Fix false-positive in equatable_if_let

clippy_lints/src/equatable_if_let.rs

@@ -4,7 +4,8 @@
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind, Pat, PatKind};
-use rustc_lint::{LateContext, LateLintPass};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::Ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
@@ -67,6 +68,7 @@ fn is_structural_partial_eq<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, other: T
 impl<'tcx> LateLintPass<'tcx> for PatternEquality {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
         if_chain! {
+            if !in_external_macro(cx.sess(), expr.span);
             if let ExprKind::Let(let_expr) = expr.kind;
             if unary_pattern(let_expr.pat);
             let exp_ty = cx.typeck_results().expr_ty(let_expr.init);

tests/ui/auxiliary/macro_rules.rs

@@ -135,3 +135,8 @@ macro_rules! manual_rem_euclid {
         let _: i32 = ((value % 4) + 4) % 4;
     };
 }
+
+#[macro_export]
+macro_rules! equatable_if_let {
+    ($a:ident) => {{ if let 2 = $a {} }};
+}

tests/ui/equatable_if_let.fixed

@@ -1,8 +1,12 @@
 // run-rustfix
+// aux-build:macro_rules.rs
 
 #![allow(unused_variables, dead_code, clippy::derive_partial_eq_without_eq)]
 #![warn(clippy::equatable_if_let)]
 
+#[macro_use]
+extern crate macro_rules;
+
 use std::cmp::Ordering;
 
 #[derive(PartialEq)]
@@ -75,4 +79,6 @@ fn main() {
     if "abc" == m1!(x) {
         println!("OK");
     }
+
+    equatable_if_let!(a);
 }

tests/ui/equatable_if_let.rs

@@ -1,8 +1,12 @@
 // run-rustfix
+// aux-build:macro_rules.rs
 
 #![allow(unused_variables, dead_code, clippy::derive_partial_eq_without_eq)]
 #![warn(clippy::equatable_if_let)]
 
+#[macro_use]
+extern crate macro_rules;
+
 use std::cmp::Ordering;
 
 #[derive(PartialEq)]
@@ -75,4 +79,6 @@ macro_rules! m1 {
     if let m1!(x) = "abc" {
         println!("OK");
     }
+
+    equatable_if_let!(a);
 }

tests/ui/equatable_if_let.stderr

@@ -1,5 +1,5 @@
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:49:8
+  --> $DIR/equatable_if_let.rs:53:8
    |
 LL |     if let 2 = a {}
    |        ^^^^^^^^^ help: try: `a == 2`
@@ -7,61 +7,61 @@ LL |     if let 2 = a {}
    = note: `-D clippy::equatable-if-let` implied by `-D warnings`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:50:8
+  --> $DIR/equatable_if_let.rs:54:8
    |
 LL |     if let Ordering::Greater = a.cmp(&b) {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `a.cmp(&b) == Ordering::Greater`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:51:8
+  --> $DIR/equatable_if_let.rs:55:8
    |
 LL |     if let Some(2) = c {}
    |        ^^^^^^^^^^^^^^^ help: try: `c == Some(2)`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:52:8
+  --> $DIR/equatable_if_let.rs:56:8
    |
 LL |     if let Struct { a: 2, b: false } = d {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `d == (Struct { a: 2, b: false })`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:53:8
+  --> $DIR/equatable_if_let.rs:57:8
    |
 LL |     if let Enum::TupleVariant(32, 64) = e {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `e == Enum::TupleVariant(32, 64)`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:54:8
+  --> $DIR/equatable_if_let.rs:58:8
    |
 LL |     if let Enum::RecordVariant { a: 64, b: 32 } = e {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `e == (Enum::RecordVariant { a: 64, b: 32 })`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:55:8
+  --> $DIR/equatable_if_let.rs:59:8
    |
 LL |     if let Enum::UnitVariant = e {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `e == Enum::UnitVariant`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:56:8
+  --> $DIR/equatable_if_let.rs:60:8
    |
 LL |     if let (Enum::UnitVariant, &Struct { a: 2, b: false }) = (e, &d) {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(e, &d) == (Enum::UnitVariant, &Struct { a: 2, b: false })`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:66:8
+  --> $DIR/equatable_if_let.rs:70:8
    |
 LL |     if let NotStructuralEq::A = g {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `g == NotStructuralEq::A`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:68:8
+  --> $DIR/equatable_if_let.rs:72:8
    |
 LL |     if let Some(NotStructuralEq::A) = Some(g) {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Some(g) == Some(NotStructuralEq::A)`
 
 error: this pattern matching can be expressed using equality
-  --> $DIR/equatable_if_let.rs:75:8
+  --> $DIR/equatable_if_let.rs:79:8
    |
 LL |     if let m1!(x) = "abc" {
    |        ^^^^^^^^^^^^^^^^^^ help: try: `"abc" == m1!(x)`