[Macros] Send termination signal to macro plugin

include/swift/AST/PluginRegistry.h

@@ -179,6 +179,7 @@ class LoadedExecutablePlugin : public CompilerPlugin {
       : CompilerPlugin(ExecutablePath),
         LastModificationTime(LastModificationTime),
         disableSandbox(disableSandbox){};
+  ~LoadedExecutablePlugin();
 
   /// The last modification time of 'ExecutablePath' when this object is
   /// created.

lib/AST/PluginRegistry.cpp

@@ -172,6 +172,16 @@ PluginRegistry::loadExecutablePlugin(StringRef path, bool disableSandbox) {
   return storage.get();
 }
 
+LoadedExecutablePlugin::~LoadedExecutablePlugin() {
+  if (Process) {
+    // If the process is alive, send an empty message as the termination signal.
+    // The plugin should exit itself when receiving it.
+    if (auto error = sendMessage(""))
+      llvm::consumeError(std::move(error));
+    Process.reset();
+  }
+}
+
 llvm::Error LoadedExecutablePlugin::spawnIfNeeded() {
   if (Process) {
     // NOTE: We don't check the mtime here because 'stat(2)' call is too heavy.

test/Macros/macro_plugin_basic.swift

@@ -34,6 +34,7 @@
 // CHECK: <-(plugin:[[#PID]]) {"expandFreestandingMacroResult":{"diagnostics":[],"expandedSource":"\"123\"\n  +   \"foo  \""}}
 // CHECK: ->(plugin:[[#PID]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","lexicalContext":[{{.*}}],"macro":{"moduleName":"TestPlugin","name":"testStringWithError","typeName":"TestStringWithErrorMacro"},"macroRole":"expression","staticBuildConfiguration"{{.*}},"syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"{{.+}}test.swift","line":6,"offset":336},"source":"#testStringWithError(321)"}}}
 // CHECK: <-(plugin:[[#PID]]) {"expandFreestandingMacroResult":{"diagnostics":[{"fixIts":[],"highlights":[],"message":"message from plugin","notes":[],"position":{"fileName":"{{.*}}test.swift","offset":336},"severity":"error"}],"expandedSource":"\"bar\""}}
+// CHECK: ->(plugin:[[#PID:]]) {{$}}
 
 //--- test.swift
 @freestanding(expression) macro testString(_: Any) -> String = #externalMacro(module: "TestPlugin", type: "TestStringMacro")

test/Macros/macro_plugin_error.swift

@@ -27,6 +27,7 @@
 // CHECK-NEXT: <-(plugin:[[#PID2]]) {"getCapabilityResult":{"capability":{"protocolVersion":1}}}
 // CHECK-NEXT: ->(plugin:[[#PID2]]) {"expandFreestandingMacro":{"discriminator":"$s{{.+}}","lexicalContext":[{{.*}}],"macro":{"moduleName":"TestPlugin","name":"fooMacro","typeName":"FooMacro"},"macroRole":"expression","staticBuildConfiguration"{{.*}},"syntax":{"kind":"expression","location":{"column":19,"fileID":"MyApp/test.swift","fileName":"{{.+}}test.swift","line":11,"offset":[[#]]},"source":"#fooMacro(3)"}}}
 // CHECK-NEXT: <-(plugin:[[#PID2:]]) {"expandFreestandingMacroResult":{"diagnostics":[],"expandedSource":"3.description"}}
+// CHECK-NEXT: ->(plugin:[[#PID2:]]) {{$}}
 
 //--- test.swift
 @freestanding(expression) macro fooMacro(_: Any) -> String = #externalMacro(module: "TestPlugin", type: "FooMacro")

test/Macros/macro_plugin_server.swift

@@ -74,6 +74,7 @@
 // CHECK-NEXT: ->(plugin:[[#PID1]]) {"expandFreestandingMacro":{"discriminator":"${{.*}}","lexicalContext":[{{.*}}],"macro":{"moduleName":"MacroDefinition","name":"stringify","typeName":"StringifyMacro"},"macroRole":"expression","staticBuildConfiguration"{{.*}},"syntax":{"kind":"expression","location":{{{.+}}},"source":"#stringify(a + b)"}}}
 // CHECK-NEXT: <-(plugin:[[#PID1]]) {"expandMacroResult":{"diagnostics":[],"expandedSource":"(a + b, \"a + b\")"}}
 // CHECK-NEXT: ->(plugin:[[#PID1]]) {"expandFreestandingMacro":{"discriminator":"${{.*}}","lexicalContext":[{{.*}}],"macro":{"moduleName":"EvilMacros","name":"evil","typeName":"CrashingMacro"},"macroRole":"expression","staticBuildConfiguration"{{.*}},"syntax":{"kind":"expression","location":{{{.+}}},"source":"#evil(42)"}}}
+// CHECK-NOT: ->(plugin:[[#PID1]]) {{$}}
 // ^ This crashes the plugin server.
 
 // CHECK: ->(plugin:[[#PID2:]]) {"getCapability":{"capability":{"protocolVersion":[[#PROTOCOL_VERSION]]}}}
@@ -89,6 +90,7 @@
 // CHECK-NEXT: <-(plugin:[[#PID2]]) {"expandMacroResult":{"diagnostics":[{"fixIts":[],"highlights":[{{{.*}}}],"message":"type 'MacroDefinition.TypeDoesNotExist' could not be found in library plugin '{{.*}}MacroDefinition.{{dylib|so|dll}}'","notes":[],"position":{{{.*}}},"severity":"error"}]}}
 // CHECK-NEXT: ->(plugin:[[#PID2]]) {"expandFreestandingMacro":{"discriminator":"${{.*}}","lexicalContext":[{{.*}}],"macro":{"moduleName":"MacroDefinition","name":"notMacro","typeName":"NotMacroStruct"},"macroRole":"expression","staticBuildConfiguration"{{.*}},"syntax":{"kind":"expression","location":{{({.+})}},"source":"#notMacro()"}}}
 // CHECK-NEXT: <-(plugin:[[#PID2]]) {"expandMacroResult":{"diagnostics":[{"fixIts":[],"highlights":[{{{.*}}}],"message":"type 'MacroDefinition.NotMacroStruct' is not a valid macro implementation type in library plugin '{{.*}}MacroDefinition.{{dylib|so|dll}}'","notes":[],"position":{{{.*}}},"severity":"error"}]}}
+// CHECK-NEXT: ->(plugin:[[#PID2]]) {{$}}
 
 @freestanding(expression) macro stringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "MacroDefinition", type: "StringifyMacro")
 @freestanding(expression) macro evil(_ value: Int) -> String = #externalMacro(module: "EvilMacros", type: "CrashingMacro")

test/Macros/macro_plugin_server_mod.swift

@@ -64,6 +64,7 @@
 // CHECK-NEXT: <-(plugin:[[#PID3]]) {"loadPluginLibraryResult":{"diagnostics":[],"loaded":true}}
 // CHECK-NEXT: ->(plugin:[[#PID3]]) {"expandFreestandingMacro":{"discriminator":"{{.*}}","lexicalContext":{{.*}},"macro":{"moduleName":"MacroDefinition","name":"stringify","typeName":"StringifyMacro"}{{.*}}
 // CHECK-NEXT: <-(plugin:[[#PID3]]) {"expandMacroResult":{"diagnostics":[],"expandedSource":"(1, \"1\")"}}
+// CHECK-NEXT: ->(plugin:[[#PID3]]) {{$}}
 
 //--- MacroDefinition.swift
 import SwiftSyntax