[Frontend] Add some paths to the output of -print-target-info.

Add various target-specific and compiler-determined paths to the output
of `-print-target-info`, such as the runtime resource path, SDK path, and
runtime library paths.

Author: DougGregor

lib/Driver/Driver.cpp

@@ -2126,9 +2126,18 @@ bool Driver::handleImmediateArgs(const ArgList &Args, const ToolChain &TC) {
     SmallVector<const char *, 5> commandLine;
     commandLine.push_back("-frontend");
     commandLine.push_back("-print-target-info");
-    if (const Arg *TargetArg = Args.getLastArg(options::OPT_target)) {
+    if (const Arg *targetArg = Args.getLastArg(options::OPT_target)) {
       commandLine.push_back("-target");
-      commandLine.push_back(TargetArg->getValue());
+      commandLine.push_back(targetArg->getValue());
+    }
+    if (const Arg *sdkArg = Args.getLastArg(options::OPT_sdk)) {
+      commandLine.push_back("-sdk");
+      commandLine.push_back(sdkArg->getValue());
+    }
+
+    if (const Arg *resourceDirArg = Args.getLastArg(options::OPT_resource_dir)) {
+      commandLine.push_back("-resource-dir");
+      commandLine.push_back(resourceDirArg->getValue());
     }
 
     std::string executable = getSwiftProgramPath();

lib/FrontendTool/FrontendTool.cpp

@@ -1892,6 +1892,38 @@ static void printTargetInfo(CompilerInvocation &invocation,
       << (tripleRequiresRPathForSwiftInOS(langOpts.Target) ? "true" : "false")
       << "\n";
 
+  out << "  },\n";
+
+  // Various paths.
+  auto &searchOpts = invocation.getSearchPathOptions();
+  out << "  \"paths\": {\n";
+
+  if (!searchOpts.SDKPath.empty()) {
+    out << "    \"sdkPath\": \"";
+    out.write_escaped(searchOpts.SDKPath);
+    out << "\",\n";
+  }
+
+  auto outputPaths = [&](StringRef name, const std::vector<std::string> &paths){
+    out << "    \"" << name << "\": [\n";
+    interleave(paths, [&out](const std::string &path) {
+      out << "      \"";
+      out.write_escaped(path);
+      out << "\"";
+    }, [&out] {
+      out << ",\n";
+    });
+    out << "\n    ],\n";
+  };
+
+  outputPaths("runtimeLibraryPaths", searchOpts.RuntimeLibraryPaths);
+  outputPaths("runtimeLibraryImportPaths",
+              searchOpts.RuntimeLibraryImportPaths);
+
+  out << "    \"runtimeResourcePath\": \"";
+  out.write_escaped(searchOpts.RuntimeResourcePath);
+  out << "\"\n";
+
   out << "  }\n";
 
   out << "}\n";

test/Driver/print_target_info.swift

@@ -11,6 +11,12 @@
 // CHECK-IOS:     "librariesRequireRPath": true
 // CHECK-IOS:   }
 
+// CHECK-IOS:   "paths": {
+// CHECK-IOS:     "runtimeLibraryPaths": [
+// CHECK-IOS:     "runtimeResourcePath":{{.*}}lib{{(/|\\)}}swift"
+// CHECK-IOS:   }
+
+
 // CHECK-LINUX:   "target": {
 // CHECK-LINUX:     "triple": "x86_64-unknown-linux",
 // CHECK-LINUX:     "moduleTriple": "x86_64-unknown-linux",