Update the compiler to not use printf/printfln

80 files changed, 170 insertions, 174 deletions

diff --git a/src/libextra/base64.rs b/src/libextra/base64.rs
index f26554c42f4..7a113f1a292 100644
--- a/src/libextra/base64.rs
+++ b/src/libextra/base64.rs
@@ -68,7 +68,7 @@ impl<'self> ToBase64 for &'self [u8] {
      *
      * fn main () {
      *     let str = [52,32].to_base64(standard);
-     *     printfln!("%s", str);
+     *     println!("{}", str);
      * }
      * ```
      */
@@ -177,11 +177,11 @@ impl<'self> FromBase64 for &'self str {
      *
      * fn main () {
      *     let hello_str = "Hello, World".to_base64(standard);
-     *     printfln!("%s", hello_str);
+     *     println!("{}", hello_str);
      *     let bytes = hello_str.from_base64();
-     *     printfln!("%?", bytes);
+     *     println!("{:?}", bytes);
      *     let result_str = str::from_utf8(bytes);
-     *     printfln!("%s", result_str);
+     *     println!("{}", result_str);
      * }
      * ```
      */
diff --git a/src/libextra/future.rs b/src/libextra/future.rs
index 72c6db6fb72..fdb296e5f40 100644
--- a/src/libextra/future.rs
+++ b/src/libextra/future.rs
@@ -19,7 +19,7 @@
  * # fn make_a_sandwich() {};
  * let mut delayed_fib = extra::future::spawn (|| fib(5000) );
  * make_a_sandwich();
- * printfln!("fib(5000) = %?", delayed_fib.get())
+ * println!("fib(5000) = {}", delayed_fib.get())
  * ```
  */
 
diff --git a/src/libextra/getopts.rs b/src/libextra/getopts.rs
index f73c34224ee..aa37c78cc57 100644
--- a/src/libextra/getopts.rs
+++ b/src/libextra/getopts.rs
@@ -43,7 +43,7 @@
 //! }
 //!
 //! fn print_usage(program: &str, _opts: &[Opt]) {
-//!     printfln!("Usage: %s [options]", program);
+//!     println!("Usage: {} [options]", program);
 //!     println("-o\t\tOutput");
 //!     println("-h --help\tUsage");
 //! }
diff --git a/src/libextra/hex.rs b/src/libextra/hex.rs
index d5b89cafced..ad812513f84 100644
--- a/src/libextra/hex.rs
+++ b/src/libextra/hex.rs
@@ -33,7 +33,7 @@ impl<'self> ToHex for &'self [u8] {
      *
      * fn main () {
      *     let str = [52,32].to_hex();
-     *     printfln!("%s", str);
+     *     println!("{}", str);
      * }
      * ```
      */
@@ -77,11 +77,11 @@ impl<'self> FromHex for &'self str {
      *
      * fn main () {
      *     let hello_str = "Hello, World".to_hex();
-     *     printfln!("%s", hello_str);
+     *     println!("{}", hello_str);
      *     let bytes = hello_str.from_hex().unwrap();
-     *     printfln!("%?", bytes);
+     *     println!("{:?}", bytes);
      *     let result_str = str::from_utf8(bytes);
-     *     printfln!("%s", result_str);
+     *     println!("{}", result_str);
      * }
      * ```
      */
diff --git a/src/libextra/task_pool.rs b/src/libextra/task_pool.rs
index 46244c15a83..804ccd2a9fd 100644
--- a/src/libextra/task_pool.rs
+++ b/src/libextra/task_pool.rs
@@ -103,6 +103,6 @@ fn test_task_pool() {
     };
     let mut pool = TaskPool::new(4, Some(SingleThreaded), f);
     do 8.times {
-        pool.execute(|i| printfln!("Hello from thread %u!", *i));
+        pool.execute(|i| println!("Hello from thread {}!", *i));
     }
 }
diff --git a/src/librust/rust.rs b/src/librust/rust.rs
index 6ebce51b29f..dcbeb03caef 100644
--- a/src/librust/rust.rs
+++ b/src/librust/rust.rs
