trans: overhaul match bindings. No more phi, one code path for guards.

Fixes #3256.
Fixes #3291.

Author: nikomatsakis

src/rustc/driver/session.rs

@@ -38,7 +38,7 @@ type config =
      uint_type: uint_ty,
      float_type: float_ty};
 
-const ppregions: uint = 1 << 0;
+const verbose: uint = 1 << 0;
 const time_passes: uint = 1 << 1;
 const count_llvm_insns: uint = 1 << 2;
 const time_llvm_passes: uint = 1 << 3;
@@ -60,8 +60,7 @@ const meta_stats: uint = 1 << 16;
 const no_opt: uint = 1 << 17;
 
 fn debugging_opts_map() -> ~[(~str, ~str, uint)] {
-    ~[(~"ppregions", ~"prettyprint regions with \
-                    internal repr details", ppregions),
+    ~[(~"verbose", ~"in general, enable more debug printouts", verbose),
      (~"time-passes", ~"measure time of each rustc pass", time_passes),
      (~"count-llvm-insns", ~"count where LLVM \
                            instrs originate", count_llvm_insns),
@@ -219,7 +218,7 @@ impl session {
     fn impossible_case(sp: span, msg: &str) -> ! {
         self.span_bug(sp, #fmt("Impossible case reached: %s", msg));
     }
-    fn ppregions() -> bool { self.debugging_opt(ppregions) }
+    fn verbose() -> bool { self.debugging_opt(verbose) }
     fn time_passes() -> bool { self.debugging_opt(time_passes) }
     fn count_llvm_insns() -> bool { self.debugging_opt(count_llvm_insns) }
     fn count_type_sizes() -> bool { self.debugging_opt(count_type_sizes) }

src/rustc/middle/pat_util.rs

@@ -6,14 +6,14 @@ use syntax::fold::*;
 use syntax::codemap::span;
 use std::map::HashMap;
 
-export pat_binding_ids, pat_bindings, pat_id_map;
-export pat_is_variant;
+export pat_binding_ids, pat_bindings, pat_id_map, PatIdMap;
+export pat_is_variant, pat_is_binding_or_wild;
 
-type pat_id_map = std::map::HashMap<ident, node_id>;
+type PatIdMap = std::map::HashMap<ident, node_id>;
 
 // This is used because same-named variables in alternative patterns need to
 // use the node_id of their namesake in the first pattern.
-fn pat_id_map(dm: resolve::DefMap, pat: @pat) -> pat_id_map {
+fn pat_id_map(dm: resolve::DefMap, pat: @pat) -> PatIdMap {
     let map = std::map::uint_hash();
     do pat_bindings(dm, pat) |_bm, p_id, _s, n| {
       map.insert(path_to_ident(n), p_id);
@@ -32,6 +32,14 @@ fn pat_is_variant(dm: resolve::DefMap, pat: @pat) -> bool {
     }
 }
 
+fn pat_is_binding_or_wild(dm: resolve::DefMap, pat: @pat) -> bool {
+    match pat.node {
+        pat_ident(*) => !pat_is_variant(dm, pat),
+        pat_wild => true,
+        _ => false
+    }
+}
+
 fn pat_bindings(dm: resolve::DefMap, pat: @pat,
                 it: fn(binding_mode, node_id, span, @path)) {
     do walk_pat(pat) |p| {