From 1fe6160c7e4b584795c66f21683064f62803acf0 Mon Sep 17 00:00:00 2001
From: Shotaro Yamada <sinkuu@sinkuu.xyz>
Date: Tue, 9 Jul 2019 16:59:34 +0900
Subject: [PATCH] Fix ICE with `impl Trait` in type bounds

---
 src/librustdoc/clean/mod.rs                         | 13 ++++++++++---
 .../inline_cross/auxiliary/impl_trait_aux.rs        |  2 ++
 src/test/rustdoc/inline_cross/impl_trait.rs         |  6 ++++++
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 37ee79aa9e4f1..ba792a413b3c4 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1725,7 +1725,7 @@ impl<'a, 'tcx> Clean<Generics> for (&'a ty::Generics,
         let mut impl_trait_proj =
             FxHashMap::<u32, Vec<(DefId, String, Ty<'tcx>)>>::default();
 
-        let mut where_predicates = preds.predicates.iter()
+        let where_predicates = preds.predicates.iter()
             .flat_map(|(p, _)| {
                 let mut projection = None;
                 let param_idx = (|| {
@@ -1747,10 +1747,10 @@ impl<'a, 'tcx> Clean<Generics> for (&'a ty::Generics,
                     None
                 })();
 
-                let p = p.clean(cx)?;
-
                 if let Some(param_idx) = param_idx {
                     if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
+                        let p = p.clean(cx)?;
+
                         b.extend(
                             p.get_bounds()
                                 .into_iter()
@@ -1805,6 +1805,13 @@ impl<'a, 'tcx> Clean<Generics> for (&'a ty::Generics,
             cx.impl_trait_bounds.borrow_mut().insert(param, bounds);
         }
 
+        // Now that `cx.impl_trait_bounds` is populated, we can process
+        // remaining predicates which could contain `impl Trait`.
+        let mut where_predicates = where_predicates
+            .into_iter()
+            .flat_map(|p| p.clean(cx))
+            .collect::<Vec<_>>();
+
         // Type parameters and have a Sized bound by default unless removed with
         // ?Sized. Scan through the predicates and mark any type parameter with
         // a Sized bound, removing the bounds as we find them.
diff --git a/src/test/rustdoc/inline_cross/auxiliary/impl_trait_aux.rs b/src/test/rustdoc/inline_cross/auxiliary/impl_trait_aux.rs
index 24efe4297103f..21c733a9bc98e 100644
--- a/src/test/rustdoc/inline_cross/auxiliary/impl_trait_aux.rs
+++ b/src/test/rustdoc/inline_cross/auxiliary/impl_trait_aux.rs
@@ -9,6 +9,8 @@ pub fn func2<T>(
 
 pub fn func3(_x: impl Iterator<Item = impl Iterator<Item = u8>> + Clone) {}
 
+pub fn func4<T: Iterator<Item = impl Clone>>(_x: T) {}
+
 pub struct Foo;
 
 impl Foo {
diff --git a/src/test/rustdoc/inline_cross/impl_trait.rs b/src/test/rustdoc/inline_cross/impl_trait.rs
index 3a9f2f880798d..b1e3f8d145b5f 100644
--- a/src/test/rustdoc/inline_cross/impl_trait.rs
+++ b/src/test/rustdoc/inline_cross/impl_trait.rs
@@ -20,6 +20,12 @@ pub use impl_trait_aux::func2;
 // @!has - '//pre[@class="rust fn"]' 'where'
 pub use impl_trait_aux::func3;
 
+
+// @has impl_trait/fn.func4.html
+// @has - '//pre[@class="rust fn"]' "func4<T>("
+// @has - '//pre[@class="rust fn"]' "T: Iterator<Item = impl Clone>,"
+pub use impl_trait_aux::func4;
+
 // @has impl_trait/struct.Foo.html
 // @has - '//code[@id="method.v"]' "pub fn method<'a>(_x: impl Clone + Into<Vec<u8>> + 'a)"
 // @!has - '//code[@id="method.v"]' 'where'