Fix some clippy warnings (rust-lang#1429)

Author: fzaiser

.cargo/config.toml

@@ -9,29 +9,14 @@ rustflags = [ # Global lints/warnings. Need to use underscore instead of -.
     "-Aclippy::or_fun_call",
 
     # todo address the following lints.
-    "-Aclippy::cargo_common_metadata",
     "-Aclippy::derive_partial_eq_without_eq",
-    "-Aclippy::explicit_auto_deref",
-    "-Aclippy::if_same_then_else",
-    "-Aclippy::iter_nth_zero",
-    "-Aclippy::let_and_return",
     "-Aclippy::manual_map",
     "-Aclippy::manual_range_contains",
-    "-Aclippy::manual_strip",
     "-Aclippy::map_entry",
-    "-Aclippy::match_like_matches_macro",
     "-Aclippy::missing_safety_doc",
     "-Aclippy::module_inception",
-    "-Aclippy::needless_arbitrary_self_type",
-    "-Aclippy::needless_bool",
-    "-Aclippy::needless_return",
     "-Aclippy::new_ret_no_self",
     "-Aclippy::new_without_default",
-    "-Aclippy::redundant_clone",
     "-Aclippy::too_many_arguments",
     "-Aclippy::type_complexity",
-    "-Aclippy::unnecessary_lazy_evaluations",
-    "-Aclippy::useless_conversion",
-    "-Aclippy::needless_borrow",
-    "-Aclippy::unnecessary_filter_map",
 ]

cprover_bindings/src/goto_program/expr.rs

@@ -330,6 +330,7 @@ impl Expr {
     pub fn can_cast_from(source: &Type, target: &Type) -> bool {
         let source = source.unwrap_typedef();
         let target = target.unwrap_typedef();
+        #[allow(clippy::needless_bool)]
         if source == target {
             true
         } else if target.is_bool() {

cprover_bindings/src/goto_program/symtab_transformer/passes.rs

@@ -16,8 +16,7 @@ pub fn do_passes(mut symtab: SymbolTable, pass_names: &[String]) -> SymbolTable
                 // the other two identifiers
                 let symtab = ExprTransformer::transform(&symtab);
                 let symtab = NondetTransformer::transform(&symtab);
-                let symtab = NameTransformer::transform(&symtab);
-                symtab
+                NameTransformer::transform(&symtab)
             }
             "identity" => IdentityTransformer::transform(&symtab),
             _ => panic!("Invalid symbol table transformation: {}", pass_name),

kani-compiler/src/codegen_cprover_gotoc/codegen/function.rs

@@ -335,7 +335,6 @@ impl<'tcx> GotocCtx<'tcx> {
                 self.tcx
                     .sess
                     .span_err(attr.span, "Exactly one Unwind Argument as Integer accepted");
-                return;
             }
             Some(unwind_integer_value) => {
                 let val: Result<u32, _> = unwind_integer_value.try_into();

kani-compiler/src/codegen_cprover_gotoc/codegen/intrinsic.rs

@@ -604,6 +604,8 @@ impl<'tcx> GotocCtx<'tcx> {
             "simd_rem" => unstable_codegen!(codegen_intrinsic_binop!(rem)),
             "simd_shl" => unstable_codegen!(codegen_intrinsic_binop!(shl)),
             "simd_shr" => {
+                // Remove this attribute once unstable_codegen! is removed.
+                #[allow(clippy::if_same_then_else)]
                 if fargs[0].typ().base_type().unwrap().is_signed(self.symbol_table.machine_model())
                 {
                     unstable_codegen!(codegen_intrinsic_binop!(ashr))

kani-compiler/src/codegen_cprover_gotoc/codegen/operand.rs

@@ -681,7 +681,7 @@ impl<'tcx> GotocCtx<'tcx> {
         let fn_singleton = self.ensure_global_var(
             &fn_singleton_name,
             false,
-            fn_struct_ty.clone(),
+            fn_struct_ty,
             Location::none(),
             |_, _| None, // zero-sized, so no initialization necessary
         );

