src/librustc_driver/pretty.rs

   1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! The various pretty print routines.
  12
  13 pub use self::UserIdentifiedItem::*;
  14 pub use self::PpSourceMode::*;
  15 pub use self::PpMode::*;
  16 use self::NodesMatchingUII::*;
  17
  18 use rustc_trans::back::link;
  19
  20 use driver;
  21
  22 use rustc::middle::ty;
  23 use rustc::middle::cfg;
  24 use rustc::middle::cfg::graphviz::LabelledCFG;
  25 use rustc::session::Session;
  26 use rustc::session::config::{self, Input};
  27 use rustc::util::ppaux;
  28 use rustc_borrowck as borrowck;
  29 use rustc_borrowck::graphviz as borrowck_dot;
  30
  31 use syntax::ast;
  32 use syntax::ast_map::{self, blocks, NodePrinter};
  33 use syntax::codemap;
  34 use syntax::fold::{self, Folder};
  35 use syntax::print::{pp, pprust};
  36 use syntax::ptr::P;
  37
  38 use graphviz as dot;
  39
  40 use std::io::{self, MemReader};
  41 use std::option;
  42 use std::str::FromStr;
  43
  44 #[derive(Copy, PartialEq, Show)]
  45 pub enum PpSourceMode {
  46     PpmNormal,
  47     PpmEveryBodyLoops,
  48     PpmExpanded,
  49     PpmTyped,
  50     PpmIdentified,
  51     PpmExpandedIdentified,
  52     PpmExpandedHygiene,
  53 }
  54
  55 #[derive(Copy, PartialEq, Show)]
  56 pub enum PpMode {
  57     PpmSource(PpSourceMode),
  58     PpmFlowGraph,
  59 }
  60
  61 pub fn parse_pretty(sess: &Session,
  62                     name: &str,
  63                     extended: bool) -> (PpMode, Option<UserIdentifiedItem>) {
  64     let mut split = name.splitn(1, '=');
  65     let first = split.next().unwrap();
  66     let opt_second = split.next();
  67     let first = match (first, extended) {
  68         ("normal", _)       => PpmSource(PpmNormal),
  69         ("everybody_loops", true) => PpmSource(PpmEveryBodyLoops),
  70         ("expanded", _)     => PpmSource(PpmExpanded),
  71         ("typed", _)        => PpmSource(PpmTyped),
  72         ("expanded,identified", _) => PpmSource(PpmExpandedIdentified),
  73         ("expanded,hygiene", _) => PpmSource(PpmExpandedHygiene),
  74         ("identified", _)   => PpmSource(PpmIdentified),
  75         ("flowgraph", true)    => PpmFlowGraph,
  76         _ => {
  77             if extended {
  78                 sess.fatal(format!(
  79                     "argument to `xpretty` must be one of `normal`, \
  80                      `expanded`, `flowgraph=<nodeid>`, `typed`, `identified`, \
  81                      `expanded,identified`, or `everybody_loops`; got {}", name).as_slice());
  82             } else {
  83                 sess.fatal(format!(
  84                     "argument to `pretty` must be one of `normal`, \
  85                      `expanded`, `typed`, `identified`, \
  86                      or `expanded,identified`; got {}", name).as_slice());
  87             }
  88         }
  89     };
  90     let opt_second = opt_second.and_then(|s| s.parse::<UserIdentifiedItem>());
  91     (first, opt_second)
  92 }
  93
  94
  95
  96 // This slightly awkward construction is to allow for each PpMode to
  97 // choose whether it needs to do analyses (which can consume the
  98 // Session) and then pass through the session (now attached to the
  99 // analysis results) on to the chosen pretty-printer, along with the
 100 // `&PpAnn` object.
 101 //
 102 // Note that since the `&PrinterSupport` is freshly constructed on each
 103 // call, it would not make sense to try to attach the lifetime of `self`
 104 // to the lifetime of the `&PrinterObject`.
