Auto merge of rust-lang#10203 - c410-f3r:macro-lint, r=giraffate

Suppress the triggering of some lints in derived structures

Fixes rust-lang#10185
Fixes rust-lang#10417

For `integer_arithmetic`, `arithmetic_side_effects` and `shadow_reuse`.

* ~~Not sure how to test these use-cases so feel free to point any method or any related PR.~~

---

changelog: FP: [`integer_arithmetic`], [`arithmetic_side_effects`]: No longer lint inside proc macros
[rust-lang#10203](rust-lang/rust-clippy#10203)
<!-- changelog_checked -->

clippy_lints/src/operators/arithmetic_side_effects.rs

@@ -1,4 +1,5 @@
 use super::ARITHMETIC_SIDE_EFFECTS;
+use clippy_utils::is_from_proc_macro;
 use clippy_utils::{
     consts::{constant, constant_simple, Constant},
     diagnostics::span_lint,
@@ -206,8 +207,9 @@ impl ArithmeticSideEffects {
         self.issue_lint(cx, expr);
     }
 
-    fn should_skip_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
+    fn should_skip_expr<'tcx>(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'tcx>) -> bool {
         is_lint_allowed(cx, ARITHMETIC_SIDE_EFFECTS, expr.hir_id)
+            || is_from_proc_macro(cx, expr)
             || self.expr_span.is_some()
             || self.const_span.map_or(false, |sp| sp.contains(expr.span))
     }

clippy_lints/src/operators/numeric_arithmetic.rs

@@ -1,12 +1,12 @@
+use super::{FLOAT_ARITHMETIC, INTEGER_ARITHMETIC};
 use clippy_utils::consts::constant_simple;
 use clippy_utils::diagnostics::span_lint;
+use clippy_utils::is_from_proc_macro;
 use clippy_utils::is_integer_literal;
 use rustc_hir as hir;
 use rustc_lint::LateContext;
 use rustc_span::source_map::Span;
 
-use super::{FLOAT_ARITHMETIC, INTEGER_ARITHMETIC};
-
 #[derive(Default)]
 pub struct Context {
     expr_id: Option<hir::HirId>,
@@ -47,6 +47,9 @@ impl Context {
 
         let (l_ty, r_ty) = (cx.typeck_results().expr_ty(l), cx.typeck_results().expr_ty(r));
         if l_ty.peel_refs().is_integral() && r_ty.peel_refs().is_integral() {
+            if is_from_proc_macro(cx, expr) {
+                return;
+            }
             match op {
                 hir::BinOpKind::Div | hir::BinOpKind::Rem => match &r.kind {
                     hir::ExprKind::Lit(_lit) => (),
@@ -79,6 +82,9 @@ impl Context {
         let ty = cx.typeck_results().expr_ty(arg);
         if constant_simple(cx, cx.typeck_results(), expr).is_none() {
             if ty.is_integral() {
+                if is_from_proc_macro(cx, expr) {
+                    return;
+                }
                 span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
                 self.expr_id = Some(expr.hir_id);
             } else if ty.is_floating_point() {

tests/ui/arithmetic_side_effects.rs

@@ -1,3 +1,5 @@
+// aux-build:proc_macro_derive.rs
+
 #![allow(
     clippy::assign_op_pattern,
     clippy::erasing_op,
@@ -11,6 +13,8 @@
 #![feature(const_mut_refs, inline_const, saturating_int_impl)]
 #![warn(clippy::arithmetic_side_effects)]
 
+extern crate proc_macro_derive;
+
 use core::num::{Saturating, Wrapping};
 
 const ONE: i32 = 1;
@@ -19,6 +23,9 @@ const ZERO: i32 = 0;
 #[derive(Clone, Copy)]
 pub struct Custom;
 
+#[derive(proc_macro_derive::ShadowDerive)]
+pub struct Nothing;
+
 macro_rules! impl_arith {
     ( $( $_trait:ident, $lhs:ty, $rhs:ty, $method:ident; )* ) => {
         $(