Option parsing: add support for alias arguments.

This makes option aliases more powerful by enabling them to
pass along arguments to the option they're aliasing.

For example, if we have a joined option "-foo=", we can now
specify a flag option "-bar" to be an alias of that, with the
argument "baz".

This is especially useful for the cl.exe compatible clang driver,
where many options are aliases. For example, this patch enables
us to alias "/Ox" to "-O3" (-O is a joined option), and "/WX" to
"-Werror" (again, -W is a joined option).

Differential Revision: http://llvm-reviews.chandlerc.com/D1245

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187537 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 13 insertions, 0 deletions

diff --git a/include/llvm/Option/OptParser.td b/include/llvm/Option/OptParser.td
index 394e0b6..32cc2c0 100644
--- a/include/llvm/Option/OptParser.td
+++ b/include/llvm/Option/OptParser.td
@@ -89,6 +89,7 @@ class Option<list<string> prefixes, string name, OptionKind kind> {
   list<OptionFlag> Flags = [];
   OptionGroup Group = ?;
   Option Alias = ?;
+  list<string> AliasArgs = [];
 }
 
 // Helpers for defining options.
@@ -113,6 +114,7 @@ class JoinedAndSeparate<list<string> prefixes, string name>
 // Mix-ins for adding optional attributes.
 
 class Alias<Option alias> { Option Alias = alias; }
+class AliasArgs<list<string> aliasargs> { list<string> AliasArgs = aliasargs; }
 class EnumName<string name> { string EnumName = name; }
 class Flags<list<OptionFlag> flags> { list<OptionFlag> Flags = flags; }
 class Group<OptionGroup group> { OptionGroup Group = group; }
diff --git a/include/llvm/Option/OptTable.h b/include/llvm/Option/OptTable.h
index 8ee219d..a5b59ce 100644
--- a/include/llvm/Option/OptTable.h
+++ b/include/llvm/Option/OptTable.h
@@ -44,6 +44,7 @@ public:
     unsigned short Flags;
     unsigned short GroupID;
     unsigned short AliasID;
+    const char *AliasArgs;
   };
 
 private:
diff --git a/include/llvm/Option/Option.h b/include/llvm/Option/Option.h
index 4861b59..47fd817 100644
--- a/include/llvm/Option/Option.h
+++ b/include/llvm/Option/Option.h
@@ -103,6 +103,16 @@ public:
     return Owner->getOption(Info->AliasID);
   }
 
+  /// \brief Get the alias arguments as a \0 separated list.
+  /// E.g. ["foo", "bar"] would be returned as "foo\0bar\0".
+  const char *getAliasArgs() const {
+    assert(Info && "Must have a valid info!");
+    assert((!Info->AliasArgs || Info->AliasArgs[0] != 0) &&
+           "AliasArgs should be either 0 or non-empty.");
+
+    return Info->AliasArgs;
+  }
+
   /// \brief Get the default prefix for this option.
   StringRef getPrefix() const {
     const char *Prefix = *Info->Prefixes;