Cleanup: Use our sym! macro more

It's much shorter that Symbol::intern and the result should still be
clear.

clippy_lints/src/get_last_with_len.rs

@@ -8,7 +8,6 @@ use rustc_hir::{BinOpKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Spanned;
-use rustc_span::symbol::Symbol;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for using `x.get(x.len() - 1)` instead of
@@ -51,12 +50,12 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for GetLastWithLen {
             if let ExprKind::MethodCall(ref path, _, ref args) = expr.kind;
 
             // Method name is "get"
-            if path.ident.name == Symbol::intern("get");
+            if path.ident.name == sym!(get);
 
             // Argument 0 (the struct we're calling the method on) is a vector
             if let Some(struct_calling_on) = args.get(0);
             let struct_ty = cx.tables.expr_ty(struct_calling_on);
-            if is_type_diagnostic_item(cx, struct_ty, Symbol::intern("vec_type"));
+            if is_type_diagnostic_item(cx, struct_ty, sym!(vec_type));
 
             // Argument to "get" is a subtraction
             if let Some(get_index_arg) = args.get(1);
@@ -71,7 +70,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for GetLastWithLen {
 
             // LHS of subtraction is "x.len()"
             if let ExprKind::MethodCall(arg_lhs_path, _, lhs_args) = &lhs.kind;
-            if arg_lhs_path.ident.name == Symbol::intern("len");
+            if arg_lhs_path.ident.name == sym!(len);
             if let Some(arg_lhs_struct) = lhs_args.get(0);
 
             // The two vectors referenced (x in x.get(...) and in x.len())

clippy_lints/src/loops.rs

@@ -28,7 +28,7 @@ use rustc_middle::middle::region;
 use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
-use rustc_span::{BytePos, Symbol};
+use rustc_span::BytePos;
 use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, Place, PlaceBase};
 use std::iter::{once, Iterator};
 use std::mem;
@@ -804,7 +804,7 @@ fn is_slice_like<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'_>) -> bool {
         _ => false,
     };
 
-    is_slice || is_type_diagnostic_item(cx, ty, Symbol::intern("vec_type")) || match_type(cx, ty, &paths::VEC_DEQUE)
+    is_slice || is_type_diagnostic_item(cx, ty, sym!(vec_type)) || match_type(cx, ty, &paths::VEC_DEQUE)
 }
 
 fn get_fixed_offset_var<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &Expr<'_>, var: HirId) -> Option<FixedOffsetVar> {
@@ -1955,7 +1955,7 @@ fn is_ref_iterable_type(cx: &LateContext<'_, '_>, e: &Expr<'_>) -> bool {
     // will allow further borrows afterwards
     let ty = cx.tables.expr_ty(e);
     is_iterable_array(ty, cx) ||
-    is_type_diagnostic_item(cx, ty, Symbol::intern("vec_type")) ||
+    is_type_diagnostic_item(cx, ty, sym!(vec_type)) ||
     match_type(cx, ty, &paths::LINKED_LIST) ||
     match_type(cx, ty, &paths::HASHMAP) ||
     match_type(cx, ty, &paths::HASHSET) ||
@@ -2465,7 +2465,7 @@ fn check_needless_collect<'a, 'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'a, '
         if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0);
         then {
             let ty = cx.tables.node_type(ty.hir_id);
-            if is_type_diagnostic_item(cx, ty, Symbol::intern("vec_type")) ||
+            if is_type_diagnostic_item(cx, ty, sym!(vec_type)) ||
                 match_type(cx, ty, &paths::VEC_DEQUE) ||
                 match_type(cx, ty, &paths::BTREEMAP) ||
                 match_type(cx, ty, &paths::HASHMAP) {

clippy_lints/src/methods/mod.rs

@@ -19,7 +19,7 @@ use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::{self, Predicate, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
-use rustc_span::symbol::{sym, Symbol, SymbolStr};
+use rustc_span::symbol::{sym, SymbolStr};
 
 use crate::consts::{constant, Constant};
 use crate::utils::usage::mutated_variables;
@@ -2089,7 +2089,7 @@ fn lint_iter_cloned_collect<'a, 'tcx>(
     iter_args: &'tcx [hir::Expr<'_>],
 ) {
     if_chain! {
-        if is_type_diagnostic_item(cx, cx.tables.expr_ty(expr), Symbol::intern("vec_type"));
+        if is_type_diagnostic_item(cx, cx.tables.expr_ty(expr), sym!(vec_type));
         if let Some(slice) = derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0]));
         if let Some(to_replace) = expr.span.trim_start(slice.span.source_callsite());
 
