Fix clippy::explicit_iter_loop (pedantic)

“it is more concise to loop over references to containers instead of
using explicit iteration methods”

https://rust-lang.github.io/rust-clippy/master/index.html#explicit_iter_loop

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

src/check_ast.rs

@@ -2648,7 +2648,7 @@ impl<'a> Checker<'a> {
                 let mut unused: BTreeMap<(ImportKind, usize, Option<usize>), Vec<&str>> =
                     BTreeMap::new();
 
-                for (name, binding) in scope.values.iter() {
+                for (name, binding) in &scope.values {
                     if !matches!(
                         binding.kind,
                         BindingKind::Importation(..)

src/flake8_boolean_trap/plugins.rs

@@ -51,7 +51,7 @@ pub fn check_boolean_default_value_in_function_definition(
     checker: &mut Checker,
     arguments: &Arguments,
 ) {
-    for arg in arguments.defaults.iter() {
+    for arg in &arguments.defaults {
         add_if_boolean(
             checker,
             arg,

src/flake8_bugbear/plugins/loop_variable_overrides_iterator.rs

@@ -31,7 +31,7 @@ where
             }
             ExprKind::Lambda { args, body } => {
                 visitor::walk_expr(self, body);
-                for arg in args.args.iter() {
+                for arg in &args.args {
                     self.names.remove(arg.node.arg.as_str());
                 }
             }

src/isort/mod.rs

@@ -437,13 +437,13 @@ pub fn format_imports(
         let mut is_first_statement = true;
 
         // Format `StmtKind::Import` statements.
-        for (alias, comments) in import_block.import.iter() {
+        for (alias, comments) in &import_block.import {
             output.append(&format::format_import(alias, comments, is_first_statement));
             is_first_statement = false;
         }
 
         // Format `StmtKind::ImportFrom` statements.
-        for (import_from, comments, aliases) in import_block.import_from.iter() {
+        for (import_from, comments, aliases) in &import_block.import_from {
             output.append(&format::format_import_from(
                 import_from,
                 comments,

src/pyflakes/checks.rs

@@ -63,7 +63,7 @@ pub fn unused_variables(scope: &Scope, dummy_variable_rgx: &Regex) -> Vec<Check>
         return checks;
     }
 
-    for (&name, binding) in scope.values.iter() {
+    for (&name, binding) in &scope.values {
         if binding.used.is_none()
             && matches!(binding.kind, BindingKind::Assignment)
             && !dummy_variable_rgx.is_match(name)

src/settings/mod.rs

@@ -129,14 +129,14 @@ impl Hash for Settings {
     fn hash<H: Hasher>(&self, state: &mut H) {
         // Add base properties in alphabetical order.
         self.dummy_variable_rgx.as_str().hash(state);
-        for value in self.enabled.iter() {
+        for value in &self.enabled {
             value.hash(state);
         }
-        for value in self.fixable.iter() {
+        for value in &self.fixable {
             value.hash(state);
         }
         self.line_length.hash(state);
-        for value in self.per_file_ignores.iter() {
+        for value in &self.per_file_ignores {
             value.hash(state);
         }
         self.show_source.hash(state);