swiftlang · DougGregor · Dec 7, 2019 · Dec 6, 2019 · Dec 7, 2019
diff --git a/include/swift/Frontend/FrontendOptions.h b/include/swift/Frontend/FrontendOptions.h
@@ -247,6 +247,10 @@ class FrontendOptions {
   /// Indicates whether full help (including "hidden" options) should be shown.
   bool PrintHelpHidden = false;
 
+  /// Indicates that the frontend should print the target triple and then
+  /// exit.
+  bool PrintTargetInfo = false;
+
   /// Should we sort SIL functions, vtables, witness tables, and global
   /// variables by name when we print it out. This eases diffing of SIL files.
   bool EmitSortedSIL = false;

diff --git a/include/swift/Option/Options.td b/include/swift/Option/Options.td
@@ -884,6 +884,9 @@ def target : Separate<["-"], "target">,
   HelpText<"Generate code for the given target <triple>, such as x86_64-apple-macos10.9">, MetaVarName<"<triple>">;
 def target_legacy_spelling : Joined<["--"], "target=">,
   Flags<[FrontendOption]>, Alias<target>;
+def print_target_info : Flag<["-"], "print-target-info">,
+    Flags<[FrontendOption]>,
+    HelpText<"Print target information for the given target <triple>, such as x86_64-apple-macos10.9">, MetaVarName<"<triple>">;
 
 def target_cpu : Separate<["-"], "target-cpu">, Flags<[FrontendOption, ModuleInterfaceOption]>,
   HelpText<"Generate code for a particular CPU variant">;

diff --git a/lib/Driver/Driver.cpp b/lib/Driver/Driver.cpp
@@ -2122,6 +2122,31 @@ bool Driver::handleImmediateArgs(const ArgList &Args, const ToolChain &TC) {
                                 std::end(commandArgs));
   }
 
+  if (Args.hasArg(options::OPT_print_target_info)) {
+    SmallVector<const char *, 5> commandLine;
+    commandLine.push_back("-frontend");
+    commandLine.push_back("-print-target-info");
+    if (const Arg *TargetArg = Args.getLastArg(options::OPT_target)) {
+      commandLine.push_back("-target");
+      commandLine.push_back(TargetArg->getValue());
+    }
+
+    std::string executable = getSwiftProgramPath();
+
+    sys::TaskQueue queue;
+    queue.addTask(executable.c_str(), commandLine);
+    queue.execute(nullptr,
+                  [](sys::ProcessId PID, int returnCode,
+                      StringRef output, StringRef errors,
+                      sys::TaskProcessInformation ProcInfo,
+                      void *unused) -> sys::TaskFinishedResponse {
+      llvm::outs() << output;
+      llvm::errs() << errors;
+      return sys::TaskFinishedResponse::ContinueExecution;
+    });
+    return false;
+  }
+
   return true;
 }
 

diff --git a/lib/Frontend/ArgsToFrontendOptionsConverter.cpp b/lib/Frontend/ArgsToFrontendOptionsConverter.cpp
@@ -104,6 +104,10 @@ bool ArgsToFrontendOptionsConverter::convert(
   Opts.IgnoreSwiftSourceInfo |= Args.hasArg(OPT_ignore_module_source_info);
   computeHelpOptions();
 
+  if (Args.hasArg(OPT_print_target_info)) {
+    Opts.PrintTargetInfo = true;
+  }
+
   if (const Arg *A = Args.getLastArg(OPT_verify_generic_signatures)) {
     Opts.VerifyGenericSignaturesInModule = A->getValue();
   }

diff --git a/lib/FrontendTool/FrontendTool.cpp b/lib/FrontendTool/FrontendTool.cpp
@@ -42,6 +42,7 @@
 #include "swift/Basic/JSONSerialization.h"
 #include "swift/Basic/LLVMContext.h"
 #include "swift/Basic/LLVMInitialize.h"
+#include "swift/Basic/Platform.h"
 #include "swift/Basic/PrettyStackTrace.h"
 #include "swift/Basic/SourceManager.h"
 #include "swift/Basic/Statistic.h"
@@ -1863,6 +1864,38 @@ createJSONFixItDiagnosticConsumerIfNeeded(
   });
 }
 
