[clang] [clang-tools-extra] [lld] [llvm] [llvm] Add subcommand support for OptTable (PR #155026)

[via llvm-commits]

================
@@ -0,0 +1,125 @@
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Option/ArgList.h"
+#include "llvm/Option/OptTable.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+using namespace llvm::opt;
+
+namespace {
+enum ID {
+  OPT_INVALID = 0,
+#define OPTION(PREFIXES, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS,       \
+               VISIBILITY, PARAM, HELPTEXT, HELPTEXTSFORVARIANTS, METAVAR,     \
+               VALUES, COMMANDIDS_OFFSET)                                      \
+  OPT_##ID,
+#include "Opts.inc"
+#undef OPTION
+};
+#define OPTTABLE_STR_TABLE_CODE
+#include "Opts.inc"
+#undef OPTTABLE_STR_TABLE_CODE
+
+#define OPTTABLE_PREFIXES_TABLE_CODE
+#include "Opts.inc"
+#undef OPTTABLE_PREFIXES_TABLE_CODE
+
+#define OPTTABLE_COMMAND_IDS_TABLE_CODE
+#include "Opts.inc"
+#undef OPTTABLE_COMMAND_IDS_TABLE_CODE
+
+#define OPTTABLE_COMMANDS_CODE
+#include "Opts.inc"
+#undef OPTTABLE_COMMANDS_CODE
+
+static constexpr OptTable::Info InfoTable[] = {
+#define OPTION(...) LLVM_CONSTRUCT_OPT_INFO(__VA_ARGS__),
+#include "Opts.inc"
+#undef OPTION
+};
+
+class HelloSubOptTable : public GenericOptTable {
+public:
+  HelloSubOptTable()
+      : GenericOptTable(OptionStrTable, OptionPrefixesTable, InfoTable,
+                        OptionCommands, OptionCommandIDsTable) {}
+};
+} // namespace
+
+int main(int argc, char **argv) {
+  InitLLVM X(argc, argv);
+  HelloSubOptTable T;
+  unsigned MissingArgIndex, MissingArgCount;
+
+  auto HandleMultipleSubcommands = [](const ArrayRef<StringRef> SubCommands) {
----------------
PiJoules wrote:

`const` might not be needed since `ArrayRef` is already immutable I believe. Same with the other `const ArrayRef`s below.

https://github.com/llvm/llvm-project/pull/155026