Merge #4660

4660: Enable hover and autocomplete docs on macro generated items r=aloucks a=aloucks

Enable hover and autocomplete docs on macro generated items. This de-sugars doc comments into `doc` attributes in some cases, but not all. Comments and `doc` attributes are then merged together. 

This PR is essentially a partial implementation of what's being suggested #3182, but it's not all the way there yet. ~I still need to add unit tests~, but I wanted to first get feedback on whether or not this was an acceptable path forward.

Fixes #4564
Fixes #3984
Fixes #3180
Related #3182

![macro_item_docs](https://user-images.githubusercontent.com/221559/83336760-15012200-a284-11ea-8d0d-b6a615850044.gif)



Co-authored-by: Aaron Loucks <[email protected]>

7 files changed, 260 insertions, 19 deletions

diff --git a/crates/ra_hir_def/src/attr.rs b/crates/ra_hir_def/src/attr.rs
index 8b6c0bede..2eeba0572 100644
--- a/crates/ra_hir_def/src/attr.rs
+++ b/crates/ra_hir_def/src/attr.rs
@@ -87,12 +87,18 @@ impl Attrs {
     }
 
     pub(crate) fn new(owner: &dyn AttrsOwner, hygiene: &Hygiene) -> Attrs {
+        let docs = ast::CommentIter::from_syntax_node(owner.syntax()).doc_comment_text().map(
+            |docs_text| Attr {
+                input: Some(AttrInput::Literal(SmolStr::new(docs_text))),
+                path: ModPath::from(hir_expand::name!(doc)),
+            },
+        );
         let mut attrs = owner.attrs().peekable();
         let entries = if attrs.peek().is_none() {
             // Avoid heap allocation
             None
         } else {
-            Some(attrs.flat_map(|ast| Attr::from_src(ast, hygiene)).collect())
+            Some(attrs.flat_map(|ast| Attr::from_src(ast, hygiene)).chain(docs).collect())
         };
         Attrs { entries }
     }
diff --git a/crates/ra_hir_def/src/docs.rs b/crates/ra_hir_def/src/docs.rs
index b221ae1ce..2630b3d89 100644
--- a/crates/ra_hir_def/src/docs.rs
+++ b/crates/ra_hir_def/src/docs.rs
@@ -29,6 +29,13 @@ impl Documentation {
         Documentation(s.into())
     }
 
+    pub fn from_ast<N>(node: &N) -> Option<Documentation>
+    where
+        N: ast::DocCommentsOwner + ast::AttrsOwner,
+    {
+        docs_from_ast(node)
+    }
+
     pub fn as_str(&self) -> &str {
         &*self.0
     }
@@ -70,6 +77,45 @@ impl Documentation {
     }
 }
 
-pub(crate) fn docs_from_ast(node: &impl ast::DocCommentsOwner) -> Option<Documentation> {
-    node.doc_comment_text().map(|it| Documentation::new(&it))
+pub(crate) fn docs_from_ast<N>(node: &N) -> Option<Documentation>
+where
+    N: ast::DocCommentsOwner + ast::AttrsOwner,
+{
+    let doc_comment_text = node.doc_comment_text();
+    let doc_attr_text = expand_doc_attrs(node);
+    let docs = merge_doc_comments_and_attrs(doc_comment_text, doc_attr_text);
+    docs.map(|it| Documentation::new(&it))
+}
+
+fn merge_doc_comments_and_attrs(
+    doc_comment_text: Option<String>,
+    doc_attr_text: Option<String>,
+) -> Option<String> {
+    match (doc_comment_text, doc_attr_text) {
+        (Some(mut comment_text), Some(attr_text)) => {
+            comment_text.push_str("\n\n");
+            comment_text.push_str(&attr_text);
+            Some(comment_text)
+        }
+        (Some(comment_text), None) => Some(comment_text),
+        (None, Some(attr_text)) => Some(attr_text),
+        (None, None) => None,
+    }
+}
+
+fn expand_doc_attrs(owner: &dyn ast::AttrsOwner) -> Option<String> {
+    let mut docs = String::new();
+    for attr in owner.attrs() {
+        if let Some(("doc", value)) =
+            attr.as_simple_key_value().as_ref().map(|(k, v)| (k.as_str(), v.as_str()))
+        {
+            docs.push_str(value);
+            docs.push_str("\n\n");
+        }
+    }
+    if docs.is_empty() {
+        None
+    } else {
+        Some(docs.trim_end_matches("\n\n").to_owned())
+    }
 }
diff --git a/crates/ra_hir_expand/src/name.rs b/crates/ra_hir_expand/src/name.rs
index ea495cb11..660bdfe33 100644
--- a/crates/ra_hir_expand/src/name.rs
+++ b/crates/ra_hir_expand/src/name.rs
@@ -153,6 +153,7 @@ pub mod known {
         str,
         // Special names
         macro_rules,
+        doc,
         // Components of known path (value or mod name)
         std,
         core,
diff --git a/crates/ra_ide/src/completion.rs b/crates/ra_ide/src/completion.rs
index d890b69d2..a721e23c6 100644
--- a/crates/ra_ide/src/completion.rs
+++ b/crates/ra_ide/src/completion.rs
@@ -125,3 +125,81 @@ pub(crate) fn completions(
 
