[Driver] Automatically disable incompatible default sanitizers

[phosek]

Summary

When a sanitizer incompatible with one of the default sanitizers
is explicitly enabled, automatically disable all the conflicting
default sanitizers.

[vitalybuka]

clang/lib/Driver/SanitizerArgs.cpp

369 ↗

(On Diff #136893)

Is this change needed to avoid errors at "Kinds & NeedsLTO" and KindsToDiagnose?
Could you create a test for this change?

[phosek]

clang/lib/Driver/SanitizerArgs.cpp

369 ↗

(On Diff #136893)

It is needed for D44065, if we enable some sanitizers like SafeStack by default, user would get an error when they enable some incompatible sanitizer like ASan and would require them passing -fno-sanitizer=safe-stack to avoid that error which is non-intuitive. Instead, with this change the incompatible default sanitizers are disabled automatically.

cfe/trunk/lib/Driver/SanitizerArgs.cpp

if (Arg->getOption().matches(options::OPT_fsanitize_EQ)) {
       Kinds |= Add;
     } else if (Arg->getOption().matches(options::OPT_fno_sanitize_EQ)) {
       Arg->claim();
       SanitizerMask Remove = parseArgValues(D, Arg, true);
       AllRemove |= expandSanitizerGroups(Remove);
     }
   }
 
+  std::pair<SanitizerMask, SanitizerMask> IncompatibleGroups[] = {
+      std::make_pair(Address, Thread | Memory),
+      std::make_pair(Thread, Memory),
+      std::make_pair(Leak, Thread | Memory),
+      std::make_pair(KernelAddress, Address | Leak | Thread | Memory),
+      std::make_pair(HWAddress, Address | Thread | Memory | KernelAddress),
+      std::make_pair(Efficiency, Address | HWAddress | Leak | Thread | Memory |
+                                     KernelAddress),
+      std::make_pair(Scudo, Address | HWAddress | Leak | Thread | Memory |
+                                KernelAddress | Efficiency),
+      std::make_pair(SafeStack, Address | HWAddress | Leak | Thread | Memory |
+                                    KernelAddress | Efficiency)};
+
   // Enable toolchain specific default sanitizers if not explicitly disabled.
-  Kinds |= TC.getDefaultSanitizers() & ~AllRemove;
+  SanitizerMask Default = TC.getDefaultSanitizers() & ~AllRemove;
+
+  // Disable default sanitizers that are incompatible with the default ones.
+  for (auto G : IncompatibleGroups) {
+    SanitizerMask Group = G.first;
+    if ((Default & Group) && (Kinds & G.second))
+      Default &= ~Group;
+  }
+
+  Kinds |= Default;
 
   // We disable the vptr sanitizer if it was enabled by group expansion but RTTI
   // is disabled.
   if ((Kinds & Vptr) &&
       (RTTIMode == ToolChain::RM_DisabledImplicitly ||
        RTTIMode == ToolChain::RM_DisabledExplicitly)) {
     Kinds &= ~Vptr;
   }
if (KindsToDiagnose) {
       S.Mask = KindsToDiagnose;
       D.Diag(diag::err_drv_unsupported_opt_for_target)
           << ("-fno-sanitize-trap=" + toString(S)) << TC.getTriple().str();
       Kinds &= ~KindsToDiagnose;
     }
   }
 
   // Warn about incompatible groups of sanitizers.
-  std::pair<SanitizerMask, SanitizerMask> IncompatibleGroups[] = {
-      std::make_pair(Address, Thread | Memory),
-      std::make_pair(Thread, Memory),
-      std::make_pair(Leak, Thread | Memory),
-      std::make_pair(KernelAddress, Address | Leak | Thread | Memory),
-      std::make_pair(HWAddress, Address | Thread | Memory | KernelAddress),
-      std::make_pair(Efficiency, Address | HWAddress | Leak | Thread | Memory |
-                                     KernelAddress),
-      std::make_pair(Scudo, Address | HWAddress | Leak | Thread | Memory |
-                                KernelAddress | Efficiency),
-      std::make_pair(SafeStack, Address | HWAddress | Leak | Thread | Memory |
-                                    KernelAddress | Efficiency)};
   for (auto G : IncompatibleGroups) {
     SanitizerMask Group = G.first;
     if (Kinds & Group) {
       if (SanitizerMask Incompatible = Kinds & G.second) {
         D.Diag(clang::diag::err_drv_argument_not_allowed_with)
             << lastArgumentForMask(D, Args, Group)
             << lastArgumentForMask(D, Args, Incompatible);
         Kinds &= ~Incompatible;