From 4b68c965feec8ce0e86d0b396baca5e33c3cf0af Mon Sep 17 00:00:00 2001
From: Joshua Holmer <jholmer@dminc.com>
Date: Wed, 17 Oct 2018 10:43:32 -0400
Subject: [PATCH] Resolve ICE in needless range loop lint

An ICE would occur if the needless range loop was triggered
within a procedural macro, because Clippy would try to produce
a code suggestion which was invalid, and caused the compiler
to crash.

This commit takes the same approach which Clippy currently takes
to work around this type of crash in the needless pass by value lint,
which is to skip the lint if Clippy is inside of a macro.
---
 clippy_lints/src/loops.rs | 6 +++++-
 mini-macro/src/lib.rs     | 5 +++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/clippy_lints/src/loops.rs b/clippy_lints/src/loops.rs
index 3c4f06077d9..950c1043802 100644
--- a/clippy_lints/src/loops.rs
+++ b/clippy_lints/src/loops.rs
@@ -31,7 +31,7 @@ use std::mem;
 use crate::syntax::ast;
 use crate::syntax::source_map::Span;
 use crate::syntax_pos::BytePos;
-use crate::utils::{sugg, sext};
+use crate::utils::{in_macro, sugg, sext};
 use crate::utils::usage::mutated_variables;
 use crate::consts::{constant, Constant};
 
@@ -1030,6 +1030,10 @@ fn check_for_loop_range<'a, 'tcx>(
     body: &'tcx Expr,
     expr: &'tcx Expr,
 ) {
+    if in_macro(expr.span) {
+        return;
+    }
+
     if let Some(higher::Range {
         start: Some(start),
         ref end,
diff --git a/mini-macro/src/lib.rs b/mini-macro/src/lib.rs
index d326dd7e679..b6405975862 100644
--- a/mini-macro/src/lib.rs
+++ b/mini-macro/src/lib.rs
@@ -17,5 +17,10 @@ use proc_macro::{TokenStream, quote};
 pub fn mini_macro(_: TokenStream) -> TokenStream {
     quote!(
         #[allow(unused)] fn needless_take_by_value(s: String) { println!("{}", s.len()); }
+        #[allow(unused)] fn needless_loop(items: &[u8]) {
+            for i in 0..items.len() {
+                println!("{}", items[i]);
+            }
+        }
     )
 }