auto merge of #6105 : Aatch/rust/linker-improv, r=pcwalton

Adds two extra flags: `--linker` which takes extra flags to pass to the linker, can be used multiple times and `--print-link-args` which prints out linker arguments. Currently `--print-link-args` needs execution to get past translation to get the `LinkMeta` data.

I haven't done tests or updated any extra documentation yet, so this pull request is currently here for review.

diff --combined src/librustc/driver/driver.rs
index 2e64c0c45bffeb18099b6070eaeb9fcd4a44cce6,0a91c29d89071e1cabc1f9c3942d7e884a884370..8c053c265fa212500d2e4ecd69692bb77e260fe3
--- 1/src/librustc/driver/driver.rs
--- 2/src/librustc/driver/driver.rs
+++ b/src/librustc/driver/driver.rs
@@@ -149,7 -149,7 +149,7 @@@ pub fn parse_input(sess: Session, cfg: 
      -> @ast::crate {
      match *input {
        file_input(ref file) => {
 -        parse::parse_crate_from_file_using_tts(&(*file), cfg, sess.parse_sess)
 +        parse::parse_crate_from_file(&(*file), cfg, sess.parse_sess)
        }
        str_input(ref src) => {
          // FIXME (#2319): Don't really want to box the source string
@@@ -234,7 -234,6 +234,6 @@@ pub fn compile_rest(sess: Session
      let rp_set = time(time_passes, ~"region parameterization inference", ||
          middle::region::determine_rp_in_crate(sess, ast_map, def_map, crate));
  
- 
      let outputs = outputs.get();
  
      let (llmod, link_meta) = {
@@@ -309,6 -308,11 +308,11 @@@
  
      };
  
+     if (sess.opts.debugging_opts & session::print_link_args) != 0 {
+         io::println(str::connect(link::link_args(sess,
+             &outputs.obj_filename, &outputs.out_filename, link_meta), " "));
+     }
+ 
      // NB: Android hack
      if sess.targ_cfg.arch == abi::Arm &&
              (sess.opts.output_type == link::output_type_object ||
@@@ -645,13 -649,21 +649,21 @@@ pub fn build_session_options(binary: @~
          Some(s) => s
      };
  
