From 96321ed7564be5264c324a7f815766ec829fd27e Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Sat, 7 May 2022 12:41:15 +0200
Subject: [PATCH 1/2] Do not lint on explicit outlives requirements from
 external macros.

---
 compiler/rustc_lint/src/builtin.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 3564f15e210ad..eae7df0301b79 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -38,7 +38,7 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID};
 use rustc_hir::{ForeignItemKind, GenericParamKind, HirId, PatKind};
 use rustc_index::vec::Idx;
-use rustc_middle::lint::LintDiagnosticBuilder;
+use rustc_middle::lint::{in_external_macro, LintDiagnosticBuilder};
 use rustc_middle::ty::layout::{LayoutError, LayoutOf};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::subst::{GenericArgKind, Subst};
@@ -2115,6 +2115,7 @@ impl ExplicitOutlivesRequirements {
                     None
                 }
             })
+            .filter(|(_, span)| !in_external_macro(tcx.sess, *span))
             .collect()
     }
 

From 89f15bfd907b0b44a851c5810ab463fe91a206e5 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Sat, 7 May 2022 13:08:04 +0200
Subject: [PATCH 2/2] Add test.

---
 .../edition-lint-infer-outlives-macro.rs      |  6 ++++
 .../edition-lint-infer-outlives-macro.rs      | 28 +++++++++++++++++++
 .../edition-lint-infer-outlives-macro.stderr  | 14 ++++++++++
 3 files changed, 48 insertions(+)
 create mode 100644 src/test/ui/rust-2018/auxiliary/edition-lint-infer-outlives-macro.rs
 create mode 100644 src/test/ui/rust-2018/edition-lint-infer-outlives-macro.rs
 create mode 100644 src/test/ui/rust-2018/edition-lint-infer-outlives-macro.stderr

diff --git a/src/test/ui/rust-2018/auxiliary/edition-lint-infer-outlives-macro.rs b/src/test/ui/rust-2018/auxiliary/edition-lint-infer-outlives-macro.rs
new file mode 100644
index 0000000000000..d45fa10f022aa
--- /dev/null
+++ b/src/test/ui/rust-2018/auxiliary/edition-lint-infer-outlives-macro.rs
@@ -0,0 +1,6 @@
+pub fn foo() {}
+
+#[macro_export]
+macro_rules! gimme_a {
+    ($($mac:tt)*) => { $($mac)* { 'a } }
+}
diff --git a/src/test/ui/rust-2018/edition-lint-infer-outlives-macro.rs b/src/test/ui/rust-2018/edition-lint-infer-outlives-macro.rs
new file mode 100644
index 0000000000000..d7a832831c1d9
--- /dev/null
+++ b/src/test/ui/rust-2018/edition-lint-infer-outlives-macro.rs
@@ -0,0 +1,28 @@
+// edition:2018
+// aux-build:edition-lint-infer-outlives-macro.rs
+
+// Test that the lint does not fire if the where predicate
+// is from the local crate, but all the bounds are from an
+// external macro.
+
+#![deny(explicit_outlives_requirements)]
+
+#[macro_use]
+extern crate edition_lint_infer_outlives_macro;
+
+macro_rules! make_foo {
+    ($a:tt) => {
+        struct Foo<$a, 'b> where 'b: $a {
+            foo: &$a &'b (),
+        }
+    }
+}
+
+gimme_a! {make_foo!}
+
+struct Bar<'a, 'b: 'a> {
+    //~^ ERROR: outlives requirements can be inferred
+    bar: &'a &'b (),
+}
+
+fn main() {}
diff --git a/src/test/ui/rust-2018/edition-lint-infer-outlives-macro.stderr b/src/test/ui/rust-2018/edition-lint-infer-outlives-macro.stderr
new file mode 100644
index 0000000000000..553b1cd976ad6
--- /dev/null
+++ b/src/test/ui/rust-2018/edition-lint-infer-outlives-macro.stderr
@@ -0,0 +1,14 @@
+error: outlives requirements can be inferred
+  --> $DIR/edition-lint-infer-outlives-macro.rs:23:18
+   |
+LL | struct Bar<'a, 'b: 'a> {
+   |                  ^^^^ help: remove this bound
+   |
+note: the lint level is defined here
+  --> $DIR/edition-lint-infer-outlives-macro.rs:8:9
+   |
+LL | #![deny(explicit_outlives_requirements)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+