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, 4 insertions, 1 deletions

diff --git a/gcc/rust/rust-backend.h b/gcc/rust/rust-backend.h
index be23fd3..4635796 100644
--- a/gcc/rust/rust-backend.h
+++ b/gcc/rust/rust-backend.h
@@ -178,6 +178,9 @@ public:
   // Get a struct type.
   virtual Btype *struct_type (const std::vector<Btyped_identifier> &fields) = 0;
 
+  // Get a union type.
+  virtual Btype *union_type (const std::vector<Btyped_identifier> &fields) = 0;
+
   // Get an array type.
   virtual Btype *array_type (Btype *element_type, Bexpression *length) = 0;
 
@@ -424,7 +427,7 @@ public:
   // corresponding fields in BTYPE.
   virtual Bexpression *
   constructor_expression (Btype *btype, const std::vector<Bexpression *> &vals,
-			  Location)
+			  int, Location)
     = 0;
 
   // Return an expression that constructs an array of BTYPE with INDEXES and