@@ -136,13 +136,13 @@ fn cmd_help(args: &[~str]) -> ValidUsage {
         match find_cmd(command_string) {
             Some(command) => {
                 match command.action {
-                    CallMain(prog, _) => printfln!(
-                        "The %s command is an alias for the %s program.",
+                    CallMain(prog, _) => println!(
+                        "The {} command is an alias for the {} program.",
                         command.cmd, prog),
                     _       => ()
                 }
                 match command.usage_full {
-                    UsgStr(msg) => printfln!("%s\n", msg),
+                    UsgStr(msg) => println!("{}\n", msg),
                     UsgCall(f)  => f(),
                 }
                 Valid(0)
@@ -215,7 +215,7 @@ fn usage() {
 
     for command in COMMANDS.iter() {
         let padding = " ".repeat(INDENT - command.cmd.len());
-        printfln!("    %s%s%s", command.cmd, padding, command.usage_line);
+        println!("    {}{}{}", command.cmd, padding, command.usage_line);
     }
 
     io::print(
diff --git a/src/librustc/metadata/encoder.rs b/src/librustc/metadata/encoder.rs
index de60927f2a2..a32b2123328 100644
--- a/src/librustc/metadata/encoder.rs
+++ b/src/librustc/metadata/encoder.rs
@@ -1822,17 +1822,17 @@ pub fn encode_metadata(parms: EncodeParams, crate: &Crate) -> ~[u8] {
         }
 
         io::println("metadata stats:");
-        printfln!("    inline bytes: %u", ecx.stats.inline_bytes);
-        printfln!(" attribute bytes: %u", ecx.stats.attr_bytes);
-        printfln!("       dep bytes: %u", ecx.stats.dep_bytes);
-        printfln!(" lang item bytes: %u", ecx.stats.lang_item_bytes);
-        printfln!(" link args bytes: %u", ecx.stats.link_args_bytes);
-        printfln!("      impl bytes: %u", ecx.stats.impl_bytes);
-        printfln!("      misc bytes: %u", ecx.stats.misc_bytes);
-        printfln!("      item bytes: %u", ecx.stats.item_bytes);
-        printfln!("     index bytes: %u", ecx.stats.index_bytes);
-        printfln!("      zero bytes: %u", ecx.stats.zero_bytes);
-        printfln!("     total bytes: %u", ecx.stats.total_bytes);
+        println!("    inline bytes: {}", ecx.stats.inline_bytes);
+        println!(" attribute bytes: {}", ecx.stats.attr_bytes);
+        println!("       dep bytes: {}", ecx.stats.dep_bytes);
+        println!(" lang item bytes: {}", ecx.stats.lang_item_bytes);
+        println!(" link args bytes: {}", ecx.stats.link_args_bytes);
+        println!("      impl bytes: {}", ecx.stats.impl_bytes);
+        println!("      misc bytes: {}", ecx.stats.misc_bytes);
+        println!("      item bytes: {}", ecx.stats.item_bytes);
+        println!("     index bytes: {}", ecx.stats.index_bytes);
+        println!("      zero bytes: {}", ecx.stats.zero_bytes);
+        println!("     total bytes: {}", ecx.stats.total_bytes);
     }
 
     // Pad this, since something (LLVM, presumably) is cutting off the
diff --git a/src/librustc/middle/borrowck/mod.rs b/src/librustc/middle/borrowck/mod.rs
index 852f1a53303..8b9dc40777a 100644
--- a/src/librustc/middle/borrowck/mod.rs
+++ b/src/librustc/middle/borrowck/mod.rs
@@ -100,16 +100,16 @@ pub fn check_crate(
 
     if tcx.sess.borrowck_stats() {
         io::println("--- borrowck stats ---");
