Auto merge of #42865 - ollie27:rustdoc_assoc_consts, r=GuillaumeGomez

rustdoc: Fix a few issues with associated consts

* Make sure private consts are stripped.
* Don't show a code block for the value if there is none.
* Make sure default values are shown in impls.
* Make sure docs from the trait are used if the impl has no docs.

3 files changed, 108 insertions, 43 deletions

diff --git a/src/librustdoc/html/render.rs b/src/librustdoc/html/render.rs
index 0299e45599b..db1bb28c890 100644
--- a/src/librustdoc/html/render.rs
+++ b/src/librustdoc/html/render.rs
@@ -1628,12 +1628,13 @@ fn plain_summary_line(s: Option<&str>) -> String {
 
 fn document(w: &mut fmt::Formatter, cx: &Context, item: &clean::Item) -> fmt::Result {
     document_stability(w, cx, item)?;
-    document_full(w, item, cx.render_type)?;
+    let prefix = render_assoc_const_value(item);
+    document_full(w, item, cx.render_type, &prefix)?;
     Ok(())
 }
 
 fn document_short(w: &mut fmt::Formatter, item: &clean::Item, link: AssocItemLink,
-                  render_type: RenderType) -> fmt::Result {
+                  render_type: RenderType, prefix: &str) -> fmt::Result {
     if let Some(s) = item.doc_value() {
         let markdown = if s.contains('\n') {
             format!("{} [Read more]({})",
@@ -1641,42 +1642,33 @@ fn document_short(w: &mut fmt::Formatter, item: &clean::Item, link: AssocItemLin
         } else {
             format!("{}", &plain_summary_line(Some(s)))
         };
-        write!(w, "<div class='docblock'>{}</div>",
-               Markdown(&markdown, render_type))?;
+        write!(w, "<div class='docblock'>{}{}</div>", prefix, Markdown(&markdown, render_type))?;
+    } else if !prefix.is_empty() {
+        write!(w, "<div class='docblock'>{}</div>", prefix)?;
     }
     Ok(())
 }
 
-fn md_render_assoc_item(item: &clean::Item) -> String {
+fn render_assoc_const_value(item: &clean::Item) -> String {
     match item.inner {
-        clean::AssociatedConstItem(ref ty, ref default) => {
-            if let Some(default) = default.as_ref() {
-                format!("```\n{}: {:#} = {}\n```\n\n", item.name.as_ref().unwrap(), ty, default)
-            } else {
-                format!("```\n{}: {:#}\n```\n\n", item.name.as_ref().unwrap(), ty)
-            }
+        clean::AssociatedConstItem(ref ty, Some(ref default)) => {
+            highlight::render_with_highlighting(
+                &format!("{}: {:#} = {}", item.name.as_ref().unwrap(), ty, default),
+                None,
+                None,
+                None,
+            )
         }
         _ => String::new(),
     }
 }
 
-fn get_doc_value(item: &clean::Item) -> Option<&str> {
-    let x = item.doc_value();
-    if x.is_none() {
-        match item.inner {
-            clean::AssociatedConstItem(_, _) => Some(""),
-            _ => None,
-        }
-    } else {
-        x
-    }
-}
-
 fn document_full(w: &mut fmt::Formatter, item: &clean::Item,
-                 render_type: RenderType) -> fmt::Result {
-    if let Some(s) = get_doc_value(item) {
-        write!(w, "<div class='docblock'>{}</div>",
-               Markdown(&format!("{}{}", md_render_assoc_item(item), s), render_type))?;
+                 render_type: RenderType, prefix: &str) -> fmt::Result {
+    if let Some(s) = item.doc_value() {
+        write!(w, "<div class='docblock'>{}{}</div>", prefix, Markdown(s, render_type))?;
+    } else if !prefix.is_empty() {
+        write!(w, "<div class='docblock'>{}</div>", prefix)?;
     }
     Ok(())
 }
@@ -2960,14 +2952,6 @@ fn render_impl(w: &mut fmt::Formatter, cx: &Context, i: &Impl, link: AssocItemLi
                 assoc_const(w, item, ty, default.as_ref(), link.anchor(&id))?;
                 write!(w, "</code></span></h4>\n")?;
             }
-            clean::ConstantItem(ref c) => {
-                let id = derive_id(format!("{}.{}", item_type, name));
-                let ns_id = derive_id(format!("{}.{}", name, item_type.name_space()));
-                write!(w, "<h4 id='{}' class=\"{}\">", id, item_type)?;
-                write!(w, "<span id='{}' class='invisible'><code>", ns_id)?;
-                assoc_const(w, item, &c.type_, Some(&c.expr), link.anchor(&id))?;
-                write!(w, "</code></span></h4>\n")?;
-            }
             clean::AssociatedTypeItem(ref bounds, ref default) => {
                 let id = derive_id(format!("{}.{}", item_type, name));
                 let ns_id = derive_id(format!("{}.{}", name, item_type.name_space()));
@@ -2981,6 +2965,7 @@ fn render_impl(w: &mut fmt::Formatter, cx: &Context, i: &Impl, link: AssocItemLi
         }
 
