From 0c11196311f7e184a104a9cd3a316810d1f077a7 Mon Sep 17 00:00:00 2001
From: Wilfred Hughes <me@wilfred.me.uk>
Date: Wed, 22 Jul 2026 18:22:37 +0100
Subject: [PATCH] fix: Failed to lookup MACRO_CALL@... in this Semantics due to
 include!

SemanticsImpl::find_file assumes that its caches always contain the file that
has the current SyntaxNode.

For macros `foo!()` we only have two files to worry about: the macro
call site and the macro definition site. Hoewver, for
include!("foo.rs") we also need to consider the included file.

Ensure that the file cache is consistently populated for include!()
invocations macro expansion, and add a test.

AI disclosure: GPT-5.5 used to minimise a repro from a real project
and write the initial implementation. Comments and commit message are
entirely mine.
---
 crates/hir/src/semantics/source_to_def.rs       | 12 ++++++++++++
 crates/ide-assists/src/handlers/inline_macro.rs | 17 +++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/crates/hir/src/semantics/source_to_def.rs b/crates/hir/src/semantics/source_to_def.rs
index 81005f48ddf8..caa7b39885fe 100644
--- a/crates/hir/src/semantics/source_to_def.rs
+++ b/crates/hir/src/semantics/source_to_def.rs
@@ -165,9 +165,21 @@ impl<'db> SourceToDefCache<'db> {
         self.expansion_info_cache.entry(macro_file).or_insert_with(|| {
             let exp_info = macro_file.expansion_info(db);
 
+            // Ensure that the cache contains syntax nodes from expanded macros,
+            // whose root may be in another file.
             let InMacroFile { file_id, value } = exp_info.expanded();
             Self::cache(&mut self.root_to_file_cache, value, file_id.into());
 
+            // include!("foo.rs") invocations are awkward: in addition to the
+            // expansion site there's the included file (foo.rs), so we need to
+            // ensure that it exists in the cache too.
+            if macro_file.is_include_macro(db) {
+                let arg = exp_info.arg();
+                if let Some(arg_node) = arg.value {
+                    Self::cache(&mut self.root_to_file_cache, arg_node.tree_top(), arg.file_id);
+                }
+            }
+
             exp_info
         })
     }
diff --git a/crates/ide-assists/src/handlers/inline_macro.rs b/crates/ide-assists/src/handlers/inline_macro.rs
index 5a185637df4e..d934fae9253f 100644
--- a/crates/ide-assists/src/handlers/inline_macro.rs
+++ b/crates/ide-assists/src/handlers/inline_macro.rs
@@ -175,6 +175,23 @@ macro_rules! num {
         );
     }
 
+    #[test]
+    fn inline_macro_in_included_file() {
+        // Regression test for climbing from the included file into an uncached includer root.
+        check_assist_not_applicable(
+            inline_macro,
+            r#"
+//- minicore:include
+//- /main.rs
+include!("a.rs");
+//- /a.rs
+fn foo() {
+    let x = 1$0;
+}
+"#,
+        );
+    }
+
     #[test]
     fn inline_macro_simple_not_applicable_broken_macro() {
         // FIXME: This is a bug. The macro should not expand, but it's