                .filter(|entry| match entry.external() {
-                    &External::Function(_) => true,
-                    _ => false,
-                })
+                .filter(|entry| matches!(entry.external(), External::Function(_)))
                 .count(),
             None => 0,
         };
@@ -64,8 +61,9 @@ fn main() {
             function_section.entries()[function_index_in_section].type_ref() as usize;
 
         // Use the reference to get an actual function type
+        #[allow(clippy::infallible_destructuring_match)]
         let function_type: &FunctionType = match &type_section.types()[func_type_ref] {
-            &Type::Function(ref func_type) => func_type,
+            Type::Function(ref func_type) => func_type,
         };
 
         // Parses arguments and constructs runtime values in correspondence of their types
@@ -74,26 +72,26 @@ fn main() {
             .iter()
             .enumerate()
             .map(|(i, value)| match value {
-                &ValueType::I32 => RuntimeValue::I32(
+                ValueType::I32 => RuntimeValue::I32(
                     program_args[i]
                         .parse::<i32>()
-                        .expect(&format!("Can't parse arg #{} as i32", program_args[i])),
+                        .unwrap_or_else(|_| panic!("Can't parse arg #{} as i32", program_args[i])),
                 ),
-                &ValueType::I64 => RuntimeValue::I64(
+                ValueType::I64 => RuntimeValue::I64(
                     program_args[i]
                         .parse::<i64>()
-                        .expect(&format!("Can't parse arg #{} as i64", program_args[i])),
+                        .unwrap_or_else(|_| panic!("Can't parse arg #{} as i64", program_args[i])),
                 ),
-                &ValueType::F32 => RuntimeValue::F32(
+                ValueType::F32 => RuntimeValue::F32(
                     program_args[i]
                         .parse::<f32>()
-                        .expect(&format!("Can't parse arg #{} as f32", program_args[i]))
+                        .unwrap_or_else(|_| panic!("Can't parse arg #{} as f32", program_args[i]))
                         .into(),
                 ),
-                &ValueType::F64 => RuntimeValue::F64(
+                ValueType::F64 => RuntimeValue::F64(
                     program_args[i]
                         .parse::<f64>()
-                        .expect(&format!("Can't parse arg #{} as f64", program_args[i]))
+                        .unwrap_or_else(|_| panic!("Can't parse arg #{} as f64", program_args[i]))
                         .into(),
                 ),
             })

examples/tictactoe.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::wrong_self_convention)]
+
 extern crate parity_wasm;
 extern crate wasmi;
 
@@ -67,7 +69,7 @@ mod tictactoe {
         }
 
         pub fn set(&mut self, idx: i32, player: Player) -> Result<(), Error> {
-            if idx < 0 || idx > 9 {
+            if !(0..9).contains(&idx) {
                 return Err(Error::OutOfRange);
             }
             if self.board[idx as usize] != None {
@@ -78,7 +80,7 @@ mod tictactoe {
         }
 
         pub fn get(&self, idx: i32) -> Result<Option<Player>, Error> {
-            if idx < 0 || idx > 9 {
+            if !(0..9).contains(&idx) {
                 return Err(Error::OutOfRange);
             }
             Ok(self.board[idx as usize])
@@ -103,6 +105,7 @@ mod tictactoe {
             ];
 
             // Returns Some(player) if all cells contain same Player.
+            #[allow(clippy::question_mark)]
             let all_same = |i1: usize, i2: usize, i3: usize| -> Option<Player> {
                 if self.board[i1].is_none() {
                     return None;
@@ -221,14 +224,13 @@ fn play(
         {
             let mut runtime = Runtime {
                 player: turn_of,
-                game: game,
+                game,
             };
             let _ = instance.invoke_export("mk_turn", &[], &mut runtime)?;
         }
 
-        match game.game_result() {
-            Some(game_result) => break game_result,
-            None => {}
+        if let Some(game_result) = game.game_result() {
+            break game_result;
         }
 
         turn_of = next_turn_of;