 105 //
 106 // (The `use_once_payload` is working around the current lack of once
 107 // functions in the compiler.)
 108
 109 impl PpSourceMode {
 110     /// Constructs a `PrinterSupport` object and passes it to `f`.
 111     fn call_with_pp_support<'tcx, A, B, F>(&self,
 112                                            sess: Session,
 113                                            ast_map: Option<ast_map::Map<'tcx>>,
 114                                            arenas: &'tcx ty::CtxtArenas<'tcx>,
 115                                            id: String,
 116                                            payload: B,
 117                                            f: F) -> A where
 118         F: FnOnce(&PrinterSupport, B) -> A,
 119     {
 120         match *self {
 121             PpmNormal | PpmEveryBodyLoops | PpmExpanded => {
 122                 let annotation = NoAnn { sess: sess, ast_map: ast_map };
 123                 f(&annotation, payload)
 124             }
 125
 126             PpmIdentified | PpmExpandedIdentified => {
 127                 let annotation = IdentifiedAnnotation { sess: sess, ast_map: ast_map };
 128                 f(&annotation, payload)
 129             }
 130             PpmExpandedHygiene => {
 131                 let annotation = HygieneAnnotation { sess: sess, ast_map: ast_map };
 132                 f(&annotation, payload)
 133             }
 134             PpmTyped => {
 135                 let ast_map = ast_map.expect("--pretty=typed missing ast_map");
 136                 let analysis = driver::phase_3_run_analysis_passes(sess, ast_map, arenas, id);
 137                 let annotation = TypedAnnotation { analysis: analysis };
 138                 f(&annotation, payload)
 139             }
 140         }
 141     }
 142 }
 143
 144 trait PrinterSupport<'ast>: pprust::PpAnn {
 145     /// Provides a uniform interface for re-extracting a reference to a
 146     /// `Session` from a value that now owns it.
 147     fn sess<'a>(&'a self) -> &'a Session;
 148
 149     /// Provides a uniform interface for re-extracting a reference to an
 150     /// `ast_map::Map` from a value that now owns it.
 151     fn ast_map<'a>(&'a self) -> Option<&'a ast_map::Map<'ast>>;
 152
 153     /// Produces the pretty-print annotation object.
 154     ///
 155     /// (Rust does not yet support upcasting from a trait object to
 156     /// an object for one of its super-traits.)
 157     fn pp_ann<'a>(&'a self) -> &'a pprust::PpAnn;
 158 }
 159
 160 struct NoAnn<'ast> {
 161     sess: Session,
 162     ast_map: Option<ast_map::Map<'ast>>
 163 }
 164
 165 impl<'ast> PrinterSupport<'ast> for NoAnn<'ast> {
 166     fn sess<'a>(&'a self) -> &'a Session { &self.sess }
 167
 168     fn ast_map<'a>(&'a self) -> Option<&'a ast_map::Map<'ast>> {
 169         self.ast_map.as_ref()
 170     }
 171
 172     fn pp_ann<'a>(&'a self) -> &'a pprust::PpAnn { self }
 173 }
 174
 175 impl<'ast> pprust::PpAnn for NoAnn<'ast> {}
 176
 177 struct IdentifiedAnnotation<'ast> {
 178     sess: Session,
 179     ast_map: Option<ast_map::Map<'ast>>,
 180 }
 181
 182 impl<'ast> PrinterSupport<'ast> for IdentifiedAnnotation<'ast> {
 183     fn sess<'a>(&'a self) -> &'a Session { &self.sess }
 184
 185     fn ast_map<'a>(&'a self) -> Option<&'a ast_map::Map<'ast>> {
 186         self.ast_map.as_ref()
 187     }
 188
 189     fn pp_ann<'a>(&'a self) -> &'a pprust::PpAnn { self }
 190 }
 191
 192 impl<'ast> pprust::PpAnn for IdentifiedAnnotation<'ast> {
