[Darwin][Driver][clang] apple-none-macho orders the resource directory after internal-externc-isystem when nostdlibinc is used

Embedded development often needs to use a different C standard library, replacing the existing one normally passed as -internal-externc-isystem. This works fine for an apple-macos target, but apple-none-macho doesn't work because the MachO driver doesn't implement AddClangSystemIncludeArgs to add the resource directory as -internal-isystem like most other drivers do. Move most of the search path logic from Darwin and DarwinClang down into an AppleMachO toolchain between the MachO and Darwin toolchains.

Also define __MACH__ for apple-none-macho, as Swift expects all MachO targets to have that defined.

Author: ian-twilightcoder

clang/lib/Basic/Targets/OSTargets.cpp

@@ -114,9 +114,6 @@ void getDarwinDefines(MacroBuilder &Builder, const LangOptions &Opts,
     assert(OsVersion.getMinor().value_or(0) < 100 &&
            OsVersion.getSubminor().value_or(0) < 100 && "Invalid version!");
     Builder.defineMacro("__ENVIRONMENT_OS_VERSION_MIN_REQUIRED__", Str);
-
-    // Tell users about the kernel if there is one.
-    Builder.defineMacro("__MACH__");
   }
 
   PlatformMinVersion = OsVersion;

clang/lib/Driver/Driver.cpp

@@ -6603,6 +6603,8 @@ const ToolChain &Driver::getToolChain(const ArgList &Args,
           TC = std::make_unique<toolchains::BareMetal>(*this, Target, Args);
         else if (Target.isOSBinFormatELF())
           TC = std::make_unique<toolchains::Generic_ELF>(*this, Target, Args);
+        else if (Target.isAppleMachO())
+          TC = std::make_unique<toolchains::AppleMachO>(*this, Target, Args);
         else if (Target.isOSBinFormatMachO())
           TC = std::make_unique<toolchains::MachO>(*this, Target, Args);
         else

clang/lib/Driver/ToolChains/Darwin.cpp

@@ -966,10 +966,14 @@ MachO::MachO(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   getProgramPaths().push_back(getDriver().Dir);
 }
 
+AppleMachO::AppleMachO(const Driver &D, const llvm::Triple &Triple,
+                       const ArgList &Args)
+    : MachO(D, Triple, Args), CudaInstallation(D, Triple, Args),
+      RocmInstallation(D, Triple, Args) {}
+
 /// Darwin - Darwin tool chain for i386 and x86_64.
 Darwin::Darwin(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
-    : MachO(D, Triple, Args), TargetInitialized(false),
-      CudaInstallation(D, Triple, Args), RocmInstallation(D, Triple, Args) {}
+    : AppleMachO(D, Triple, Args), TargetInitialized(false) {}
 
 types::ID MachO::LookupTypeForExtension(StringRef Ext) const {
   types::ID Ty = ToolChain::LookupTypeForExtension(Ext);
@@ -1018,13 +1022,13 @@ bool Darwin::hasBlocksRuntime() const {
   }
 }
 
-void Darwin::AddCudaIncludeArgs(const ArgList &DriverArgs,
-                                ArgStringList &CC1Args) const {
+void AppleMachO::AddCudaIncludeArgs(const ArgList &DriverArgs,
+                                    ArgStringList &CC1Args) const {
   CudaInstallation->AddCudaIncludeArgs(DriverArgs, CC1Args);
 }
 
-void Darwin::AddHIPIncludeArgs(const ArgList &DriverArgs,
-                               ArgStringList &CC1Args) const {
+void AppleMachO::AddHIPIncludeArgs(const ArgList &DriverArgs,
+                                   ArgStringList &CC1Args) const {
   RocmInstallation->AddHIPIncludeArgs(DriverArgs, CC1Args);
 }
 
@@ -1119,6 +1123,8 @@ VersionTuple MachO::getLinkerVersion(const llvm::opt::ArgList &Args) const {
 
