Added -toolchain option to swiftc

include/swift/Option/Options.td

@@ -133,6 +133,10 @@ def j : JoinedOrSeparate<["-"], "j">, Flags<[DoesNotAffectIncrementalBuild]>,
 def sdk : Separate<["-"], "sdk">, Flags<[FrontendOption]>,
   HelpText<"Compile against <sdk>">, MetaVarName<"<sdk>">;
 
+def tools_directory : Separate<["-"], "tools-directory">,
+  Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>,
+  HelpText<"Look for external executables (ld, clang, binutils) in <directory>">, MetaVarName<"<directory>">;
+
 def D : JoinedOrSeparate<["-"], "D">, Flags<[FrontendOption]>,
   HelpText<"Marks a conditional compilation flag as true">;
 

lib/Driver/ToolChains.cpp

@@ -951,7 +951,19 @@ toolchains::Darwin::constructInvocation(const LinkJobAction &job,
   const Driver &D = getDriver();
   const llvm::Triple &Triple = getTriple();
 
-  InvocationInfo II{"ld"};
+  // Configure the toolchain.
+  // By default, use the system `ld` to link.
+  const char *LD = "ld";
+  if (const Arg *A = context.Args.getLastArg(options::OPT_tools_directory)) {
+    StringRef toolchainPath(A->getValue());
+
+    // If there is a 'ld' in the toolchain folder, use that instead.
+    if (auto toolchainLD = llvm::sys::findProgramByName("ld", {toolchainPath})) {
+      LD = context.Args.MakeArgString(toolchainLD.get());
+    }
+  }
+
+  InvocationInfo II = {LD};
   ArgStringList &Arguments = II.Arguments;
 
   if (context.Args.hasArg(options::OPT_driver_use_filelists) ||
@@ -1269,14 +1281,14 @@ toolchains::GenericUnix::constructInvocation(const LinkJobAction &job,
   case LinkKind::None:
     llvm_unreachable("invalid link kind");
   case LinkKind::Executable:
-    // Default case, nothing extra needed
+    // Default case, nothing extra needed.
     break;
   case LinkKind::DynamicLibrary:
     Arguments.push_back("-shared");
     break;
   }
 
-  // Select the linker to use
+  // Select the linker to use.
   std::string Linker;
   if (const Arg *A = context.Args.getLastArg(options::OPT_use_ld)) {
     Linker = A->getValue();
@@ -1287,6 +1299,22 @@ toolchains::GenericUnix::constructInvocation(const LinkJobAction &job,
     Arguments.push_back(context.Args.MakeArgString("-fuse-ld=" + Linker));
   }
 
+  // Configure the toolchain.
+  // By default, use the system clang++ to link.
+  const char * Clang = "clang++";
+  if (const Arg *A = context.Args.getLastArg(options::OPT_tools_directory)) {
+    StringRef toolchainPath(A->getValue());
+
+    // If there is a clang in the toolchain folder, use that instead.
+    if (auto toolchainClang = llvm::sys::findProgramByName("clang++", {toolchainPath})) {
+      Clang = context.Args.MakeArgString(toolchainClang.get());
+    }
+
+    // Look for binutils in the toolchain folder.
+    Arguments.push_back("-B");
+    Arguments.push_back(context.Args.MakeArgString(A->getValue()));
+  }
+
   std::string Target = getTargetForLinker();
   if (!Target.empty()) {
     Arguments.push_back("-target");
@@ -1393,7 +1421,7 @@ toolchains::GenericUnix::constructInvocation(const LinkJobAction &job,
   Arguments.push_back("-o");
   Arguments.push_back(context.Output.getPrimaryOutputFilename().c_str());
 
-  return {"clang++", Arguments};
+  return {Clang, Arguments};
 }
 
 std::string

test/Driver/Inputs/fake-toolchain/clang++

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+# clang++ - Fake Clang to test finding clang++ in the toolchain path
+#
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+# Licensed under Apache License v2.0 with Runtime Library Exception
+#
+# See http://swift.org/LICENSE.txt for license information
+# See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+#
+# ----------------------------------------------------------------------------
+
+from __future__ import print_function
+
+print("Sorry, I'm lazy-clang")

test/Driver/Inputs/fake-toolchain/ld

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+# ld - Fake ld to test finding the Darwin linker in the toolchain path
+#
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+# Licensed under Apache License v2.0 with Runtime Library Exception
+#
+# See http://swift.org/LICENSE.txt for license information
+# See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+#
+# ----------------------------------------------------------------------------
+
+from __future__ import print_function
+
+print("Sorry, wrong number!")

test/Driver/tools_directory.swift

@@ -0,0 +1,36 @@
+//=================================================
+// ** GENERIC UNIX TARGETS - linking via clang++ **
+//=================================================
+
+// RUN: %swiftc_driver -### -target x86_64-linux-unknown -tools-directory %S/Inputs/fake-toolchain %s 2>&1 | %FileCheck -check-prefix CLANGSUB %s
+// RUN: %swiftc_driver -### -target x86_64-linux-unknown -tools-directory /Something/obviously/fake %s 2>&1 | %FileCheck -check-prefix BINUTILS %s
+
+// CLANGSUB: swift
+// CLANGSUB-SAME: -o [[OBJECTFILE:.*]]
+// CLANGSUB: swift-autolink-extract [[OBJECTFILE]]
+// CLANGSUB-SAME: -o [[AUTOLINKFILE:.*]]
+// CLANGSUB: {{[^ ]+}}/Inputs/fake-toolchain/clang++
+// CLANGSUB-DAG: [[OBJECTFILE]]
+// CLANGSUB-DAG: @[[AUTOLINKFILE]]
+// CLANGSUB: -o tools_directory
+
+// BINUTILS: swift
+// BINUTILS-SAME: -o [[OBJECTFILE:.*]]
+// BINUTILS: swift-autolink-extract [[OBJECTFILE]]
+// BINUTILS-SAME: -o [[AUTOLINKFILE:.*]]
+// BINUTILS: clang++
+// BINUTILS-DAG: [[OBJECTFILE]]
+// BINUTILS-DAG: @[[AUTOLINKFILE]]
+// BINUTILS-DAG: -B /Something/obviously/fake
+// BINUTILS: -o tools_directory
+
+//======================================
+// ** DARWIN TARGETS - linking via ld **
+//======================================
+
+// RUN: %swiftc_driver -### -target x86_64-apple-macosx10.9 -tools-directory %S/Inputs/fake-toolchain %s 2>&1 | %FileCheck -check-prefix LDSUB %s
+
+// LDSUB: swift
+// LDSUB-SAME: -o [[OBJECTFILE:.*]]
+// LDSUB: {{[^ ]+}}/Inputs/fake-toolchain/ld [[OBJECTFILE]]
+// LDSUB: -o tools_directory