fix pretty print for loop in mir and hir

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1950,7 +1950,6 @@ impl<'a> State<'a> {
                     self.word_space(":");
                 }
                 self.head("loop");
-                self.s.space();
                 self.print_block_with_attrs(blk, attrs);
             }
             ast::ExprKind::Match(ref expr, ref arms) => {

compiler/rustc_hir_pretty/src/lib.rs

@@ -1538,7 +1538,6 @@ impl<'a> State<'a> {
                     self.word_space(":");
                 }
                 self.head("loop");
-                self.s.space();
                 self.print_block(&blk);
             }
             hir::ExprKind::Match(ref expr, arms, _) => {

src/test/pretty/ast-stmt-expr-attr.rs

@@ -39,7 +39,7 @@ fn syntax() {
                     #![attr]
                 };
     let _ =
-        #[attr] loop  {
+        #[attr] loop {
                     #![attr]
                 };
     let _ =

src/test/pretty/hir-pretty-loop.pp

@@ -0,0 +1,9 @@
+#[prelude_import]
+use ::std::prelude::rust_2015::*;
+#[macro_use]
+extern crate std;
+// pretty-compare-only
+// pretty-mode:hir
+// pp-exact:hir-pretty-loop.pp
+
+pub fn foo() { loop { break ; } }

src/test/pretty/hir-pretty-loop.rs

@@ -0,0 +1,9 @@
+// pretty-compare-only
+// pretty-mode:hir
+// pp-exact:hir-pretty-loop.pp
+
+pub fn foo(){
+    loop{
+        break;
+    }
+}

src/test/pretty/stmt_expr_attributes.rs

@@ -159,9 +159,8 @@ fn _11() {
         #[rustc_dummy] for _ in 0..0 {
                            #![rustc_dummy]
                        };
-    // FIXME: pp bug, two spaces after the loop
     let _ =
-        #[rustc_dummy] loop  {
+        #[rustc_dummy] loop {
                            #![rustc_dummy]
                        };
     let _ = #[rustc_dummy] match false { _ => (), };