clippy_lints/src/unsafe_removed_from_name.rs

   1 use rustc::lint::*;
   2 use rustc::{declare_lint, lint_array};
   3 use syntax::ast::*;
   4 use syntax::source_map::Span;
   5 use syntax::symbol::LocalInternedString;
   6 use crate::utils::span_lint;
   7
   8 /// **What it does:** Checks for imports that remove "unsafe" from an item's
   9 /// name.
  10 ///
  11 /// **Why is this bad?** Renaming makes it less clear which traits and
  12 /// structures are unsafe.
  13 ///
  14 /// **Known problems:** None.
  15 ///
  16 /// **Example:**
  17 /// ```rust,ignore
  18 /// use std::cell::{UnsafeCell as TotallySafeCell};
  19 ///
  20 /// extern crate crossbeam;
  21 /// use crossbeam::{spawn_unsafe as spawn};
  22 /// ```
  23 declare_clippy_lint! {
  24     pub UNSAFE_REMOVED_FROM_NAME,
  25     style,
  26     "`unsafe` removed from API names on import"
  27 }
  28
  29 pub struct UnsafeNameRemoval;
  30
  31 impl LintPass for UnsafeNameRemoval {
  32     fn get_lints(&self) -> LintArray {
  33         lint_array!(UNSAFE_REMOVED_FROM_NAME)
  34     }
  35 }
  36
  37 impl EarlyLintPass for UnsafeNameRemoval {
  38     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
  39         if let ItemKind::Use(ref use_tree) = item.node {
  40             check_use_tree(use_tree, cx, item.span);
  41         }
  42     }
  43 }
  44
  45 fn check_use_tree(use_tree: &UseTree, cx: &EarlyContext<'_>, span: Span) {
  46     match use_tree.kind {
  47         UseTreeKind::Simple(Some(new_name), ..) => {
  48             let old_name = use_tree
  49                 .prefix
  50                 .segments
  51                 .last()
  52                 .expect("use paths cannot be empty")
  53                 .ident;
  54             unsafe_to_safe_check(old_name, new_name, cx, span);
  55         }
  56         UseTreeKind::Simple(None, ..) |
  57         UseTreeKind::Glob => {},
  58         UseTreeKind::Nested(ref nested_use_tree) => {
  59             for &(ref use_tree, _) in nested_use_tree {
  60                 check_use_tree(use_tree, cx, span);
  61             }
  62         }
  63     }
  64 }
  65
  66 fn unsafe_to_safe_check(old_name: Ident, new_name: Ident, cx: &EarlyContext<'_>, span: Span) {
  67     let old_str = old_name.name.as_str();
  68     let new_str = new_name.name.as_str();
  69     if contains_unsafe(&old_str) && !contains_unsafe(&new_str) {
  70         span_lint(
  71             cx,
  72             UNSAFE_REMOVED_FROM_NAME,
  73             span,
  74             &format!("removed \"unsafe\" from the name of `{}` in use as `{}`", old_str, new_str),
  75         );
  76     }
  77 }
  78
  79 fn contains_unsafe(name: &LocalInternedString) -> bool {
  80     name.contains("Unsafe") || name.contains("unsafe")
  81 }