clippy_lints/src/unsafe_removed_from_name.rs

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