[clang][ToolChains] explicitly return LangOptions::StackProtectorMode

[nickdesaulniers]

Summary

Make the virtual method Toolchain::GetDefaultStackProtectorLevel()
return an explict enum value rather than an integral constant. This
makes the code subjectively easier to read, and should help prevent bugs
that may (or may never) arise from changing the enum values. Previously,
these were just kept in sync via a comment, which is brittle. The trade
off is including a additional header in a few new places. It is not
necessary, but in my opinion helps the readability.

Split off from https://reviews.llvm.org/D90194 to help cut down on lines
changed in code review.

[phosek]

LGTM

[SolarAquarion]

You missed a change https://bugs.llvm.org/show_bug.cgi?id=48413

[nickdesaulniers]

In D90271#2436080, @SolarAquarion wrote:

You missed a change https://bugs.llvm.org/show_bug.cgi?id=48413

Discussed off thread; Arch Linux has patches on top of their distribution of LLVM.

clang/include/clang/Driver/ToolChain.h

public:
   /// UseObjCMixedDispatchDefault - When using non-legacy dispatch, should the
   /// mixed dispatch method be used?
   virtual bool UseObjCMixedDispatch() const { return false; }
 
   /// Check whether to enable x86 relax relocations by default.
   virtual bool useRelaxRelocations() const;
 
   /// GetDefaultStackProtectorLevel - Get the default stack protector level for
-  /// this tool chain (0=off, 1=on, 2=strong, 3=all).
-  virtual unsigned GetDefaultStackProtectorLevel(bool KernelOrKext) const {
-    return 0;
+  /// this tool chain.
+  virtual LangOptions::StackProtectorMode
+  GetDefaultStackProtectorLevel(bool KernelOrKext) const {
+    return LangOptions::SSPOff;
   }
 
   /// Get the default trivial automatic variable initialization.
   virtual LangOptions::TrivialAutoVarInitKind
   GetDefaultTrivialAutoVarInit() const {
     return LangOptions::TrivialAutoVarInitKind::Uninitialized;
   }
 

clang/lib/Driver/ToolChains/Clang.cpp

static void RenderSSPOptions(const Driver &D, const ToolChain &TC,
   const llvm::Triple &EffectiveTriple = TC.getEffectiveTriple();
 
   // NVPTX doesn't support stack protectors; from the compiler's perspective, it
   // doesn't even have a stack!
   if (EffectiveTriple.isNVPTX())
     return;
 
   // -stack-protector=0 is default.
-  unsigned StackProtectorLevel = 0;
-  unsigned DefaultStackProtectorLevel =
+  LangOptions::StackProtectorMode StackProtectorLevel = LangOptions::SSPOff;
+  LangOptions::StackProtectorMode DefaultStackProtectorLevel =
       TC.GetDefaultStackProtectorLevel(KernelOrKext);
 
   if (Arg *A = Args.getLastArg(options::OPT_fno_stack_protector,
                                options::OPT_fstack_protector_all,
                                options::OPT_fstack_protector_strong,
                                options::OPT_fstack_protector)) {
     if (A->getOption().matches(options::OPT_fstack_protector))
       StackProtectorLevel =
-          std::max<unsigned>(LangOptions::SSPOn, DefaultStackProtectorLevel);
+          std::max<>(LangOptions::SSPOn, DefaultStackProtectorLevel);
     else if (A->getOption().matches(options::OPT_fstack_protector_strong))
       StackProtectorLevel = LangOptions::SSPStrong;
     else if (A->getOption().matches(options::OPT_fstack_protector_all))
       StackProtectorLevel = LangOptions::SSPReq;
   } else {
     StackProtectorLevel = DefaultStackProtectorLevel;
   }
 

clang/lib/Driver/ToolChains/CrossWindows.h

 //===--- CrossWindows.h - CrossWindows ToolChain Implementation -*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_CROSSWINDOWS_H
 #define LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_CROSSWINDOWS_H
 
 #include "Cuda.h"
 #include "Gnu.h"
+#include "clang/Basic/LangOptions.h"
 #include "clang/Driver/Tool.h"
 #include "clang/Driver/ToolChain.h"
 
 namespace clang {
 namespace driver {
 namespace tools {
 
 namespace CrossWindows {
CrossWindowsToolChain(const Driver &D, const llvm::Triple &T,
                         const llvm::opt::ArgList &Args);
 
   bool IsIntegratedAssemblerDefault() const override { return true; }
   bool IsUnwindTablesDefault(const llvm::opt::ArgList &Args) const override;
   bool isPICDefault() const override;
   bool isPIEDefault() const override;
   bool isPICDefaultForced() const override;
 
-  unsigned int GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
-    return 0;
+  LangOptions::StackProtectorMode
+  GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
+    return LangOptions::SSPOff;
   }
 
   void
   AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &CC1Args) const override;
   void AddClangCXXStdlibIncludeArgs(
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;

clang/lib/Driver/ToolChains/Darwin.h

 //===--- Darwin.h - Darwin ToolChain Implementations ------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_DARWIN_H
 #define LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_DARWIN_H
 
 #include "Cuda.h"
 #include "ROCm.h"
+#include "clang/Basic/LangOptions.h"
 #include "clang/Driver/DarwinSDKInfo.h"
 #include "clang/Driver/Tool.h"
 #include "clang/Driver/ToolChain.h"
 #include "clang/Driver/XRayArgs.h"
 
 namespace clang {
 namespace driver {
 
public:
 
   bool UseObjCMixedDispatch() const override {
     // This is only used with the non-fragile ABI and non-legacy dispatch.
 
