Avoid cyclic queries in name resolution when processing enums

1 files changed, 8 insertions, 0 deletions

diff --git a/crates/ra_hir_def/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index 1c33a6520..98c74fe25 100644
--- a/crates/ra_hir_def/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -462,6 +462,14 @@ impl DefCollector<'_> {
                 Some(ModuleDefId::AdtId(AdtId::EnumId(e))) => {
                     tested_by!(glob_enum);
                     // glob import from enum => just import all the variants
+
+                    // XXX: urgh, so this works by accident! Here, we look at
+                    // the enum data, and, in theory, this might require us to
+                    // look back at the crate_def_map, creating a cycle. For
+                    // example, `enum E { crate::some_macro!(); }`. Luckely, the
+                    // only kind of macro that is allowed inside enum is a
+                    // `cfg_macro`, and we don't need to run name resolution for
+                    // it, but this is sheer luck!
                     let enum_data = self.db.enum_data(e);
                     let resolutions = enum_data
                         .variants