[clang] [Driver] [NetBSD] Add -D_REENTRANT when using sanitizers

[mgorny]

Summary

NetBSD intends to support only reentrant interfaces in interceptors.
When -lpthread is used without _REENTRANT defined, things are
not guaranteed to work.

This is especially important for <stdio.h> and sanitization of
interfaces around FILE. Some APIs have alternative modes depending
on the _REENTRANT definition, and NetBSD intends to support sanitization
of the _REENTRANT ones.

[krytarowski]

Please normalize the description to resemble a typical commit message.

[krytarowski]

lib/Driver/ToolChains/NetBSD.cpp

465

There should be some way to express any sanitizer (-fsanitize) and we want _REENTRANT for all of them.

[mgorny]

lib/Driver/ToolChains/NetBSD.cpp

465

I've added it in dependent commit.

lib/Driver/ToolChains/NetBSD.h

bool IsUnwindTablesDefault(const llvm::opt::ArgList &Args) const override {
     return true;
   }
 
   llvm::ExceptionHandling GetExceptionModel(
       const llvm::opt::ArgList &Args) const override;
 
   SanitizerMask getSupportedSanitizers() const override;
 
+  void addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
+                             llvm::opt::ArgStringList &CC1Args,
+                             Action::OffloadKind DeviceOffloadKind) 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_NETBSD_H

lib/Driver/ToolChains/NetBSD.cpp

if (IsX86_64) {
     Res |= SanitizerKind::Fuzzer;
     Res |= SanitizerKind::FuzzerNoLink;
     Res |= SanitizerKind::KernelAddress;
     Res |= SanitizerKind::Memory;
     Res |= SanitizerKind::Thread;
   }
   return Res;
 }
+
+void NetBSD::addClangTargetOptions(const ArgList &,
+                                   ArgStringList &CC1Args,
+                                   Action::OffloadKind) const {
+  const SanitizerArgs &SanArgs = getSanitizerArgs();
+  if (SanArgs.hasAnySanitizer())
+    CC1Args.push_back("-D_REENTRANT");
+}