src/tools/clippy/clippy_lints/src/unit_types/unit_cmp.rs

   1 use clippy_utils::diagnostics::span_lint;
   2 use rustc_hir::{BinOpKind, Expr, ExprKind};
   3 use rustc_lint::LateContext;
   4 use rustc_span::hygiene::{ExpnKind, MacroKind};
   5
   6 use super::UNIT_CMP;
   7
   8 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) {
   9     if expr.span.from_expansion() {
  10         if let Some(callee) = expr.span.source_callee() {
  11             if let ExpnKind::Macro(MacroKind::Bang, symbol) = callee.kind {
  12                 if let ExprKind::Binary(ref cmp, left, _) = expr.kind {
  13                     let op = cmp.node;
  14                     if op.is_comparison() && cx.typeck_results().expr_ty(left).is_unit() {
  15                         let result = match &*symbol.as_str() {
  16                             "assert_eq" | "debug_assert_eq" => "succeed",
  17                             "assert_ne" | "debug_assert_ne" => "fail",
  18                             _ => return,
  19                         };
  20                         span_lint(
  21                             cx,
  22                             UNIT_CMP,
  23                             expr.span,
  24                             &format!(
  25                                 "`{}` of unit values detected. This will always {}",
  26                                 symbol.as_str(),
  27                                 result
  28                             ),
  29                         );
  30                     }
  31                 }
  32             }
  33         }
  34         return;
  35     }
  36
  37     if let ExprKind::Binary(ref cmp, left, _) = expr.kind {
  38         let op = cmp.node;
  39         if op.is_comparison() && cx.typeck_results().expr_ty(left).is_unit() {
  40             let result = match op {
  41                 BinOpKind::Eq | BinOpKind::Le | BinOpKind::Ge => "true",
  42                 _ => "false",
  43             };
  44             span_lint(
  45                 cx,
  46                 UNIT_CMP,
  47                 expr.span,
  48                 &format!(
  49                     "{}-comparison of unit values detected. This will always be {}",
  50                     op.as_str(),
  51                     result
  52                 ),
  53             );
  54         }
  55     }
  56 }