 193     fn pre(&self,
 194            s: &mut pprust::State,
 195            node: pprust::AnnNode) -> io::IoResult<()> {
 196         match node {
 197             pprust::NodeExpr(_) => s.popen(),
 198             _ => Ok(())
 199         }
 200     }
 201     fn post(&self,
 202             s: &mut pprust::State,
 203             node: pprust::AnnNode) -> io::IoResult<()> {
 204         match node {
 205             pprust::NodeIdent(_) | pprust::NodeName(_) => Ok(()),
 206
 207             pprust::NodeItem(item) => {
 208                 try!(pp::space(&mut s.s));
 209                 s.synth_comment(item.id.to_string())
 210             }
 211             pprust::NodeBlock(blk) => {
 212                 try!(pp::space(&mut s.s));
 213                 s.synth_comment(format!("block {}", blk.id))
 214             }
 215             pprust::NodeExpr(expr) => {
 216                 try!(pp::space(&mut s.s));
 217                 try!(s.synth_comment(expr.id.to_string()));
 218                 s.pclose()
 219             }
 220             pprust::NodePat(pat) => {
 221                 try!(pp::space(&mut s.s));
 222                 s.synth_comment(format!("pat {}", pat.id))
 223             }
 224         }
 225     }
 226 }
 227
 228 struct HygieneAnnotation<'ast> {
 229     sess: Session,
 230     ast_map: Option<ast_map::Map<'ast>>,
 231 }
 232
 233 impl<'ast> PrinterSupport<'ast> for HygieneAnnotation<'ast> {
 234     fn sess<'a>(&'a self) -> &'a Session { &self.sess }
 235
 236     fn ast_map<'a>(&'a self) -> Option<&'a ast_map::Map<'ast>> {
 237         self.ast_map.as_ref()
 238     }
 239
 240     fn pp_ann<'a>(&'a self) -> &'a pprust::PpAnn { self }
 241 }
 242
 243 impl<'ast> pprust::PpAnn for HygieneAnnotation<'ast> {
 244     fn post(&self,
 245             s: &mut pprust::State,
 246             node: pprust::AnnNode) -> io::IoResult<()> {
 247         match node {
 248             pprust::NodeIdent(&ast::Ident { name: ast::Name(nm), ctxt }) => {
 249                 try!(pp::space(&mut s.s));
 250                 // FIXME #16420: this doesn't display the connections
 251                 // between syntax contexts
 252                 s.synth_comment(format!("{}#{}", nm, ctxt))
 253             }
 254             pprust::NodeName(&ast::Name(nm)) => {
 255                 try!(pp::space(&mut s.s));
 256                 s.synth_comment(nm.to_string())
 257             }
 258             _ => Ok(())
 259         }
 260     }
 261 }
 262
 263
 264 struct TypedAnnotation<'tcx> {
 265     analysis: ty::CrateAnalysis<'tcx>,
 266 }
 267
 268 impl<'tcx> PrinterSupport<'tcx> for TypedAnnotation<'tcx> {
 269     fn sess<'a>(&'a self) -> &'a Session { &self.analysis.ty_cx.sess }
 270
 271     fn ast_map<'a>(&'a self) -> Option<&'a ast_map::Map<'tcx>> {
 272         Some(&self.analysis.ty_cx.map)
 273     }
 274
 275     fn pp_ann<'a>(&'a self) -> &'a pprust::PpAnn { self }
 276 }
 277
 278 impl<'tcx> pprust::PpAnn for TypedAnnotation<'tcx> {
 279     fn pre(&self,
 280            s: &mut pprust::State,
 281            node: pprust::AnnNode) -> io::IoResult<()> {
 282         match node {
 283             pprust::NodeExpr(_) => s.popen(),
 284             _ => Ok(())
 285         }
 286     }
 287     fn post(&self,
 288             s: &mut pprust::State,
 289             node: pprust::AnnNode) -> io::IoResult<()> {
 290         let tcx = &self.analysis.ty_cx;
 291         match node {