+/// Print information about the selected target in JSON.
+static void printTargetInfo(CompilerInvocation &invocation,
+                            llvm::raw_ostream &out) {
+  out << "{\n";
+
+  // Target information.
+  auto &langOpts = invocation.getLangOptions();
+  out << "  \"target\": {\n";
+
+  out << "    \"triple\": \"";
+  out.write_escaped(langOpts.Target.getTriple());
+  out << "\",\n";
+
+  out << "    \"moduleTriple\": \"";
+  out.write_escaped(getTargetSpecificModuleTriple(langOpts.Target).getTriple());
+  out << "\",\n";
+
+  if (auto runtimeVersion = getSwiftRuntimeCompatibilityVersionForTarget(
+          langOpts.Target)) {
+    out << "    \"swiftRuntimeCompatibilityVersion\": \"";
+    out.write_escaped(runtimeVersion->getAsString());
+    out << "\",\n";
+  }
+
+  out << "    \"librariesRequireRPath\": "
+      << (tripleRequiresRPathForSwiftInOS(langOpts.Target) ? "true" : "false")
+      << "\n";
+
+  out << "  }\n";
+
+  out << "}\n";
+}
 
 int swift::performFrontend(ArrayRef<const char *> Args,
                            const char *Argv0, void *MainAddr,
@@ -1987,6 +2020,11 @@ int swift::performFrontend(ArrayRef<const char *> Args,
     return finishDiagProcessing(0);
   }
 
+  if (Invocation.getFrontendOptions().PrintTargetInfo) {
+    printTargetInfo(Invocation, llvm::outs());
+    return finishDiagProcessing(0);
+  }
+
   if (Invocation.getFrontendOptions().RequestedAction ==
       FrontendOptions::ActionType::NoneAction) {
     Instance->getDiags().diagnose(SourceLoc(),

diff --git a/test/Driver/print_target_info.swift b/test/Driver/print_target_info.swift
@@ -0,0 +1,18 @@
+// RUN: %swift_driver -print-target-info -target arm64-apple-ios12.0 | %FileCheck -check-prefix CHECK-IOS %s
+// RUN: %target-swift-frontend -print-target-info -target arm64-apple-ios12.0 | %FileCheck -check-prefix CHECK-IOS %s
+
+// RUN: %swift_driver -print-target-info -target x86_64-unknown-linux | %FileCheck -check-prefix CHECK-LINUX %s
+// RUN: %target-swift-frontend -print-target-info -target x86_64-unknown-linux | %FileCheck -check-prefix CHECK-LINUX %s
+
+// CHECK-IOS:   "target": {
+// CHECK-IOS:     "triple": "arm64-apple-ios12.0",
+// CHECK-IOS:     "moduleTriple": "arm64-apple-ios",
+// CHECK-IOS:     "swiftRuntimeCompatibilityVersion": "5.0",
+// CHECK-IOS:     "librariesRequireRPath": true
+// CHECK-IOS:   }
+
+// CHECK-LINUX:   "target": {
+// CHECK-LINUX:     "triple": "x86_64-unknown-linux",
+// CHECK-LINUX:     "moduleTriple": "x86_64-unknown-linux",
+// CHECK-LINUX:     "librariesRequireRPath": false
+// CHECK-LINUX:   }
diff --git a/test/Driver/print_target_info_macos.swift b/test/Driver/print_target_info_macos.swift
@@ -0,0 +1,10 @@
+// Test that -print-target-info infers the host OS when that host OS is macOS
+//
+// We could duplicate this test for other host platforms.
+
+// RUN: %swift_driver -print-target-info  | %FileCheck %s
+// RUN: %target-swift-frontend -print-target-info | %FileCheck %s
+
+// REQUIRES: OS=macosx
+
+// CHECK: "triple": "x86_64-apple-macosx