add --xpretty flowgraph,unlabelled variant.

src/librustc/middle/cfg/graphviz.rs

@@ -28,6 +28,8 @@ pub struct LabelledCFG<'a, 'ast: 'a> {
     pub ast_map: &'a ast_map::Map<'ast>,
     pub cfg: &'a cfg::CFG,
     pub name: String,
+    /// `labelled_edges` controls whether we emit labels on the edges
+    pub labelled_edges: bool,
 }
 
 fn replace_newline_with_backslash_l(s: String) -> String {
@@ -75,6 +77,9 @@ impl<'a, 'ast> dot::Labeller<'a, Node<'a>, Edge<'a>> for LabelledCFG<'a, 'ast> {
 
     fn edge_label(&self, e: &Edge<'a>) -> dot::LabelText<'a> {
         let mut label = String::new();
+        if !self.labelled_edges {
+            return dot::LabelText::EscStr(label.into_cow());
+        }
         let mut put_one = false;
         for (i, &node_id) in e.data.exiting_scopes.iter().enumerate() {
             if put_one {

src/librustc_driver/pretty.rs

@@ -53,10 +53,20 @@ pub enum PpSourceMode {
     PpmExpandedHygiene,
 }
 
+
+#[derive(Copy, PartialEq, Show)]
+pub enum PpFlowGraphMode {
+    Default,
+    /// Drops the labels from the edges in the flowgraph output. This
+    /// is mostly for use in the --xpretty flowgraph run-make tests,
+    /// since the labels are largely uninteresting in those cases and
+    /// have become a pain to maintain.
+    UnlabelledEdges,
+}
 #[derive(Copy, PartialEq, Show)]
 pub enum PpMode {
     PpmSource(PpSourceMode),
-    PpmFlowGraph,
+    PpmFlowGraph(PpFlowGraphMode),
 }
 
 pub fn parse_pretty(sess: &Session,
@@ -73,12 +83,13 @@ pub fn parse_pretty(sess: &Session,
         ("expanded,identified", _) => PpmSource(PpmExpandedIdentified),
         ("expanded,hygiene", _) => PpmSource(PpmExpandedHygiene),
         ("identified", _)   => PpmSource(PpmIdentified),
-        ("flowgraph", true)    => PpmFlowGraph,
+        ("flowgraph", true)    => PpmFlowGraph(PpFlowGraphMode::Default),
+        ("flowgraph,unlabelled", true)    => PpmFlowGraph(PpFlowGraphMode::UnlabelledEdges),
         _ => {
             if extended {
                 sess.fatal(format!(
                     "argument to `xpretty` must be one of `normal`, \
-                     `expanded`, `flowgraph=<nodeid>`, `typed`, `identified`, \
+                     `expanded`, `flowgraph[,unlabelled]=<nodeid>`, `typed`, `identified`, \
                      `expanded,identified`, or `everybody_loops`; got {}", name).as_slice());
             } else {
                 sess.fatal(format!(
@@ -417,7 +428,7 @@ fn needs_ast_map(ppm: &PpMode, opt_uii: &Option<UserIdentifiedItem>) -> bool {
         PpmSource(PpmExpandedIdentified) |
         PpmSource(PpmExpandedHygiene) |
         PpmSource(PpmTyped) |
-        PpmFlowGraph => true
+        PpmFlowGraph(_) => true
     }
 }
 
@@ -431,7 +442,7 @@ fn needs_expansion(ppm: &PpMode) -> bool {
         PpmSource(PpmExpandedIdentified) |
         PpmSource(PpmExpandedHygiene) |
         PpmSource(PpmTyped) |
-        PpmFlowGraph => true
+        PpmFlowGraph(_) => true
     }
 }
 
@@ -589,7 +600,7 @@ pub fn pretty_print_input(sess: Session,
                     pp::eof(&mut pp_state.s)
                 }),
 
-        (PpmFlowGraph, opt_uii) => {
+        (PpmFlowGraph(mode), opt_uii) => {
             debug!("pretty printing flow graph for {:?}", opt_uii);
             let uii = opt_uii.unwrap_or_else(|| {
                 sess.fatal(&format!("`pretty flowgraph=..` needs NodeId (int) or
@@ -613,7 +624,7 @@ pub fn pretty_print_input(sess: Session,
                                                                        &arenas,
                                                                        id,
                                                                        resolve::MakeGlobMap::No);
-                    print_flowgraph(variants, analysis, code, out)
+                    print_flowgraph(variants, analysis, code, mode, out)
                 }
                 None => {
                     let message = format!("--pretty=flowgraph needs \
@@ -635,20 +646,23 @@ pub fn pretty_print_input(sess: Session,
 fn print_flowgraph<W:io::Writer>(variants: Vec<borrowck_dot::Variant>,
                                  analysis: ty::CrateAnalysis,
                                  code: blocks::Code,
+                                 mode: PpFlowGraphMode,
                                  mut out: W) -> io::IoResult<()> {
     let ty_cx = &analysis.ty_cx;
     let cfg = match code {
         blocks::BlockCode(block) => cfg::CFG::new(ty_cx, &*block),
         blocks::FnLikeCode(fn_like) => cfg::CFG::new(ty_cx, &*fn_like.body()),
     };
+    let labelled_edges = mode != PpFlowGraphMode::UnlabelledEdges;
+    let lcfg = LabelledCFG {
+        ast_map: &ty_cx.map,
+        cfg: &cfg,
+        name: format!("node_{}", code.id()),
+        labelled_edges: labelled_edges,
+    };
 
     match code {
         _ if variants.len() == 0 => {
-            let lcfg = LabelledCFG {
-                ast_map: &ty_cx.map,
-                cfg: &cfg,
-                name: format!("node_{}", code.id()),
-            };
             let r = dot::render(&lcfg, &mut out);
             return expand_err_details(r);
         }
@@ -662,11 +676,6 @@ fn print_flowgraph<W:io::Writer>(variants: Vec<borrowck_dot::Variant>,
             let (bccx, analysis_data) =
                 borrowck::build_borrowck_dataflow_data_for_fn(ty_cx, fn_parts);
 
-            let lcfg = LabelledCFG {
-                ast_map: &ty_cx.map,
-                cfg: &cfg,
-                name: format!("node_{}", code.id()),
-            };
             let lcfg = borrowck_dot::DataflowLabeller {
                 inner: lcfg,
                 variants: variants,