[PATCH] SanitizerArgs: add ability to filter/diagnose unsupported sanitizers.

[Richard Smith]

================
Comment at: lib/Driver/SanitizerArgs.cpp:56
@@ +55,3 @@
+    // Avoid diagnosing any sanitizer which is disabled later.
+    Add &= ~AllRemove;
+    // At this point we have not expanded groups, so any unsupported sanitizers
----------------
Hmm, should we mask out `AllAdd` here too? We don't want to issue two diagnostics for `-fsanitize=bad -fsanitize=bad`. But on the other hand diagnosing `-fsanitize=bad -fsanitize=group-including-bad` might be nice. Ugh. Maybe what we want is a limit of one diagnostic per problem?

================
Comment at: lib/Driver/SanitizerArgs.cpp:132-135
@@ -109,6 +131,6 @@
   // command line).
-  if ((Kind & AddressFull) != 0 && (AllKinds & Address) == 0)
+  if ((Kind & AddressFull) != 0 && (AllAdd & Address) == 0)
     D.Diag(diag::warn_drv_unused_sanitizer)
      << lastArgumentForKind(D, Args, AddressFull)
      << "-fsanitize=address";
 
----------------
This looks a bit strange. We won't diagnose

  -fsanitize=address -fno-sanitize=address -fsanitize=init-order

Following the principle of later arguments overriding earlier ones, I would have expected a diagnostic for that, but not for:

  -fsanitize=address -fsanitize=init-order -fno-sanitize=address

Seems to be a pre-existing oddness, though.


http://llvm-reviews.chandlerc.com/D1990