gccrs: Add support for TuplePattern in let statements

gcc/rust/ChangeLog:

	* hir/tree/rust-hir-pattern.h
	(TuplePatternItemsRanged::get_lower_patterns): Add method.
	(TuplePatternItemsRanged::get_upper_patterns): Add method.
	* backend/rust-compile-pattern.cc
	(CompilePatternLet::visit): Implement TuplePattern visitor.
	* backend/rust-compile-pattern.h
	(CompilePatternLet::visit): Move TuplePattern visitor out of header file.

gcc/testsuite/ChangeLog:

	* rust/execute/torture/let-pattern-1.rs: New test.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>

gcc/rust/backend/rust-compile-pattern.cc

@@ -387,5 +387,92 @@ CompilePatternLet::visit (HIR::WildcardPattern &pattern)
     }
 }
 
+void
+CompilePatternLet::visit (HIR::TuplePattern &pattern)
+{
+  rust_assert (pattern.has_tuple_pattern_items ());
+
+  tree tuple_type = TyTyResolveCompile::compile (ctx, ty);
+  tree init_stmt;
+  Bvariable *tmp_var
+    = ctx->get_backend ()->temporary_variable (ctx->peek_fn ().fndecl,
+					       NULL_TREE, tuple_type, init_expr,
+					       false, pattern.get_locus (),
+					       &init_stmt);
+  tree access_expr
+    = ctx->get_backend ()->var_expression (tmp_var, pattern.get_locus ());
+  ctx->add_statement (init_stmt);
+
+  switch (pattern.get_items ()->get_pattern_type ())
+    {
+      case HIR::TuplePatternItems::TuplePatternItemType::RANGED: {
+	size_t tuple_idx = 0;
+	auto &items
+	  = static_cast<HIR::TuplePatternItemsRanged &> (*pattern.get_items ());
+
+	auto &items_lower = items.get_lower_patterns ();
+	auto &items_upper = items.get_upper_patterns ();
+
+	for (auto &sub : items_lower)
+	  {
+	    TyTy::BaseType *ty_sub = nullptr;
+	    HirId pattern_id = pattern.get_pattern_mappings ().get_hirid ();
+	    bool ok = ctx->get_tyctx ()->lookup_type (pattern_id, &ty_sub);
+	    rust_assert (ok);
+
+	    tree sub_init = ctx->get_backend ()->struct_field_expression (
+	      access_expr, tuple_idx, sub->get_locus ());
+	    CompilePatternLet::Compile (sub.get (), sub_init, ty_sub,
+					rval_locus, ctx);
+	    tuple_idx++;
+	  }
+
+	rust_assert (ty->get_kind () == TyTy::TypeKind::TUPLE);
+	tuple_idx = static_cast<TyTy::TupleType &> (*ty).num_fields ()
+		    - items_upper.size ();
+
+	for (auto &sub : items_upper)
+	  {
+	    TyTy::BaseType *ty_sub = nullptr;
+	    HirId pattern_id = pattern.get_pattern_mappings ().get_hirid ();
+	    bool ok = ctx->get_tyctx ()->lookup_type (pattern_id, &ty_sub);
+	    rust_assert (ok);
+
+	    tree sub_init = ctx->get_backend ()->struct_field_expression (
+	      access_expr, tuple_idx, sub->get_locus ());
+	    CompilePatternLet::Compile (sub.get (), sub_init, ty_sub,
+					rval_locus, ctx);
+	    tuple_idx++;
+	  }
+
+	return;
+      }
+      case HIR::TuplePatternItems::TuplePatternItemType::MULTIPLE: {
+	size_t tuple_idx = 0;
+	auto &items = static_cast<HIR::TuplePatternItemsMultiple &> (
+	  *pattern.get_items ());
+
+	for (auto &sub : items.get_patterns ())
+	  {
+	    TyTy::BaseType *ty_sub = nullptr;
+	    HirId pattern_id = pattern.get_pattern_mappings ().get_hirid ();
+	    bool ok = ctx->get_tyctx ()->lookup_type (pattern_id, &ty_sub);
+	    rust_assert (ok);
+
+	    tree sub_init = ctx->get_backend ()->struct_field_expression (
+	      access_expr, tuple_idx, sub->get_locus ());
+	    CompilePatternLet::Compile (sub.get (), sub_init, ty_sub,
+					rval_locus, ctx);
+	    tuple_idx++;
+	  }
+
+	return;
+      }
+      default: {
+	gcc_unreachable ();
+      }
+    }
+}
+
 } // namespace Compile
 } // namespace Rust

gcc/rust/backend/rust-compile-pattern.h

@@ -101,6 +101,7 @@ public:
 
   void visit (HIR::IdentifierPattern &) override;
   void visit (HIR::WildcardPattern &) override;
+  void visit (HIR::TuplePattern &) override;
 
   // check for unimplemented Pattern HIR nodes.
   void visit (HIR::LiteralPattern &pattern) override
@@ -146,12 +147,6 @@ public:
 		   "struct pattern let statements not supported");
   }
 
-  void visit (HIR::TuplePattern &pattern) override
-  {
-    rust_sorry_at (pattern.get_locus (),
-		   "tuple pattern let statements not supported");
-  }
-
   void visit (HIR::TupleStructPattern &pattern) override
   {
     rust_sorry_at (pattern.get_locus (),

gcc/rust/hir/tree/rust-hir-pattern.h

@@ -1142,6 +1142,24 @@ public:
     return TuplePatternItemType::RANGED;
   }
 
+  std::vector<std::unique_ptr<Pattern> > &get_lower_patterns ()
+  {
+    return lower_patterns;
+  }
+  const std::vector<std::unique_ptr<Pattern> > &get_lower_patterns () const
+  {
+    return lower_patterns;
+  }
+
+  std::vector<std::unique_ptr<Pattern> > &get_upper_patterns ()
+  {
+    return upper_patterns;
+  }
+  const std::vector<std::unique_ptr<Pattern> > &get_upper_patterns () const
+  {
+    return upper_patterns;
+  }
+
 protected:
   /* Use covariance to implement clone function as returning this object rather
    * than base */

gcc/testsuite/rust/execute/torture/let-pattern-1.rs

@@ -0,0 +1,4 @@
+fn main() -> i32 {
+    let (x, y, z) = (2, 3, 6);
+    x * y - z
+}