clippy_lints/src/unsafe_removed_from_name.rs

   1 use crate::utils::span_lint;
   2 use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
   3 use rustc::{declare_tool_lint, lint_array};
   4 use syntax::ast::*;
   5 use syntax::source_map::Span;
   6 use syntax::symbol::LocalInternedString;
   7
   8 declare_clippy_lint! {
   9     /// **What it does:** Checks for imports that remove "unsafe" from an item's
  10     /// name.
  11     ///
  12     /// **Why is this bad?** Renaming makes it less clear which traits and
  13     /// structures are unsafe.
  14     ///
  15     /// **Known problems:** None.
  16     ///
  17     /// **Example:**
  18     /// ```rust,ignore
  19     /// use std::cell::{UnsafeCell as TotallySafeCell};
  20     ///
  21     /// extern crate crossbeam;
  22     /// use crossbeam::{spawn_unsafe as spawn};
  23     /// ```
  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     fn name(&self) -> &'static str {
  37         "UnsafeNameRemoval"
  38     }
  39 }
  40
  41 impl EarlyLintPass for UnsafeNameRemoval {
  42     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
  43         if let ItemKind::Use(ref use_tree) = item.node {
  44             check_use_tree(use_tree, cx, item.span);
  45         }
  46     }
  47 }
  48
  49 fn check_use_tree(use_tree: &UseTree, cx: &EarlyContext<'_>, span: Span) {
  50     match use_tree.kind {
  51         UseTreeKind::Simple(Some(new_name), ..) => {
  52             let old_name = use_tree
  53                 .prefix
  54                 .segments
  55                 .last()
  56                 .expect("use paths cannot be empty")
  57                 .ident;
  58             unsafe_to_safe_check(old_name, new_name, cx, span);
  59         },
  60         UseTreeKind::Simple(None, ..) | UseTreeKind::Glob => {},
  61         UseTreeKind::Nested(ref nested_use_tree) => {
  62             for &(ref use_tree, _) in nested_use_tree {
  63                 check_use_tree(use_tree, cx, span);
  64             }
  65         },
  66     }
  67 }
  68
  69 fn unsafe_to_safe_check(old_name: Ident, new_name: Ident, cx: &EarlyContext<'_>, span: Span) {
  70     let old_str = old_name.name.as_str();
  71     let new_str = new_name.name.as_str();
  72     if contains_unsafe(&old_str) && !contains_unsafe(&new_str) {
  73         span_lint(
  74             cx,
  75             UNSAFE_REMOVED_FROM_NAME,
  76             span,
  77             &format!(
  78                 "removed \"unsafe\" from the name of `{}` in use as `{}`",
  79                 old_str, new_str
  80             ),
  81         );
  82     }
  83 }
  84
  85 fn contains_unsafe(name: &LocalInternedString) -> bool {
  86     name.contains("Unsafe") || name.contains("unsafe")
  87 }