-        printfln!("paths requiring guarantees: %u",
-                  bccx.stats.guaranteed_paths);
-        printfln!("paths requiring loans     : %s",
-                  make_stat(bccx, bccx.stats.loaned_paths_same));
-        printfln!("paths requiring imm loans : %s",
-                  make_stat(bccx, bccx.stats.loaned_paths_imm));
-        printfln!("stable paths              : %s",
-                  make_stat(bccx, bccx.stats.stable_paths));
-        printfln!("paths requiring purity    : %s",
-                  make_stat(bccx, bccx.stats.req_pure_paths));
+        println!("paths requiring guarantees: {}",
+                 bccx.stats.guaranteed_paths);
+        println!("paths requiring loans     : {}",
+                 make_stat(bccx, bccx.stats.loaned_paths_same));
+        println!("paths requiring imm loans : {}",
+                 make_stat(bccx, bccx.stats.loaned_paths_imm));
+        println!("stable paths              : {}",
+                 make_stat(bccx, bccx.stats.stable_paths));
+        println!("paths requiring purity    : {}",
+                 make_stat(bccx, bccx.stats.req_pure_paths));
     }
 
     return (bccx.root_map, bccx.write_guard_map);
diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
index 479f10a3b4a..04873dfa6ae 100644
--- a/src/librustc/middle/trans/base.rs
+++ b/src/librustc/middle/trans/base.rs
@@ -121,7 +121,7 @@ impl Drop for _InsnCtxt {
 }
 
 pub fn push_ctxt(s: &'static str) -> _InsnCtxt {
-    debug!("new InsnCtxt: %s", s);
+    debug2!("new InsnCtxt: {}", s);
     do local_data::modify(task_local_insn_key) |c| {
         do c.map_move |ctx| {
             let mut ctx = (*ctx).clone();
@@ -3156,15 +3156,15 @@ pub fn trans_crate(sess: session::Session,
     write_metadata(ccx, crate);
     if ccx.sess.trans_stats() {
         io::println("--- trans stats ---");
-        printfln!("n_static_tydescs: %u", ccx.stats.n_static_tydescs);
-        printfln!("n_glues_created: %u", ccx.stats.n_glues_created);
-        printfln!("n_null_glues: %u", ccx.stats.n_null_glues);
-        printfln!("n_real_glues: %u", ccx.stats.n_real_glues);
-
-        printfln!("n_fns: %u", ccx.stats.n_fns);
-        printfln!("n_monos: %u", ccx.stats.n_monos);
-        printfln!("n_inlines: %u", ccx.stats.n_inlines);
-        printfln!("n_closures: %u", ccx.stats.n_closures);
+        println!("n_static_tydescs: {}", ccx.stats.n_static_tydescs);
+        println!("n_glues_created: {}", ccx.stats.n_glues_created);
+        println!("n_null_glues: {}", ccx.stats.n_null_glues);
+        println!("n_real_glues: {}", ccx.stats.n_real_glues);
+
+        println!("n_fns: {}", ccx.stats.n_fns);
+        println!("n_monos: {}", ccx.stats.n_monos);
+        println!("n_inlines: {}", ccx.stats.n_inlines);
+        println!("n_closures: {}", ccx.stats.n_closures);
         io::println("fn stats:");
         do sort::quick_sort(ccx.stats.fn_stats) |&(_, _, insns_a), &(_, _, insns_b)| {
             insns_a > insns_b
@@ -3172,14 +3172,14 @@ pub fn trans_crate(sess: session::Session,
         for tuple in ccx.stats.fn_stats.iter() {
             match *tuple {
                 (ref name, ms, insns) => {
-                    printfln!("%u insns, %u ms, %s", insns, ms, *name);
+                    println!("{} insns, {} ms, {}", insns, ms, *name);
                 }
