clippy_lints/src/unsafe_removed_from_name.rs

   1 // Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution.
   3 //
   4 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   5 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   7 // option. This file may not be copied, modified, or distributed
   8 // except according to those terms.
   9
  10 use crate::rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
  11 use crate::rustc::{declare_tool_lint, lint_array};
  12 use crate::syntax::ast::*;
  13 use crate::syntax::source_map::Span;
  14 use crate::syntax::symbol::LocalInternedString;
  15 use crate::utils::span_lint;
  16
  17 /// **What it does:** Checks for imports that remove "unsafe" from an item's
  18 /// name.
  19 ///
  20 /// **Why is this bad?** Renaming makes it less clear which traits and
  21 /// structures are unsafe.
  22 ///
  23 /// **Known problems:** None.
  24 ///
  25 /// **Example:**
  26 /// ```rust,ignore
  27 /// use std::cell::{UnsafeCell as TotallySafeCell};
  28 ///
  29 /// extern crate crossbeam;
  30 /// use crossbeam::{spawn_unsafe as spawn};
  31 /// ```
  32 declare_clippy_lint! {
  33     pub UNSAFE_REMOVED_FROM_NAME,
  34     style,
  35     "`unsafe` removed from API names on import"
  36 }
  37
  38 pub struct UnsafeNameRemoval;
  39
  40 impl LintPass for UnsafeNameRemoval {
  41     fn get_lints(&self) -> LintArray {
  42         lint_array!(UNSAFE_REMOVED_FROM_NAME)
  43     }
  44 }
  45
  46 impl EarlyLintPass for UnsafeNameRemoval {
  47     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
  48         if let ItemKind::Use(ref use_tree) = item.node {
  49             check_use_tree(use_tree, cx, item.span);
  50         }
  51     }
  52 }
  53
  54 fn check_use_tree(use_tree: &UseTree, cx: &EarlyContext<'_>, span: Span) {
  55     match use_tree.kind {
  56         UseTreeKind::Simple(Some(new_name), ..) => {
  57             let old_name = use_tree
  58                 .prefix
  59                 .segments
  60                 .last()
  61                 .expect("use paths cannot be empty")
  62                 .ident;
  63             unsafe_to_safe_check(old_name, new_name, cx, span);
  64         },
  65         UseTreeKind::Simple(None, ..) | UseTreeKind::Glob => {},
  66         UseTreeKind::Nested(ref nested_use_tree) => {
  67             for &(ref use_tree, _) in nested_use_tree {
  68                 check_use_tree(use_tree, cx, span);
  69             }
  70         },
  71     }
  72 }
  73
  74 fn unsafe_to_safe_check(old_name: Ident, new_name: Ident, cx: &EarlyContext<'_>, span: Span) {
  75     let old_str = old_name.name.as_str();
  76     let new_str = new_name.name.as_str();
  77     if contains_unsafe(&old_str) && !contains_unsafe(&new_str) {
  78         span_lint(
  79             cx,
  80             UNSAFE_REMOVED_FROM_NAME,
  81             span,
  82             &format!(
  83                 "removed \"unsafe\" from the name of `{}` in use as `{}`",
  84                 old_str, new_str
  85             ),
  86         );
  87     }
  88 }
  89
  90 fn contains_unsafe(name: &LocalInternedString) -> bool {
  91     name.contains("Unsafe") || name.contains("unsafe")
  92 }