     Some(acc)
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::completion::completion_config::CompletionConfig;
+    use crate::mock_analysis::analysis_and_position;
+
+    struct DetailAndDocumentation<'a> {
+        detail: &'a str,
+        documentation: &'a str,
+    }
+
+    fn check_detail_and_documentation(fixture: &str, expected: DetailAndDocumentation) {
+        let (analysis, position) = analysis_and_position(fixture);
+        let config = CompletionConfig::default();
+        let completions = analysis.completions(&config, position).unwrap().unwrap();
+        for item in completions {
+            if item.detail() == Some(expected.detail) {
+                let opt = item.documentation();
+                let doc = opt.as_ref().map(|it| it.as_str());
+                assert_eq!(doc, Some(expected.documentation));
+                return;
+            }
+        }
+        panic!("completion detail not found: {}", expected.detail)
+    }
+
+    #[test]
+    fn test_completion_detail_from_macro_generated_struct_fn_doc_attr() {
+        check_detail_and_documentation(
+            r#"
+            //- /lib.rs
+            macro_rules! bar {
+                () => {
+                    struct Bar;
+                    impl Bar {
+                        #[doc = "Do the foo"]
+                        fn foo(&self) {}
+                    }
+                }
+            }
+
+            bar!();
+
+            fn foo() {
+                let bar = Bar;
+                bar.fo<|>;
+            }
+            "#,
+            DetailAndDocumentation { detail: "fn foo(&self)", documentation: "Do the foo" },
+        );
+    }
+
+    #[test]
+    fn test_completion_detail_from_macro_generated_struct_fn_doc_comment() {
+        check_detail_and_documentation(
+            r#"
+            //- /lib.rs
+            macro_rules! bar {
+                () => {
+                    struct Bar;
+                    impl Bar {
+                        /// Do the foo
+                        fn foo(&self) {}
+                    }
+                }
+            }
+
+            bar!();
+
+            fn foo() {
+                let bar = Bar;
+                bar.fo<|>;
+            }
+            "#,
+            DetailAndDocumentation { detail: "fn foo(&self)", documentation: " Do the foo" },
+        );
+    }
+}
diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index d96cb5596..9636cd0d6 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -1,8 +1,8 @@
 use std::iter::once;
 
 use hir::{
-    Adt, AsAssocItem, AssocItemContainer, FieldSource, HasSource, HirDisplay, ModuleDef,
-    ModuleSource, Semantics,
+    Adt, AsAssocItem, AssocItemContainer, Documentation, FieldSource, HasSource, HirDisplay,
+    ModuleDef, ModuleSource, Semantics,
 };
 use itertools::Itertools;
 use ra_db::SourceDatabase;
@@ -10,12 +10,7 @@ use ra_ide_db::{
     defs::{classify_name, classify_name_ref, Definition},
     RootDatabase,
 };
-use ra_syntax::{
-    ast::{self, DocCommentsOwner},
-    match_ast, AstNode,
-    SyntaxKind::*,
-    SyntaxToken, TokenAtOffset,
-};
+use ra_syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset};
 
 use crate::{
     display::{macro_label, rust_code_markup, rust_code_markup_with_doc, ShortLabel},
@@ -169,13 +164,15 @@ fn hover_text_from_name_kind(db: &RootDatabase, def: Definition) -> Option<Strin
     return match def {
         Definition::Macro(it) => {
             let src = it.source(db);
-            hover_text(src.value.doc_comment_text(), Some(macro_label(&src.value)), mod_path)
+            let docs = Documentation::from_ast(&src.value).map(Into::into);
+            hover_text(docs, Some(macro_label(&src.value)), mod_path)
         }
         Definition::Field(it) => {
             let src = it.source(db);
             match src.value {
                 FieldSource::Named(it) => {
-                    hover_text(it.doc_comment_text(), it.short_label(), mod_path)
+                    let docs = Documentation::from_ast(&it).map(Into::into);
+                    hover_text(docs, it.short_label(), mod_path)
                 }
                 _ => None,
             }
@@ -183,7 +180,8 @@ fn hover_text_from_name_kind(db: &RootDatabase, def: Definition) -> Option<Strin
         Definition::ModuleDef(it) => match it {
             ModuleDef::Module(it) => match it.definition_source(db).value {
                 ModuleSource::Module(it) => {
-                    hover_text(it.doc_comment_text(), it.short_label(), mod_path)
+                    let docs = Documentation::from_ast(&it).map(Into::into);
+                    hover_text(docs, it.short_label(), mod_path)
                 }
                 _ => None,
             },
@@ -208,10 +206,11 @@ fn hover_text_from_name_kind(db: &RootDatabase, def: Definition) -> Option<Strin
     fn from_def_source<A, D>(db: &RootDatabase, def: D, mod_path: Option<String>) -> Option<String>
     where
         D: HasSource<Ast = A>,
-        A: ast::DocCommentsOwner + ast::NameOwner + ShortLabel,
+        A: ast::DocCommentsOwner + ast::NameOwner + ShortLabel + ast::AttrsOwner,
     {
         let src = def.source(db);
-        hover_text(src.value.doc_comment_text(), src.value.short_label(), mod_path)
+        let docs = Documentation::from_ast(&src.value).map(Into::into);
+        hover_text(docs, src.value.short_label(), mod_path)
     }
 }
 
