Fix most clippy warnings

This fixes most clippy warnings that I'm seeing.

crates/fuzz-utils/src/lib.rs

@@ -99,20 +99,20 @@ where
     }
 
     fn interp(&self, wasm: &[u8]) -> Result<String> {
-        fs::write(self.scratch.path(), &wasm).context("failed to write to scratch file")?;
+        fs::write(self.scratch.path(), wasm).context("failed to write to scratch file")?;
         wasm_interp(self.scratch.path())
     }
 
     fn round_trip_through_walrus(&self, wasm: &[u8]) -> Result<Vec<u8>> {
         let mut module =
-            walrus::Module::from_buffer(&wasm).context("walrus failed to parse the wasm buffer")?;
+            walrus::Module::from_buffer(wasm).context("walrus failed to parse the wasm buffer")?;
         walrus::passes::gc::run(&mut module);
         let buf = module.emit_wasm();
         Ok(buf)
     }
 
     fn test_wat(&self, wat: &str) -> Result<()> {
-        let wasm = self.wat2wasm(&wat)?;
+        let wasm = self.wat2wasm(wat)?;
         let expected = self.interp(&wasm)?;
 
         let walrus_wasm = self.round_trip_through_walrus(&wasm)?;
@@ -313,7 +313,7 @@ impl<R: Rng> WatGen<R> {
         self.wat.push_str(&operator.to_string());
 
         for op in immediates.into_iter() {
-            self.wat.push_str(" ");
+            self.wat.push(' ');
             self.wat.push_str(op.as_ref());
         }
 

crates/macro/src/lib.rs

@@ -103,7 +103,7 @@ impl Parse for WalrusFieldOpts {
                 if attr == "skip_visit" {
                     return Ok(Attr::SkipVisit);
                 }
-                return Err(Error::new(attr.span(), "unexpected attribute"));
+                Err(Error::new(attr.span(), "unexpected attribute"))
             }
         }
     }
@@ -144,7 +144,7 @@ impl Parse for WalrusVariantOpts {
                 if attr == "skip_builder" {
                     return Ok(Attr::SkipBuilder);
                 }
-                return Err(Error::new(attr.span(), "unexpected attribute"));
+                Err(Error::new(attr.span(), "unexpected attribute"))
             }
         }
     }
@@ -166,7 +166,7 @@ fn walrus_attrs(attrs: &mut Vec<syn::Attribute>) -> TokenStream {
         ret.extend(group);
         ret.extend(quote! { , });
     }
-    return ret.into();
+    ret.into()
 }
 
 fn create_types(attrs: &[syn::Attribute], variants: &[WalrusVariant]) -> impl quote::ToTokens {
@@ -328,10 +328,10 @@ fn create_types(attrs: &[syn::Attribute], variants: &[WalrusVariant]) -> impl qu
     }
 }
 
-fn visit_fields<'a>(
-    variant: &'a WalrusVariant,
+fn visit_fields(
+    variant: &WalrusVariant,
     allow_skip: bool,
-) -> impl Iterator<Item = (syn::Ident, proc_macro2::TokenStream, bool)> + 'a {
+) -> impl Iterator<Item = (syn::Ident, proc_macro2::TokenStream, bool)> + '_ {
     return variant
         .syn
         .fields
@@ -439,7 +439,7 @@ fn create_visit(variants: &[WalrusVariant]) -> impl quote::ToTokens {
             }
         });
 