 292             pprust::NodeExpr(expr) => {
 293                 try!(pp::space(&mut s.s));
 294                 try!(pp::word(&mut s.s, "as"));
 295                 try!(pp::space(&mut s.s));
 296                 try!(pp::word(&mut s.s,
 297                               ppaux::ty_to_string(
 298                                   tcx,
 299                                   ty::expr_ty(tcx, expr))[]));
 300                 s.pclose()
 301             }
 302             _ => Ok(())
 303         }
 304     }
 305 }
 306
 307 fn gather_flowgraph_variants(sess: &Session) -> Vec<borrowck_dot::Variant> {
 308     let print_loans   = config::FLOWGRAPH_PRINT_LOANS;
 309     let print_moves   = config::FLOWGRAPH_PRINT_MOVES;
 310     let print_assigns = config::FLOWGRAPH_PRINT_ASSIGNS;
 311     let print_all     = config::FLOWGRAPH_PRINT_ALL;
 312     let opt = |&: print_which| sess.debugging_opt(print_which);
 313     let mut variants = Vec::new();
 314     if opt(print_all) || opt(print_loans) {
 315         variants.push(borrowck_dot::Loans);
 316     }
 317     if opt(print_all) || opt(print_moves) {
 318         variants.push(borrowck_dot::Moves);
 319     }
 320     if opt(print_all) || opt(print_assigns) {
 321         variants.push(borrowck_dot::Assigns);
 322     }
 323     variants
 324 }
 325
 326 #[derive(Clone, Show)]
 327 pub enum UserIdentifiedItem {
 328     ItemViaNode(ast::NodeId),
 329     ItemViaPath(Vec<String>),
 330 }
 331
 332 impl FromStr for UserIdentifiedItem {
 333     fn from_str(s: &str) -> Option<UserIdentifiedItem> {
 334         s.parse().map(ItemViaNode).or_else(|| {
 335             let v : Vec<_> = s.split_str("::")
 336                 .map(|x|x.to_string())
 337                 .collect();
 338             Some(ItemViaPath(v))
 339         })
 340     }
 341 }
 342
 343 enum NodesMatchingUII<'a, 'ast: 'a> {
 344     NodesMatchingDirect(option::IntoIter<ast::NodeId>),
 345     NodesMatchingSuffix(ast_map::NodesMatchingSuffix<'a, 'ast>),
 346 }
 347
 348 impl<'a, 'ast> Iterator for NodesMatchingUII<'a, 'ast> {
 349     type Item = ast::NodeId;
 350
 351     fn next(&mut self) -> Option<ast::NodeId> {
 352         match self {
 353             &NodesMatchingDirect(ref mut iter) => iter.next(),
 354             &NodesMatchingSuffix(ref mut iter) => iter.next(),
 355         }
 356     }
 357 }
 358
 359 impl UserIdentifiedItem {
 360     fn reconstructed_input(&self) -> String {
 361         match *self {
 362             ItemViaNode(node_id) => node_id.to_string(),
 363             ItemViaPath(ref parts) => parts.connect("::"),
 364         }
 365     }
 366
 367     fn all_matching_node_ids<'a, 'ast>(&'a self, map: &'a ast_map::Map<'ast>)
 368                                        -> NodesMatchingUII<'a, 'ast> {
 369         match *self {
 370             ItemViaNode(node_id) =>
 371                 NodesMatchingDirect(Some(node_id).into_iter()),
 372             ItemViaPath(ref parts) =>
 373                 NodesMatchingSuffix(map.nodes_matching_suffix(parts[])),
 374         }
 375     }
 376
 377     fn to_one_node_id(self, user_option: &str, sess: &Session, map: &ast_map::Map) -> ast::NodeId {
 378         let fail_because = |&: is_wrong_because| -> ast::NodeId {
 379             let message =
 380                 format!("{} needs NodeId (int) or unique \
 381                          path suffix (b::c::d); got {}, which {}",
 382                         user_option,
 383                         self.reconstructed_input(),
