Auto merge of #115367 - frank-king:feature/unnamed-fields-hir, r=davidtwco

Lowering unnamed fields and anonymous adt

This implements #49804.

Goals:
- [x] lowering anonymous ADTs from AST to HIR
- [x] generating definitions of anonymous ADTs
- [x] uniqueness check of the unnamed fields
- [x] field projection of anonymous ADTs
- [x] `#[repr(C)]` check of the anonymous ADTs

Non-Goals (will be in the next PRs)
- capturing generic params for the anonymous ADTs from the parent ADT
- pattern matching of anonymous ADTs
- structural expressions of anonymous ADTs
- rustdoc support of anonymous ADTs

2 files changed, 5 insertions, 0 deletions

diff --git a/compiler/rustc_middle/src/query/erase.rs b/compiler/rustc_middle/src/query/erase.rs
index a272a51f327..7039749b1b7 100644
--- a/compiler/rustc_middle/src/query/erase.rs
+++ b/compiler/rustc_middle/src/query/erase.rs
@@ -238,6 +238,7 @@ trivial! {
     Option<rustc_span::def_id::DefId>,
     Option<rustc_span::def_id::LocalDefId>,
     Option<rustc_span::Span>,
+    Option<rustc_target::abi::FieldIdx>,
     Option<rustc_target::spec::PanicStrategy>,
     Option<usize>,
     Result<(), rustc_errors::ErrorGuaranteed>,
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 938fba0ed09..e9f61a54270 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -2217,6 +2217,10 @@ rustc_queries! {
         desc { "whether the item should be made inlinable across crates" }
         separate_provide_extern
     }
+
+    query find_field((def_id, ident): (DefId, rustc_span::symbol::Ident)) -> Option<rustc_target::abi::FieldIdx> {
+        desc { |tcx| "find the index of maybe nested field `{ident}` in `{}`", tcx.def_path_str(def_id) }
+    }
 }
 
 rustc_query_append! { define_callbacks! }