[Frontend] Forward intent to launch REPL to new driver

Now that the new driver no longer runs the REPL by default
when there are no arguments, the frontend needs to update
its assumption as it is still used to launch the new driver.

rdar://88595293

Author: bitjammer

lib/DriverTool/driver.cpp

@@ -97,8 +97,7 @@ extern int swift_api_extract_main(ArrayRef<const char *> Args,
 /// \returns True if running as a subcommand.
 static bool shouldRunAsSubcommand(StringRef ExecName,
                                   SmallString<256> &SubcommandName,
-                                  const ArrayRef<const char *> Args,
-                                  bool &isRepl) {
+                                  const ArrayRef<const char *> Args) {
   assert(!Args.empty());
 
   // If we are not run as 'swift', don't do anything special. This doesn't work
@@ -125,7 +124,6 @@ static bool shouldRunAsSubcommand(StringRef ExecName,
   // If the subcommand is the "built-in" 'repl', then use the
   // normal driver.
   if (Subcommand == "repl") {
-    isRepl = true;
     return false;
   }
 
@@ -184,15 +182,18 @@ static bool appendSwiftDriverName(SmallString<256> &buffer) {
 }
 
 static int run_driver(StringRef ExecName,
-                       const ArrayRef<const char *> argv,
+                       ArrayRef<const char *> argv,
                        const ArrayRef<const char *> originalArgv) {
   // This is done here and not done in FrontendTool.cpp, because
   // FrontendTool.cpp is linked to tools, which don't use swift modules.
   initializeSwiftModules();
 
+  bool isRepl = false;
+
   // Handle integrated tools.
   if (argv.size() > 1) {
     StringRef FirstArg(argv[1]);
+
     if (FirstArg == "-frontend") {
       return performFrontend(llvm::makeArrayRef(argv.data()+2,
                                                 argv.data()+argv.size()),
@@ -212,6 +213,11 @@ static int run_driver(StringRef ExecName,
                                                 argv.data()+argv.size()),
                              argv[0], (void *)(intptr_t)getExecutablePath);
     }
+
+    if (FirstArg == "repl") {
+      isRepl = true;
+      argv = argv.drop_front();
+    }
   }
 
   std::string Path = getExecutablePath(argv[0]);
@@ -245,8 +251,14 @@ static int run_driver(StringRef ExecName,
       subCommandArgs.push_back(NewDriverPath.c_str());
 
       // Push on the source program arguments
-      subCommandArgs.insert(subCommandArgs.end(),
-                            originalArgv.begin() + 1, originalArgv.end());
+      if (isRepl) {
+        subCommandArgs.push_back("-repl");
+        subCommandArgs.insert(subCommandArgs.end(),
+                              originalArgv.begin() + 2, originalArgv.end());
+      } else {
+        subCommandArgs.insert(subCommandArgs.end(),
+                              originalArgv.begin() + 1, originalArgv.end());
+      }
 
       // Execute the subcommand.
       subCommandArgs.push_back(nullptr);
@@ -361,8 +373,7 @@ int swift::mainEntry(int argc_, const char **argv_) {
   // Check if this invocation should execute a subcommand.
   StringRef ExecName = llvm::sys::path::stem(argv[0]);
   SmallString<256> SubcommandName;
-  bool isRepl = false;
-  if (shouldRunAsSubcommand(ExecName, SubcommandName, argv, isRepl)) {
+  if (shouldRunAsSubcommand(ExecName, SubcommandName, argv)) {
     // Preserve argv for the stack trace.
     SmallVector<const char *, 256> subCommandArgs(argv.begin(), argv.end());
     subCommandArgs.erase(&subCommandArgs[1]);
@@ -396,12 +407,5 @@ int swift::mainEntry(int argc_, const char **argv_) {
   }
 
   ArrayRef<const char *> originalArgv(argv_, &argv_[argc_]);
-  if (isRepl) {
-    // Preserve argv for the stack trace.
-    SmallVector<const char *, 256> replArgs(argv.begin(), argv.end());
-    replArgs.erase(&replArgs[1]);
-    return run_driver(ExecName, replArgs, originalArgv);
-  } else {
-    return run_driver(ExecName, argv, originalArgv);
-  }
+  return run_driver(ExecName, argv, originalArgv);
 }