Missing options in `clang -help` and `flang-new -help`

[banach-space]

Clang's driver library doesn't print -fsyntax-only or -O{0|1|2|3} options when using the -help option. This can be reproduced with clang as well as flang-new (which is built in terms of clangDriver):

$ clang  -help | grep syntax
  -objcmt-migrate-property-dot-syntax
                          Enable migration of setter/getter messages to property-dot syntax
$

(-fsyntax-only is missing). I suspect that this might affect other options too. Printing happens via OptTable::printHelp, but I don't see any obvious issues with that method.

This isn't that noticeable in Clang as clang -help | wc -l gives me ~1200. But for flang-new this is ~50. Checked with 333f98b.

Thanks,
-Andrzej

[llvmbot]

@llvm/issue-subscribers-good-first-issue

[llvmbot]

@llvm/issue-subscribers-clang-driver

[llvmbot]

@llvm/issue-subscribers-flang-driver

[Meinersbur]

Clang has a --help-hidden flag which prints a few more options, but still no -fsyntax-only. It has no HelpText text in

llvm-project/clang/include/clang/Driver/Options.td

Line 2797 in b83d0d4

def fsyntax_only : Flag<["-"], "fsyntax-only">,

[banach-space]

It has no HelpText text

Ah, that's the badger! No help text, no output in clang/flang-new -help:

llvm-project/llvm/lib/Option/OptTable.cpp

Lines 670 to 674 in e5e93b6

	if (HelpText && (strlen(HelpText) != 0)) {
	const char *HelpGroup = getOptionHelpGroup(*this, Id);
	const std::string &OptName = getOptionHelpName(*this, Id);
	GroupedOptionHelp[HelpGroup].push_back({OptName, HelpText});
	}

Well spotted @Meinersbur ! So one just needs to add some basic description.

[alexiprof]

Hi, I would like to try myself in solving this issue.

[alexiprof]

I have attached a patch with a fix here
https://reviews.llvm.org/D131808

[alexiprof]

ping, reviewers.