diff --git a/src/allocator.rs b/src/allocator.rs
index 5cfd654a204..deeb55e9d12 100644
--- a/src/allocator.rs
+++ b/src/allocator.rs
@@ -63,7 +63,7 @@ pub(crate) unsafe fn codegen(
         tcx,
         context,
         "__rust_alloc_error_handler",
-        &alloc_error_handler_name(alloc_error_handler_kind),
+        alloc_error_handler_name(alloc_error_handler_kind),
         &[usize, usize],
         None,
     );
@@ -93,7 +93,7 @@ fn create_wrapper_function(
     let args: Vec<_> = types
         .iter()
         .enumerate()
-        .map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
+        .map(|(index, typ)| context.new_parameter(None, *typ, format!("param{}", index)))
         .collect();
     let func = context.new_function(
         None,
@@ -115,7 +115,7 @@ fn create_wrapper_function(
     let args: Vec<_> = types
         .iter()
         .enumerate()
-        .map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
+        .map(|(index, typ)| context.new_parameter(None, *typ, format!("param{}", index)))
         .collect();
     let callee = context.new_function(
         None,
diff --git a/src/asm.rs b/src/asm.rs
index bded806cafd..a237f3e6490 100644
--- a/src/asm.rs
+++ b/src/asm.rs
@@ -96,7 +96,7 @@ fn to_constraint(&self) -> String {
             res.push('&');
         }
 
-        res.push_str(&self.constraint);
+        res.push_str(self.constraint);
         res
     }
 }
@@ -304,7 +304,7 @@ fn codegen_inline_asm(
                         tmp_var.set_register_name(reg_name);
 
                         outputs.push(AsmOutOperand {
-                            constraint: "r".into(),
+                            constraint: "r",
                             rust_idx,
                             late,
                             readwrite: false,
@@ -343,7 +343,7 @@ fn codegen_inline_asm(
                         tmp_var.set_register_name(reg_name);
 
                         outputs.push(AsmOutOperand {
-                            constraint: "r".into(),
+                            constraint: "r",
                             rust_idx,
                             late,
                             readwrite: false,
diff --git a/src/back/lto.rs b/src/back/lto.rs
index 42837a57bad..61e0f203ee0 100644
--- a/src/back/lto.rs
+++ b/src/back/lto.rs
@@ -106,11 +106,10 @@ fn prepare_lto(
             if !crate_type_allows_lto(*crate_type) {
                 dcx.emit_err(LtoDisallowed);
                 return Err(FatalError);
-            } else if *crate_type == CrateType::Dylib {
-                if !cgcx.opts.unstable_opts.dylib_lto {
-                    dcx.emit_err(LtoDylib);
-                    return Err(FatalError);
-                }
+            }
+            if *crate_type == CrateType::Dylib && !cgcx.opts.unstable_opts.dylib_lto {
+                dcx.emit_err(LtoDylib);
+                return Err(FatalError);
             }
         }
 
diff --git a/src/consts.rs b/src/consts.rs
index 1c66ad8cc5a..327c9bdada9 100644
--- a/src/consts.rs
+++ b/src/consts.rs
@@ -77,10 +77,8 @@ fn codegen_static(&self, def_id: DefId, is_mutable: bool) {
         // boolean SSA values are i1, but they have to be stored in i8 slots,
         // otherwise some LLVM optimization passes don't work as expected
         let val_llty = self.val_ty(value);
-        let value = if val_llty == self.type_i1() {
+        if val_llty == self.type_i1() {
             unimplemented!();
-        } else {
-            value
         };
 
         let instance = Instance::mono(self.tcx, def_id);
@@ -94,11 +92,9 @@ fn codegen_static(&self, def_id: DefId, is_mutable: bool) {
 
         // As an optimization, all shared statics which do not have interior
         // mutability are placed into read-only memory.
-        if !is_mutable {
-            if self.type_is_freeze(ty) {
-                #[cfg(feature = "master")]
-                global.global_set_readonly();
-            }
+        if !is_mutable && self.type_is_freeze(ty) {
+            #[cfg(feature = "master")]
+            global.global_set_readonly();
         }
 
         if attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) {
diff --git a/src/debuginfo.rs b/src/debuginfo.rs
index a072a5092a7..aed15769025 100644
--- a/src/debuginfo.rs
+++ b/src/debuginfo.rs
@@ -255,7 +255,6 @@ fn create_dbg_var(
         _variable_kind: VariableKind,
         _span: Span,
     ) -> Self::DIVariable {
-        ()
     }
 
     fn dbg_scope_fn(
diff --git a/src/intrinsic/mod.rs b/src/intrinsic/mod.rs
index 22176ab9cd7..0fd91fc10f1 100644
--- a/src/intrinsic/mod.rs
+++ b/src/intrinsic/mod.rs
@@ -1065,7 +1065,7 @@ fn saturating_sub(
 
