[MinGW] Implement --help for the MinGW driver

Differential Revision: https://reviews.llvm.org/D62029

llvm-svn: 361015

2 files changed, 16 insertions, 2 deletions

diff --git a/lld/MinGW/Driver.cpp b/lld/MinGW/Driver.cpp
index 9ef85141771..28ce49d6e1b 100644
--- a/lld/MinGW/Driver.cpp
+++ b/lld/MinGW/Driver.cpp
@@ -78,6 +78,13 @@ public:
 };
 } // namespace
 
+static void printHelp(const char *Argv0) {
+  MinGWOptTable().PrintHelp(
+      outs(), (std::string(Argv0) + " [options] file...").c_str(), "lld",
+      false /*ShowHidden*/, true /*ShowAllAliases*/);
+  outs() << "\n";
+}
+
 opt::InputArgList MinGWOptTable::parse(ArrayRef<const char *> Argv) {
   unsigned MissingIndex;
   unsigned MissingCount;
@@ -89,8 +96,6 @@ opt::InputArgList MinGWOptTable::parse(ArrayRef<const char *> Argv) {
     fatal(StringRef(Args.getArgString(MissingIndex)) + ": missing argument");
   for (auto *Arg : Args.filtered(OPT_UNKNOWN))
     fatal("unknown argument: " + Arg->getSpelling());
-  if (!Args.hasArg(OPT_INPUT) && !Args.hasArg(OPT_l))
-    fatal("no input files");
   return Args;
 }
 
@@ -129,6 +134,14 @@ 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_INPUT) && !Args.hasArg(OPT_l))
+    fatal("no input files");
+
   std::vector<std::string> LinkArgs;
   auto Add = [&](const Twine &S) { LinkArgs.push_back(S.str()); };
 
diff --git a/lld/MinGW/Options.td b/lld/MinGW/Options.td
index 2cfce15abae..b6e6b09c754 100644
--- a/lld/MinGW/Options.td
+++ b/lld/MinGW/Options.td
@@ -16,6 +16,7 @@ def exclude_all_symbols: F<"exclude-all-symbols">,
 def export_all_symbols: F<"export-all-symbols">,
     HelpText<"Export all symbols even if a def file or dllexport attributes are used">;
 def gc_sections: F<"gc-sections">, HelpText<"Remove unused sections">;
+def help: F<"help">, HelpText<"Print option help">;
 def icf: J<"icf=">, HelpText<"Identical code folding">;
 def image_base: S<"image-base">, HelpText<"Base address of the program">;
 def insert_timestamp: F<"insert-timestamp">,