         if render_method_item || render_mode == RenderMode::Normal {
+            let prefix = render_assoc_const_value(item);
             if !is_default_item {
                 if let Some(t) = trait_ {
                     // The trait item may have been stripped so we might not
@@ -2989,20 +2974,21 @@ fn render_impl(w: &mut fmt::Formatter, cx: &Context, i: &Impl, link: AssocItemLi
                         // We need the stability of the item from the trait
                         // because impls can't have a stability.
                         document_stability(w, cx, it)?;
-                        if get_doc_value(item).is_some() {
-                            document_full(w, item, cx.render_type)?;
+                        if item.doc_value().is_some() {
+                            document_full(w, item, cx.render_type, &prefix)?;
                         } else {
                             // In case the item isn't documented,
                             // provide short documentation from the trait.
-                            document_short(w, it, link, cx.render_type)?;
+                            document_short(w, it, link, cx.render_type, &prefix)?;
                         }
                     }
                 } else {
-                    document(w, cx, item)?;
+                    document_stability(w, cx, item)?;
+                    document_full(w, item, cx.render_type, &prefix)?;
                 }
             } else {
                 document_stability(w, cx, item)?;
-                document_short(w, item, link, cx.render_type)?;
+                document_short(w, item, link, cx.render_type, &prefix)?;
             }
         }
         Ok(())
diff --git a/src/librustdoc/passes/mod.rs b/src/librustdoc/passes/mod.rs
index 8f6faabd157..41fd9efe61e 100644
--- a/src/librustdoc/passes/mod.rs
+++ b/src/librustdoc/passes/mod.rs
@@ -83,7 +83,8 @@ impl<'a> fold::DocFolder for Stripper<'a> {
             clean::TraitItem(..) | clean::FunctionItem(..) |
             clean::VariantItem(..) | clean::MethodItem(..) |
             clean::ForeignFunctionItem(..) | clean::ForeignStaticItem(..) |
-            clean::ConstantItem(..) | clean::UnionItem(..) => {
+            clean::ConstantItem(..) | clean::UnionItem(..) |
+            clean::AssociatedConstItem(..) => {
                 if i.def_id.is_local() {
                     if !self.access_levels.is_exported(i.def_id) {
                         return None;
@@ -117,8 +118,7 @@ impl<'a> fold::DocFolder for Stripper<'a> {
             // Primitives are never stripped
             clean::PrimitiveItem(..) => {}
 
-            // Associated consts and types are never stripped
-            clean::AssociatedConstItem(..) |
+            // Associated types are never stripped
             clean::AssociatedTypeItem(..) => {}
         }
 
diff --git a/src/test/rustdoc/assoc-consts.rs b/src/test/rustdoc/assoc-consts.rs
index 04709407e58..8720d419a4d 100644
--- a/src/test/rustdoc/assoc-consts.rs
+++ b/src/test/rustdoc/assoc-consts.rs
@@ -16,10 +16,28 @@ pub trait Foo {
     // @has - '//*[@id="associatedconstant.FOO"]' 'const FOO: usize'
     // @has - '//*[@class="docblock"]' 'FOO: usize = 12'
     const FOO: usize = 12;
+    // @has - '//*[@id="associatedconstant.FOO_NO_DEFAULT"]' 'const FOO_NO_DEFAULT: bool'
+    const FOO_NO_DEFAULT: bool;
+    // @!has - FOO_HIDDEN
+    #[doc(hidden)]
+    const FOO_HIDDEN: u8 = 0;
 }
 
 pub struct Bar;
 
