Don't pp extra lines after block open when preserving whitespace. Closes

 rust-lang#759

src/comp/syntax/print/pprust.rs

@@ -172,6 +172,20 @@ fn bclose_(s: &ps, span: codemap::span, indented: uint) {
 }
 fn bclose(s: &ps, span: codemap::span) { bclose_(s, span, indent_unit); }
 
+fn is_begin(s: &ps) -> bool {
+    alt s.s.last_token() {
+      pp::BEGIN(_) { true }
+      _ { false }
+    }
+}
+
+fn is_end(s: &ps) -> bool {
+    alt s.s.last_token() {
+      pp::END. { true }
+      _ { false }
+    }
+}
+
 fn is_bol(s: &ps) -> bool {
     ret s.s.last_token() == pp::EOF ||
         s.s.last_token() == pp::hardbreak_tok();
@@ -1403,7 +1417,7 @@ fn print_comment(s: &ps, cmnt: lexer::cmnt) {
       }
       lexer::blank_line. {
         // We need to do at least one, possibly two hardbreaks.
-        pprust::hardbreak_if_not_bol(s);
+        if is_begin(s) || is_end(s) { hardbreak(s.s) }
         hardbreak(s.s);
       }
     }

src/test/bench/shootout-fibo.rs

@@ -1,4 +1,3 @@
-// xfail-pretty
 
 
 // -*- rust -*-

src/test/bench/shootout-nbody.rs

@@ -1,4 +1,3 @@
-// xfail-pretty
 // based on:
 // http://shootout.alioth.debian.org/u32/benchmark.php?test=nbody&lang=java
 

src/test/bench/task-perf-word-count.rs

@@ -1,4 +1,3 @@
-// xfail-pretty
 /**
    A parallel word-frequency counting program.
 

src/test/pretty/empty-lines.rs

@@ -0,0 +1,7 @@
+// Issue #759
+// Whitespace under block opening should not expand forever
+
+fn a() -> uint {
+
+    1u
+}

src/test/run-pass/hashmap-memory.rs

@@ -1,4 +1,3 @@
-// xfail-pretty
 /**
    A somewhat reduced test case to expose some Valgrind issues.
 

src/test/run-pass/interior-vec.rs

@@ -1,4 +1,5 @@
 // xfail-stage0
+// xfail-pretty
 
 import rusti::ivec_len;
 

src/test/run-pass/issue-687.rs

@@ -1,5 +1,4 @@
 // xfail-stage0
-// xfail-pretty
 
 use std;
 import std::ivec;

src/test/run-pass/pattern-bound-var-in-for-each.rs

@@ -1,5 +1,4 @@
 // xfail-stage0
-// xfail-pretty
 // Tests that trans_path checks whether a
 // pattern-bound var is an upvar (when translating
 // the for-each body)

src/test/run-pass/while-prelude-drop.rs

@@ -1,4 +1,3 @@
-// xfail-pretty
 
 tag t { a; b(str); }