Always cache macro expansions' root node in Semantics

Previously some expansions were not cached, but were cached in the expansion cache, which caused panics when later queries tried to lookup the node from the expansion cache.

crates/test-fixture/src/lib.rs

@@ -13,7 +13,7 @@ use hir_expand::{
     proc_macro::{
         ProcMacro, ProcMacroExpander, ProcMacroExpansionError, ProcMacroKind, ProcMacrosBuilder,
     },
-    FileRange,
+    quote, FileRange,
 };
 use intern::Symbol;
 use rustc_hash::FxHashMap;
@@ -374,7 +374,7 @@ impl ChangeFixture {
     }
 }
 
-fn default_test_proc_macros() -> [(String, ProcMacro); 5] {
+fn default_test_proc_macros() -> [(String, ProcMacro); 6] {
     [
         (
             r#"
@@ -451,6 +451,21 @@ pub fn shorten(input: TokenStream) -> TokenStream {
                 disabled: false,
             },
         ),
+        (
+            r#"
+#[proc_macro_attribute]
+pub fn issue_18089(_attr: TokenStream, _item: TokenStream) -> TokenStream {
+    loop {}
+}
+"#
+            .into(),
+            ProcMacro {
+                name: Symbol::intern("issue_18089"),
+                kind: ProcMacroKind::Attr,
+                expander: sync::Arc::new(Issue18089ProcMacroExpander),
+                disabled: false,
+            },
+        ),
     ]
 }
 
@@ -577,6 +592,35 @@ impl ProcMacroExpander for IdentityProcMacroExpander {
     }
 }
 
+// Expands to a macro_rules! macro, for issue #18089.
+#[derive(Debug)]
+struct Issue18089ProcMacroExpander;
+impl ProcMacroExpander for Issue18089ProcMacroExpander {
+    fn expand(
+        &self,
+        subtree: &Subtree<Span>,
+        _: Option<&Subtree<Span>>,
+        _: &Env,
+        _: Span,
+        call_site: Span,
+        _: Span,
+        _: Option<String>,
+    ) -> Result<Subtree<Span>, ProcMacroExpansionError> {
+        let macro_name = &subtree.token_trees[1];
+        Ok(quote! { call_site =>
+            #[macro_export]
+            macro_rules! my_macro___ {
+                ($($token:tt)*) => {{
+                }};
+            }
+
+            pub use my_macro___ as #macro_name;
+
+            #subtree
+        })
+    }
+}
+
 // Pastes the attribute input as its output
 #[derive(Debug)]
 struct AttributeInputReplaceProcMacroExpander;