             }
         }
     }
     if ccx.sess.count_llvm_insns() {
         for (k, v) in ccx.stats.llvm_insns.iter() {
-            printfln!("%-7u %s", *v, *k);
+            println!("{:7u} {}", *v, *k);
         }
     }
 
diff --git a/src/librustc/middle/trans/glue.rs b/src/librustc/middle/trans/glue.rs
index a760801d73a..28fffb6a80a 100644
--- a/src/librustc/middle/trans/glue.rs
+++ b/src/librustc/middle/trans/glue.rs
@@ -646,8 +646,8 @@ pub fn declare_tydesc(ccx: &mut CrateContext, t: ty::t) -> @mut tydesc_info {
     let llty = type_of(ccx, t);
 
     if ccx.sess.count_type_sizes() {
-        printfln!("%u\t%s", llsize_of_real(ccx, llty),
-                  ppaux::ty_to_str(ccx.tcx, t));
+        println!("{}\t{}", llsize_of_real(ccx, llty),
+                 ppaux::ty_to_str(ccx.tcx, t));
     }
 
     let has_header = match ty::get(t).sty {
diff --git a/src/librustc/rustc.rs b/src/librustc/rustc.rs
index 7599de1a9a3..9602c189455 100644
--- a/src/librustc/rustc.rs
+++ b/src/librustc/rustc.rs
@@ -130,13 +130,13 @@ pub fn version(argv0: &str) {
         Some(vers) => vers,
         None => "unknown version"
     };
-    printfln!("%s %s", argv0, vers);
-    printfln!("host: %s", host_triple());
+    println!("{} {}", argv0, vers);
+    println!("host: {}", host_triple());
 }
 
 pub fn usage(argv0: &str) {
     let message = fmt!("Usage: %s [OPTIONS] INPUT", argv0);
-    printfln!("%s\n\
+    println!("{}\n\
 Additional help:
     -W help             Print 'lint' options and default settings
     -Z help             Print internal options for debugging rustc\n",
@@ -167,16 +167,16 @@ Available lint options:
         str::from_utf8(vec::from_elem(max - s.len(), ' ' as u8)) + s
     }
     println("\nAvailable lint checks:\n");
-    printfln!("    %s  %7.7s  %s",
-              padded(max_key, "name"), "default", "meaning");
-    printfln!("    %s  %7.7s  %s\n",
-              padded(max_key, "----"), "-------", "-------");
+    println!("    {}  {:7.7s}  {}",
+             padded(max_key, "name"), "default", "meaning");
+    println!("    {}  {:7.7s}  {}\n",
+             padded(max_key, "----"), "-------", "-------");
     for (spec, name) in lint_dict.move_iter() {
         let name = name.replace("_", "-");
-        printfln!("    %s  %7.7s  %s",
-                  padded(max_key, name),
-                  lint::level_to_str(spec.default),
-                  spec.desc);
+        println!("    {}  {:7.7s}  {}",
+                 padded(max_key, name),
+                 lint::level_to_str(spec.default),
+                 spec.desc);
     }
     io::println("");
 }
@@ -187,7 +187,7 @@ pub fn describe_debug_flags() {
     for tuple in r.iter() {
         match *tuple {
             (ref name, ref desc, _) => {
-                printfln!("    -Z %-20s -- %s", *name, *desc);
+                println!("    -Z {:>20s} -- {}", *name, *desc);
             }
         }
     }
diff --git a/src/librustc/util/common.rs b/src/librustc/util/common.rs
index eeef2b798e2..bd7ca3a5529 100644
--- a/src/librustc/util/common.rs
+++ b/src/librustc/util/common.rs
@@ -22,7 +22,7 @@ pub fn time<T>(do_it: bool, what: ~str, thunk: &fn() -> T) -> T {
     let start = extra::time::precise_time_s();
     let rv = thunk();
     let end = extra::time::precise_time_s();
