auto merge of #7465 : alexcrichton/rust/issue-4432, r=cmr

This stems from trying to perform as few allocations as possible throughout the standard libraries.

This specializes the `ToStr` implementation for floats/ints separately because it's known that ints will have a maximum length (whereas floats could be very very large).

I also removed a `FIXME` to remove a malloc from the `to_str()` of floats in `repr.rs` because I think that this should be addressed elsewhere. I think that we may not be able to avoid it easily because floats can have such large representations, but regardless this should be a problem with the implementation of `float_to_str_bytes_common` now and not in the `Repr` module.

2 files changed, 12 insertions, 4 deletions

diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index 94147825da4..a50fa416832 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -16,7 +16,6 @@ use util::interner::StrInterner;
 use util::interner;
 
 use std::cast;
-use std::char;
 use std::cmp::Equiv;
 use std::local_data;
 use std::rand;
@@ -166,7 +165,12 @@ pub fn to_str(in: @ident_interner, t: &Token) -> ~str {
 
       /* Literals */
       LIT_INT(c, ast::ty_char) => {
-        ~"'" + char::escape_default(c as char) + "'"
+          let mut res = ~"'";
+          do (c as char).escape_default |c| {
+              res.push_char(c);
+          }
+          res.push_char('\'');
+          res
       }
       LIT_INT(i, t) => {
           i.to_str() + ast_util::int_ty_to_str(t)
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 978561eaa67..5e685d85f95 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -27,7 +27,6 @@ use print::pp::{breaks, consistent, inconsistent, eof};
 use print::pp;
 use print::pprust;
 
-use std::char;
 use std::io;
 use std::u64;
 use std::uint;
@@ -2016,7 +2015,12 @@ pub fn print_literal(s: @ps, lit: @ast::lit) {
     match lit.node {
       ast::lit_str(st) => print_string(s, st),
       ast::lit_int(ch, ast::ty_char) => {
-        word(s.s, ~"'" + char::escape_default(ch as char) + "'");
+          let mut res = ~"'";
+          do (ch as char).escape_default |c| {
+              res.push_char(c);
+          }
+          res.push_char('\'');
+          word(s.s, res);
       }
       ast::lit_int(i, t) => {
         if i < 0_i64 {