[Driver] Add option to print the resource directory

[clm]

Summary

This patch adds the option -print-resource-dir. It simply prints the resource directory. This information will eventually be used in compiler-rt to setup COMPILER_RT_LIBRARY_INSTALL_DIR.

[beanz]

One minor nitpick on the test case, but otherwise this looks fine to me.

test/Driver/immediate-options.c

19

This should probably be matching + instead of *. As written this would succeed even if the output was empty.

[clm]

I've now updated the patch to include your suggested revision of the test case. I don't have commit access yet, but meadori said that he would commit it for me.

include/clang/Driver/Options.td

def print_libgcc_file_name : Flag<["-", "--"], "print-libgcc-file-name">,
   HelpText<"Print the library path for the currently used compiler runtime "
            "library (\"libgcc.a\" or \"libclang_rt.builtins.*.a\")">;
 def print_multi_directory : Flag<["-", "--"], "print-multi-directory">;
 def print_multi_lib : Flag<["-", "--"], "print-multi-lib">;
 def print_multi_os_directory : Flag<["-", "--"], "print-multi-os-directory">,
   Flags<[Unsupported]>;
 def print_prog_name_EQ : Joined<["-", "--"], "print-prog-name=">,
   HelpText<"Print the full program path of <name>">, MetaVarName<"<name>">;
+def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
+  HelpText<"Print the full pathname of the resource directory">;
 def print_search_dirs : Flag<["-", "--"], "print-search-dirs">,
   HelpText<"Print the paths used for finding libraries and programs">;
 def private__bundle : Flag<["-"], "private_bundle">;
 def pthreads : Flag<["-"], "pthreads">;
 def pthread : Flag<["-"], "pthread">, Flags<[CC1Option]>,
   HelpText<"Support POSIX threads in generated code">;
 def no_pthread : Flag<["-"], "no-pthread">, Flags<[CC1Option]>;
 def p : Flag<["-"], "p">;

lib/Driver/Driver.cpp

if (C.getArgs().hasArg(options::OPT_v) ||
     SuppressMissingInputWarning = true;
   }
 
   const ToolChain &TC = C.getDefaultToolChain();
 
   if (C.getArgs().hasArg(options::OPT_v))
     TC.printVerboseInfo(llvm::errs());
 
+  if (C.getArgs().hasArg(options::OPT_print_resource_dir)) {
+    llvm::outs() << ResourceDir << "\n";
+    return false;
+  }
+
   if (C.getArgs().hasArg(options::OPT_print_search_dirs)) {
     llvm::outs() << "programs: =";
     bool separator = false;
     for (const std::string &Path : TC.getProgramPaths()) {
       if (separator)
         llvm::outs() << ':';
       llvm::outs() << Path;
       separator = true;

test/Driver/immediate-options.c

 // RUN: %clang --help | FileCheck %s -check-prefix=HELP
 // HELP: isystem
 // HELP-NOT: ast-dump
 // HELP-NOT: driver-mode
 
 // RUN: %clang --help-hidden | FileCheck %s -check-prefix=HELP-HIDDEN
 // HELP-HIDDEN: driver-mode
 
 // RUN: %clang -dumpversion | FileCheck %s -check-prefix=DUMPVERSION
 // DUMPVERSION: 4.2.1
 
 // RUN: %clang -print-search-dirs | FileCheck %s -check-prefix=PRINT-SEARCH-DIRS
 // PRINT-SEARCH-DIRS: programs: ={{.*}}
 // PRINT-SEARCH-DIRS: libraries: ={{.*}}
+
+// Test if the -print-resource-dir option is accepted without error.
+// Allow unspecified output because the value of CLANG_RESOURCE_DIR is unknown.
+// RUN: %clang -print-resource-dir | FileCheck %s -check-prefix=PRINT-RESOURCE-DIR
+// PRINT-RESOURCE-DIR: {{.*}}
+