Support: Fix option handling when using cl::Required with aliasopt

Until now, attempting to create an alias of a required option would
complain if the user supplied the alias, because the required option
didn't have a value. Similarly, if you said the alias was required,
then using the base option would complain that the alias wasn't
supplied. Lastly, if you put required on both, *neither* option would
work.

By changning alias to overload addOccurrence and setting cl::Required
on the original option, we can get this to behave in a more useful
way. I've also added a test and updated a user that was getting this
wrong.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212986 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/CommandLine.h

@@ -270,8 +270,8 @@ public:
 
   // addOccurrence - Wrapper around handleOccurrence that enforces Flags.
   //
-  bool addOccurrence(unsigned pos, StringRef ArgName,
-                     StringRef Value, bool MultiArg = false);
+  virtual bool addOccurrence(unsigned pos, StringRef ArgName,
+                             StringRef Value, bool MultiArg = false);
 
   // Prints option name followed by message.  Always returns true.
   bool error(const Twine &Message, StringRef ArgName = StringRef());
@@ -1649,6 +1649,10 @@ class alias : public Option {
                                 StringRef Arg) override {
     return AliasFor->handleOccurrence(pos, AliasFor->ArgStr, Arg);
   }
+  bool addOccurrence(unsigned pos, StringRef /*ArgName*/,
+                     StringRef Value, bool MultiArg = false) override {
+    return AliasFor->addOccurrence(pos, AliasFor->ArgStr, Value, MultiArg);
+  }
   // Handle printing stuff...
   size_t getOptionWidth() const override;
   void printOptionInfo(size_t GlobalWidth) const override;

tools/llvm-profdata/llvm-profdata.cpp

@@ -38,9 +38,9 @@ int merge_main(int argc, const char *argv[]) {
                                cl::desc("<filenames...>"));
 
   cl::opt<std::string> OutputFilename("output", cl::value_desc("output"),
-                                      cl::init("-"),
+                                      cl::init("-"), cl::Required,
                                       cl::desc("Output file"));
-  cl::alias OutputFilenameA("o", cl::desc("Alias for --output"), cl::Required,
+  cl::alias OutputFilenameA("o", cl::desc("Alias for --output"),
                             cl::aliasopt(OutputFilename));
 
   cl::ParseCommandLineOptions(argc, argv, "LLVM profile data merger\n");

unittests/Support/CommandLineTest.cpp

@@ -212,4 +212,23 @@ TEST(CommandLineTest, AliasesWithArguments) {
   }
 }
 
+void testAliasRequired(int argc, const char *const *argv) {
+  StackOption<std::string> Option("option", cl::Required);
+  cl::alias Alias("o", llvm::cl::aliasopt(Option));
+
+  cl::ParseCommandLineOptions(argc, argv);
+  EXPECT_EQ("x", Option);
+  EXPECT_EQ(1, Option.getNumOccurrences());
+
+  Alias.removeArgument();
+}
+
+TEST(CommandLineTest, AliasRequired) {
+  const char *opts1[] = { "-tool", "-option=x" };
+  const char *opts2[] = { "-tool", "-o", "x" };
+  testAliasRequired(array_lengthof(opts1), opts1);
+  testAliasRequired(array_lengthof(opts2), opts2);
+}
+
+
 }  // anonymous namespace