kani-compiler/src/codegen_cprover_gotoc/codegen/place.rs

@@ -277,7 +277,7 @@ impl<'tcx> GotocCtx<'tcx> {
                     }
                     ty::Closure(..) => Ok(res.member(&f.index().to_string(), &self.symbol_table)),
                     ty::Generator(..) => {
-                        let field_name = self.generator_field_name(f.index().into());
+                        let field_name = self.generator_field_name(f.index());
                         Ok(res
                             .member("direct_fields", &self.symbol_table)
                             .member(field_name, &self.symbol_table))
@@ -291,7 +291,7 @@ impl<'tcx> GotocCtx<'tcx> {
                 Ok(res.member(&field.name.to_string(), &self.symbol_table))
             }
             TypeOrVariant::GeneratorVariant(_var_idx) => {
-                let field_name = self.generator_field_name(f.index().into());
+                let field_name = self.generator_field_name(f.index());
                 Ok(res.member(field_name, &self.symbol_table))
             }
         }

kani-compiler/src/codegen_cprover_gotoc/codegen/rvalue.rs

@@ -689,12 +689,10 @@ impl<'tcx> GotocCtx<'tcx> {
                                 .tcx
                                 .normalize_erasing_regions(ty::ParamEnv::reveal_all(), src_subt);
                             match src_subt.kind() {
-                                ty::Slice(_) | ty::Str | ty::Dynamic(..) => {
-                                    return self
-                                        .codegen_operand(src)
-                                        .member("data", &self.symbol_table)
-                                        .cast_to(self.codegen_ty(dst_t));
-                                }
+                                ty::Slice(_) | ty::Str | ty::Dynamic(..) => self
+                                    .codegen_operand(src)
+                                    .member("data", &self.symbol_table)
+                                    .cast_to(self.codegen_ty(dst_t)),
                                 _ => self.codegen_operand(src).cast_to(self.codegen_ty(dst_t)),
                             }
                         }

kani-compiler/src/codegen_cprover_gotoc/codegen/statement.rs

@@ -609,23 +609,23 @@ impl<'tcx> GotocCtx<'tcx> {
                     }
                 };
                 stmts.push(self.codegen_end_call(target.as_ref(), loc));
-                return Stmt::block(stmts, loc);
+                Stmt::block(stmts, loc)
             }
             // Function call through a pointer
             ty::FnPtr(_) => {
                 let func_expr = self.codegen_operand(func).dereference();
                 // Actually generate the function call and return.
-                return Stmt::block(
+                Stmt::block(
                     vec![
                         self.codegen_expr_to_place(destination, func_expr.call(fargs))
                             .with_location(loc),
                         Stmt::goto(self.current_fn().find_label(&target.unwrap()), loc),
                     ],
                     loc,
-                );
+                )
             }
             x => unreachable!("Function call where the function was of unexpected type: {:?}", x),
-        };
+        }
     }
 
     /// Extract a reference to self for virtual method calls.