             // Return `result_type`'s maximum or minimum value on overflow
             // NOTE: convert the type to unsigned to have an unsigned shift.
-            let unsigned_type = result_type.to_unsigned(&self.cx);
+            let unsigned_type = result_type.to_unsigned(self.cx);
             let shifted = self.gcc_lshr(
                 self.gcc_int_cast(lhs, unsigned_type),
                 self.gcc_int(unsigned_type, width as i64 - 1),
@@ -1108,9 +1108,10 @@ fn try_intrinsic<'a, 'b, 'gcc, 'tcx>(
         // we can never unwind.
         let ret_align = bx.tcx.data_layout.i32_align.abi;
         bx.store(bx.const_i32(0), dest, ret_align);
-    } else if wants_msvc_seh(bx.sess()) {
-        unimplemented!();
     } else {
+        if wants_msvc_seh(bx.sess()) {
+            unimplemented!();
+        }
         #[cfg(feature = "master")]
         codegen_gnu_try(bx, try_func, data, _catch_func, dest);
         #[cfg(not(feature = "master"))]
@@ -1160,7 +1161,7 @@ fn codegen_gnu_try<'gcc>(
         let catch_func = func.get_param(2).to_rvalue();
         let try_func_ty = bx.type_func(&[bx.type_i8p()], bx.type_void());
 
-        let current_block = bx.block.clone();
+        let current_block = bx.block;
 
         bx.switch_to_block(then);
         bx.ret(bx.const_i32(0));
diff --git a/src/lib.rs b/src/lib.rs
index 19e441bae96..a4ee3015b8d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -187,7 +187,7 @@ fn init(&self, sess: &Session) {
             // Get the second TargetInfo with the correct CPU features by setting the arch.
             let context = Context::default();
             if target_cpu != "generic" {
-                context.add_command_line_option(&format!("-march={}", target_cpu));
+                context.add_command_line_option(format!("-march={}", target_cpu));
             }
 
             **self.target_info.info.lock().expect("lock") = context.get_target_info();
@@ -224,9 +224,9 @@ fn provide(&self, providers: &mut Providers) {
         providers.global_backend_features = |tcx, ()| gcc_util::global_gcc_features(tcx.sess, true)
     }
 
-    fn codegen_crate<'tcx>(
+    fn codegen_crate(
         &self,
-        tcx: TyCtxt<'tcx>,
+        tcx: TyCtxt<'_>,
         metadata: EncodedMetadata,
         need_metadata_module: bool,
     ) -> Box<dyn Any> {
@@ -292,9 +292,9 @@ fn new_context<'gcc, 'tcx>(tcx: TyCtxt<'tcx>) -> Context<'gcc> {
 }
 
 impl ExtraBackendMethods for GccCodegenBackend {
-    fn codegen_allocator<'tcx>(
+    fn codegen_allocator(
         &self,
-        tcx: TyCtxt<'tcx>,
+        tcx: TyCtxt<'_>,
         module_name: &str,
         kind: AllocatorKind,
         alloc_error_handler_kind: AllocatorKind,
@@ -486,6 +486,6 @@ pub fn target_features(
               sha, sse, sse2, sse3, sse4.1, sse4.2, sse4a, ssse3, tbm, vaes, vpclmulqdq, xsave, xsavec, xsaveopt, xsaves
             */
         })
-        .map(|feature| Symbol::intern(feature))
+        .map(Symbol::intern)
         .collect()
 }
diff --git a/src/mono_item.rs b/src/mono_item.rs
index 2f75cec69e9..e56c49686c0 100644
--- a/src/mono_item.rs
+++ b/src/mono_item.rs
@@ -47,7 +47,7 @@ fn predefine_fn(
 
         let fn_abi = self.fn_abi_of_instance(instance, ty::List::empty());
         self.linkage.set(base::linkage_to_gcc(linkage));
-        let decl = self.declare_fn(symbol_name, &fn_abi);
+        let decl = self.declare_fn(symbol_name, fn_abi);
         //let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
 