src/func.rs

@@ -60,12 +60,12 @@ pub(crate) enum FuncInstanceInternal {
 impl fmt::Debug for FuncInstance {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self.as_internal() {
-            &FuncInstanceInternal::Internal { ref signature, .. } => {
+            FuncInstanceInternal::Internal { ref signature, .. } => {
                 // We can't write description of self.module here, because it generate
                 // debug string for function instances and this will lead to infinite loop.
                 write!(f, "Internal {{ signature={:?} }}", signature,)
             }
-            &FuncInstanceInternal::Host { ref signature, .. } => {
+            FuncInstanceInternal::Host { ref signature, .. } => {
                 write!(f, "Host {{ signature={:?} }}", signature)
             }
         }
@@ -112,7 +112,7 @@ impl FuncInstance {
     ) -> FuncRef {
         let func = FuncInstanceInternal::Internal {
             signature,
-            module: module,
+            module,
             body: Rc::new(body),
         };
         FuncRef(Rc::new(FuncInstance(func)))
@@ -269,19 +269,19 @@ impl<'args> FuncInvocation<'args> {
     /// Whether this invocation is currently resumable.
     pub fn is_resumable(&self) -> bool {
         match &self.kind {
-            &FuncInvocationKind::Internal(ref interpreter) => interpreter.state().is_resumable(),
-            &FuncInvocationKind::Host { .. } => false,
+            FuncInvocationKind::Internal(ref interpreter) => interpreter.state().is_resumable(),
+            FuncInvocationKind::Host { .. } => false,
         }
     }
 
     /// If the invocation is resumable, the expected return value type to be feed back in.
     pub fn resumable_value_type(&self) -> Option<ValueType> {
         match &self.kind {
-            &FuncInvocationKind::Internal(ref interpreter) => match interpreter.state() {
-                &InterpreterState::Resumable(ref value_type) => value_type.clone(),
+            FuncInvocationKind::Internal(ref interpreter) => match interpreter.state() {
+                InterpreterState::Resumable(ref value_type) => *value_type,
                 _ => None,
             },
-            &FuncInvocationKind::Host { .. } => None,
+            FuncInvocationKind::Host { .. } => None,
         }
     }
 

src/host.rs

@@ -32,10 +32,10 @@ impl<'a> RuntimeArgs<'a> {
     where
         T: FromRuntimeValue,
     {
-        Ok(self
-            .nth_value_checked(idx)?
+        self.nth_value_checked(idx)?
             .try_into()
-            .ok_or_else(|| TrapKind::UnexpectedSignature)?)
+            .ok_or(TrapKind::UnexpectedSignature)
+            .map_err(Into::into)
     }
 
     /// Extract argument as a [`RuntimeValue`] by index `idx`.

src/imports.rs

@@ -255,56 +255,46 @@ pub trait ModuleImportResolver {
 
 impl ModuleImportResolver for ModuleRef {
     fn resolve_func(&self, field_name: &str, _signature: &Signature) -> Result<FuncRef, Error> {
-        Ok(self
-            .export_by_name(field_name)
+        self.export_by_name(field_name)
             .ok_or_else(|| Error::Instantiation(format!("Export {} not found", field_name)))?
             .as_func()
             .cloned()
-            .ok_or_else(|| {
-                Error::Instantiation(format!("Export {} is not a function", field_name))
-            })?)
+            .ok_or_else(|| Error::Instantiation(format!("Export {} is not a function", field_name)))
     }
 
     fn resolve_global(
         &self,
         field_name: &str,
         _global_type: &GlobalDescriptor,
     ) -> Result<GlobalRef, Error> {
-        Ok(self
-            .export_by_name(field_name)
+        self.export_by_name(field_name)
             .ok_or_else(|| Error::Instantiation(format!("Export {} not found", field_name)))?
             .as_global()
             .cloned()
-            .ok_or_else(|| {
-                Error::Instantiation(format!("Export {} is not a global", field_name))
-            })?)
+            .ok_or_else(|| Error::Instantiation(format!("Export {} is not a global", field_name)))
     }
 
     fn resolve_memory(
         &self,
         field_name: &str,
         _memory_type: &MemoryDescriptor,
     ) -> Result<MemoryRef, Error> {
-        Ok(self
-            .export_by_name(field_name)
+        self.export_by_name(field_name)
             .ok_or_else(|| Error::Instantiation(format!("Export {} not found", field_name)))?
             .as_memory()
             .cloned()
-            .ok_or_else(|| {
-                Error::Instantiation(format!("Export {} is not a memory", field_name))
-            })?)
+            .ok_or_else(|| Error::Instantiation(format!("Export {} is not a memory", field_name)))
     }
 
     fn resolve_table(
         &self,
         field_name: &str,
         _table_type: &TableDescriptor,
     ) -> Result<TableRef, Error> {
-        Ok(self
-            .export_by_name(field_name)
+        self.export_by_name(field_name)
             .ok_or_else(|| Error::Instantiation(format!("Export {} not found", field_name)))?
             .as_table()
             .cloned()
-            .ok_or_else(|| Error::Instantiation(format!("Export {} is not a table", field_name)))?)
+            .ok_or_else(|| Error::Instantiation(format!("Export {} is not a table", field_name)))
     }
 }