 Darwin::~Darwin() {}
 
+AppleMachO::~AppleMachO() {}
+
 MachO::~MachO() {}
 
 std::string Darwin::ComputeEffectiveClangTriple(const ArgList &Args,
@@ -2482,7 +2488,7 @@ static void AppendPlatformPrefix(SmallString<128> &Path,
 // Returns the effective sysroot from either -isysroot or --sysroot, plus the
 // platform prefix (if any).
 llvm::SmallString<128>
-DarwinClang::GetEffectiveSysroot(const llvm::opt::ArgList &DriverArgs) const {
+AppleMachO::GetEffectiveSysroot(const llvm::opt::ArgList &DriverArgs) const {
   llvm::SmallString<128> Path("/");
   if (DriverArgs.hasArg(options::OPT_isysroot))
     Path = DriverArgs.getLastArgValue(options::OPT_isysroot);
@@ -2495,8 +2501,9 @@ DarwinClang::GetEffectiveSysroot(const llvm::opt::ArgList &DriverArgs) const {
   return Path;
 }
 
-void DarwinClang::AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
-                                            llvm::opt::ArgStringList &CC1Args) const {
+void AppleMachO::AddClangSystemIncludeArgs(
+    const llvm::opt::ArgList &DriverArgs,
+    llvm::opt::ArgStringList &CC1Args) const {
   const Driver &D = getDriver();
 
   llvm::SmallString<128> Sysroot = GetEffectiveSysroot(DriverArgs);
@@ -2574,7 +2581,7 @@ bool DarwinClang::AddGnuCPlusPlusIncludePaths(const llvm::opt::ArgList &DriverAr
   return getVFS().exists(Base);
 }
 
-void DarwinClang::AddClangCXXStdlibIncludeArgs(
+void AppleMachO::AddClangCXXStdlibIncludeArgs(
     const llvm::opt::ArgList &DriverArgs,
     llvm::opt::ArgStringList &CC1Args) const {
   // The implementation from a base class will pass through the -stdlib to
@@ -2631,55 +2638,60 @@ void DarwinClang::AddClangCXXStdlibIncludeArgs(
   }
 
   case ToolChain::CST_Libstdcxx:
-    llvm::SmallString<128> UsrIncludeCxx = Sysroot;
-    llvm::sys::path::append(UsrIncludeCxx, "usr", "include", "c++");
-
-    llvm::Triple::ArchType arch = getTriple().getArch();
-    bool IsBaseFound = true;
-    switch (arch) {
-    default: break;
-
-    case llvm::Triple::x86:
-    case llvm::Triple::x86_64:
-      IsBaseFound = AddGnuCPlusPlusIncludePaths(DriverArgs, CC1Args, UsrIncludeCxx,
-                                                "4.2.1",
-                                                "i686-apple-darwin10",
-                                                arch == llvm::Triple::x86_64 ? "x86_64" : "");
-      IsBaseFound |= AddGnuCPlusPlusIncludePaths(DriverArgs, CC1Args, UsrIncludeCxx,
-                                                "4.0.0", "i686-apple-darwin8",
-                                                 "");
-      break;
+    AddGnuCPlusPlusIncludePaths(DriverArgs, CC1Args);
+    break;
+  }
+}
 
-    case llvm::Triple::arm:
-    case llvm::Triple::thumb:
-      IsBaseFound = AddGnuCPlusPlusIncludePaths(DriverArgs, CC1Args, UsrIncludeCxx,
-                                                "4.2.1",
-                                                "arm-apple-darwin10",
-                                                "v7");
-      IsBaseFound |= AddGnuCPlusPlusIncludePaths(DriverArgs, CC1Args, UsrIncludeCxx,
-                                                "4.2.1",
-                                                "arm-apple-darwin10",
-                                                 "v6");
-      break;
+void AppleMachO::AddGnuCPlusPlusIncludePaths(
+    const llvm::opt::ArgList &DriverArgs,
+    llvm::opt::ArgStringList &CC1Args) const {}
 
-    case llvm::Triple::aarch64:
-      IsBaseFound = AddGnuCPlusPlusIncludePaths(DriverArgs, CC1Args, UsrIncludeCxx,
-                                                "4.2.1",
-                                                "arm64-apple-darwin10",
-                                                "");
-      break;
-    }
+void DarwinClang::AddGnuCPlusPlusIncludePaths(
+    const llvm::opt::ArgList &DriverArgs,
+    llvm::opt::ArgStringList &CC1Args) const {
+  llvm::SmallString<128> UsrIncludeCxx = GetEffectiveSysroot(DriverArgs);
+  llvm::sys::path::append(UsrIncludeCxx, "usr", "include", "c++");
 
