[llvm-dwarfdump] Print [=<offset>] after --debug-* options in help output.

Some of the --debug-* options can take an optional offset. Although the
man page does a good job of making that clear, it's much harder to
discover from the help output.

Currently the only reference to this is the following sentence:

> Where applicable these parameters take an optional =<offset> argument
> to dump only the entry at the specified offset.

This patch changes the help output from to print [=<offset>] after the
options that take an offset.

  --debug-info[=<offset>]    - Dump the .debug_info section

rdar://problem/63150066

Differential revision: https://reviews.llvm.org/D80959

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Support/CommandLine.cpp b/llvm/lib/Support/CommandLine.cpp
index 25612b7e..52053df 100644
--- a/llvm/lib/Support/CommandLine.cpp
+++ b/llvm/lib/Support/CommandLine.cpp
@@ -1778,9 +1778,10 @@ void basic_parser_impl::printOptionInfo(const Option &O,
   if (!ValName.empty()) {
     if (O.getMiscFlags() & PositionalEatsArgs) {
       outs() << " <" << getValueStr(O, ValName) << ">...";
-    } else {
+    } else if (O.getValueExpectedFlag() == ValueOptional)
+      outs() << "[=<" << getValueStr(O, ValName) << ">]";
+    else
       outs() << "=<" << getValueStr(O, ValName) << '>';
-    }
   }
 
   Option::printHelpStr(O.HelpStr, GlobalWidth, getOptionWidth(O));