-    printfln!("time: %3.3f s\t%s", end - start, what);
+    println!("time: {:3.3f} s\t{}", end - start, what);
     rv
 }
 
diff --git a/src/librusti/rusti.rs b/src/librusti/rusti.rs
index eb94a112dd1..bb7ad99006c 100644
--- a/src/librusti/rusti.rs
+++ b/src/librusti/rusti.rs
@@ -437,7 +437,7 @@ fn run_cmd(repl: &mut Repl, _in: @io::Reader, _out: @io::Writer,
             if loaded_crates.is_empty() {
                 println("no crates loaded");
             } else {
-                printfln!("crates loaded: %s", loaded_crates.connect(", "));
+                println!("crates loaded: {}", loaded_crates.connect(", "));
             }
         }
         ~"{" => {
diff --git a/src/librustpkg/testsuite/pass/src/fancy-lib/pkg.rs b/src/librustpkg/testsuite/pass/src/fancy-lib/pkg.rs
index 27818dea1a6..db11ffa0cc6 100644
--- a/src/librustpkg/testsuite/pass/src/fancy-lib/pkg.rs
+++ b/src/librustpkg/testsuite/pass/src/fancy-lib/pkg.rs
@@ -34,7 +34,7 @@ pub fn main() {
     }
 
     if args[2] != ~"install" {
-        printfln!("Warning: I don't know how to %s", args[2]);
+        println!("Warning: I don't know how to {}", args[2]);
         return;
     }
 
diff --git a/src/libstd/iter.rs b/src/libstd/iter.rs
index 0e4cb895249..4695123548b 100644
--- a/src/libstd/iter.rs
+++ b/src/libstd/iter.rs
@@ -413,7 +413,7 @@ pub trait Iterator<A> {
     /// use std::iter::count;
     ///
     /// for i in count(0, 10) {
-    ///     printfln!("%d", i);
+    ///     println!("{}", i);
     /// }
     /// ```
     #[inline]
diff --git a/src/libstd/rand/distributions.rs b/src/libstd/rand/distributions.rs
index 1cdf4d6da95..0902100dca6 100644
--- a/src/libstd/rand/distributions.rs
+++ b/src/libstd/rand/distributions.rs
@@ -70,7 +70,7 @@ fn ziggurat<R:Rng>(rng: &mut R,
 ///
 /// fn main() {
 ///     let normal = 2.0 + (*rand::random::<StandardNormal>()) * 3.0;
-///     printfln!("%f is from a N(2, 9) distribution", normal)
+///     println!("{} is from a N(2, 9) distribution", normal)
 /// }
 /// ```
 pub struct StandardNormal(f64);
@@ -124,7 +124,7 @@ impl Rand for StandardNormal {
 ///
 /// fn main() {
 ///     let exp2 = (*rand::random::<Exp1>()) * 0.5;
-///     printfln!("%f is from a Exp(2) distribution", exp2);
+///     println!("{} is from a Exp(2) distribution", exp2);
 /// }
 /// ```
 pub struct Exp1(f64);
diff --git a/src/libstd/rand/mod.rs b/src/libstd/rand/mod.rs
index 832978a0f10..2b9727f6eb0 100644
--- a/src/libstd/rand/mod.rs
+++ b/src/libstd/rand/mod.rs
@@ -28,7 +28,7 @@ use std::rand::Rng;
 fn main() {
     let mut rng = rand::rng();
     if rng.gen() { // bool
-        printfln!("int: %d, uint: %u", rng.gen(), rng.gen())
+        println!("int: {}, uint: {}", rng.gen::<int>(), rng.gen::<uint>())
     }
 }
  ```
@@ -38,7 +38,7 @@ use std::rand;
 
 fn main () {
     let tuple_ptr = rand::random::<~(f64, char)>();
-    printfln!(tuple_ptr)
+    println!(tuple_ptr)
 }
  ```
 */
@@ -270,8 +270,8 @@ pub trait Rng {
     /// fn main() {
     ///    let rng = rand::task_rng();
     ///    let x: uint = rng.gen();
-    ///    printfln!(x);
-    ///    printfln!(rng.gen::<(float, bool)>());
+    ///    println!("{}", x);
+    ///    println!("{:?}", rng.gen::<(float, bool)>());
     /// }
     /// ```
     #[inline(always)]
@@ -289,8 +289,8 @@ pub trait Rng {
     /// fn main() {