kani-compiler/src/codegen_cprover_gotoc/codegen/typ.rs

@@ -667,7 +667,7 @@ impl<'tcx> GotocCtx<'tcx> {
                     self.ensure_struct(
                         self.ty_mangled_name(ty),
                         self.ty_pretty_name(ty),
-                        |tcx, _| tcx.codegen_ty_tuple_fields(ty, *ts),
+                        |tcx, _| tcx.codegen_ty_tuple_fields(ty, ts),
                     )
                 }
             }
@@ -786,7 +786,7 @@ impl<'tcx> GotocCtx<'tcx> {
                 }
                 final_fields.extend(self.codegen_alignment_padding(
                     offset,
-                    &layout,
+                    layout,
                     final_fields.len(),
                 ));
                 final_fields
@@ -991,7 +991,7 @@ impl<'tcx> GotocCtx<'tcx> {
                 let field_name = if Some(idx) == discriminant_field {
                     "case".into()
                 } else {
-                    ctx.generator_field_name(idx).into()
+                    ctx.generator_field_name(idx)
                 };
                 let field_ty = type_and_layout.field(ctx, idx).ty;
                 let field_offset = type_and_layout.fields.offset(idx);
@@ -1139,24 +1139,24 @@ impl<'tcx> GotocCtx<'tcx> {
         let params = sig
             .inputs()
             .iter()
-            .filter_map(|arg_type| {
+            .map(|arg_type| {
                 if is_first {
                     is_first = false;
                     debug!(self_type=?arg_type, fn_signature=?sig, "codegen_dynamic_function_sig");
                     if arg_type.is_ref() {
                         // Convert fat pointer to thin pointer to data portion.
                         let first_ty = pointee_type(*arg_type).unwrap();
-                        Some(self.codegen_trait_data_pointer(first_ty))
+                        self.codegen_trait_data_pointer(first_ty)
                     } else if arg_type.is_trait() {
                         // Convert dyn T to thin pointer.
-                        Some(self.codegen_trait_data_pointer(*arg_type))
+                        self.codegen_trait_data_pointer(*arg_type)
                     } else {
                         // Codegen type with thin pointer (E.g.: Box<dyn T> -> Box<data_ptr>).
-                        Some(self.codegen_trait_receiver(*arg_type))
+                        self.codegen_trait_receiver(*arg_type)
                     }
                 } else {
                     debug!("Using type {:?} in function signature", arg_type);
-                    Some(self.codegen_ty(*arg_type))
+                    self.codegen_ty(*arg_type)
                 }
             })
             .collect();
@@ -1404,7 +1404,7 @@ impl<'tcx> GotocCtx<'tcx> {
                     // fields.
                     Some(
                         lo.fields()
-                            .offset(lo.fields().index_by_increasing_offset().nth(0).unwrap()),
+                            .offset(lo.fields().index_by_increasing_offset().next().unwrap()),
                     )
                 }
             })
@@ -1700,7 +1700,7 @@ impl<'tcx> GotocCtx<'tcx> {
     /// Pre-condition: The argument must be a valid receiver for dispatchable trait functions.
     /// See <https://doc.rust-lang.org/reference/items/traits.html#object-safety> for more details.
     pub fn receiver_data_path<'a>(
-        self: &'a Self,
+        &'a self,
         typ: Ty<'tcx>,
     ) -> impl Iterator<Item = (String, Ty<'tcx>)> + 'a {
         struct ReceiverIter<'tcx, 'a> {

kani-driver/src/call_cargo.rs

@@ -76,15 +76,15 @@ impl KaniSession {
                 outdir: outdir.clone(),
                 symtabs: vec![outdir.join("*.symtab.json")],
                 metadata: vec![outdir.join("*.kani-metadata.json")],
-                restrictions: self.args.restrict_vtable().then(|| outdir),
+                restrictions: self.args.restrict_vtable().then_some(outdir),
             });
         }
 
         Ok(CargoOutputs {
             outdir: outdir.clone(),
             symtabs: glob(&outdir.join("*.symtab.json"))?,
             metadata: glob(&outdir.join("*.kani-metadata.json"))?,
-            restrictions: self.args.restrict_vtable().then(|| outdir),
+            restrictions: self.args.restrict_vtable().then_some(outdir),
         })
     }
 }

tools/compiletest/src/header.rs

@@ -115,8 +115,8 @@ fn iter_header<R: Read>(testfile: &Path, rdr: R, it: &mut dyn FnMut(Option<&str>
         let ln = ln.trim();
         if ln.starts_with("fn") || ln.starts_with("mod") {
             return;
-        } else if ln.starts_with(comment) {
-            it(None, ln[comment.len()..].trim_start());
+        } else if let Some(rest) = ln.strip_prefix(comment) {
+            it(None, rest.trim_start());
         }
     }
 }