Add a dedicated library for compiler support.

The compiler support library is going to pull in a number of different
modules from this package, and provide APIs that only make sense for
the compiler itself. Separate those into their own module.

Author: DougGregor

Package.swift

@@ -124,6 +124,11 @@ let package = Package(
       name: "SwiftOperators",
       dependencies: ["SwiftSyntax", "SwiftParser", "SwiftDiagnostics"]
     ),
+    .target(
+      name: "SwiftCompilerSupport",
+      dependencies: [
+        "SwiftSyntax", "SwiftParser", "SwiftDiagnostics", "SwiftOperators"]
+    ),
     .executableTarget(
       name: "lit-test-helper",
       dependencies: ["SwiftSyntax", "SwiftSyntaxParser"]

Sources/CMakeLists.txt

@@ -10,3 +10,4 @@ add_subdirectory(SwiftSyntax)
 add_subdirectory(SwiftDiagnostics)
 add_subdirectory(SwiftParser)
 add_subdirectory(SwiftOperators)
+add_subdirectory(SwiftCompilerSupport)

Sources/SwiftCompilerSupport/CMakeLists.txt

@@ -0,0 +1,31 @@
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
+# Licensed under Apache License v2.0 with Runtime Library Exception
+#
+# See http://swift.org/LICENSE.txt for license information
+# See http://swift.org/CONTRIBUTORS.txt for Swift project authors
+
+add_library(SwiftCompilerSupport STATIC
+  ConsistencyCheck.swift
+)
+
+target_link_libraries(SwiftCompilerSupport PUBLIC
+  SwiftSyntax
+  SwiftDiagnostics
+  SwiftParser
+  SwiftOperators
+)
+
+set_property(GLOBAL APPEND PROPERTY SWIFTSYNTAX_EXPORTS SwiftCompilerSupport)
+
+# NOTE: workaround for CMake not setting up include flags yet
+set_target_properties(SwiftCompilerSupport PROPERTIES
+  INTERFACE_INCLUDE_DIRECTORIES
+  "${CMAKE_Swift_MODULE_DIRECTORY} ${CMAKE_CURRENT_SOURCE_DIR}")
+
+install(TARGETS SwiftCompilerSupport
+  EXPORT SwiftSyntaxTargets
+  ARCHIVE DESTINATION lib
+  LIBRARY DESTINATION lib
+  RUNTIME DESTINATION bin)

Sources/SwiftCompilerSupport/ConsistencyCheck.swift

@@ -0,0 +1,15 @@
+//===-------------------------- ConsistencyCheck.swift --------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftOperators
+import SwiftParser
+import SwiftSyntax