     // Mixed dispatch is used everywhere except OS X before 10.6.
     return !(isTargetMacOS() && isMacosxVersionLT(10, 6));
   }
 
-  unsigned GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
+  LangOptions::StackProtectorMode
+  GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
     // Stack protectors default to on for user code on 10.5,
     // and for everything in 10.6 and beyond
     if (isTargetIOSBased() || isTargetWatchOSBased())
-      return 1;
+      return LangOptions::SSPOn;
     else if (isTargetMacOS() && !isMacosxVersionLT(10, 6))
-      return 1;
+      return LangOptions::SSPOn;
     else if (isTargetMacOS() && !isMacosxVersionLT(10, 5) && !KernelOrKext)
-      return 1;
+      return LangOptions::SSPOn;
 
-    return 0;
+    return LangOptions::SSPOff;
   }
 
   void CheckObjCARC() const override;
 
   llvm::ExceptionHandling GetExceptionModel(
       const llvm::opt::ArgList &Args) const override;
 
   bool SupportsEmbeddedBitcode() const override;

clang/lib/Driver/ToolChains/Fuchsia.h

 //===--- Fuchsia.h - Fuchsia ToolChain Implementations ----------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_FUCHSIA_H
 #define LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_FUCHSIA_H
 
 #include "Gnu.h"
+#include "clang/Basic/LangOptions.h"
 #include "clang/Driver/Tool.h"
 #include "clang/Driver/ToolChain.h"
 
 namespace clang {
 namespace driver {
 namespace tools {
 namespace fuchsia {
 class LLVM_LIBRARY_VISIBILITY Linker : public Tool {
public:
   }
   bool isPICDefault() const override { return false; }
   bool isPIEDefault() const override { return true; }
   bool isPICDefaultForced() const override { return false; }
   llvm::DebuggerKind getDefaultDebuggerTuning() const override {
     return llvm::DebuggerKind::GDB;
   }
 
-  unsigned GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
-    return 2; // SSPStrong
+  LangOptions::StackProtectorMode
+  GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
+    return LangOptions::SSPStrong;
   }
 
   std::string ComputeEffectiveClangTriple(const llvm::opt::ArgList &Args,
                                           types::ID InputType) const override;
 
   SanitizerMask getSupportedSanitizers() const override;
   SanitizerMask getDefaultSanitizers() const override;
 

clang/lib/Driver/ToolChains/OpenBSD.h

 //===--- OpenBSD.h - OpenBSD ToolChain Implementations ----------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_OPENBSD_H
 #define LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_OPENBSD_H
 
 #include "Gnu.h"
+#include "clang/Basic/LangOptions.h"
 #include "clang/Driver/Tool.h"
 #include "clang/Driver/ToolChain.h"
 
 namespace clang {
 namespace driver {
 namespace tools {
 
 /// openbsd -- Directly call GNU Binutils assembler and linker
public:
   void addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                              llvm::opt::ArgStringList &CC1Args) const override;
   void AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
                            llvm::opt::ArgStringList &CmdArgs) const override;
 
   std::string getCompilerRT(const llvm::opt::ArgList &Args, StringRef Component,
                             FileType Type = ToolChain::FT_Static) const override;
 
-  unsigned GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
-    return 2;
+  LangOptions::StackProtectorMode
+  GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
+    return LangOptions::SSPStrong;
   }
   unsigned GetDefaultDwarfVersion() const override { return 2; }
 
   SanitizerMask getSupportedSanitizers() const override;
 
 protected:
   Tool *buildAssembler() const override;
   Tool *buildLinker() const override;
 };
 
 } // end namespace toolchains
 } // end namespace driver
 } // end namespace clang
 
 #endif // LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_OPENBSD_H

clang/lib/Driver/ToolChains/PS4CPU.h

 //===--- PS4CPU.h - PS4CPU ToolChain Implementations ------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_PS4CPU_H
 #define LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_PS4CPU_H
 
 #include "Gnu.h"
+#include "clang/Basic/LangOptions.h"
 #include "clang/Driver/Tool.h"
 #include "clang/Driver/ToolChain.h"
 
 namespace clang {
 namespace driver {
 namespace tools {
 
 namespace PS4cpu {
void addLibStdCxxIncludePaths(
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override {}
 
   bool IsMathErrnoDefault() const override { return false; }
   bool IsObjCNonFragileABIDefault() const override { return true; }
   bool HasNativeLLVMSupport() const override;
   bool isPICDefault() const override;
 
-  unsigned GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
-    return 2; // SSPStrong
+  LangOptions::StackProtectorMode
+  GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
+    return LangOptions::SSPStrong;
   }
 
   llvm::DebuggerKind getDefaultDebuggerTuning() const override {
     return llvm::DebuggerKind::SCE;
   }
 
   SanitizerMask getSupportedSanitizers() const override;