-        let doc = format!("Visit `{}`.", name.to_string());
+        let doc = format!("Visit `{}`.", name);
         visitor_trait_methods.push(quote! {
             #[doc=#doc]
             #[inline]
@@ -723,13 +723,13 @@ fn create_builder(variants: &[WalrusVariant]) -> impl quote::ToTokens {
 
         let doc = format!(
             "Push a new `{}` instruction onto this builder's block.",
-            name.to_string()
+            name
         );
         let at_doc = format!(
             "Splice a new `{}` instruction into this builder's block at the given index.\n\n\
              # Panics\n\n\
              Panics if `position > self.instrs.len()`.",
-            name.to_string()
+            name
         );
 
         let arg_names = &arg_names;

crates/tests-utils/src/lib.rs

@@ -67,7 +67,7 @@ where
     cmd.arg(input);
     cmd.arg("-o");
     cmd.arg(tmp.path());
-    cmd.args(&[
+    cmd.args([
         "--enable-threads",
         "--enable-bulk-memory",
         // "--enable-reference-types",

crates/tests/src/lib.rs

@@ -79,11 +79,11 @@ impl FileCheck {
         let mut iter = contents.lines().map(str::trim);
         while let Some(line) = iter.next() {
             if line.starts_with("(; CHECK-ALL:") {
-                if patterns.len() != 0 {
+                if !patterns.is_empty() {
                     panic!("CHECK cannot be used with CHECK-ALL");
                 }
                 let mut pattern = Vec::new();
-                while let Some(line) = iter.next() {
+                for line in iter.by_ref() {
                     if line == ";)" {
                         break;
                     }
@@ -95,18 +95,17 @@ impl FileCheck {
                 return FileCheck::Exhaustive(pattern, path.to_path_buf());
             }
 
-            if line.starts_with(";; CHECK:") {
-                let p = line[";; CHECK:".len()..].to_string();
-                patterns.push(vec![p]);
+            if let Some(p) = line.strip_prefix(";; CHECK:") {
+                patterns.push(vec![p.to_string()]);
             }
-            if line.starts_with(";; NEXT:") {
+            if let Some(n) = line.strip_prefix(";; NEXT:") {
                 let p = patterns
                     .last_mut()
                     .expect("NEXT should never come before CHECK");
-                p.push(line[";; NEXT:".len()..].to_string());
+                p.push(n.to_string());
             }
         }
-        if patterns.len() == 0 {
+        if patterns.is_empty() {
             FileCheck::None(path.to_path_buf())
         } else {
             FileCheck::Patterns(patterns)
@@ -125,7 +124,7 @@ impl FileCheck {
 
                     'inner: while let Some(pos) = output_lines[start..]
                         .iter()
-                        .position(|l| matches(*l, first_line))
+                        .position(|l| matches(l, first_line))
                     {
                         start = pos + 1;
                         if output_lines[pos..].len() + 1 < pattern.len() {
@@ -155,11 +154,11 @@ impl FileCheck {
                 }
             }
             FileCheck::None(_) => {
-                println!("");
+                println!();
                 println!("no test assertions were found in this file, but");
                 println!("you can rerun tests with `WALRUS_BLESS=1` to");
                 println!("automatically add assertions to this file");
-                println!("");
+                println!();
                 panic!("no tests to run")
             }
         }
@@ -210,7 +209,7 @@ fn update_output(path: &Path, output: &str) {
             new_output.push_str("  ");
             new_output.push_str(line.trim_end());
         }
-        new_output.push_str("\n");
+        new_output.push('\n');
     }
     let new = format!(
         "{}\n\n(; CHECK-ALL:\n{}\n;)\n",

crates/tests/tests/custom_sections.rs

@@ -87,8 +87,8 @@ fn smoke_test_code_transform() {
         fn apply_code_transform(&mut self, transform: &CodeTransform) {
             APPLIED_CODE_TRANSFORM.store(1, Ordering::SeqCst);
             assert!(!transform.instruction_map.is_empty());
-            for (input_offset, output_offset) in transform.instruction_map.iter().cloned() {
-                assert_eq!(input_offset.data() as usize + 3, output_offset);
+            for (input_offset, output_offset) in transform.instruction_map.iter() {
+                assert_eq!(input_offset.data() as usize + 3, *output_offset);
             }
         }
     }

crates/tests/tests/spec-tests.rs

@@ -19,8 +19,7 @@ fn run(wast: &Path) -> Result<(), anyhow::Error> {
     let proposal = wast
         .iter()
         .skip_while(|part| *part != "proposals")
-        .skip(1)
-        .next()
+        .nth(1)
         .map(|s| s.to_str().unwrap());
 
