[clang][Fuchsia] Ensure static sanitizer libs are only linked in after the -nostdlib check

[mcgrathr]

clang/lib/Driver/ToolChains/Fuchsia.cpp

129–130

I think all these runtime additions need to be conditional. There must be no kinds of implicit link inputs at all when using -nostdlib.
I'm not sure what matters or doesn't wrt their relative order vs AddLinkerInputs.

[mcgrathr]

clang/lib/Driver/ToolChains/Fuchsia.cpp

153–156

This function is a no-op because it tests for fuchsia targets. So it probably makes more sense not to call it and to remove its fuchsia special-case.

[phosek]

Have you checked if all the tests are still passing?

clang/lib/Driver/ToolChains/Fuchsia.cpp

162

This shouldn't move, these are linker inputs provided by the used and should be always passed to the linker.

[leonardchan]

In D119201#3303275, @phosek wrote:

Have you checked if all the tests are still passing?

All the clang tests seem to be passing, but I'll run the llvm and runtimes tests also.

[phosek]

LGTM

clang/lib/Driver/ToolChains/Fuchsia.cpp

158–160

I think this can be dropped as well.

clang/lib/Driver/ToolChains/CommonArgs.cpp

static const char *getAsNeededOption(const ToolChain &TC, bool as_needed) {
   if (TC.getTriple().isOSSolaris())
     return as_needed ? "-zignore" : "-zrecord";
   else
     return as_needed ? "--as-needed" : "--no-as-needed";
 }
 
 void tools::linkSanitizerRuntimeDeps(const ToolChain &TC,
                                      ArgStringList &CmdArgs) {
-  // Fuchsia never needs these.  Any sanitizer runtimes with system
-  // dependencies use the `.deplibs` feature instead.
-  if (TC.getTriple().isOSFuchsia())
-    return;
-
   // Force linking against the system libraries sanitizers depends on
   // (see PR15823 why this is necessary).
   CmdArgs.push_back(getAsNeededOption(TC, false));
   // There's no libpthread or librt on RTEMS & Android.
   if (TC.getTriple().getOS() != llvm::Triple::RTEMS &&
       !TC.getTriple().isAndroid()) {
     CmdArgs.push_back("-lpthread");
     if (!TC.getTriple().isOSOpenBSD())

clang/lib/Driver/ToolChains/Fuchsia.cpp

void fuchsia::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   ToolChain.AddFilePathLibArgs(Args, CmdArgs);
 
   if (D.isUsingLTO()) {
     assert(!Inputs.empty() && "Must have at least one input.");
     addLTOOptions(ToolChain, Args, CmdArgs, Output, Inputs[0],
                   D.getLTOMode() == LTOK_Thin);
   }
 
-  bool NeedsSanitizerDeps = addSanitizerRuntimes(ToolChain, Args, CmdArgs);
-  bool NeedsXRayDeps = addXRayRuntime(ToolChain, Args, CmdArgs);
   AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
-  ToolChain.addProfileRTLibs(Args, CmdArgs);
 
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs,
                    options::OPT_r)) {
     if (Args.hasArg(options::OPT_static))
       CmdArgs.push_back("-Bdynamic");
 
     if (D.CCCIsCXX()) {
       if (ToolChain.ShouldLinkCXXStdlib(Args)) {
         bool OnlyLibstdcxxStatic = Args.hasArg(options::OPT_static_libstdcxx) &&
                                    !Args.hasArg(options::OPT_static);
         CmdArgs.push_back("--push-state");
         CmdArgs.push_back("--as-needed");
         if (OnlyLibstdcxxStatic)
           CmdArgs.push_back("-Bstatic");
         ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
         if (OnlyLibstdcxxStatic)
           CmdArgs.push_back("-Bdynamic");
         CmdArgs.push_back("-lm");
         CmdArgs.push_back("--pop-state");
       }
     }
 
-    if (NeedsSanitizerDeps)
-      linkSanitizerRuntimeDeps(ToolChain, CmdArgs);
+    // Note that Fuchsia never needs to link in sanitizer runtime deps.  Any
+    // sanitizer runtimes with system dependencies use the `.deplibs` feature
+    // instead.
+    addSanitizerRuntimes(ToolChain, Args, CmdArgs);
+
+    addXRayRuntime(ToolChain, Args, CmdArgs);
 
-    if (NeedsXRayDeps)
-      linkXRayRuntimeDeps(ToolChain, CmdArgs);
+    ToolChain.addProfileRTLibs(Args, CmdArgs);
 
     AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
 
     if (Args.hasArg(options::OPT_pthread) ||
         Args.hasArg(options::OPT_pthreads))
       CmdArgs.push_back("-lpthread");
 
     if (Args.hasArg(options::OPT_fsplit_stack))
       CmdArgs.push_back("--wrap=pthread_create");