+impl Foo for Bar {
+    // @has assoc_consts/struct.Bar.html '//code' 'impl Foo for Bar'
+    // @has - '//*[@id="associatedconstant.FOO"]' 'const FOO: usize'
+    // @has - '//*[@class="docblock"]' 'FOO: usize = 12'
+    const FOO: usize = 12;
+    // @has - '//*[@id="associatedconstant.FOO_NO_DEFAULT"]' 'const FOO_NO_DEFAULT: bool'
+    // @has - '//*[@class="docblock"]' 'FOO_NO_DEFAULT: bool = false'
+    const FOO_NO_DEFAULT: bool = false;
+    // @!has - FOO_HIDDEN
+    #[doc(hidden)]
+    const FOO_HIDDEN: u8 = 0;
+}
+
 impl Bar {
     // @has assoc_consts/struct.Bar.html '//*[@id="associatedconstant.BAR"]' \
     //      'const BAR: usize'
@@ -44,3 +62,64 @@ impl Bar {
     // @has - '//*[@class="docblock"]' "F: fn(_: &(ToString + 'static)) = f"
     pub const F: fn(_: &(ToString + 'static)) = f;
 }
+
+impl Bar {
+    // @!has assoc_consts/struct.Bar.html 'BAR_PRIVATE'
+    const BAR_PRIVATE: char = 'a';
+    // @!has assoc_consts/struct.Bar.html 'BAR_HIDDEN'
+    #[doc(hidden)]
+    pub const BAR_HIDDEN: &'static str = "a";
+}
+
+// @has assoc_consts/trait.Qux.html
+pub trait Qux {
+    // @has - '//*[@id="associatedconstant.QUX0"]' 'const QUX0: u8'
+    // @has - '//*[@class="docblock"]' "Docs for QUX0 in trait."
+    /// Docs for QUX0 in trait.
+    const QUX0: u8;
+    // @has - '//*[@id="associatedconstant.QUX1"]' 'const QUX1: i8'
+    // @has - '//*[@class="docblock"]' "Docs for QUX1 in trait."
+    /// Docs for QUX1 in trait.
+    const QUX1: i8;
+    // @has - '//*[@id="associatedconstant.QUX_DEFAULT0"]' 'const QUX_DEFAULT0: u16'
+    // @has - '//*[@class="docblock"]' "QUX_DEFAULT0: u16 = 1"
+    // @has - '//*[@class="docblock"]' "Docs for QUX_DEFAULT0 in trait."
+    /// Docs for QUX_DEFAULT0 in trait.
+    const QUX_DEFAULT0: u16 = 1;
+    // @has - '//*[@id="associatedconstant.QUX_DEFAULT1"]' 'const QUX_DEFAULT1: i16'
+    // @has - '//*[@class="docblock"]' "QUX_DEFAULT1: i16 = 2"
+    // @has - '//*[@class="docblock"]' "Docs for QUX_DEFAULT1 in trait."
+    /// Docs for QUX_DEFAULT1 in trait.
+    const QUX_DEFAULT1: i16 = 2;
+    // @has - '//*[@id="associatedconstant.QUX_DEFAULT2"]' 'const QUX_DEFAULT2: u32'
+    // @has - '//*[@class="docblock"]' "QUX_DEFAULT2: u32 = 3"
+    // @has - '//*[@class="docblock"]' "Docs for QUX_DEFAULT2 in trait."
+    /// Docs for QUX_DEFAULT2 in trait.
+    const QUX_DEFAULT2: u32 = 3;
+}
+
+// @has assoc_consts/struct.Bar.html '//code' 'impl Qux for Bar'
+impl Qux for Bar {
+    // @has - '//*[@id="associatedconstant.QUX0"]' 'const QUX0: u8'
+    // @has - '//*[@class="docblock"]' "QUX0: u8 = 4"
+    // @has - '//*[@class="docblock"]' "Docs for QUX0 in trait."
+    /// Docs for QUX0 in trait.
+    const QUX0: u8 = 4;
+    // @has - '//*[@id="associatedconstant.QUX1"]' 'const QUX1: i8'
+    // @has - '//*[@class="docblock"]' "QUX1: i8 = 5"
+    // @has - '//*[@class="docblock"]' "Docs for QUX1 in impl."
+    /// Docs for QUX1 in impl.
+    const QUX1: i8 = 5;
+    // @has - '//*[@id="associatedconstant.QUX_DEFAULT0"]' 'const QUX_DEFAULT0: u16'
+    // @has - '//*[@class="docblock"]' "QUX_DEFAULT0: u16 = 6"
+    // @has - '//*[@class="docblock"]' "Docs for QUX_DEFAULT0 in trait."
+    const QUX_DEFAULT0: u16 = 6;
+    // @has - '//*[@id="associatedconstant.QUX_DEFAULT1"]' 'const QUX_DEFAULT1: i16'
+    // @has - '//*[@class="docblock"]' "QUX_DEFAULT1: i16 = 7"
+    // @has - '//*[@class="docblock"]' "Docs for QUX_DEFAULT1 in impl."
+    /// Docs for QUX_DEFAULT1 in impl.
+    const QUX_DEFAULT1: i16 = 7;
+    // @has - '//*[@id="associatedconstant.QUX_DEFAULT2"]' 'const QUX_DEFAULT2: u32'
+    // @has - '//*[@class="docblock"]' "QUX_DEFAULT2: u32 = 3"
+    // @has - '//*[@class="docblock"]' "Docs for QUX_DEFAULT2 in trait."
+}