Introduce semantic::Info

Will hold the mutable fields that currently reside in the otherwise immutable-AST.

Change the AST string methods to accept a `const semantic::Info&`. This is required as some nodes include type-resolved information in their output strings.

Bug: tint:390
Change-Id: Iba494a9c5645ce2096da0a8cfe63a4309a9d9c3c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/39003
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>

src/semantic/info.h

@@ -0,0 +1,43 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_SEMANTIC_INFO_H_
+#define SRC_SEMANTIC_INFO_H_
+
+namespace tint {
+
+namespace semantic {
+
+/// Info will hold all the resolved semantic information for a Program.
+class Info {
+ public:
+  /// Constructor
+  Info();
+
+  /// Move constructor
+  Info(Info&&);
+
+  /// Destructor
+  ~Info();
+
+  /// Move assignment operator
+  /// @param rhs the Program to move
+  /// @return this Program
+  Info& operator=(Info&& rhs);
+};
+
+}  // namespace semantic
+}  // namespace tint
+
+#endif  // SRC_SEMANTIC_INFO_H_

src/semantic/sem_info.cc

@@ -0,0 +1,29 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/semantic/info.h"
+
+namespace tint {
+namespace semantic {
+
+Info::Info() = default;
+
+Info::Info(Info&&) = default;
+
+Info::~Info() = default;
+
+Info& Info::operator=(Info&&) = default;
+
+}  // namespace semantic
+}  // namespace tint