Revert "[Support]Look up in top-level subcommand as a fallback when looking options for a custom subcommand (llvm#71975)

…ooking options for a custom subcommand. (llvm#71776)"

This reverts commit b88308b.

The build-bot is unhappy
(https://lab.llvm.org/buildbot/#/builders/186/builds/13096),
`GroupingAndPrefix` fails after `TopLevelOptInSubcommand` (the newly
added test).

Revert while I look into this (might be related with test sharding but
not sure)

```

[----------] 3 tests from CommandLineTest
[ RUN      ] CommandLineTest.TokenizeWindowsCommandLine2
[       OK ] CommandLineTest.TokenizeWindowsCommandLine2 (0 ms)
[ RUN      ] CommandLineTest.TopLevelOptInSubcommand
[       OK ] CommandLineTest.TopLevelOptInSubcommand (0 ms)
[ RUN      ] CommandLineTest.GroupingAndPrefix
 #0 0x00ba8118 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x594118)
 #1 0x00ba5914 llvm::sys::RunSignalHandlers() (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x591914)
 llvm#2 0x00ba89c4 SignalHandler(int) (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x5949c4)
 llvm#3 0xf7828530 __default_sa_restorer /build/glibc-9MGTF6/glibc-2.31/signal/../sysdeps/unix/sysv/linux/arm/sigrestorer.S:67:0
 llvm#4 0x00af91f0 (anonymous namespace)::CommandLineParser::ResetAllOptionOccurrences() (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x4e51f0)
 llvm#5 0x00af8e1c llvm::cl::ResetCommandLineParser() (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x4e4e1c)
 llvm#6 0x0077cda0 (anonymous namespace)::CommandLineTest_GroupingAndPrefix_Test::TestBody() (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x168da0)
 llvm#7 0x00bc5adc testing::Test::Run() (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x5b1adc)
 llvm#8 0x00bc6cc0 testing::TestInfo::Run() (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x5b2cc0)
 llvm#9 0x00bc7880 testing::TestSuite::Run() (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x5b3880)
llvm#10 0x00bd7974 testing::internal::UnitTestImpl::RunAllTests() (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x5c3974)
llvm#11 0x00bd6ebc testing::UnitTest::Run() (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x5c2ebc)
llvm#12 0x00bb1058 main (/home/tcwg-buildbot/worker/clang-armv7-global-isel/stage1/unittests/Support/./SupportTests+0x59d058)
llvm#13 0xf78185a4 __libc_start_main /build/glibc-9MGTF6/glibc-2.31/csu/libc-start.c:342:3
```

Author: mingmingl-llvm

llvm/lib/Support/CommandLine.cpp

@@ -1667,13 +1667,6 @@ bool CommandLineParser::ParseCommandLineOptions(int argc,
       Handler = LookupLongOption(*ChosenSubCommand, ArgName, Value,
                                  LongOptionsUseDoubleDash, HaveDoubleDash);
 
-      // If Handler is not found in a specialized subcommand, look up handler
-      // in the top-level subcommand.
-      // cl::opt without cl::sub belongs to top-level subcommand.
-      if (!Handler && ChosenSubCommand != &SubCommand::getTopLevel())
-        Handler = LookupLongOption(SubCommand::getTopLevel(), ArgName, Value,
-                                   LongOptionsUseDoubleDash, HaveDoubleDash);
-
       // Check to see if this "option" is really a prefixed or grouped argument.
       if (!Handler && !(LongOptionsUseDoubleDash && HaveDoubleDash))
         Handler = HandlePrefixedOrGroupedOption(ArgName, Value, ErrorParsing,

llvm/unittests/Support/CommandLineTest.cpp

@@ -525,59 +525,6 @@ TEST(CommandLineTest, LookupFailsInWrongSubCommand) {
   EXPECT_FALSE(Errs.empty());
 }
 
-TEST(CommandLineTest, TopLevelOptInSubcommand) {
-  enum LiteralOptionEnum {
-    foo,
-    bar,
-    baz,
-  };
-
-  cl::ResetCommandLineParser();
-
-  // This is a top-level option and not associated with a subcommand.
-  // A command line using subcommand should parse both subcommand options and
-  // top-level options.  A valid use case is that users of llvm command line
-  // tools should be able to specify top-level options defined in any library.
-  cl::opt<std::string> TopLevelOpt("str", cl::init("txt"),
-                                   cl::desc("A top-level option."));
-
-  StackSubCommand SC("sc", "Subcommand");
-  StackOption<std::string> PositionalOpt(
-      cl::Positional, cl::desc("positional argument test coverage"),
-      cl::sub(SC));
-  StackOption<LiteralOptionEnum> LiteralOpt(
-      cl::desc("literal argument test coverage"), cl::sub(SC), cl::init(bar),
-      cl::values(clEnumVal(foo, "foo"), clEnumVal(bar, "bar"),
-                 clEnumVal(baz, "baz")));
-  StackOption<bool> EnableOpt("enable", cl::sub(SC), cl::init(false));
-  StackOption<int> ThresholdOpt("threshold", cl::sub(SC), cl::init(1));
-
-  const char *PositionalOptVal = "input-file";
-  const char *args[] = {"prog",    "sc",        PositionalOptVal,
-                        "-enable", "--str=csv", "--threshold=2"};
-
-  // cl::ParseCommandLineOptions returns true on success. Otherwise, it will
-  // print the error message to stderr and exit in this setting (`Errs` ostream
-  // is not set).
-  ASSERT_TRUE(cl::ParseCommandLineOptions(sizeof(args) / sizeof(args[0]), args,
-                                          StringRef()));
-  EXPECT_STREQ(PositionalOpt.getValue().c_str(), PositionalOptVal);
-  EXPECT_TRUE(EnableOpt);
-  // Tests that the value of `str` option is `csv` as specified.
-  EXPECT_STREQ(TopLevelOpt.getValue().c_str(), "csv");
-  EXPECT_EQ(ThresholdOpt, 2);
-
-  for (auto &[LiteralOptVal, WantLiteralOpt] :
-       {std::pair{"--bar", bar}, {"--foo", foo}, {"--baz", baz}}) {
-    const char *args[] = {"prog", "sc", LiteralOptVal};
-    ASSERT_TRUE(cl::ParseCommandLineOptions(sizeof(args) / sizeof(args[0]),
-                                            args, StringRef()));
-
-    // Tests that literal options are parsed correctly.
-    EXPECT_EQ(LiteralOpt, WantLiteralOpt);
-  }
-}
-
 TEST(CommandLineTest, AddToAllSubCommands) {
   cl::ResetCommandLineParser();