     ///    let rng = rand::task_rng();
     ///    let x: ~[uint] = rng.gen_vec(10);
-    ///    printfln!(x);
-    ///    printfln!(rng.gen_vec::<(float, bool)>(5));
+    ///    println!("{:?}", x);
+    ///    println!("{:?}", rng.gen_vec::<(float, bool)>(5));
     /// }
     /// ```
     fn gen_vec<T: Rand>(&mut self, len: uint) -> ~[T] {
@@ -314,9 +314,9 @@ pub trait Rng {
     /// fn main() {
     ///    let rng = rand::task_rng();
     ///    let n: uint = rng.gen_integer_range(0u, 10);
-    ///    printfln!(n);
+    ///    println!("{}", n);
     ///    let m: i16 = rng.gen_integer_range(-40, 400);
-    ///    printfln!(m);
+    ///    println!("{}", m);
     /// }
     /// ```
     fn gen_integer_range<T: Rand + Int>(&mut self, low: T, high: T) -> T {
@@ -341,7 +341,7 @@ pub trait Rng {
     ///
     /// fn main() {
     ///     let mut rng = rand::rng();
-    ///     printfln!("%b", rng.gen_weighted_bool(3));
+    ///     println!("{:b}", rng.gen_weighted_bool(3));
     /// }
     /// ```
     fn gen_weighted_bool(&mut self, n: uint) -> bool {
@@ -385,8 +385,8 @@ pub trait Rng {
     /// use std::rand;
     ///
     /// fn main() {
-    ///     printfln!(rand::task_rng().choose_option([1,2,4,8,16,32]));
-    ///     printfln!(rand::task_rng().choose_option([]));
+    ///     println!("{:?}", rand::task_rng().choose_option([1,2,4,8,16,32]));
+    ///     println!("{:?}", rand::task_rng().choose_option([]));
     /// }
     /// ```
     fn choose_option<'a, T>(&mut self, values: &'a [T]) -> Option<&'a T> {
@@ -411,7 +411,7 @@ pub trait Rng {
     ///     let x = [rand::Weighted {weight: 4, item: 'a'},
     ///              rand::Weighted {weight: 2, item: 'b'},
     ///              rand::Weighted {weight: 2, item: 'c'}];
-    ///     printfln!("%c", rng.choose_weighted(x));
+    ///     println!("{}", rng.choose_weighted(x));
     /// }
     /// ```
     fn choose_weighted<T:Clone>(&mut self, v: &[Weighted<T>]) -> T {
@@ -432,7 +432,7 @@ pub trait Rng {
     ///     let x = [rand::Weighted {weight: 4, item: 'a'},
     ///              rand::Weighted {weight: 2, item: 'b'},
     ///              rand::Weighted {weight: 2, item: 'c'}];
-    ///     printfln!(rng.choose_weighted_option(x));
+    ///     println!("{:?}", rng.choose_weighted_option(x));
     /// }
     /// ```
     fn choose_weighted_option<T:Clone>(&mut self, v: &[Weighted<T>])
@@ -469,7 +469,7 @@ pub trait Rng {
     ///     let x = [rand::Weighted {weight: 4, item: 'a'},
     ///              rand::Weighted {weight: 2, item: 'b'},
     ///              rand::Weighted {weight: 2, item: 'c'}];
-    ///     printfln!(rng.weighted_vec(x));
+    ///     println!("{}", rng.weighted_vec(x));
     /// }
     /// ```
     fn weighted_vec<T:Clone>(&mut self, v: &[Weighted<T>]) -> ~[T] {
@@ -490,7 +490,7 @@ pub trait Rng {
     /// use std::rand;
     ///
     /// fn main() {
-    ///     printfln!(rand::task_rng().shuffle(~[1,2,3]));
+    ///     println!("{:?}", rand::task_rng().shuffle(~[1,2,3]));
     /// }
     /// ```
     fn shuffle<T>(&mut self, values: ~[T]) -> ~[T] {
@@ -510,9 +510,9 @@ pub trait Rng {
     ///    let rng = rand::task_rng();
     ///    let mut y = [1,2,3];
     ///    rng.shuffle_mut(y);
-    ///    printfln!(y);
+    ///    println!("{:?}", y);
     ///    rng.shuffle_mut(y);
-    ///    printfln!(y);
