From 375079a549c584bd14dad501ecc4575738cea3c1 Mon Sep 17 00:00:00 2001
From: Hans Wennborg <hans@hanshq.net>
Date: Mon, 4 May 2015 18:00:13 +0000
Subject: [PATCH] Option parsing: properly handle flag aliases for joined
 options (PR23394)

A joined option always needs to have an argument, even if it's an empty one.

Clang would previously assert when trying to use --extra-warnings, which is
a flag alias for -W, which is a joined option.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236434 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Option/Option.cpp                  |  5 +++++
 unittests/Option/OptionParsingTest.cpp | 14 ++++++++++++++
 unittests/Option/Opts.td               |  2 ++
 3 files changed, 21 insertions(+)

diff --git a/lib/Option/Option.cpp b/lib/Option/Option.cpp
index e29d6491c7f..221414d79e7 100644
--- a/lib/Option/Option.cpp
+++ b/lib/Option/Option.cpp
@@ -125,6 +125,11 @@ Arg *Option::accept(const ArgList &Args,
         Val += strlen(Val) + 1;
       }
     }
+
+    if (UnaliasedOption.getKind() == JoinedClass && !getAliasArgs())
+      // A Flag alias for a Joined option must provide an argument.
+      A->getValues().push_back("");
+
     return A;
   }
   case JoinedClass: {
diff --git a/unittests/Option/OptionParsingTest.cpp b/unittests/Option/OptionParsingTest.cpp
index aa32da3a595..521009a9e66 100644
--- a/unittests/Option/OptionParsingTest.cpp
+++ b/unittests/Option/OptionParsingTest.cpp
@@ -209,3 +209,17 @@ TEST(Option, Slurp) {
   EXPECT_EQ(AL->getAllArgValues(OPT_Slurp)[1], "--");
   EXPECT_EQ(AL->getAllArgValues(OPT_Slurp)[2], "foo");
 }
+
+TEST(Option, FlagAliasToJoined) {
+  TestOptTable T;
+  unsigned MAI, MAC;
+
+  // Check that a flag alias provides an empty argument to a joined option.
+  const char *MyArgs[] = { "-K" };
+  std::unique_ptr<InputArgList> AL(
+      T.ParseArgs(std::begin(MyArgs), std::end(MyArgs), MAI, MAC));
+  EXPECT_EQ(AL->size(), 1U);
+  EXPECT_TRUE(AL->hasArg(OPT_B));
+  EXPECT_EQ(AL->getAllArgValues(OPT_B).size(), 1U);
+  EXPECT_EQ(AL->getAllArgValues(OPT_B)[0], "");
+}
diff --git a/unittests/Option/Opts.td b/unittests/Option/Opts.td
index aaed6b2101e..c96774a68e0 100644
--- a/unittests/Option/Opts.td
+++ b/unittests/Option/Opts.td
@@ -23,4 +23,6 @@ def I : Flag<["-"], "I">, Alias<H>, Group<my_group>;
 def J : Flag<["-"], "J">, Alias<B>, AliasArgs<["foo"]>;
 def Joo : Flag<["-"], "Joo">, Alias<B>, AliasArgs<["bar"]>;
 
+def K : Flag<["-"], "K">, Alias<B>;
+
 def Slurp : Option<["-"], "slurp", KIND_REMAINING_ARGS>;
-- 
2.34.1