-     let addl_lib_search_paths =
-         getopts::opt_strs(matches, ~"L")
-         .map(|s| Path(*s));
+     let addl_lib_search_paths = getopts::opt_strs(matches, ~"L").map(|s| Path(*s));
+ 
+     let linker_args = getopts::opt_strs(matches, ~"link-args").flat_map( |a| {
+         let mut args = ~[];
+         for str::each_split_char(*a, ',') |arg| {
+             args.push(str::from_slice(arg));
+         }
+         args
+     });
+ 
      let cfg = parse_cfgspecs(getopts::opt_strs(matches, ~"cfg"), demitter);
      let test = opt_present(matches, ~"test");
      let android_cross_path = getopts::opt_maybe_str(
          matches, ~"android-cross-path");
+ 
      let sopts = @session::options {
          crate_type: crate_type,
          is_static: static,
@@@ -664,6 -676,7 +676,7 @@@
          jit: jit,
          output_type: output_type,
          addl_lib_search_paths: addl_lib_search_paths,
+         linker_args: linker_args,
          maybe_sysroot: sysroot_opt,
          target_triple: target,
          target_feature: target_feature,
@@@ -737,62 -750,64 +750,64 @@@ pub fn parse_pretty(sess: Session, name
  // rustc command line options
  pub fn optgroups() -> ~[getopts::groups::OptGroup] {
   ~[
-   optflag(~"",  ~"bin", ~"Compile an executable crate (default)"),
-   optflag(~"c", ~"",    ~"Compile and assemble, but do not link"),
-   optmulti(~"", ~"cfg", ~"Configure the compilation
-                           environment", ~"SPEC"),
-   optflag(~"",  ~"emit-llvm",
-                         ~"Produce an LLVM bitcode file"),
-   optflag(~"h", ~"help",~"Display this message"),
-   optmulti(~"L", ~"",   ~"Add a directory to the library search path",
-                               ~"PATH"),
-   optflag(~"",  ~"lib", ~"Compile a library crate"),
-   optflag(~"",  ~"ls",  ~"List the symbols defined by a library crate"),
-   optflag(~"", ~"no-trans",
-                         ~"Run all passes except translation; no output"),
-   optflag(~"O", ~"",    ~"Equivalent to --opt-level=2"),
-   optopt(~"o", ~"",     ~"Write output to <filename>", ~"FILENAME"),
-   optopt(~"", ~"opt-level",
-                         ~"Optimize with possible levels 0-3", ~"LEVEL"),
-   optopt( ~"",  ~"out-dir",
-                         ~"Write output to compiler-chosen filename
-                           in <dir>", ~"DIR"),
-   optflag(~"", ~"parse-only",
-                         ~"Parse only; do not compile, assemble, or link"),
-   optflagopt(~"", ~"pretty",
-                         ~"Pretty-print the input instead of compiling;
+   optflag("",  "bin", "Compile an executable crate (default)"),
+   optflag("c", "",    "Compile and assemble, but do not link"),
+   optmulti("", "cfg", "Configure the compilation
+                           environment", "SPEC"),
+   optflag("",  "emit-llvm",
+                         "Produce an LLVM bitcode file"),
+   optflag("h", "help","Display this message"),
+   optmulti("L", "",   "Add a directory to the library search path",
+                               "PATH"),
+   optflag("",  "lib", "Compile a library crate"),
+   optmulti("",  "link-args", "FLAGS is a comma-separated list of flags
+                             passed to the linker", "FLAGS"),
+   optflag("",  "ls",  "List the symbols defined by a library crate"),
+   optflag("", "no-trans",
+                         "Run all passes except translation; no output"),
+   optflag("O", "",    "Equivalent to --opt-level=2"),
+   optopt("o", "",     "Write output to <filename>", "FILENAME"),
+   optopt("", "opt-level",
+                         "Optimize with possible levels 0-3", "LEVEL"),
+   optopt( "",  "out-dir",
+                         "Write output to compiler-chosen filename
+                           in <dir>", "DIR"),
+   optflag("", "parse-only",
+                         "Parse only; do not compile, assemble, or link"),
+   optflagopt("", "pretty",
+                         "Pretty-print the input instead of compiling;
                            valid types are: normal (un-annotated source),
                            expanded (crates expanded),
                            typed (crates expanded, with type annotations),
                            or identified (fully parenthesized,
-                           AST nodes and blocks with IDs)", ~"TYPE"),
-   optflag(~"S", ~"",    ~"Compile only; do not assemble or link"),
-   optflag(~"", ~"save-temps",
-                         ~"Write intermediate files (.bc, .opt.bc, .o)
+                           AST nodes and blocks with IDs)", "TYPE"),
+   optflag("S", "",    "Compile only; do not assemble or link"),
+   optflag("", "save-temps",
+                         "Write intermediate files (.bc, .opt.bc, .o)
                            in addition to normal output"),
-   optopt(~"", ~"sysroot",
-                         ~"Override the system root", ~"PATH"),
-   optflag(~"", ~"test", ~"Build a test harness"),
-   optopt(~"", ~"target",
-                         ~"Target triple cpu-manufacturer-kernel[-os]
+   optopt("", "sysroot",
+                         "Override the system root", "PATH"),
+   optflag("", "test", "Build a test harness"),
+   optopt("", "target",
+                         "Target triple cpu-manufacturer-kernel[-os]
                            to compile for (see chapter 3.4 of http://www.sourceware.org/autobook/
-                           for detail)", ~"TRIPLE"),
-   optopt(~"", ~"target-feature",
-                         ~"Target specific attributes (llc -mattr=help
-                           for detail)", ~"FEATURE"),
-   optopt(~"", ~"android-cross-path",
-          ~"The path to the Android NDK", "PATH"),
-   optmulti(~"W", ~"warn",
-                         ~"Set lint warnings", ~"OPT"),
-   optmulti(~"A", ~"allow",
-                         ~"Set lint allowed", ~"OPT"),
-   optmulti(~"D", ~"deny",
-                         ~"Set lint denied", ~"OPT"),
-   optmulti(~"F", ~"forbid",
-                         ~"Set lint forbidden", ~"OPT"),
-   optmulti(~"Z", ~"",   ~"Set internal debugging options", "FLAG"),
-   optflag( ~"v", ~"version",
-                         ~"Print version info and exit"),
+                           for detail)", "TRIPLE"),
+   optopt("", "target-feature",
+                         "Target specific attributes (llc -mattr=help
+                           for detail)", "FEATURE"),
+   optopt("", "android-cross-path",
+          "The path to the Android NDK", "PATH"),
+   optmulti("W", "warn",
+                         "Set lint warnings", "OPT"),
+   optmulti("A", "allow",
+                         "Set lint allowed", "OPT"),
+   optmulti("D", "deny",
+                         "Set lint denied", "OPT"),
+   optmulti("F", "forbid",
+                         "Set lint forbidden", "OPT"),
+   optmulti("Z", "",   "Set internal debugging options", "FLAG"),
+   optflag( "v", "version",
+                         "Print version info and exit"),
   ]
  }