 384                         is_wrong_because);
 385             sess.fatal(message[])
 386         };
 387
 388         let mut saw_node = ast::DUMMY_NODE_ID;
 389         let mut seen = 0u;
 390         for node in self.all_matching_node_ids(map) {
 391             saw_node = node;
 392             seen += 1;
 393             if seen > 1 {
 394                 fail_because("does not resolve uniquely");
 395             }
 396         }
 397         if seen == 0 {
 398             fail_because("does not resolve to any item");
 399         }
 400
 401         assert!(seen == 1);
 402         return saw_node;
 403     }
 404 }
 405
 406 fn needs_ast_map(ppm: &PpMode, opt_uii: &Option<UserIdentifiedItem>) -> bool {
 407     match *ppm {
 408         PpmSource(PpmNormal) |
 409         PpmSource(PpmEveryBodyLoops) |
 410         PpmSource(PpmIdentified) => opt_uii.is_some(),
 411
 412         PpmSource(PpmExpanded) |
 413         PpmSource(PpmExpandedIdentified) |
 414         PpmSource(PpmExpandedHygiene) |
 415         PpmSource(PpmTyped) |
 416         PpmFlowGraph => true
 417     }
 418 }
 419
 420 fn needs_expansion(ppm: &PpMode) -> bool {
 421     match *ppm {
 422         PpmSource(PpmNormal) |
 423         PpmSource(PpmEveryBodyLoops) |
 424         PpmSource(PpmIdentified) => false,
 425
 426         PpmSource(PpmExpanded) |
 427         PpmSource(PpmExpandedIdentified) |
 428         PpmSource(PpmExpandedHygiene) |
 429         PpmSource(PpmTyped) |
 430         PpmFlowGraph => true
 431     }
 432 }
 433
 434 struct ReplaceBodyWithLoop {
 435     within_static_or_const: bool,
 436 }
 437
 438 impl ReplaceBodyWithLoop {
 439     fn new() -> ReplaceBodyWithLoop {
 440         ReplaceBodyWithLoop { within_static_or_const: false }
 441     }
 442 }
 443
 444 impl fold::Folder for ReplaceBodyWithLoop {
 445     fn fold_item_underscore(&mut self, i: ast::Item_) -> ast::Item_ {
 446         match i {
 447             ast::ItemStatic(..) | ast::ItemConst(..) => {
 448                 self.within_static_or_const = true;
 449                 let ret = fold::noop_fold_item_underscore(i, self);
 450                 self.within_static_or_const = false;
 451                 return ret;
 452             }
 453             _ => {
 454                 fold::noop_fold_item_underscore(i, self)
 455             }
 456         }
 457     }
 458
 459
 460     fn fold_block(&mut self, b: P<ast::Block>) -> P<ast::Block> {
 461         fn expr_to_block(rules: ast::BlockCheckMode,
 462                          e: Option<P<ast::Expr>>) -> P<ast::Block> {
 463             P(ast::Block {
 464                 expr: e,
 465                 view_items: vec![], stmts: vec![], rules: rules,
 466                 id: ast::DUMMY_NODE_ID, span: codemap::DUMMY_SP,
 467             })
 468         }
 469
 470         if !self.within_static_or_const {
 471
 472             let empty_block = expr_to_block(ast::DefaultBlock, None);
 473             let loop_expr = P(ast::Expr {
 474                 node: ast::ExprLoop(empty_block, None),
 475                 id: ast::DUMMY_NODE_ID, span: codemap::DUMMY_SP
 476             });
 477
 478             expr_to_block(b.rules, Some(loop_expr))
 479
 480         } else {
 481             fold::noop_fold_block(b, self)
 482         }
 483     }
 484
 485     // in general the pretty printer processes unexpanded code, so
 486     // we override the default `fold_mac` method which panics.
