Support LIBRARY_PATH on all Darwin targets.

r197490 changed the behavior of LIBRARY_PATH to try to match GCC's behavior
for cross compilers and make clang work better on "bare metal" targets.
Unfortunately that change is breaking a number of MacPorts projects because
the LIBRARY_PATH environment variable is being ignored when compiling on a
64-bit host for a 32-bit target. Because the host and target architectures
differ, isCrossCompiling returns true. This does not make sense for Darwin,
where multiple architectures are supported natively via "fat" Mach-O slices
and where development is generally done against SDKs regardless. This patch
fixes the problem by overriding isCrossCompiling to return false for Darwin
toolchains.

llvm-svn: 214208

clang/include/clang/Driver/ToolChain.h

@@ -116,9 +116,6 @@ public:
   StringRef getPlatform() const { return Triple.getVendorName(); }
   StringRef getOS() const { return Triple.getOSName(); }
 
-  /// \brief Returns true if the toolchain is targeting a non-native architecture.
-  bool isCrossCompiling() const;
-
   /// \brief Provide the default architecture name (as expected by -arch) for
   /// this toolchain. Note t
   StringRef getDefaultUniversalArchName() const;
@@ -171,6 +168,10 @@ public:
 
   // Platform defaults information
 
+  /// \brief Returns true if the toolchain is targeting a non-native
+  /// architecture.
+  virtual bool isCrossCompiling() const;
+
   /// HasNativeLTOLinker - Check whether the linker and related tools have
   /// native LLVM support.
   virtual bool HasNativeLLVMSupport() const;

clang/lib/Driver/ToolChains.h

@@ -427,6 +427,11 @@ public:
   /// @name ToolChain Implementation
   /// {
 
+  // Darwin tools support multiple architecture (e.g., i386 and x86_64) and
+  // most development is done against SDKs, so compiling for a different
+  // architecture should not get any special treatment.
+  bool isCrossCompiling() const override { return false; }
+
   llvm::opt::DerivedArgList *
   TranslateArgs(const llvm::opt::DerivedArgList &Args,
                 const char *BoundArch) const override;

clang/test/Driver/linker-opts.c

@@ -5,3 +5,7 @@
 // XFAIL: win32
 // REQUIRES: clang-driver
 // REQUIRES: native
+
+// Make sure that LIBRARY_PATH works for both i386 and x86_64 on Darwin.
+// RUN: env LIBRARY_PATH=%T/test1 %clang -target x86_64-apple-darwin %s -### 2>&1 | FileCheck %s
+// RUN: env LIBRARY_PATH=%T/test1 %clang -target i386-apple-darwin  %s -### 2>&1 | FileCheck %s