Add test for impl blocks containing only private items

Author: GuillaumeGomez

Diff for: src/test/rustdoc/empty-impl-block-private-with-doc.rs

@@ -0,0 +1,44 @@
+// compile-flags: --document-private-items
+
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+#![crate_name = "foo"]
+
+// @has 'foo/struct.Foo.html'
+pub struct Foo;
+
+// There are 3 impl blocks with public item and one that should not be displayed
+// by default because it only contains private items (but not in this case because
+// we used `--document-private-items`).
+// @count - '//*[@class="impl has-srclink"]' 'impl Foo' 4
+
+// Impl block only containing private items should not be displayed unless the
+// `--document-private-items` flag is used.
+/// Private
+impl Foo {
+    const BAR: u32 = 0;
+    type FOO = i32;
+    fn hello() {}
+}
+
+// But if any element of the impl block is public, it should be displayed.
+/// Not private
+impl Foo {
+    pub const BAR: u32 = 0;
+    type FOO = i32;
+    fn hello() {}
+}
+
+/// Not private
+impl Foo {
+    const BAR: u32 = 0;
+    pub type FOO = i32;
+    fn hello() {}
+}
+
+/// Not private
+impl Foo {
+    const BAR: u32 = 0;
+    type FOO = i32;
+    pub fn hello() {}
+}

Diff for: src/test/rustdoc/empty-impl-block-private.rs

@@ -0,0 +1,40 @@
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+#![crate_name = "foo"]
+
+// @has 'foo/struct.Foo.html'
+pub struct Foo;
+
+// There are 3 impl blocks with public item and one that should not be displayed
+// because it only contains private items.
+// @count - '//*[@class="impl has-srclink"]' 'impl Foo' 3
+
+// Impl block only containing private items should not be displayed.
+/// Private
+impl Foo {
+    const BAR: u32 = 0;
+    type FOO = i32;
+    fn hello() {}
+}
+
+// But if any element of the impl block is public, it should be displayed.
+/// Not private
+impl Foo {
+    pub const BAR: u32 = 0;
+    type FOO = i32;
+    fn hello() {}
+}
+
+/// Not private
+impl Foo {
+    const BAR: u32 = 0;
+    pub type FOO = i32;
+    fn hello() {}
+}
+
+/// Not private
+impl Foo {
+    const BAR: u32 = 0;
+    type FOO = i32;
+    pub fn hello() {}
+}