[OptTable] Improve error message output for grouped short options

As seen in https://bugs.llvm.org/show_bug.cgi?id=48880 the current
implementation for parsing grouped short options can return unclear
error messages. This change fixes the example given in the ticket in
which a flag is incorrectly given an argument. Also when parsing a
group we now keep reading past the first incorrect option and output
errors for all incorrect options in the group.

Differential Revision: https://reviews.llvm.org/D108770

1 files changed, 13 insertions, 4 deletions

diff --git a/llvm/lib/Option/OptTable.cpp b/llvm/lib/Option/OptTable.cpp
index a994a42..2770f4d41 100644
--- a/llvm/lib/Option/OptTable.cpp
+++ b/llvm/lib/Option/OptTable.cpp
@@ -376,14 +376,23 @@ Arg *OptTable::parseOneArgGrouped(InputArgList &Args, unsigned &Index) const {
   if (Fallback) {
     Option Opt(Fallback, this);
     if (Arg *A = Opt.accept(Args, Str.substr(0, 2), true, Index)) {
-      if (Str.size() == 2)
-        ++Index;
-      else
-        Args.replaceArgString(Index, Twine('-') + Str.substr(2));
+      // Check that the last option isn't a flag wrongly given an argument.
+      if (Str[2] == '=')
+        return new Arg(getOption(TheUnknownOptionID), Str, Index++, CStr);
+
+      Args.replaceArgString(Index, Twine('-') + Str.substr(2));
       return A;
     }
   }
 
+  // In the case of an incorrect short option extract the character and move to
+  // the next one.
+  if (Str[1] != '-') {
+    CStr = Args.MakeArgString(Str.substr(0, 2));
+    Args.replaceArgString(Index, Twine('-') + Str.substr(2));
+    return new Arg(getOption(TheUnknownOptionID), CStr, Index, CStr);
+  }
+
   return new Arg(getOption(TheUnknownOptionID), Str, Index++, CStr);
 }