         attributes::from_fn_attrs(self, decl, instance);
diff --git a/src/type_.rs b/src/type_.rs
index f5e2ace725c..0465d0bbdfe 100644
--- a/src/type_.rs
+++ b/src/type_.rs
@@ -133,13 +133,13 @@ fn type_func(&self, params: &[Type<'gcc>], return_type: Type<'gcc>) -> Type<'gcc
     fn type_struct(&self, fields: &[Type<'gcc>], packed: bool) -> Type<'gcc> {
         let types = fields.to_vec();
         if let Some(typ) = self.struct_types.borrow().get(fields) {
-            return typ.clone();
+            return *typ;
         }
         let fields: Vec<_> = fields
             .iter()
             .enumerate()
             .map(|(index, field)| {
-                self.context.new_field(None, *field, &format!("field{}_TODO", index))
+                self.context.new_field(None, *field, format!("field{}_TODO", index))
             })
             .collect();
         let typ = self.context.new_struct_type(None, "struct", &fields).as_type();
@@ -240,7 +240,7 @@ pub fn set_struct_body(&self, typ: Struct<'gcc>, fields: &[Type<'gcc>], packed:
         let fields: Vec<_> = fields
             .iter()
             .enumerate()
-            .map(|(index, field)| self.context.new_field(None, *field, &format!("field_{}", index)))
+            .map(|(index, field)| self.context.new_field(None, *field, format!("field_{}", index)))
             .collect();
         typ.set_fields(None, &fields);
         if packed {
@@ -265,7 +265,7 @@ pub fn struct_fields<'gcc, 'tcx>(
     let mut prev_effective_align = layout.align.abi;
     let mut result: Vec<_> = Vec::with_capacity(1 + field_count * 2);
     for i in layout.fields.index_by_increasing_offset() {
-        let target_offset = layout.fields.offset(i as usize);
+        let target_offset = layout.fields.offset(i);
         let field = layout.field(cx, i);
         let effective_field_align =
             layout.align.abi.min(field.align.abi).restrict_for_offset(target_offset);
diff --git a/tests/lang_tests_common.rs b/tests/lang_tests_common.rs
index d116daab7c4..d321ffc8ff5 100644
--- a/tests/lang_tests_common.rs
+++ b/tests/lang_tests_common.rs
@@ -76,7 +76,7 @@ fn filter(filename: &Path) -> bool {
             exe.push(&tempdir);
             exe.push(path.file_stem().expect("file_stem"));
             let mut compiler = Command::new("rustc");
-            compiler.args(&[
+            compiler.args([
                 &format!("-Zcodegen-backend={}/target/debug/librustc_codegen_gcc.so", current_dir),
                 "--sysroot",
                 &format!("{}/build_sysroot/sysroot/", current_dir),
@@ -91,7 +91,7 @@ fn filter(filename: &Path) -> bool {
             // TODO(antoyo): find a way to send this via a cli argument.
             let test_target = std::env::var("CG_GCC_TEST_TARGET");
             if let Ok(ref target) = test_target {
-                compiler.args(&["--target", &target]);
+                compiler.args(["--target", target]);
                 let linker = format!("{}-gcc", target);
                 compiler.args(&[format!("-Clinker={}", linker)]);
                 let mut env_path = std::env::var("PATH").unwrap_or_default();
@@ -102,32 +102,32 @@ fn filter(filename: &Path) -> bool {
 
             if let Some(flags) = option_env!("TEST_FLAGS") {
                 for flag in flags.split_whitespace() {
-                    compiler.arg(&flag);
+                    compiler.arg(flag);
                 }
             }
             match profile {
                 Profile::Debug => {}
                 Profile::Release => {
-                    compiler.args(&["-C", "opt-level=3", "-C", "lto=no"]);
+                    compiler.args(["-C", "opt-level=3", "-C", "lto=no"]);
                 }
             }
             // Test command 2: run `tempdir/x`.
             if test_target.is_ok() {
                 let vm_parent_dir = std::env::var("CG_GCC_VM_DIR")
-                    .map(|dir| PathBuf::from(dir))
+                    .map(PathBuf::from)
                     .unwrap_or_else(|_| std::env::current_dir().unwrap());
                 let vm_dir = "vm";
                 let exe_filename = exe.file_name().unwrap();
                 let vm_home_dir = vm_parent_dir.join(vm_dir).join("home");
                 let vm_exe_path = vm_home_dir.join(exe_filename);
                 // FIXME(antoyo): panicking here makes the test pass.
-                let inside_vm_exe_path = PathBuf::from("/home").join(&exe_filename);
+                let inside_vm_exe_path = PathBuf::from("/home").join(exe_filename);
                 let mut copy = Command::new("sudo");
                 copy.arg("cp");
-                copy.args(&[&exe, &vm_exe_path]);
+                copy.args([&exe, &vm_exe_path]);
 
                 let mut runtime = Command::new("sudo");
-                runtime.args(&["chroot", vm_dir, "qemu-m68k-static"]);
+                runtime.args(["chroot", vm_dir, "qemu-m68k-static"]);
                 runtime.arg(inside_vm_exe_path);
                 runtime.current_dir(vm_parent_dir);
                 vec![("Compiler", compiler), ("Copy", copy), ("Run-time", runtime)]