Add symlinks for the legacy driver invocation (for emergency fallback invoked from 'swift-driver')

Author: artemcm

lib/Driver/Driver.cpp

@@ -99,6 +99,8 @@ void Driver::parseDriverKind(ArrayRef<const char *> Args) {
       llvm::StringSwitch<llvm::Optional<DriverKind>>(DriverName)
           .Case("swift", DriverKind::Interactive)
           .Case("swiftc", DriverKind::Batch)
+          .Case("swift-legacy-driver", DriverKind::Interactive)
+          .Case("swiftc-legacy-driver", DriverKind::Batch)
           .Case("sil-opt", DriverKind::SILOpt)
           .Case("sil-func-extractor", DriverKind::SILFuncExtractor)
           .Case("sil-nm", DriverKind::SILNM)

lib/DriverTool/driver.cpp

@@ -167,8 +167,15 @@ static bool shouldRunAsSubcommand(StringRef ExecName,
 static bool shouldDisallowNewDriver(DiagnosticEngine &diags,
                                     StringRef ExecName,
                                     const ArrayRef<const char *> argv) {
+  // We are expected to use the legacy driver to `exec` an overload
+  // for testing purposes.
+  if (llvm::sys::Process::GetEnv("SWIFT_OVERLOAD_DRIVER").has_value()) {
+    return false;
+  }
   // We are not invoking the driver, so don't forward.
-  if (ExecName != "swift" && ExecName != "swiftc") {
+  if (ExecName != "swift" && ExecName != "swiftc" &&
+      ExecName != "swift-legacy-driver" &&
+      ExecName != "swiftc-legacy-driver") {
     return true;
   }
   StringRef disableArg = "-disallow-use-new-driver";
@@ -193,7 +200,7 @@ static bool shouldDisallowNewDriver(DiagnosticEngine &diags,
 
 static bool appendSwiftDriverName(SmallString<256> &buffer) {
   assert(llvm::sys::fs::exists(buffer));
-  if (auto driverNameOp = llvm::sys::Process::GetEnv("SWIFT_USE_NEW_DRIVER")) {
+  if (auto driverNameOp = llvm::sys::Process::GetEnv("SWIFT_OVERLOAD_DRIVER")) {
     llvm::sys::path::append(buffer, *driverNameOp);
     return true;
   }

test/Driver/LegacyDriver/legacy-driver-propagates-response-file-to-new-driver.swift

@@ -6,7 +6,7 @@
 // REQUIRES: shell
 // RUN: %{python} -c 'for i in range(500001): print("-DTEST5_" + str(i))' > %t.resp
 // RUN: cp %S/Inputs/print-args.sh %swift-bin-dir/legacy-driver-propagates-response-file.sh
-// RUN: env SWIFT_USE_NEW_DRIVER=legacy-driver-propagates-response-file.sh %swiftc_driver_plain %s @%t.resp | %FileCheck %s
+// RUN: env SWIFT_OVERLOAD_DRIVER=legacy-driver-propagates-response-file.sh %swiftc_driver_plain -disallow-use-new-driver %s @%t.resp | %FileCheck %s
 // RUN: rm %swift-bin-dir/legacy-driver-propagates-response-file.sh
 
 // CHECK:      -Xfrontend

tools/driver/CMakeLists.txt

@@ -85,11 +85,20 @@ if(EXISTS "${SWIFT_RUNTIME_OUTPUT_INTDIR}/swift-driver${CMAKE_EXECUTABLE_SUFFIX}
     SOURCE "swift-driver${CMAKE_EXECUTABLE_SUFFIX}"
     DESTINATION "swift${CMAKE_EXECUTABLE_SUFFIX}"
     WORKING_DIRECTORY "${SWIFT_RUNTIME_OUTPUT_INTDIR}")
-
   swift_create_post_build_symlink(swift-frontend
     SOURCE "swift-driver${CMAKE_EXECUTABLE_SUFFIX}"
     DESTINATION "swiftc${CMAKE_EXECUTABLE_SUFFIX}"
     WORKING_DIRECTORY "${SWIFT_RUNTIME_OUTPUT_INTDIR}")
+
+  message(STATUS "Pointing 'swift-legacy-driver' and 'swiftc-legacy-driver' symlinks at 'swift-frontend'.")
+  swift_create_post_build_symlink(swift-frontend
+    SOURCE "swift-frontend${CMAKE_EXECUTABLE_SUFFIX}"
+    DESTINATION "swift-legacy-driver${CMAKE_EXECUTABLE_SUFFIX}"
+    WORKING_DIRECTORY "${SWIFT_RUNTIME_OUTPUT_INTDIR}")
+  swift_create_post_build_symlink(swift-frontend
+    SOURCE "swift-frontend${CMAKE_EXECUTABLE_SUFFIX}"
+    DESTINATION "swiftc-legacy-driver${CMAKE_EXECUTABLE_SUFFIX}"
+    WORKING_DIRECTORY "${SWIFT_RUNTIME_OUTPUT_INTDIR}")
 else()
   message(STATUS "Pointing 'swift' and 'swiftc' symlinks at 'swift-frontend' - no early SwiftDriver build found.")
   swift_create_post_build_symlink(swift-frontend
@@ -207,4 +216,10 @@ if(EXISTS "${SWIFT_RUNTIME_OUTPUT_INTDIR}/swift-driver${CMAKE_EXECUTABLE_SUFFIX}
   swift_install_in_component(PROGRAMS "${SWIFT_RUNTIME_OUTPUT_INTDIR}/swift-help${CMAKE_EXECUTABLE_SUFFIX}"
                              DESTINATION "bin"
                              COMPONENT compiler)
+  swift_install_in_component(FILES "${SWIFT_RUNTIME_OUTPUT_INTDIR}/swiftc-legacy-driver${CMAKE_EXECUTABLE_SUFFIX}"
+                             DESTINATION "bin"
+                             COMPONENT compiler)
+  swift_install_in_component(FILES "${SWIFT_RUNTIME_OUTPUT_INTDIR}/swift-legacy-driver${CMAKE_EXECUTABLE_SUFFIX}"
+                             DESTINATION "bin"
+                             COMPONENT compiler)
 endif()