-    if (!IsBaseFound) {
-      getDriver().Diag(diag::warn_drv_libstdcxx_not_found);
-    }
+  llvm::Triple::ArchType arch = getTriple().getArch();
+  bool IsBaseFound = true;
+  switch (arch) {
+  default:
+    break;
 
+  case llvm::Triple::x86:
+  case llvm::Triple::x86_64:
+    IsBaseFound = AddGnuCPlusPlusIncludePaths(
+        DriverArgs, CC1Args, UsrIncludeCxx, "4.2.1", "i686-apple-darwin10",
+        arch == llvm::Triple::x86_64 ? "x86_64" : "");
+    IsBaseFound |= AddGnuCPlusPlusIncludePaths(
+        DriverArgs, CC1Args, UsrIncludeCxx, "4.0.0", "i686-apple-darwin8", "");
+    break;
+
+  case llvm::Triple::arm:
+  case llvm::Triple::thumb:
+    IsBaseFound =
+        AddGnuCPlusPlusIncludePaths(DriverArgs, CC1Args, UsrIncludeCxx, "4.2.1",
+                                    "arm-apple-darwin10", "v7");
+    IsBaseFound |=
+        AddGnuCPlusPlusIncludePaths(DriverArgs, CC1Args, UsrIncludeCxx, "4.2.1",
+                                    "arm-apple-darwin10", "v6");
+    break;
+
+  case llvm::Triple::aarch64:
+    IsBaseFound =
+        AddGnuCPlusPlusIncludePaths(DriverArgs, CC1Args, UsrIncludeCxx, "4.2.1",
+                                    "arm64-apple-darwin10", "");
     break;
   }
+
+  if (!IsBaseFound) {
+    getDriver().Diag(diag::warn_drv_libstdcxx_not_found);
+  }
 }
 
-void DarwinClang::AddCXXStdlibLibArgs(const ArgList &Args,
-                                      ArgStringList &CmdArgs) const {
+void AppleMachO::AddCXXStdlibLibArgs(const ArgList &Args,
+                                     ArgStringList &CmdArgs) const {
   CXXStdlibType Type = GetCXXStdlibType(Args);
 
   switch (Type) {
@@ -3615,7 +3627,7 @@ SanitizerMask Darwin::getSupportedSanitizers() const {
   return Res;
 }
 
-void Darwin::printVerboseInfo(raw_ostream &OS) const {
+void AppleMachO::printVerboseInfo(raw_ostream &OS) const {
   CudaInstallation->print(OS);
   RocmInstallation->print(OS);
 }

clang/lib/Driver/ToolChains/Darwin.h

@@ -290,8 +290,49 @@ class LLVM_LIBRARY_VISIBILITY MachO : public ToolChain {
   /// }
 };
 
+/// Apple specific MachO extensions
+class LLVM_LIBRARY_VISIBILITY AppleMachO : public MachO {
+public:
+  AppleMachO(const Driver &D, const llvm::Triple &Triple,
+             const llvm::opt::ArgList &Args);
+  ~AppleMachO() override;
+
+  /// }
+  /// @name Apple Specific ToolChain Implementation
+  /// {
+  void
+  AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                            llvm::opt::ArgStringList &CC1Args) const override;
+
+  void AddCudaIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                          llvm::opt::ArgStringList &CC1Args) const override;
+  void AddHIPIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                         llvm::opt::ArgStringList &CC1Args) const override;
+
+  void AddClangCXXStdlibIncludeArgs(
+      const llvm::opt::ArgList &DriverArgs,
+      llvm::opt::ArgStringList &CC1Args) const override;
+  void AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
+                           llvm::opt::ArgStringList &CmdArgs) const override;
+
+  void printVerboseInfo(raw_ostream &OS) const override;
+  /// }
+
+  LazyDetector<CudaInstallationDetector> CudaInstallation;
+  LazyDetector<RocmInstallationDetector> RocmInstallation;
+
+protected:
+  llvm::SmallString<128>
+  GetEffectiveSysroot(const llvm::opt::ArgList &DriverArgs) const;
+
+private:
+  virtual void
+  AddGnuCPlusPlusIncludePaths(const llvm::opt::ArgList &DriverArgs,
+                              llvm::opt::ArgStringList &CC1Args) const;
+};
+
 /// Darwin - The base Darwin tool chain.
-class LLVM_LIBRARY_VISIBILITY Darwin : public MachO {
+class LLVM_LIBRARY_VISIBILITY Darwin : public AppleMachO {
 public:
   /// Whether the information on the target has been initialized.
   //
@@ -329,9 +370,6 @@ class LLVM_LIBRARY_VISIBILITY Darwin : public MachO {
   /// The target variant triple that was specified (if any).
   mutable std::optional<llvm::Triple> TargetVariantTriple;
 