@@ -2218,7 +2218,7 @@ fn lint_iter_nth<'a, 'tcx>(
     let mut_str = if is_mut { "_mut" } else { "" };
     let caller_type = if derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0])).is_some() {
         "slice"
-    } else if is_type_diagnostic_item(cx, cx.tables.expr_ty(&iter_args[0]), Symbol::intern("vec_type")) {
+    } else if is_type_diagnostic_item(cx, cx.tables.expr_ty(&iter_args[0]), sym!(vec_type)) {
         "Vec"
     } else if match_type(cx, cx.tables.expr_ty(&iter_args[0]), &paths::VEC_DEQUE) {
         "VecDeque"
@@ -2275,7 +2275,7 @@ fn lint_get_unwrap<'a, 'tcx>(
     let caller_type = if derefs_to_slice(cx, &get_args[0], expr_ty).is_some() {
         needs_ref = get_args_str.parse::<usize>().is_ok();
         "slice"
-    } else if is_type_diagnostic_item(cx, expr_ty, Symbol::intern("vec_type")) {
+    } else if is_type_diagnostic_item(cx, expr_ty, sym!(vec_type)) {
         needs_ref = get_args_str.parse::<usize>().is_ok();
         "Vec"
     } else if match_type(cx, expr_ty, &paths::VEC_DEQUE) {
@@ -2356,7 +2356,7 @@ fn derefs_to_slice<'a, 'tcx>(
         match ty.kind {
             ty::Slice(_) => true,
             ty::Adt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()),
-            ty::Adt(..) => is_type_diagnostic_item(cx, ty, Symbol::intern("vec_type")),
+            ty::Adt(..) => is_type_diagnostic_item(cx, ty, sym!(vec_type)),
             ty::Array(_, size) => {
                 if let Some(size) = size.try_eval_usize(cx.tcx, cx.param_env) {
                     size < 32

clippy_lints/src/needless_pass_by_value.rs

@@ -13,7 +13,7 @@ use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::{self, TypeFoldable};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::{Span, Symbol};
+use rustc_span::Span;
 use rustc_target::spec::abi::Abi;
 use rustc_trait_selection::traits;
 use rustc_trait_selection::traits::misc::can_type_implement_copy;
@@ -214,7 +214,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessPassByValue {
 
                         let deref_span = spans_need_deref.get(&canonical_id);
                         if_chain! {
-                            if is_type_diagnostic_item(cx, ty, Symbol::intern("vec_type"));
+                            if is_type_diagnostic_item(cx, ty, sym!(vec_type));
                             if let Some(clone_spans) =
                                 get_spans(cx, Some(body.id()), idx, &[("clone", ".to_owned()")]);
                             if let TyKind::Path(QPath::Resolved(_, ref path)) = input.kind;

clippy_lints/src/ptr.rs

@@ -15,7 +15,7 @@ use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
-use rustc_span::{MultiSpan, Symbol};
+use rustc_span::MultiSpan;
 use std::borrow::Cow;
 
 declare_clippy_lint! {
@@ -153,7 +153,7 @@ fn check_fn(cx: &LateContext<'_, '_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_
 
     for (idx, (arg, ty)) in decl.inputs.iter().zip(fn_ty.inputs()).enumerate() {
         if let ty::Ref(_, ty, Mutability::Not) = ty.kind {
-            if is_type_diagnostic_item(cx, ty, Symbol::intern("vec_type")) {
+            if is_type_diagnostic_item(cx, ty, sym!(vec_type)) {
                 let mut ty_snippet = None;
                 if_chain! {
                     if let TyKind::Path(QPath::Resolved(_, ref path)) = walk_ptrs_hir_ty(arg).kind;

clippy_lints/src/swap.rs

@@ -9,7 +9,6 @@ use rustc_hir::{Block, Expr, ExprKind, PatKind, QPath, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::Symbol;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for manual swapping.
@@ -199,7 +198,7 @@ fn check_for_slice<'a>(cx: &LateContext<'_, '_>, lhs1: &'a Expr<'_>, lhs2: &'a E
 
                 if matches!(ty.kind, ty::Slice(_))
                     || matches!(ty.kind, ty::Array(_, _))
-                    || is_type_diagnostic_item(cx, ty, Symbol::intern("vec_type"))
+                    || is_type_diagnostic_item(cx, ty, sym!(vec_type))
                     || match_type(cx, ty, &paths::VEC_DEQUE)
                 {
                     return Slice::Swappable(lhs1, idx1, idx2);

clippy_lints/src/types.rs

@@ -21,7 +21,7 @@ use rustc_middle::ty::{self, InferTy, Ty, TyCtxt, TypeckTables};
 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use rustc_span::source_map::Span;
-use rustc_span::symbol::{sym, Symbol};
+use rustc_span::symbol::sym;
 use rustc_target::abi::LayoutOf;
 use rustc_target::spec::abi::Abi;
 use rustc_typeck::hir_ty_to_ty;
@@ -384,7 +384,7 @@ impl Types {
                             );
                             return; // don't recurse into the type
                         }
-                    } else if cx.tcx.is_diagnostic_item(Symbol::intern("vec_type"), def_id) {
+                    } else if cx.tcx.is_diagnostic_item(sym!(vec_type), def_id) {
                         if_chain! {
                             // Get the _ part of Vec<_>
                             if let Some(ref last) = last_path_segment(qpath).args;