     let extra_args: &[&str] = match proposal {
@@ -168,7 +167,7 @@ fn run(wast: &Path) -> Result<(), anyhow::Error> {
         }
 
         let wasm = module.emit_wasm();
-        fs::write(&file, wasm)?;
+        fs::write(file, wasm)?;
     }
 
     run_spectest_interp(tempdir.path(), extra_args)?;

src/dot.rs

@@ -103,7 +103,7 @@ impl<T: DotNode> Dot for T {
 
         impl FieldAggregator for AppendFields<'_> {
             fn add_field(&mut self, field: &[&str]) {
-                assert!(field.len() > 0);
+                assert!(!field.is_empty());
                 self.out.push_str("<tr>");
                 for f in field {
                     self.out.push_str("<td>");
@@ -114,7 +114,7 @@ impl<T: DotNode> Dot for T {
             }
 
             fn add_field_with_port(&mut self, port: &str, field: &str) {
-                assert!(field.len() > 0);
+                assert!(!field.is_empty());
                 self.out.push_str("<tr>");
                 self.out.push_str("<td port=\"");
                 self.out.push_str(port);
@@ -142,7 +142,7 @@ impl<T: DotNode> Dot for T {
             fn add_edge_from_port(&mut self, port: &str, to: &impl DotName) {
                 self.out.push_str("    ");
                 self.out.push_str(self.from);
-                self.out.push_str(":");
+                self.out.push(':');
                 self.out.push_str(port);
                 self.out.push_str(" -> ");
                 self.out.push_str(&to.dot_name());
@@ -174,7 +174,7 @@ impl Dot for Module {
         // self.name.dot(out);
         // self.config.dot(out);
 
-        out.push_str("}");
+        out.push('}');
     }
 }
 

src/module/custom.rs

@@ -193,10 +193,7 @@ where
     T: CustomSection,
 {
     fn clone(&self) -> Self {
-        TypedCustomSectionId {
-            id: self.id,
-            _phantom: PhantomData,
-        }
+        *self
     }
 }
 
@@ -366,26 +363,18 @@ impl ModuleCustomSections {
 
     /// Iterate over shared references to custom sections and their ids.
     pub fn iter(&self) -> impl Iterator<Item = (UntypedCustomSectionId, &dyn CustomSection)> {
-        self.arena.iter().flat_map(|(id, s)| {
-            if let Some(s) = s.as_ref() {
-                Some((UntypedCustomSectionId(id), &**s))
-            } else {
-                None
-            }
-        })
+        self.arena
+            .iter()
+            .flat_map(|(id, s)| Some((UntypedCustomSectionId(id), &**s.as_ref()?)))
     }
 
     /// Iterate over exclusive references to custom sections and their ids.
     pub fn iter_mut(
         &mut self,
     ) -> impl Iterator<Item = (UntypedCustomSectionId, &mut dyn CustomSection)> {
-        self.arena.iter_mut().flat_map(|(id, s)| {
-            if let Some(s) = s.as_mut() {
-                Some((UntypedCustomSectionId(id), &mut **s))
-            } else {
-                None
-            }
-        })
+        self.arena
+            .iter_mut()
+            .flat_map(|(id, s)| Some((UntypedCustomSectionId(id), &mut **s.as_mut()?)))
     }
 
     /// Remove a custom section (by type) from the module.

src/module/data.rs

@@ -64,10 +64,7 @@ impl Data {
 
     /// Is this a passive data segment?
     pub fn is_passive(&self) -> bool {
-        match self.kind {
-            DataKind::Passive => true,
-            _ => false,
-        }
+        matches!(self.kind, DataKind::Passive)
     }
 }
 