-  LazyDetector<CudaInstallationDetector> CudaInstallation;
-  LazyDetector<RocmInstallationDetector> RocmInstallation;
-
 private:
   void AddDeploymentTarget(llvm::opt::DerivedArgList &Args) const;
 
@@ -343,7 +381,7 @@ class LLVM_LIBRARY_VISIBILITY Darwin : public MachO {
   std::string ComputeEffectiveClangTriple(const llvm::opt::ArgList &Args,
                                           types::ID InputType) const override;
 
-  /// @name Apple Specific Toolchain Implementation
+  /// @name Darwin Specific Toolchain Implementation
   /// {
 
   void addMinVersionArgs(const llvm::opt::ArgList &Args,
@@ -559,11 +597,6 @@ class LLVM_LIBRARY_VISIBILITY Darwin : public MachO {
   ObjCRuntime getDefaultObjCRuntime(bool isNonFragile) const override;
   bool hasBlocksRuntime() const override;
 
-  void AddCudaIncludeArgs(const llvm::opt::ArgList &DriverArgs,
-                          llvm::opt::ArgStringList &CC1Args) const override;
-  void AddHIPIncludeArgs(const llvm::opt::ArgList &DriverArgs,
-                         llvm::opt::ArgStringList &CC1Args) const override;
-
   bool UseObjCMixedDispatch() const override {
     // This is only used with the non-fragile ABI and non-legacy dispatch.
 
@@ -594,8 +627,6 @@ class LLVM_LIBRARY_VISIBILITY Darwin : public MachO {
   bool SupportsEmbeddedBitcode() const override;
 
   SanitizerMask getSupportedSanitizers() const override;
-
-  void printVerboseInfo(raw_ostream &OS) const override;
 };
 
 /// DarwinClang - The Darwin toolchain used by Clang.
@@ -613,16 +644,6 @@ class LLVM_LIBRARY_VISIBILITY DarwinClang : public Darwin {
                              llvm::opt::ArgStringList &CmdArgs,
                              bool ForceLinkBuiltinRT = false) const override;
 
-  void AddClangCXXStdlibIncludeArgs(
-      const llvm::opt::ArgList &DriverArgs,
-      llvm::opt::ArgStringList &CC1Args) const override;
-
-  void AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
-                                 llvm::opt::ArgStringList &CC1Args) const override;
-
-  void AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
-                           llvm::opt::ArgStringList &CmdArgs) const override;
-
   void AddCCKextLibArgs(const llvm::opt::ArgList &Args,
                         llvm::opt::ArgStringList &CmdArgs) const override;
 
@@ -647,15 +668,16 @@ class LLVM_LIBRARY_VISIBILITY DarwinClang : public Darwin {
                                StringRef Sanitizer,
                                bool shared = true) const;
 
+  void
+  AddGnuCPlusPlusIncludePaths(const llvm::opt::ArgList &DriverArgs,
+                              llvm::opt::ArgStringList &CC1Args) const override;
+
   bool AddGnuCPlusPlusIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                    llvm::opt::ArgStringList &CC1Args,
                                    llvm::SmallString<128> Base,
                                    llvm::StringRef Version,
                                    llvm::StringRef ArchDir,
                                    llvm::StringRef BitDir) const;
-
-  llvm::SmallString<128>
-  GetEffectiveSysroot(const llvm::opt::ArgList &DriverArgs) const;
 };
 
 } // end namespace toolchains

clang/lib/Frontend/InitPreprocessor.cpp

@@ -1507,6 +1507,11 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   // ELF targets define __ELF__
   if (TI.getTriple().isOSBinFormatELF())
     Builder.defineMacro("__ELF__");
+  else if (TI.getTriple().isAppleMachO())
+    // Apple MachO targets define __MACH__ even when not using DarwinTargetInfo.
+    // Hurd will also define this in some circumstances, but that's done in
+    // HurdTargetInfo. Windows targets don't define this.
+    Builder.defineMacro("__MACH__");
 