src/isa.rs

@@ -595,11 +595,7 @@ impl<'a> Iterator for InstructionIter<'a> {
 
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
-        let internal = if let Some(i) = self.instructions.get(self.position as usize) {
-            i
-        } else {
-            return None;
-        };
+        let internal = self.instructions.get(self.position as usize)?;
 
         let out = match *internal {
             InstructionInternal::GetLocal(x) => Instruction::GetLocal(x),

src/lib.rs

@@ -96,6 +96,8 @@
 
 #![warn(missing_docs)]
 #![cfg_attr(not(feature = "std"), no_std)]
+#![allow(clippy::len_without_is_empty)]
+#![allow(clippy::new_ret_no_self)]
 
 #[cfg(not(feature = "std"))]
 #[macro_use]
@@ -246,10 +248,7 @@ pub enum TrapKind {
 impl TrapKind {
     /// Whether this trap is specified by the host.
     pub fn is_host(&self) -> bool {
-        match self {
-            &TrapKind::Host(_) => true,
-            _ => false,
-        }
+        matches!(self, TrapKind::Host(_))
     }
 }
 
@@ -333,6 +332,7 @@ impl Error {
     }
 }
 
+#[allow(clippy::from_over_into)]
 impl Into<String> for Error {
     fn into(self) -> String {
         match self {

src/memory/mod.rs

@@ -143,13 +143,11 @@ impl MemoryInstance {
 
         let initial_size: Bytes = initial.into();
         Ok(MemoryInstance {
-            limits: limits,
-            buffer: RefCell::new(
-                ByteBuf::new(initial_size.0).map_err(|err| Error::Memory(err.to_string()))?,
-            ),
-            initial: initial,
+            limits,
+            buffer: RefCell::new(ByteBuf::new(initial_size.0).map_err(Error::Memory)?),
+            initial,
             current_size: Cell::new(initial_size.0),
-            maximum: maximum,
+            maximum,
         })
     }
 
@@ -267,9 +265,9 @@ impl MemoryInstance {
             return Ok(size_before_grow);
         }
         if additional > Pages(65536) {
-            return Err(Error::Memory(format!(
-                "Trying to grow memory by more than 65536 pages"
-            )));
+            return Err(Error::Memory(
+                "Trying to grow memory by more than 65536 pages".to_string(),
+            ));
         }
 
         let new_size: Pages = size_before_grow + additional;
@@ -287,7 +285,7 @@ impl MemoryInstance {
         self.buffer
             .borrow_mut()
             .realloc(new_buffer_length.0)
-            .map_err(|err| Error::Memory(err.to_string()))?;
+            .map_err(Error::Memory)?;
 
         self.current_size.set(new_buffer_length.0);
 
@@ -316,10 +314,7 @@ impl MemoryInstance {
             )));
         }
 
-        Ok(CheckedRegion {
-            offset: offset,
-            size: size,
-        })
+        Ok(CheckedRegion { offset, size })
     }
 
     fn checked_region_pair(
@@ -421,9 +416,9 @@ impl MemoryInstance {
             self.checked_region_pair(&mut buffer, src_offset, len, dst_offset, len)?;
 
         if read_region.intersects(&write_region) {
-            return Err(Error::Memory(format!(
-                "non-overlapping copy is used for overlapping regions"
-            )));
+            return Err(Error::Memory(
+                "non-overlapping copy is used for overlapping regions".to_string(),
+            ));
         }
 
         unsafe {
@@ -501,10 +496,7 @@ impl MemoryInstance {
     ///
     /// Might be useful for some optimization shenanigans.
     pub fn erase(&self) -> Result<(), Error> {
-        self.buffer
-            .borrow_mut()
-            .erase()
-            .map_err(|err| Error::Memory(err))
+        self.buffer.borrow_mut().erase().map_err(Error::Memory)
     }
 
     /// Provides direct access to the underlying memory buffer.
@@ -564,7 +556,7 @@ mod tests {
 
         for (index, &(initial, maybe_max, expected_ok)) in fixtures.iter().enumerate() {
             let initial: Pages = Pages(initial);
-            let maximum: Option<Pages> = maybe_max.map(|m| Pages(m));
+            let maximum: Option<Pages> = maybe_max.map(Pages);
             let result = MemoryInstance::alloc(initial, maximum);
             if result.is_ok() != expected_ok {
                 panic!(