@@ -951,4 +950,106 @@ fn func(foo: i32) { if true { <|>foo; }; }
             &["mod my"],
         );
     }
+
+    #[test]
+    fn test_hover_struct_doc_comment() {
+        check_hover_result(
+            r#"
+            //- /lib.rs
+            /// bar docs
+            struct Bar;
+
+            fn foo() {
+                let bar = Ba<|>r;
+            }
+            "#,
+            &["struct Bar\n```\n___\n\nbar docs"],
+        );
+    }
+
+    #[test]
+    fn test_hover_struct_doc_attr() {
+        check_hover_result(
+            r#"
+            //- /lib.rs
+            #[doc = "bar docs"]
+            struct Bar;
+
+            fn foo() {
+                let bar = Ba<|>r;
+            }
+            "#,
+            &["struct Bar\n```\n___\n\nbar docs"],
+        );
+    }
+
+    #[test]
+    fn test_hover_struct_doc_attr_multiple_and_mixed() {
+        check_hover_result(
+            r#"
+            //- /lib.rs
+            /// bar docs 0
+            #[doc = "bar docs 1"]
+            #[doc = "bar docs 2"]
+            struct Bar;
+
+            fn foo() {
+                let bar = Ba<|>r;
+            }
+            "#,
+            &["struct Bar\n```\n___\n\nbar docs 0\n\nbar docs 1\n\nbar docs 2"],
+        );
+    }
+
+    #[test]
+    fn test_hover_macro_generated_struct_fn_doc_comment() {
+        check_hover_result(
+            r#"
+            //- /lib.rs
+            macro_rules! bar {
+                () => {
+                    struct Bar;
+                    impl Bar {
+                        /// Do the foo
+                        fn foo(&self) {}
+                    }
+                }
+            }
+
+            bar!();
+
+            fn foo() {
+                let bar = Bar;
+                bar.fo<|>o();
+            }
+            "#,
+            &["Bar\n```\n\n```rust\nfn foo(&self)\n```\n___\n\n Do the foo"],
+        );
+    }
+
+    #[test]
+    fn test_hover_macro_generated_struct_fn_doc_attr() {
+        check_hover_result(
+            r#"
+            //- /lib.rs
+            macro_rules! bar {
+                () => {
+                    struct Bar;
+                    impl Bar {
+                        #[doc = "Do the foo"]
+                        fn foo(&self) {}
+                    }
+                }
+            }
+
+            bar!();
+
+            fn foo() {
+                let bar = Bar;
+                bar.fo<|>o();
+            }
+            "#,
+            &["Bar\n```\n\n```rust\nfn foo(&self)\n```\n___\n\nDo the foo"],
+        );
+    }
 }
diff --git a/crates/ra_syntax/src/ast/traits.rs b/crates/ra_syntax/src/ast/traits.rs
index bfc05e08b..a8f2454fd 100644
--- a/crates/ra_syntax/src/ast/traits.rs
+++ b/crates/ra_syntax/src/ast/traits.rs
@@ -83,13 +83,22 @@ pub trait DocCommentsOwner: AstNode {
         CommentIter { iter: self.syntax().children_with_tokens() }
     }
 
+    fn doc_comment_text(&self) -> Option<String> {
+        self.doc_comments().doc_comment_text()
+    }
+}
+
+impl CommentIter {
+    pub fn from_syntax_node(syntax_node: &ast::SyntaxNode) -> CommentIter {
+        CommentIter { iter: syntax_node.children_with_tokens() }
+    }
+
     /// Returns the textual content of a doc comment block as a single string.
     /// That is, strips leading `///` (+ optional 1 character of whitespace),
     /// trailing `*/`, trailing whitespace and then joins the lines.
-    fn doc_comment_text(&self) -> Option<String> {
+    pub fn doc_comment_text(self) -> Option<String> {
         let mut has_comments = false;
         let docs = self
-            .doc_comments()
             .filter(|comment| comment.kind().doc.is_some())
             .map(|comment| {
                 has_comments = true;
diff --git a/docs/user/generated_features.adoc b/docs/user/generated_features.adoc
index 12812fa0b..4b93b759f 100644
--- a/docs/user/generated_features.adoc
+++ b/docs/user/generated_features.adoc
@@ -76,7 +76,7 @@ Navigates to the type of an identifier.
 
 
 === Hover
-**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide/src/hover.rs#L63[hover.rs]
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide/src/hover.rs#L58[hover.rs]
 
 Shows additional information, like type of an expression or documentation for definition when "focusing" code.
 Focusing is usually hovering with a mouse, but can also be triggered with a shortcut.