   // Target OS macro definitions.
   if (PPOpts.DefineTargetOSMacros) {

clang/lib/Lex/InitHeaderSearch.cpp

@@ -313,7 +313,7 @@ bool InitHeaderSearch::ShouldAddDefaultIncludePaths(
     break;
 
   case llvm::Triple::UnknownOS:
-    if (triple.isWasm())
+    if (triple.isWasm() || triple.isAppleMachO())
       return false;
     break;
 

clang/test/Driver/Inputs/MacOSX15.1.sdk/embedded/usr/include/.keep

@@ -0,0 +1,43 @@
+// UNSUPPORTED: system-windows
+//   Windows is unsupported because we use the Unix path separator `/` in the test.
+
+// Unlike the Darwin driver, the MachO driver doesn't add any framework search paths,
+// only the normal header ones.
+// RUN: %clang -x c -target arm64-apple-none-macho -isysroot %S/Inputs/MacOSX15.1.sdk -### -c %s 2>&1 \
+// RUN: | FileCheck --check-prefixes=CC1,NO-CXX,ULI,CI,UI,NO-FW -DSDKROOT=%S/Inputs/MacOSX15.1.sdk %s
+
+// Unlike the Darwin driver, the MachO driver doesn't default to libc++
+// RUN: %clang -x c++ -target arm64-apple-none-macho -isysroot %S/Inputs/MacOSX15.1.sdk -### -c %s 2>&1 \
+// RUN: | FileCheck --check-prefixes=CC1,NO-CXX,ULI,CI,UI,NO-FW -DSDKROOT=%S/Inputs/MacOSX15.1.sdk %s
+
+// However, if the user requests libc++, the MachO driver should find the search path.
+// RUN: %clang -x c++ -stdlib=libc++ -target arm64-apple-none-macho -isysroot %S/Inputs/MacOSX15.1.sdk -### -c %s 2>&1 \
+// RUN: | FileCheck --check-prefixes=CC1,CXX,ULI,CI,UI,NO-FW -DSDKROOT=%S/Inputs/MacOSX15.1.sdk %s
+
+// Verify that embedded uses can swap in alternate usr/include and usr/local/include directories.
+// usr/local/include is specified in the driver as -internal-isystem, however, the driver generated
+// paths come before the paths in the driver arguments. In order to keep usr/local/include in the
+// same position, -isystem has to be used instead of -Xclang -internal-isystem. There isn't an
+// -externc-isystem, but it's ok to use -Xclang -internal-externc-isystem since the driver doesn't
+// use that if -nostdlibinc or -nostdinc is passed.
+// RUN: %clang -x c++ -stdlib=libc++ -target arm64-apple-none-macho -isysroot %S/Inputs/MacOSX15.1.sdk \
+// RUN:        -nostdlibinc -isystem %S/Inputs/MacOSX15.1.sdk/embedded/usr/local/include \
+// RUN:        -Xclang -internal-externc-isystem -Xclang %S/Inputs/MacOSX15.1.sdk/embedded/usr/include \
+// RUN:        -### -c %s 2>&1 | FileCheck --check-prefixes=CC1,NO-CXX,EULI,CI,EUI,NO-FW -DSDKROOT=%S/Inputs/MacOSX15.1.sdk %s
+
+
+// The ordering of these flags doesn't matter, and so this test is a little
+// fragile. i.e. all of the -internal-isystem paths will be searched before the
+// -internal-externc-isystem ones, and their order on the command line doesn't
+// matter. The line order here is just the current order that the driver writes
+// the cc1 arguments.
+
+// CC1: "-cc1"
+// NO-CXX-NOT: "-internal-isystem" "[[SDKROOT]]/usr/include/c++/v1"
+// CXX-SAME: "-internal-isystem" "[[SDKROOT]]/usr/include/c++/v1"
+// ULI-SAME: "-internal-isystem" "[[SDKROOT]]/usr/local/include"
+// EULI-SAME: "-isystem" "[[SDKROOT]]/embedded/usr/local/include"
+// CI-SAME: "-internal-isystem" "{{.*}}/clang/{{[[:digit:].]*}}/include"
+// UI-SAME: "-internal-externc-isystem" "[[SDKROOT]]/usr/include"
+// EUI-SAME: "-internal-externc-isystem" "[[SDKROOT]]/embedded/usr/include"
+// NO-FW-NOT: "-internal-iframework"