Revert let_chains stabilization

[rust.git] / clippy_lints / src / if_not_else.rs

diff --git a/clippy_lints/src/if_not_else.rs b/clippy_lints/src/if_not_else.rs
index c11e291f98e4b41766dbf22c8940d8f9fff3b74c..3d59b783337a441b3ca1151f19667fe0174b41b4 100644 (file)
--- a/clippy_lints/src/if_not_else.rs
+++ b/clippy_lints/src/if_not_else.rs
@@ -1,22 +1,21 @@
 //! lint on if branches that could be swapped so no `!` operation is necessary
 //! on the condition
 
-use rustc_ast::ast::{BinOpKind, Expr, ExprKind, UnOp};
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
-use rustc_middle::lint::in_external_macro;
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::is_else_clause;
+use rustc_hir::{BinOpKind, Expr, ExprKind, UnOp};
+use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
-use crate::utils::span_lint_and_help;
-
 declare_clippy_lint! {
-    /// **What it does:** Checks for usage of `!` or `!=` in an if condition with an
+    /// ### What it does
+    /// Checks for usage of `!` or `!=` in an if condition with an
     /// else branch.
     ///
-    /// **Why is this bad?** Negations reduce the readability of statements.
-    ///
-    /// **Known problems:** None.
+    /// ### Why is this bad?
+    /// Negations reduce the readability of statements.
     ///
-    /// **Example:**
+    /// ### Example
     /// ```rust
     /// # let v: Vec<usize> = vec![];
     /// # fn a() {}
@@ -40,6 +39,7 @@
     ///     a()
     /// }
     /// ```
+    #[clippy::version = "pre 1.29.0"]
     pub IF_NOT_ELSE,
     pedantic,
     "`if` branches that could be swapped so no negation operation is necessary on the condition"
@@ -47,20 +47,27 @@
 
 declare_lint_pass!(IfNotElse => [IF_NOT_ELSE]);
 
-impl EarlyLintPass for IfNotElse {
-    fn check_expr(&mut self, cx: &EarlyContext<'_>, item: &Expr) {
-        if in_external_macro(cx.sess(), item.span) {
+impl LateLintPass<'_> for IfNotElse {
+    fn check_expr(&mut self, cx: &LateContext<'_>, item: &Expr<'_>) {
+        // While loops will be desugared to ExprKind::If. This will cause the lint to fire.
+        // To fix this, return early if this span comes from a macro or desugaring.
+        if item.span.from_expansion() {
             return;
         }
-        if let ExprKind::If(ref cond, _, Some(ref els)) = item.kind {
+        if let ExprKind::If(cond, _, Some(els)) = item.kind {
             if let ExprKind::Block(..) = els.kind {
-                match cond.kind {
+                // Disable firing the lint in "else if" expressions.
+                if is_else_clause(cx.tcx, item) {
+                    return;
+                }
+
+                match cond.peel_drop_temps().kind {
                     ExprKind::Unary(UnOp::Not, _) => {
                         span_lint_and_help(
                             cx,
                             IF_NOT_ELSE,
                             item.span,
-                            "Unnecessary boolean `not` operation",
+                            "unnecessary boolean `not` operation",
                             None,
                             "remove the `!` and swap the blocks of the `if`/`else`",
                         );
@@ -70,7 +77,7 @@ fn check_expr(&mut self, cx: &EarlyContext<'_>, item: &Expr) {
                             cx,
                             IF_NOT_ELSE,
                             item.span,
-                            "Unnecessary `!=` operation",
+                            "unnecessary `!=` operation",
                             None,
                             "change to `==` and swap the blocks of the `if`/`else`",
                         );