Auto merge of #4809 - iankronquist:patch-1, r=flip1995

[rust.git] / clippy_lints / src / loops.rs

diff --git a/clippy_lints/src/loops.rs b/clippy_lints/src/loops.rs
index 239d453a9f85ee02b215723d515c05ad1b63cfe4..1aea630efe4ed9e276e9cba07a65a851efb703fe 100644 (file)
--- a/clippy_lints/src/loops.rs
+++ b/clippy_lints/src/loops.rs
@@ -1,22 +1,28 @@
+use crate::consts::{constant, Constant};
 use crate::reexport::*;
+use crate::utils::paths;
+use crate::utils::usage::{is_unused, mutated_variables};
+use crate::utils::{
+    get_enclosing_block, get_parent_expr, get_trait_def_id, has_iter_method, higher, implements_trait,
+    is_integer_const, is_no_std_crate, is_refutable, last_path_segment, match_trait_method, match_type, match_var,
+    multispan_sugg, snippet, snippet_opt, snippet_with_applicability, span_lint, span_lint_and_help,
+    span_lint_and_sugg, span_lint_and_then, SpanlessEq,
+};
+use crate::utils::{is_type_diagnostic_item, qpath_res, same_tys, sext, sugg};
 use if_chain::if_chain;
 use itertools::Itertools;
+use rustc::hir::map::Map;
 use rustc::lint::in_external_macro;
 use rustc::middle::region;
+use rustc::ty::{self, Ty};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id;
 use rustc_hir::intravisit::{walk_block, walk_expr, walk_pat, walk_stmt, NestedVisitorMap, Visitor};
 use rustc_hir::*;
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-// use rustc::middle::region::CodeExtent;
-use crate::consts::{constant, Constant};
-use crate::utils::usage::mutated_variables;
-use crate::utils::{is_type_diagnostic_item, qpath_res, same_tys, sext, sugg};
-use rustc::hir::map::Map;
-use rustc::ty::{self, Ty};
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_errors::Applicability;
 use rustc_span::source_map::Span;
 use rustc_span::{BytePos, Symbol};
 use rustc_typeck::expr_use_visitor::*;
@@ -24,14 +30,6 @@
 use std::mem;
 use syntax::ast;
 
-use crate::utils::paths;
-use crate::utils::{
-    get_enclosing_block, get_parent_expr, get_trait_def_id, has_iter_method, higher, implements_trait,
-    is_integer_const, is_refutable, last_path_segment, match_trait_method, match_type, match_var, multispan_sugg,
-    snippet, snippet_opt, snippet_with_applicability, span_help_and_lint, span_lint, span_lint_and_sugg,
-    span_lint_and_then, SpanlessEq,
-};
-
 declare_clippy_lint! {
     /// **What it does:** Checks for for-loops that manually copy items between
     /// slices that could be optimized by having a memcpy.
@@ -504,7 +502,7 @@ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
         // (even if the "match" or "if let" is used for declaration)
         if let ExprKind::Loop(ref block, _, LoopSource::Loop) = expr.kind {
             // also check for empty `loop {}` statements
-            if block.stmts.is_empty() && block.expr.is_none() {
+            if block.stmts.is_empty() && block.expr.is_none() && !is_no_std_crate(cx.tcx.hir().krate()) {
                 span_lint(
                     cx,
                     EMPTY_LOOP,
@@ -1392,7 +1390,7 @@ fn check_for_loop_arg(cx: &LateContext<'_, '_>, pat: &Pat<'_>, arg: &Expr<'_>, e
 fn check_arg_type(cx: &LateContext<'_, '_>, pat: &Pat<'_>, arg: &Expr<'_>) {
     let ty = cx.tables.expr_ty(arg);
     if match_type(cx, ty, &paths::OPTION) {
-        span_help_and_lint(
+        span_lint_and_help(
             cx,
             FOR_LOOP_OVER_OPTION,
             arg.span,
@@ -1408,7 +1406,7 @@ fn check_arg_type(cx: &LateContext<'_, '_>, pat: &Pat<'_>, arg: &Expr<'_>) {
             ),
         );
     } else if match_type(cx, ty, &paths::RESULT) {
-        span_help_and_lint(
+        span_lint_and_help(
             cx,
             FOR_LOOP_OVER_RESULT,
             arg.span,
@@ -1689,39 +1687,11 @@ fn check_for_mutation(
 fn pat_is_wild<'tcx>(pat: &'tcx PatKind<'_>, body: &'tcx Expr<'_>) -> bool {
     match *pat {
         PatKind::Wild => true,
-        PatKind::Binding(.., ident, None) if ident.as_str().starts_with('_') => {
-            let mut visitor = UsedVisitor {
-                var: ident.name,
-                used: false,
-            };
-            walk_expr(&mut visitor, body);
-            !visitor.used
-        },
+        PatKind::Binding(.., ident, None) if ident.as_str().starts_with('_') => is_unused(&ident, body),
         _ => false,
     }
 }
 
-struct UsedVisitor {
-    var: ast::Name, // var to look for
-    used: bool,     // has the var been used otherwise?
-}
-
-impl<'tcx> Visitor<'tcx> for UsedVisitor {
-    type Map = Map<'tcx>;
-
-    fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
-        if match_var(expr, self.var) {
-            self.used = true;
-        } else {
-            walk_expr(self, expr);
-        }
-    }
-
-    fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
-        NestedVisitorMap::None
-    }
-}
-
 struct LocalUsedVisitor<'a, 'tcx> {
     cx: &'a LateContext<'a, 'tcx>,
     local: HirId,