[LLD] [MinGW] Implement the -v and --version flags for the MinGW driver

[ruiu]

MinGW/Driver.cpp

144

Do we need "(compatible with GNU linkers)"? This is a hack for compatibility with configure scripts (https://www.sigbus.info/software-compatibility-and-our-own-user-agent-problem). I don't know much about how linkers are detected on Windows for MinGW, but if you don't need it, you can remove it from the version message.

[mstorsjo]

MinGW/Driver.cpp

144

One of the main selling points of MinGW is that it works with the same configure/autotools/libtool based builds as lots of unix libraries. So yes, unfortunately, the same compatibility hack is needed here as well. Do you want me to bring along a bit more of the comment to point this out, to indicate that this is intentional?

[mstorsjo]

Added more of the original comment about "compatible with GNU linkers" which also applies for MinGW.

[ruiu]

LGTM

MinGW/Driver.cpp

 // ld/MinGW implements a few GNU-specific features. Such features are directly
 // implemented in lld/COFF and enabled only when the linker is running in MinGW
 // mode.
 //
 //===----------------------------------------------------------------------===//
 
 #include "lld/Common/Driver.h"
 #include "lld/Common/ErrorHandler.h"
+#include "lld/Common/Version.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/Option.h"
 #include "llvm/Support/CommandLine.h"
bool mingw::link(ArrayRef<const char *> ArgsArr, raw_ostream &Diag) {
   MinGWOptTable Parser;
   opt::InputArgList Args = Parser.parse(ArgsArr.slice(1));
 
   if (Args.hasArg(OPT_help)) {
     printHelp(ArgsArr[0]);
     return true;
   }
 
+  if (Args.hasArg(OPT_v) || Args.hasArg(OPT_version))
+    message(getLLDVersion() + " (compatible with GNU linkers)");
+
+  // The behavior of -v or --version is a bit strange, but this is
+  // needed for compatibility with GNU linkers.
+  if (Args.hasArg(OPT_v) && !Args.hasArg(OPT_INPUT) && !Args.hasArg(OPT_l))
+    return true;
+  if (Args.hasArg(OPT_version))
+    return true;
+
   if (!Args.hasArg(OPT_INPUT) && !Args.hasArg(OPT_l))
     fatal("no input files");
 
   std::vector<std::string> LinkArgs;
   auto Add = [&](const Twine &S) { LinkArgs.push_back(S.str()); };
 
   Add("lld-link");
   Add("-lldmingw");

MinGW/Options.td

 def subs: S<"subsystem">, HelpText<"Specify subsystem">;
 def stack: S<"stack">;
 def strip_all: F<"strip-all">,
     HelpText<"Omit all symbol information from the output binary">;
 def strip_debug: F<"strip-debug">,
     HelpText<"Omit all debug information, but keep symbol information">;
 def whole_archive: F<"whole-archive">,
     HelpText<"Include all object files for following archives">;
+def v: Flag<["-"], "v">, HelpText<"Display the version number">;
 def verbose: F<"verbose">, HelpText<"Verbose mode">;
+def version: F<"version">, HelpText<"Display the version number and exit">;
 def require_defined: S<"require-defined">,
     HelpText<"Force symbol to be added to symbol table as an undefined one">;
 def require_defined_eq: J<"require-defined=">, Alias<require_defined>;
 
 // LLD specific options
 def _HASH_HASH_HASH : Flag<["-"], "###">,
     HelpText<"Print (but do not run) the commands to run for this compilation">;
 def appcontainer: F<"appcontainer">, HelpText<"Set the appcontainer flag in the executable">;

 def: F<"pic-executable">;
 def: S<"plugin">;
 def: J<"plugin=">;
 def: S<"plugin-opt">;
 def: J<"plugin-opt=">;
 def: J<"sysroot">;
 def: F<"start-group">;
 def: F<"tsaware">;
-def: Flag<["-"], "v">;
-def: F<"version">;

test/MinGW/driver.test

 RUN: ld.lld -### -m i386pep foo.o --insert-timestamp --no-insert-timestamp | FileCheck -check-prefix NOTIMESTAMP %s
 NOTIMESTAMP: -timestamp:0
 RUN: ld.lld -### -m i386pep foo.o --no-insert-timestamp --insert-timestamp | FileCheck -check-prefix TIMESTAMP %s
 TIMESTAMP-NOT: -timestamp:0
 
 RUN: ld.lld -### -m i386pep foo.o -appcontainer | FileCheck -check-prefix APPCONTAINER %s
 RUN: ld.lld -### -m i386pep foo.o --appcontainer | FileCheck -check-prefix APPCONTAINER %s
 APPCONTAINER: -appcontainer
+
+# RUN: ld.lld -m i386pep --version 2>&1 | FileCheck -check-prefix=VERSION %s
+# RUN: ld.lld -m i386pep -v 2>&1 | FileCheck -check-prefix=VERSION %s
+# RUN: not ld.lld -m i386pep -v xyz 2>&1 | FileCheck -check-prefix=VERSION %s
+# VERSION: LLD {{.*}} (compatible with GNU linkers)