clippy_lints/src/unsafe_removed_from_name.rs

   1 use rustc::lint::*;
   2 use syntax::ast::*;
   3 use syntax::codemap::Span;
   4 use syntax::symbol::LocalInternedString;
   5 use crate::utils::span_lint;
   6
   7 /// **What it does:** Checks for imports that remove "unsafe" from an item's
   8 /// name.
   9 ///
  10 /// **Why is this bad?** Renaming makes it less clear which traits and
  11 /// structures are unsafe.
  12 ///
  13 /// **Known problems:** None.
  14 ///
  15 /// **Example:**
  16 /// ```rust,ignore
  17 /// use std::cell::{UnsafeCell as TotallySafeCell};
  18 ///
  19 /// extern crate crossbeam;
  20 /// use crossbeam::{spawn_unsafe as spawn};
  21 /// ```
  22 declare_clippy_lint! {
  23     pub UNSAFE_REMOVED_FROM_NAME,
  24     style,
  25     "`unsafe` removed from API names on import"
  26 }
  27
  28 pub struct UnsafeNameRemoval;
  29
  30 impl LintPass for UnsafeNameRemoval {
  31     fn get_lints(&self) -> LintArray {
  32         lint_array!(UNSAFE_REMOVED_FROM_NAME)
  33     }
  34 }
  35
  36 impl EarlyLintPass for UnsafeNameRemoval {
  37     fn check_item(&mut self, cx: &EarlyContext, item: &Item) {
  38         if let ItemKind::Use(ref use_tree) = item.node {
  39             check_use_tree(use_tree, cx, item.span);
  40         }
  41     }
  42 }
  43
  44 fn check_use_tree(use_tree: &UseTree, cx: &EarlyContext, span: Span) {
  45     match use_tree.kind {
  46         UseTreeKind::Simple(Some(new_name)) => {
  47             let old_name = use_tree
  48                 .prefix
  49                 .segments
  50                 .last()
  51                 .expect("use paths cannot be empty")
  52                 .ident;
  53             unsafe_to_safe_check(old_name, new_name, cx, span);
  54         }
  55         UseTreeKind::Simple(None) |
  56         UseTreeKind::Glob => {},
  57         UseTreeKind::Nested(ref nested_use_tree) => {
  58             for &(ref use_tree, _) in nested_use_tree {
  59                 check_use_tree(use_tree, cx, span);
  60             }
  61         }
  62     }
  63 }
  64
  65 fn unsafe_to_safe_check(old_name: Ident, new_name: Ident, cx: &EarlyContext, span: Span) {
  66     let old_str = old_name.name.as_str();
  67     let new_str = new_name.name.as_str();
  68     if contains_unsafe(&old_str) && !contains_unsafe(&new_str) {
  69         span_lint(
  70             cx,
  71             UNSAFE_REMOVED_FROM_NAME,
  72             span,
  73             &format!("removed \"unsafe\" from the name of `{}` in use as `{}`", old_str, new_str),
  74         );
  75     }
  76 }
  77
  78 fn contains_unsafe(name: &LocalInternedString) -> bool {
  79     name.contains("Unsafe") || name.contains("unsafe")
  80 }