Merge #6771

6771: Properly attach inner attributes in Attrs::new r=matklad a=Veykril

Properly attach inner and outer attributes to the things they actually belong to in the HIR. ~~I can add some tests for this if wanted once I know where to put them/how to test for this.~~ Put some tests into `hover.rs`.
 
So the following snippet
```rust
mod foo {
	//! Hello
}
```
now shows `Hello` on hover 🎉

Fixes #2148


Co-authored-by: Lukas Wirth <[email protected]>

1 files changed, 47 insertions, 5 deletions

diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index 12f4b02e2..228d706db 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -9,7 +9,7 @@ use itertools::Itertools;
 use mbe::ast_to_token_tree;
 use syntax::{
     ast::{self, AstNode, AttrsOwner},
-    AstToken, SmolStr,
+    match_ast, AstToken, SmolStr, SyntaxNode,
 };
 use tt::Subtree;
 
@@ -110,7 +110,17 @@ impl Attrs {
     }
 
     pub(crate) fn new(owner: &dyn AttrsOwner, hygiene: &Hygiene) -> Attrs {
-        let docs = ast::CommentIter::from_syntax_node(owner.syntax()).map(|docs_text| {
+        let (inner_attrs, inner_docs) = inner_attributes(owner.syntax())
+            .map_or((None, None), |(attrs, docs)| ((Some(attrs), Some(docs))));
+
+        let outer_attrs = owner.attrs().filter(|attr| attr.excl_token().is_none());
+        let attrs = outer_attrs
+            .chain(inner_attrs.into_iter().flatten())
+            .map(|attr| (attr.syntax().text_range().start(), Attr::from_src(attr, hygiene)));
+
+        let outer_docs =
+            ast::CommentIter::from_syntax_node(owner.syntax()).filter(ast::Comment::is_outer);
+        let docs = outer_docs.chain(inner_docs.into_iter().flatten()).map(|docs_text| {
             (
                 docs_text.syntax().text_range().start(),
                 docs_text.doc_comment().map(|doc| Attr {
@@ -119,9 +129,6 @@ impl Attrs {
                 }),
             )
         });
-        let attrs = owner
-            .attrs()
-            .map(|attr| (attr.syntax().text_range().start(), Attr::from_src(attr, hygiene)));
         // sort here by syntax node offset because the source can have doc attributes and doc strings be interleaved
         let attrs: Vec<_> = docs.chain(attrs).sorted_by_key(|&(offset, _)| offset).collect();
         let entries = if attrs.is_empty() {
@@ -184,6 +191,41 @@ impl Attrs {
     }
 }
 
+fn inner_attributes(
+    syntax: &SyntaxNode,
+) -> Option<(impl Iterator<Item = ast::Attr>, impl Iterator<Item = ast::Comment>)> {
+    let (attrs, docs) = match_ast! {
+        match syntax {
+            ast::SourceFile(it) => (it.attrs(), ast::CommentIter::from_syntax_node(it.syntax())),
+            ast::ExternBlock(it) => {
+                let extern_item_list = it.extern_item_list()?;
+                (extern_item_list.attrs(), ast::CommentIter::from_syntax_node(extern_item_list.syntax()))
+            },
+            ast::Fn(it) => {
+                let body = it.body()?;
+                (body.attrs(), ast::CommentIter::from_syntax_node(body.syntax()))
+            },
+            ast::Impl(it) => {
+                let assoc_item_list = it.assoc_item_list()?;
+                (assoc_item_list.attrs(), ast::CommentIter::from_syntax_node(assoc_item_list.syntax()))
+            },
+            ast::Module(it) => {
+                let item_list = it.item_list()?;
+                (item_list.attrs(), ast::CommentIter::from_syntax_node(item_list.syntax()))
+            },
+            // FIXME: BlockExpr's only accept inner attributes in specific cases
+            // Excerpt from the reference:
+            // Block expressions accept outer and inner attributes, but only when they are the outer
+            // expression of an expression statement or the final expression of another block expression.
+            ast::BlockExpr(it) => return None,
+            _ => return None,
+        }
+    };
+    let attrs = attrs.filter(|attr| attr.excl_token().is_some());
+    let docs = docs.filter(|doc| doc.is_inner());
+    Some((attrs, docs))
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Attr {
     pub(crate) path: ModPath,