Rewrite exhaustiveness checker

Issue #2111

src/librustsyntax/ast_util.rs

@@ -102,7 +102,6 @@ fn unop_to_str(op: unop) -> str {
       deref { ret "*"; }
       not { ret "!"; }
       neg { ret "-"; }
-      addr_of { ret "&"; }
     }
 }
 

src/librustsyntax/ext/fmt.rs

@@ -190,7 +190,6 @@ fn pieces_to_expr(cx: ext_ctxt, sp: span, pieces: [piece], args: [@ast::expr])
           ty_octal { ret make_conv_call(cx, arg.span, "uint", cnv, arg); }
           ty_float { ret make_conv_call(cx, arg.span, "float", cnv, arg); }
           ty_poly { ret make_conv_call(cx, arg.span, "poly", cnv, arg); }
-          _ { cx.span_unimpl(sp, unsupported); }
         }
     }
     fn log_conv(c: conv) {

src/libstd/net.rs

@@ -17,7 +17,6 @@ fn format_addr(ip: ip_addr) -> str {
       ipv4(a, b, c, d) {
         #fmt["%u.%u.%u.%u", a as uint, b as uint, c as uint, d as uint]
       }
-      _ { fail "Unsupported address type"; }
     }
 }
 

src/rustc/driver/driver.rs

@@ -25,7 +25,7 @@ fn default_configuration(sess: session, argv0: str, input: str) ->
       session::os_macos { "libc.dylib" }
       session::os_linux { "libc.so.6" }
       session::os_freebsd { "libc.so.7" }
-      _ { "libc.so" }
+      // _ { "libc.so" }
     };
 
     let mk = attr::mk_name_value_item_str;