From 2bcbb25cb5463873591e779cbace39d9aef66a96 Mon Sep 17 00:00:00 2001
From: inquisitivecrystal
 <22333129+inquisitivecrystal@users.noreply.github.com>
Date: Wed, 7 Jul 2021 17:42:03 -0700
Subject: [PATCH 1/3] Remove `missing_docs` lint on private 2.0 macros

---
 compiler/rustc_lint/src/builtin.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index b303f55cf772b..24d9e8fc23962 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -571,6 +571,11 @@ impl<'tcx> LateLintPass<'tcx> for MissingDoc {
         self.check_missing_docs_attrs(cx, hir::CRATE_HIR_ID, krate.item.inner, "the", "crate");
 
         for macro_def in krate.exported_macros {
+            // Non exported MBE 2.0 macros should be skipped
+            if !macro_def.ast.macro_rules && !cx.access_levels.is_exported(macro_def.hir_id()) {
+                continue;
+            }
+
             let attrs = cx.tcx.hir().attrs(macro_def.hir_id());
             let has_doc = attrs.iter().any(|a| has_doc(cx.sess(), a));
             if !has_doc {

From 88fd46e129ca01c92c2c8273f03202ed4bc3876f Mon Sep 17 00:00:00 2001
From: inquisitivecrystal
 <22333129+inquisitivecrystal@users.noreply.github.com>
Date: Wed, 7 Jul 2021 17:55:09 -0700
Subject: [PATCH 2/3] Add regression test

---
 src/test/ui/lint/missing-doc-private-macro.rs | 43 +++++++++++++++++++
 .../ui/lint/missing-doc-private-macro.stderr  | 20 +++++++++
 2 files changed, 63 insertions(+)
 create mode 100644 src/test/ui/lint/missing-doc-private-macro.rs
 create mode 100644 src/test/ui/lint/missing-doc-private-macro.stderr

diff --git a/src/test/ui/lint/missing-doc-private-macro.rs b/src/test/ui/lint/missing-doc-private-macro.rs
new file mode 100644
index 0000000000000..8d1d5c568803b
--- /dev/null
+++ b/src/test/ui/lint/missing-doc-private-macro.rs
@@ -0,0 +1,43 @@
+// Checks that undocumented private macros will not generate `missing_docs`
+// lints, but public ones will.
+//
+// This is a regression test for issue #57569
+#![deny(missing_docs)]
+#![feature(decl_macro)]
+//! Empty documentation.
+
+macro new_style_private_macro {
+    () => ()
+}
+
+pub(crate) macro new_style_crate_macro {
+    () => ()
+}
+
+macro_rules! old_style_private_macro {
+    () => ()
+}
+
+mod submodule {
+    pub macro new_style_macro_in_private_module {
+        () => ()
+    }
+
+    macro_rules! old_style_mod_private_macro {
+        () => ()
+    }
+
+    #[macro_export]
+    macro_rules! exported_to_top_level {
+        //~^ ERROR missing documentation for macro
+        () => ()
+    }
+}
+
+pub macro top_level_pub_macro {
+    //~^ ERROR missing documentation for macro
+    () => ()
+}
+
+/// Empty documentation.
+pub fn main() {}
diff --git a/src/test/ui/lint/missing-doc-private-macro.stderr b/src/test/ui/lint/missing-doc-private-macro.stderr
new file mode 100644
index 0000000000000..a5d39faf40562
--- /dev/null
+++ b/src/test/ui/lint/missing-doc-private-macro.stderr
@@ -0,0 +1,20 @@
+error: missing documentation for macro
+  --> $DIR/missing-doc-private-macro.rs:31:5
+   |
+LL |     macro_rules! exported_to_top_level {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/missing-doc-private-macro.rs:5:9
+   |
+LL | #![deny(missing_docs)]
+   |         ^^^^^^^^^^^^
+
+error: missing documentation for macro
+  --> $DIR/missing-doc-private-macro.rs:37:1
+   |
+LL | pub macro top_level_pub_macro {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+

From b49936c0bfe5d6748765c4f2898f765ff4a53a05 Mon Sep 17 00:00:00 2001
From: inquisitivecrystal
 <22333129+inquisitivecrystal@users.noreply.github.com>
Date: Thu, 8 Jul 2021 22:39:31 -0700
Subject: [PATCH 3/3] Improve handing of `missing_docs` for macros

---
 compiler/rustc_lint/src/builtin.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 24d9e8fc23962..92e627bce0293 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -571,8 +571,9 @@ impl<'tcx> LateLintPass<'tcx> for MissingDoc {
         self.check_missing_docs_attrs(cx, hir::CRATE_HIR_ID, krate.item.inner, "the", "crate");
 
         for macro_def in krate.exported_macros {
-            // Non exported MBE 2.0 macros should be skipped
-            if !macro_def.ast.macro_rules && !cx.access_levels.is_exported(macro_def.hir_id()) {
+            // Non exported macros should be skipped, since `missing_docs` only
+            // applies to externally visible items.
+            if !cx.access_levels.is_exported(macro_def.hir_id()) {
                 continue;
             }