Ignore -f(no)objc-arc-exception when -fno-objc-arc set

[• onhachoe]

Summary

Sometime clang would be supplied -fobjc-arc -f(no)objc-arc-exceptions
and then later disable ARC with -fno-objc-arc, which only negate first
option, but not the latter, resulting usused argument warning.
Silence this warning only when -fno-objc-arc option is present.

[rjmccall]

Yes, that seems reasonable.

[compnerd]

SVN r293014.

lib/Driver/Tools.cpp

if (ARC) {
     }
 
     // Allow the user to enable full exceptions code emission.
     // We define off for Objective-CC, on for Objective-C++.
     if (Args.hasFlag(options::OPT_fobjc_arc_exceptions,
                      options::OPT_fno_objc_arc_exceptions,
                      /*default*/ types::isCXX(InputType)))
       CmdArgs.push_back("-fobjc-arc-exceptions");
+  }
 
+  // Silence warning for full exception code emission options when explicitly
+  // set to use no ARC.
+  if (Args.hasArg(options::OPT_fno_objc_arc)) {
+    Args.ClaimAllArgs(options::OPT_fobjc_arc_exceptions);
+    Args.ClaimAllArgs(options::OPT_fno_objc_arc_exceptions);
   }
 
   // -fobjc-infer-related-result-type is the default, except in the Objective-C
   // rewriter.
   if (rewriteKind != RK_None)
     CmdArgs.push_back("-fno-objc-infer-related-result-type");
 
   // Pass down -fobjc-weak or -fno-objc-weak if present.

test/Driver/no-arc-exception-silence.m

+// RUN: %clang -Werror -fobjc-arc -fobjc-arc-exceptions -fno-objc-arc -Xclang -verify -c %s
+// expected-no-diagnostics