Merge #601

601: union support for hir type checking and gcc backend r=dkm a=dkm

From Mark Wielaard : https://gcc.gnu.org/pipermail/gcc-rust/2021-August/000107.html

> 
> Treat a union as a Struct variant like a tuple struct.  Add an
> iterator and get_identifier functions to the AST Union class.  Same
> for the HIR Union class, plus a get_generics_params method. Add a new
> ADTKind enum and adt_kind field to the ADTType to select the
> underlying abstract data type (struct struct, tuple struct or union,
> with enum as possible future variant).
> 
> An union constructor can have only one field. Add an union_index field
> to StructExprStruct which is set during type checking in the
> TypeCheckStructExpr HIR StructExprStructFields visitor.
> 
> For the Gcc_backend class rename fill_in_struct to fill_in_fields and
> use it from a new union_type method. Handle union_index in
> constructor_expression (so only one field is initialized).

Fixes #157 

Co-authored-by: Mark Wielaard <mark@klomp.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/gcc/rust/backend/rust-compile-context.h b/gcc/rust/backend/rust-compile-context.h
index 0aaf084..8007c2f 100644
--- a/gcc/rust/backend/rust-compile-context.h
+++ b/gcc/rust/backend/rust-compile-context.h
@@ -417,9 +417,13 @@ public:
 	fields.push_back (std::move (f));
       }
 
-    Btype *struct_type_record = ctx->get_backend ()->struct_type (fields);
+    Btype *type_record;
+    if (type.is_union ())
+      type_record = ctx->get_backend ()->union_type (fields);
+    else
+      type_record = ctx->get_backend ()->struct_type (fields);
     Btype *named_struct
-      = ctx->get_backend ()->named_type (type.get_name (), struct_type_record,
+      = ctx->get_backend ()->named_type (type.get_name (), type_record,
 					 ctx->get_mappings ()->lookup_location (
 					   type.get_ty_ref ()));