[Macros] Add a library to make simple executable plugins for testing

Add `_swiftMockPlugin` library.
Usage:
  #include "swift/swift-c/MockPlugin/MockPlugin.h"

  MOCK_PLUGIN([
    {"expect": {...},
     "response: {...}}
  ])

Author: rintaro

include/swift-c/MockPlugin/MockPlugin.h

@@ -0,0 +1,31 @@
+//===--- MockPlugin.h ---------------------------------------------*- C -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2023 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_C_MOCK_PLUGIN_H
+#define SWIFT_C_MOCK_PLUGIN_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int _mock_plugin_main(const char *);
+
+#ifdef __cplusplus
+}
+#endif
+
+/// Usage: MOCK_PLUGIN(JSON)
+/// 'JSON' is a *bare* JSON value.
+#define MOCK_PLUGIN(...)                                                       \
+  int main() { return _mock_plugin_main(#__VA_ARGS__); }
+
+#endif // SWIFT_C_MOCK_PLUGIN_H

test/Macros/macro_plugin_basic.swift

@@ -3,11 +3,23 @@
 // RUN: %empty-directory(%t)
 // RUN: split-file %s %t
 
-// RUN: sed -i '' -e 's#PYTHON_EXEC_PATH#%{python}#' %t/plugin
-// RUN: sed -i '' -e 's#UTILS_DIR_PATH#%utils#' %t/plugin
-// RUN: chmod +x %t/plugin
+// RUN: %clang \
+// RUN:  -isysroot %sdk \
+// RUN:  -I %swift_src_root/include \
+// RUN:  -L %swift-lib-dir -l_swiftMockPlugin \
+// RUN:  -Wl,-rpath,%swift-lib-dir \
+// RUN:  -o %t/mock-plugin \
+// RUN:  %t/plugin.c
 
-// RUN: %swift-target-frontend -typecheck -verify -swift-version 5 -enable-experimental-feature Macros -load-plugin-executable %t/plugin#TestPlugin %t/test.swift
+// RUN: %swift-target-frontend \
+// RUN:   -typecheck -verify \
+// RUN:   -swift-version 5 -enable-experimental-feature Macros \
+// RUN:   -load-plugin-executable %t/mock-plugin#TestPlugin \
+// RUN:   -dump-macro-expansions \
+// RUN:   %t/test.swift \
+// RUN:   2>&1 | tee %t/macro-expansions.txt
+
+// RUN: %FileCheck -strict-whitespace %s < %t/macro-expansions.txt
 
 //--- test.swift
 @freestanding(expression) macro testString(_: Any) -> String = #externalMacro(module: "TestPlugin", type: "TestStringMacro")
@@ -19,41 +31,43 @@ func test() {
   // expected-error @-1 {{message from plugin}} 
 }
 
-//--- plugin
-#!PYTHON_EXEC_PATH
-import sys
-sys.path.append('UTILS_DIR_PATH')
+// CHECK:      ------------------------------
+// CHECK-NEXT: {{^}}"123"
+// CHECK-NEXT: {{^}}  +   "foo  "
+// CHECK-NEXT: ------------------------------
+
+// CHECK:      ------------------------------
+// CHECK-NEXT: {{^}}"bar"
+// CHECK-NEXT: ------------------------------
 
-import mock_plugin
+//--- plugin.c
+#include "swift-c/MockPlugin/MockPlugin.h"
 
-mock_plugin.TEST_SPEC = [
+MOCK_PLUGIN([
   {
     "expect": {"getCapability": {}},
-    "response": {"getCapabilityResult": {"capability": {"protocolVersion": 1}}},
+    "response": {"getCapabilityResult": {"capability": {"protocolVersion": 1}}}
   },
   {
     "expect": {"expandFreestandingMacro": {
                 "macro": {"moduleName": "TestPlugin", "typeName": "TestStringMacro"},
                 "syntax": {"kind": "expression", "source": "#testString(123)"}}},
-    "response": {"expandFreestandingMacroResult": {"expandedSource": "\"123\"", "diagnostics": []}},
+    "response": {"expandFreestandingMacroResult": {"expandedSource": "\"123\"\n  +   \"foo  \"", "diagnostics": []}}
   },
   {
     "expect": {"expandFreestandingMacro": {
                 "macro": {"moduleName": "TestPlugin", "typeName": "TestStringWithErrorMacro"},
                 "syntax": {"kind": "expression", "source": "#testStringWithError(321)"}}},
     "response": {"expandFreestandingMacroResult": {
-                   "expandedSource": "\"123\"",
+                   "expandedSource": "\"bar\"",
                    "diagnostics": [
                      {"severity": "error",
-                      "position": {"offset": "={req[expandFreestandingMacro][syntax][location][offset]}",
-                                   "fileName": "{req[expandFreestandingMacro][syntax][location][fileName]}"},
+                      "position": {"offset": "=req.expandFreestandingMacro.syntax.location.offset",
+                                   "fileName": "=req.expandFreestandingMacro.syntax.location.fileName"},
                       "message":"message from plugin",
                       "highlights": [],
                       "notes": [],
                       "fixIts": []}
-                   ]}},
-  },
-]
-
-mock_plugin.main()
-
+                   ]}}
+  }
+])

tools/CMakeLists.txt

@@ -33,6 +33,7 @@ add_swift_tool_subdirectory(swift-ast-script)
 add_swift_tool_subdirectory(swift-refactor)
 add_swift_tool_subdirectory(libSwiftScan)
 add_swift_tool_subdirectory(libStaticMirror)
+add_swift_tool_subdirectory(libMockPlugin)
 
 if(SWIFT_INCLUDE_TESTS OR SWIFT_INCLUDE_TEST_BINARIES)
   add_swift_tool_subdirectory(swift-ide-test)

tools/libMockPlugin/CMakeLists.txt

@@ -0,0 +1,19 @@
+set(MOCK_PLUGIN_LIB_NAME "_swiftMockPlugin")
+
+set(LLVM_EXPORTED_SYMBOL_FILE
+    ${CMAKE_CURRENT_SOURCE_DIR}/libMockPlugin.exports)
+
+add_swift_host_library(libMockPlugin SHARED
+  MockPlugin.cpp
+  c-include-check.c
+  LLVM_LINK_COMPONENTS support)
+
+set_target_properties(libMockPlugin
+    PROPERTIES
+    OUTPUT_NAME ${MOCK_PLUGIN_LIB_NAME})
+
+add_llvm_symbol_exports(libMockPlugin ${LLVM_EXPORTED_SYMBOL_FILE})
+
+add_dependencies(tools libMockPlugin)
+# Adds -dead_strip option
+add_link_opts(libStaticMirror)