@@ -129,7 +126,7 @@ impl ModuleData {
         let mut any_passive = false;
 
         for data in self.iter() {
-            cx.indices.set_data_index(data.id(), count as u32);
+            cx.indices.set_data_index(data.id(), count);
             count += 1;
             any_passive |= data.is_passive();
         }

src/module/debug/dwarf.rs

@@ -324,9 +324,9 @@ mod tests {
     use gimli::*;
     use std::cell::RefCell;
 
-    fn make_test_debug_line<'a>(
-        debug_line: &'a mut write::DebugLine<write::EndianVec<LittleEndian>>,
-    ) -> IncompleteLineProgram<EndianSlice<'a, LittleEndian>> {
+    fn make_test_debug_line(
+        debug_line: &mut write::DebugLine<write::EndianVec<LittleEndian>>,
+    ) -> IncompleteLineProgram<EndianSlice<'_, LittleEndian>> {
         let encoding = Encoding {
             format: Format::Dwarf32,
             version: 4,
@@ -368,11 +368,9 @@ mod tests {
             .unwrap();
 
         let debug_line = read::DebugLine::new(debug_line.slice(), LittleEndian);
-        let incomplete_debug_line = debug_line
+        debug_line
             .program(DebugLineOffset(0), 4, None, None)
-            .unwrap();
-
-        incomplete_debug_line
+            .unwrap()
     }
 
     #[test]
@@ -559,11 +557,11 @@ mod tests {
     #[test]
     fn test_convert_high_pc() {
         let sections = make_test_debug_info();
-        let mut read_dwarf = Dwarf::default();
-
-        read_dwarf.debug_info = read::DebugInfo::new(sections.debug_info.slice(), LittleEndian);
-        read_dwarf.debug_abbrev =
-            read::DebugAbbrev::new(sections.debug_abbrev.slice(), LittleEndian);
+        let read_dwarf = Dwarf {
+            debug_info: read::DebugInfo::new(sections.debug_info.slice(), LittleEndian),
+            debug_abbrev: read::DebugAbbrev::new(sections.debug_abbrev.slice(), LittleEndian),
+            ..Default::default()
+        };
 
         let read_first_unit_header = read_dwarf.units().next().unwrap().unwrap();
         let read_first_unit = read_dwarf.unit(read_first_unit_header).unwrap();

src/module/debug/units.rs

@@ -76,10 +76,10 @@ mod tests {
 
         let mut cursor = DebuggingInformationCursor::new(&mut unit1);
 
-        assert_eq!(cursor.current().is_none(), true);
+        assert!(cursor.current().is_none());
         assert_eq!(cursor.next_dfs().unwrap().id(), root_id);
         assert_eq!(cursor.next_dfs().unwrap().id(), child1_id);
         assert_eq!(cursor.next_dfs().unwrap().id(), child2_id);
-        assert_eq!(cursor.next_dfs().is_none(), true);
+        assert!(cursor.next_dfs().is_none());
     }
 }

src/module/elements.rs

@@ -258,7 +258,7 @@ impl Emit for ModuleElements {
                             Some(cx.indices.get_table_index(*table)).filter(|&index| index != 0);
                         wasm_element_section.active(
                             table_index,
-                            &offset.to_wasmencoder_type(&cx),
+                            &offset.to_wasmencoder_type(cx),
                             els,
                         );
                     }

src/module/functions/local_function/context.rs

@@ -110,7 +110,7 @@ impl<'a> ValidationContext<'a> {
     }
 
     pub fn pop_control(&mut self) -> Result<(ControlFrame, InstrSeqId)> {
-        let frame = impl_pop_control(&mut self.controls)?;
+        let frame = impl_pop_control(self.controls)?;
         let block = frame.block;
         Ok((frame, block))
     }
@@ -214,7 +214,7 @@ fn impl_push_control_with_ty(
 fn impl_pop_control(controls: &mut ControlStack) -> Result<ControlFrame> {
     controls
         .last()
-        .ok_or_else(|| ErrorKind::InvalidWasm)
+        .ok_or(ErrorKind::InvalidWasm)
         .context("attempted to pop a frame from an empty control stack")?;
     let frame = controls.pop().unwrap();
     Ok(frame)