From e9b2487db73a6088267650538f20d12c5a5dbf33 Mon Sep 17 00:00:00 2001
From: Marijn Haverbeke <marijnh@gmail.com>
Date: Wed, 27 Jul 2011 13:48:28 +0200
Subject: [PATCH] Have the pretty-printer parentesize unary ops when needed

---
 src/comp/syntax/print/pprust.rs | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/comp/syntax/print/pprust.rs b/src/comp/syntax/print/pprust.rs
index 4ee25df2607..0a83f826c49 100644
--- a/src/comp/syntax/print/pprust.rs
+++ b/src/comp/syntax/print/pprust.rs
@@ -741,7 +741,7 @@ fn print_expr(&ps s, &@ast::expr expr) {
             word(s.s, "}");
         }
         case (ast::expr_call(?func, ?args)) {
-            print_expr(s, func);
+            print_expr_parens_if_unary(s, func);
             popen(s);
             commasep_exprs(s, inconsistent, args);
             pclose(s);
@@ -909,12 +909,12 @@ fn print_expr(&ps s, &@ast::expr expr) {
             print_expr(s, rhs);
         }
         case (ast::expr_field(?expr, ?id)) {
-            print_expr(s, expr);
+            print_expr_parens_if_unary(s, expr);
             word(s.s, ".");
             word(s.s, id);
         }
         case (ast::expr_index(?expr, ?index)) {
-            print_expr(s, expr);
+            print_expr_parens_if_unary(s, expr);
             word(s.s, ".");
             popen(s);
             print_expr(s, index);
@@ -1051,6 +1051,16 @@ fn print_expr(&ps s, &@ast::expr expr) {
     end(s);
 }
 
+fn print_expr_parens_if_unary(&ps s, &@ast::expr ex) {
+    auto parens = alt ex.node {
+      ast::expr_unary(_, _) { true }
+      _ { false }
+    };
+    if parens { popen(s); }
+    print_expr(s, ex);
+    if parens { pclose(s); }
+}
+
 fn print_decl(&ps s, &@ast::decl decl) {
     maybe_print_comment(s, decl.span.lo);
     alt (decl.node) {