From e2ede38d479a1b8e2b739bcb4c478d1e857e6cec Mon Sep 17 00:00:00 2001
From: Lukas Wirth <lukastw97@gmail.com>
Date: Thu, 2 Sep 2021 17:30:02 +0200
Subject: [PATCH] Use correct search scopes for macros

---
 crates/ide/src/highlight_related.rs | 13 +++++++-----
 crates/ide_db/src/search.rs         | 31 ++++++++++++++++++++++-------
 2 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/crates/ide/src/highlight_related.rs b/crates/ide/src/highlight_related.rs
index 67ad263fa2..6994e41c8a 100644
--- a/crates/ide/src/highlight_related.rs
+++ b/crates/ide/src/highlight_related.rs
@@ -9,7 +9,9 @@ use ide_db::{
 use rustc_hash::FxHashSet;
 use syntax::{
     ast::{self, LoopBodyOwner},
-    match_ast, AstNode, SyntaxNode, SyntaxToken, TextRange, TextSize, T,
+    match_ast, AstNode,
+    SyntaxKind::IDENT,
+    SyntaxNode, SyntaxToken, TextRange, TextSize, T,
 };
 
 use crate::{display::TryToNav, references, NavigationTarget};
@@ -46,9 +48,10 @@ pub(crate) fn highlight_related(
     let syntax = sema.parse(position.file_id).syntax().clone();
 
     let token = pick_best_token(syntax.token_at_offset(position.offset), |kind| match kind {
-        T![?] => 3, // prefer `?` when the cursor is sandwiched like in `await$0?`
-        T![->] => 2,
-        kind if kind.is_keyword() => 1,
+        T![?] => 4, // prefer `?` when the cursor is sandwiched like in `await$0?`
+        T![->] => 3,
+        kind if kind.is_keyword() => 2,
+        IDENT => 1,
         _ => 0,
     })?;
 
@@ -75,7 +78,7 @@ fn highlight_references(
     let defs = find_defs(sema, syntax, offset);
     let usages = defs
         .iter()
-        .flat_map(|&d| {
+        .filter_map(|&d| {
             d.usages(sema)
                 .set_scope(Some(SearchScope::single_file(file_id)))
                 .include_self_refs()
diff --git a/crates/ide_db/src/search.rs b/crates/ide_db/src/search.rs
index 14c896cdd0..8b8c91b2fc 100644
--- a/crates/ide_db/src/search.rs
+++ b/crates/ide_db/src/search.rs
@@ -71,7 +71,7 @@ pub enum ReferenceAccess {
 /// For `pub(crate)` things it's a crate, for `pub` things it's a crate and dependant crates.
 /// In some cases, the location of the references is known to within a `TextRange`,
 /// e.g. for things like local variables.
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct SearchScope {
     entries: FxHashMap<FileId, Option<TextRange>>,
 }
@@ -216,6 +216,14 @@ impl Definition {
             return SearchScope::crate_graph(db);
         }
 
+        // def is crate root
+        // FIXME: We don't do searches for crates currently, as a crate does not actually have a single name
+        if let &Definition::ModuleDef(hir::ModuleDef::Module(module)) = self {
+            if module.crate_root(db) == module {
+                return SearchScope::reverse_dependencies(db, module.krate());
+            }
+        }
+
         let module = match self.module(db) {
             Some(it) => it,
             None => return SearchScope::empty(),
@@ -273,13 +281,22 @@ impl Definition {
         }
 
         if let Definition::Macro(macro_def) = self {
-            if macro_def.kind() == hir::MacroKind::Declarative {
-                return if macro_def.attrs(db).by_key("macro_export").exists() {
+            return match macro_def.kind() {
+                hir::MacroKind::Declarative => {
+                    if macro_def.attrs(db).by_key("macro_export").exists() {
+                        SearchScope::reverse_dependencies(db, module.krate())
+                    } else {
+                        SearchScope::krate(db, module.krate())
+                    }
+                }
+                hir::MacroKind::BuiltIn => SearchScope::crate_graph(db),
+                // FIXME: We don't actually see derives in derive attributes as these do not
+                // expand to something that references the derive macro in the output.
+                // We could get around this by emitting dummy `use DeriveMacroPathHere as _;` items maybe?
+                hir::MacroKind::Derive | hir::MacroKind::Attr | hir::MacroKind::ProcMacro => {
                     SearchScope::reverse_dependencies(db, module.krate())
-                } else {
-                    SearchScope::krate(db, module.krate())
-                };
-            }
+                }
+            };
         }
 
         let vis = self.visibility(db);