clippy_lints/src/invalid_ref.rs

   1 use crate::utils::{match_def_path, paths, span_help_and_lint};
   2 use if_chain::if_chain;
   3 use rustc::hir::*;
   4 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
   5 use rustc::ty;
   6 use rustc::{declare_tool_lint, lint_array};
   7
   8 declare_clippy_lint! {
   9     /// **What it does:** Checks for creation of references to zeroed or uninitialized memory.
  10     ///
  11     /// **Why is this bad?** Creation of null references is undefined behavior.
  12     ///
  13     /// **Known problems:** None.
  14     ///
  15     /// **Example:**
  16     /// ```no_run
  17     /// let bad_ref: &usize = unsafe { std::mem::zeroed() };
  18     /// ```
  19     pub INVALID_REF,
  20     correctness,
  21     "creation of invalid reference"
  22 }
  23
  24 const ZERO_REF_SUMMARY: &str = "reference to zeroed memory";
  25 const UNINIT_REF_SUMMARY: &str = "reference to uninitialized memory";
  26 const HELP: &str = "Creation of a null reference is undefined behavior; \
  27                     see https://doc.rust-lang.org/reference/behavior-considered-undefined.html";
  28
  29 pub struct InvalidRef;
  30
  31 impl LintPass for InvalidRef {
  32     fn get_lints(&self) -> LintArray {
  33         lint_array!(INVALID_REF)
  34     }
  35
  36     fn name(&self) -> &'static str {
  37         "InvalidRef"
  38     }
  39 }
  40
  41 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidRef {
  42     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
  43         if_chain! {
  44             if let ExprKind::Call(ref path, ref args) = expr.node;
  45             if let ExprKind::Path(ref qpath) = path.node;
  46             if args.len() == 0;
  47             if let ty::Ref(..) = cx.tables.expr_ty(expr).sty;
  48             if let Some(def_id) = cx.tables.qpath_def(qpath, path.hir_id).opt_def_id();
  49             then {
  50                 let msg = if match_def_path(cx.tcx, def_id, &paths::MEM_ZEROED) |
  51                              match_def_path(cx.tcx, def_id, &paths::INIT)
  52                 {
  53                     ZERO_REF_SUMMARY
  54                 } else if match_def_path(cx.tcx, def_id, &paths::MEM_UNINIT) |
  55                           match_def_path(cx.tcx, def_id, &paths::UNINIT)
  56                 {
  57                     UNINIT_REF_SUMMARY
  58                 } else {
  59                     return;
  60                 };
  61                 span_help_and_lint(cx, INVALID_REF, expr.span, msg, HELP);
  62             }
  63         }
  64         return;
  65     }
  66 }