From 37bee6daad3a91fc60817db5180e1231b542c400 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20K=C3=A5re=20Alsaker?= <john.kare.alsaker@gmail.com>
Date: Mon, 16 Mar 2020 19:17:40 +0100
Subject: [PATCH] Allow `hir().find` to return `None`

---
 src/librustc/hir/map/mod.rs           | 25 ++++++++++++++++---------
 src/librustc/hir/mod.rs               |  7 +++----
 src/librustc/query/mod.rs             |  4 ++--
 src/test/ui/issues/issue-70041.rs     | 13 +++++++++++++
 src/test/ui/issues/issue-70041.stderr | 19 +++++++++++++++++++
 5 files changed, 53 insertions(+), 15 deletions(-)
 create mode 100644 src/test/ui/issues/issue-70041.rs
 create mode 100644 src/test/ui/issues/issue-70041.stderr

diff --git a/src/librustc/hir/map/mod.rs b/src/librustc/hir/map/mod.rs
index 55ed07a97d168..67d43d5f98f18 100644
--- a/src/librustc/hir/map/mod.rs
+++ b/src/librustc/hir/map/mod.rs
@@ -342,20 +342,25 @@ impl<'hir> Map<'hir> {
     }
 
     fn find_entry(&self, id: HirId) -> Option<Entry<'hir>> {
-        Some(self.get_entry(id))
-    }
-
-    fn get_entry(&self, id: HirId) -> Entry<'hir> {
         if id.local_id == ItemLocalId::from_u32_const(0) {
             let owner = self.tcx.hir_owner(id.owner_def_id());
-            Entry { parent: owner.parent, node: owner.node }
+            owner.map(|owner| Entry { parent: owner.parent, node: owner.node })
         } else {
             let owner = self.tcx.hir_owner_items(id.owner_def_id());
-            let item = owner.items[id.local_id].as_ref().unwrap();
-            Entry { parent: HirId { owner: id.owner, local_id: item.parent }, node: item.node }
+            owner.and_then(|owner| {
+                let item = owner.items[id.local_id].as_ref();
+                item.map(|item| Entry {
+                    parent: HirId { owner: id.owner, local_id: item.parent },
+                    node: item.node,
+                })
+            })
         }
     }
 
+    fn get_entry(&self, id: HirId) -> Entry<'hir> {
+        self.find_entry(id).unwrap()
+    }
+
     pub fn item(&self, id: HirId) -> &'hir Item<'hir> {
         match self.find(id).unwrap() {
             Node::Item(item) => item,
@@ -380,6 +385,7 @@ impl<'hir> Map<'hir> {
     pub fn body(&self, id: BodyId) -> &'hir Body<'hir> {
         self.tcx
             .hir_owner_items(DefId::local(id.hir_id.owner))
+            .unwrap()
             .bodies
             .get(&id.hir_id.local_id)
             .unwrap()
@@ -541,8 +547,9 @@ impl<'hir> Map<'hir> {
 
     /// Retrieves the `Node` corresponding to `id`, returning `None` if cannot be found.
     pub fn find(&self, hir_id: HirId) -> Option<Node<'hir>> {
-        let node = self.get_entry(hir_id).node;
-        if let Node::Crate(..) = node { None } else { Some(node) }
+        self.find_entry(hir_id).and_then(|entry| {
+            if let Node::Crate(..) = entry.node { None } else { Some(entry.node) }
+        })
     }
 
     /// Similar to `get_parent`; returns the parent HIR Id, or just `hir_id` if there
diff --git a/src/librustc/hir/mod.rs b/src/librustc/hir/mod.rs
index 3b69fc8d8f2ac..9fdcaadde4f85 100644
--- a/src/librustc/hir/mod.rs
+++ b/src/librustc/hir/mod.rs
@@ -78,9 +78,8 @@ pub fn provide(providers: &mut Providers<'_>) {
         let module = hir.as_local_hir_id(id).unwrap();
         &tcx.untracked_crate.modules[&module]
     };
-    providers.hir_owner = |tcx, id| tcx.index_hir(id.krate).map[id.index].signature.unwrap();
-    providers.hir_owner_items = |tcx, id| {
-        tcx.index_hir(id.krate).map[id.index].with_bodies.as_ref().map(|items| &**items).unwrap()
-    };
+    providers.hir_owner = |tcx, id| tcx.index_hir(id.krate).map[id.index].signature;
+    providers.hir_owner_items =
+        |tcx, id| tcx.index_hir(id.krate).map[id.index].with_bodies.as_ref().map(|items| &**items);
     map::provide(providers);
 }
diff --git a/src/librustc/query/mod.rs b/src/librustc/query/mod.rs
index ff3a82e53639e..19a9f6b2d5ac0 100644
--- a/src/librustc/query/mod.rs
+++ b/src/librustc/query/mod.rs
@@ -74,7 +74,7 @@ rustc_queries! {
         // a `DefId`.
         // This can be conveniently accessed by methods on `tcx.hir()`.
         // Avoid calling this query directly.
-        query hir_owner(key: DefId) -> &'tcx HirOwner<'tcx> {
+        query hir_owner(key: DefId) -> Option<&'tcx HirOwner<'tcx>> {
             eval_always
         }
 
@@ -82,7 +82,7 @@ rustc_queries! {
         // with a `DefId`.
         // This can be conveniently accessed by methods on `tcx.hir()`.
         // Avoid calling this query directly.
-        query hir_owner_items(key: DefId) -> &'tcx HirOwnerItems<'tcx> {
+        query hir_owner_items(key: DefId) -> Option<&'tcx HirOwnerItems<'tcx>> {
             eval_always
         }
 
diff --git a/src/test/ui/issues/issue-70041.rs b/src/test/ui/issues/issue-70041.rs
new file mode 100644
index 0000000000000..22e42295eedf3
--- /dev/null
+++ b/src/test/ui/issues/issue-70041.rs
@@ -0,0 +1,13 @@
+// compile-flags: --edition=2018
+// run-pass
+
+macro_rules! regex {
+    //~^ WARN unused macro definition
+    () => {};
+}
+
+#[allow(dead_code)]
+use regex;
+//~^ WARN unused import
+
+fn main() {}
diff --git a/src/test/ui/issues/issue-70041.stderr b/src/test/ui/issues/issue-70041.stderr
new file mode 100644
index 0000000000000..b180175c5ab76
--- /dev/null
+++ b/src/test/ui/issues/issue-70041.stderr
@@ -0,0 +1,19 @@
+warning: unused macro definition
+  --> $DIR/issue-70041.rs:4:1
+   |
+LL | / macro_rules! regex {
+LL | |
+LL | |     () => {};
+LL | | }
+   | |_^
+   |
+   = note: `#[warn(unused_macros)]` on by default
+
+warning: unused import: `regex`
+  --> $DIR/issue-70041.rs:10:5
+   |
+LL | use regex;
+   |     ^^^^^
+   |
+   = note: `#[warn(unused_imports)]` on by default
+