 487     fn fold_mac(&mut self, _macro: ast::Mac) -> ast::Mac {
 488         fold::noop_fold_mac(_macro, self)
 489     }
 490 }
 491
 492 pub fn pretty_print_input(sess: Session,
 493                           cfg: ast::CrateConfig,
 494                           input: &Input,
 495                           ppm: PpMode,
 496                           opt_uii: Option<UserIdentifiedItem>,
 497                           ofile: Option<Path>) {
 498     let krate = driver::phase_1_parse_input(&sess, cfg, input);
 499
 500     let krate = if let PpmSource(PpmEveryBodyLoops) = ppm {
 501         let mut fold = ReplaceBodyWithLoop::new();
 502         fold.fold_crate(krate)
 503     } else {
 504         krate
 505     };
 506
 507     let id = link::find_crate_name(Some(&sess), krate.attrs.as_slice(), input);
 508
 509     let is_expanded = needs_expansion(&ppm);
 510     let compute_ast_map = needs_ast_map(&ppm, &opt_uii);
 511     let krate = if compute_ast_map {
 512         match driver::phase_2_configure_and_expand(&sess, krate, id[], None) {
 513             None => return,
 514             Some(k) => k
 515         }
 516     } else {
 517         krate
 518     };
 519
 520     let mut forest = ast_map::Forest::new(krate);
 521     let arenas = ty::CtxtArenas::new();
 522
 523     let (krate, ast_map) = if compute_ast_map {
 524         let map = driver::assign_node_ids_and_map(&sess, &mut forest);
 525         (map.krate(), Some(map))
 526     } else {
 527         (forest.krate(), None)
 528     };
 529
 530     let src_name = driver::source_name(input);
 531     let src = sess.codemap().get_filemap(src_name[])
 532                             .src.as_bytes().to_vec();
 533     let mut rdr = MemReader::new(src);
 534
 535     let out = match ofile {
 536         None => box io::stdout() as Box<Writer+'static>,
 537         Some(p) => {
 538             let r = io::File::create(&p);
 539             match r {
 540                 Ok(w) => box w as Box<Writer+'static>,
 541                 Err(e) => panic!("print-print failed to open {} due to {}",
 542                                 p.display(), e),
 543             }
 544         }
 545     };
 546
 547     match (ppm, opt_uii) {
 548         (PpmSource(s), None) =>
 549             s.call_with_pp_support(
 550                 sess, ast_map, &arenas, id, out, |annotation, out| {
 551                     debug!("pretty printing source code {}", s);
 552                     let sess = annotation.sess();
 553                     pprust::print_crate(sess.codemap(),
 554                                         sess.diagnostic(),
 555                                         krate,
 556                                         src_name.to_string(),
 557                                         &mut rdr,
 558                                         out,
 559                                         annotation.pp_ann(),
 560                                         is_expanded)
 561                 }),
 562
 563         (PpmSource(s), Some(uii)) =>
 564             s.call_with_pp_support(
 565                 sess, ast_map, &arenas, id, (out,uii), |annotation, (out,uii)| {
 566                     debug!("pretty printing source code {}", s);
 567                     let sess = annotation.sess();
 568                     let ast_map = annotation.ast_map()
 569                         .expect("--pretty missing ast_map");
 570                     let mut pp_state =
 571                         pprust::State::new_from_input(sess.codemap(),
 572                                                       sess.diagnostic(),
 573                                                       src_name.to_string(),
 574                                                       &mut rdr,
 575                                                       out,
 576                                                       annotation.pp_ann(),
 577                                                       is_expanded);
 578                     for node_id in uii.all_matching_node_ids(ast_map) {
 579                         let node = ast_map.get(node_id);
 580                         try!(pp_state.print_node(&node));
 581                         try!(pp::space(&mut pp_state.s));
 582                         try!(pp_state.synth_comment(ast_map.path_to_string(node_id)));
 583                         try!(pp::hardbreak(&mut pp_state.s));
 584                     }
 585                     pp::eof(&mut pp_state.s)
 586                 }),
 587
 588         (PpmFlowGraph, opt_uii) => {
 589             debug!("pretty printing flow graph for {}", opt_uii);
 590             let uii = opt_uii.unwrap_or_else(|| {
 591                 sess.fatal(format!("`pretty flowgraph=..` needs NodeId (int) or
 592                                      unique path suffix (b::c::d)")[])
 593
 594             });
 595             let ast_map = ast_map.expect("--pretty flowgraph missing ast_map");
 596             let nodeid = uii.to_one_node_id("--pretty", &sess, &ast_map);
 597
 598             let node = ast_map.find(nodeid).unwrap_or_else(|| {
 599                 sess.fatal(format!("--pretty flowgraph couldn't find id: {}",
 600                                    nodeid)[])
 601             });
 602
 603             let code = blocks::Code::from_node(node);
 604             match code {
 605                 Some(code) => {
 606                     let variants = gather_flowgraph_variants(&sess);
 607                     let analysis = driver::phase_3_run_analysis_passes(sess, ast_map, &arenas, id);
 608                     print_flowgraph(variants, analysis, code, out)
 609                 }
 610                 None => {
 611                     let message = format!("--pretty=flowgraph needs \
 612                                            block, fn, or method; got {}",
 613                                           node);
 614
 615                     // point to what was found, if there's an
 616                     // accessible span.
 617                     match ast_map.opt_span(nodeid) {
 618                         Some(sp) => sess.span_fatal(sp, message[]),
 619                         None => sess.fatal(message[])
 620                     }
 621                 }
 622             }
 623         }
 624     }.unwrap()
 625 }
 626
 627 fn print_flowgraph<W:io::Writer>(variants: Vec<borrowck_dot::Variant>,
 628                                  analysis: ty::CrateAnalysis,
 629                                  code: blocks::Code,
 630                                  mut out: W) -> io::IoResult<()> {
 631     let ty_cx = &analysis.ty_cx;
 632     let cfg = match code {
 633         blocks::BlockCode(block) => cfg::CFG::new(ty_cx, &*block),
 634         blocks::FnLikeCode(fn_like) => cfg::CFG::new(ty_cx, &*fn_like.body()),
 635     };
 636
 637     match code {
 638         _ if variants.len() == 0 => {
 639             let lcfg = LabelledCFG {
 640                 ast_map: &ty_cx.map,
 641                 cfg: &cfg,
 642                 name: format!("node_{}", code.id()),
 643             };
 644             let r = dot::render(&lcfg, &mut out);
 645             return expand_err_details(r);
 646         }
 647         blocks::BlockCode(_) => {
 648             ty_cx.sess.err("--pretty flowgraph with -Z flowgraph-print \
 649                             annotations requires fn-like node id.");
 650             return Ok(())
 651         }
 652         blocks::FnLikeCode(fn_like) => {
 653             let fn_parts = borrowck::FnPartsWithCFG::from_fn_like(&fn_like, &cfg);
 654             let (bccx, analysis_data) =
 655                 borrowck::build_borrowck_dataflow_data_for_fn(ty_cx, fn_parts);
 656
 657             let lcfg = LabelledCFG {
 658                 ast_map: &ty_cx.map,
 659                 cfg: &cfg,
 660                 name: format!("node_{}", code.id()),
 661             };
 662             let lcfg = borrowck_dot::DataflowLabeller {
 663                 inner: lcfg,
 664                 variants: variants,
 665                 borrowck_ctxt: &bccx,
 666                 analysis_data: &analysis_data,
 667             };
 668             let r = dot::render(&lcfg, &mut out);
 669             return expand_err_details(r);
 670         }
 671     }
 672
 673     fn expand_err_details(r: io::IoResult<()>) -> io::IoResult<()> {
 674         r.map_err(|ioerr| {
 675             let orig_detail = ioerr.detail.clone();
 676             let m = "graphviz::render failed";
 677             io::IoError {
 678                 detail: Some(match orig_detail {
 679                     None => m.to_string(),
 680                     Some(d) => format!("{}: {}", m, d)
 681                 }),
 682                 ..ioerr
 683             }
 684         })
 685     }
 686 }