+    ///    println!("{:?}", y);
     /// }
     /// ```
     fn shuffle_mut<T>(&mut self, values: &mut [T]) {
@@ -535,7 +535,7 @@ pub trait Rng {
     /// fn main() {
     ///    let rng = rand::task_rng();
     ///    let sample = rng.sample(range(1, 100), 5);
-    ///    printfln!(sample);
+    ///    println!("{:?}", sample);
     /// }
     /// ```
     fn sample<A, T: Iterator<A>>(&mut self, iter: T, n: uint) -> ~[A] {
diff --git a/src/libstd/str.rs b/src/libstd/str.rs
index 9562346c70d..e22b376e44f 100644
--- a/src/libstd/str.rs
+++ b/src/libstd/str.rs
@@ -1695,7 +1695,7 @@ pub trait StrSlice<'self> {
     /// let i = 0u;
     /// while i < s.len() {
     ///     let CharRange {ch, next} = s.char_range_at(i);
-    ///     printfln!("%u: %c", i, ch);
+    ///     println!("{}: {}", i, ch);
     ///     i = next;
     /// }
     /// ```
diff --git a/src/libstd/vec.rs b/src/libstd/vec.rs
index e54717053e9..be5ab35ff88 100644
--- a/src/libstd/vec.rs
+++ b/src/libstd/vec.rs
@@ -1003,7 +1003,7 @@ impl<'self,T> ImmutableVector<'self, T> for &'self [T] {
      * ```rust
      * let v = &[1,2,3,4];
      * for win in v.window_iter() {
-     *     printfln!(win);
+     *     println!("{:?}", win);
      * }
      * ```
      *
@@ -1032,7 +1032,7 @@ impl<'self,T> ImmutableVector<'self, T> for &'self [T] {
      * ```rust
      * let v = &[1,2,3,4,5];
      * for win in v.chunk_iter() {
-     *     printfln!(win);
+     *     println!("{:?}", win);
      * }
      * ```
      *
diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index 3fd394b3652..57ecfed15b8 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -66,7 +66,7 @@ fn generic_extension(cx: @ExtCtxt,
                      rhses: &[@named_match])
                      -> MacResult {
     if cx.trace_macros() {
-        printfln!("%s! { %s }",
+        println!("{}! \\{ {} \\}",
                   cx.str_of(name),
                   print::pprust::tt_to_str(
                       &ast::tt_delim(@mut arg.to_owned()),
@@ -194,7 +194,7 @@ pub fn add_new_extension(cx: @ExtCtxt,
                          rhses: &[@named_match])
                          -> MacResult {
         if cx.trace_macros() {
-            printfln!("%s! { %s }",
+            println!("{}! \\{ {} \\}",
                       cx.str_of(name),
                       print::pprust::tt_to_str(
                           &ast::tt_delim(@mut arg.to_owned()),
diff --git a/src/test/bench/core-map.rs b/src/test/bench/core-map.rs
index 7077cee80e9..3a3466eebff 100644
--- a/src/test/bench/core-map.rs
+++ b/src/test/bench/core-map.rs
@@ -24,7 +24,7 @@ fn timed(label: &str, f: &fn()) {
     let start = time::precise_time_s();
     f();
     let end = time::precise_time_s();
-    printfln!("  %s: %f", label, end - start);
+    println!("  {}: {}", label, end - start);
 }
 
 fn ascending<M: MutableMap<uint, uint>>(map: &mut M, n_keys: uint) {
@@ -116,7 +116,7 @@ fn main() {
         }
     }
 
-    printfln!("%? keys", n_keys);
+    println!("{} keys", n_keys);
 
     io::println("\nTreeMap:");
 
diff --git a/src/test/bench/core-std.rs b/src/test/bench/core-std.rs
index 807f62ece7a..82c1b196c12 100644
--- a/src/test/bench/core-std.rs
+++ b/src/test/bench/core-std.rs
@@ -55,7 +55,7 @@ fn maybe_run_test(argv: &[~str], name: ~str, test: &fn()) {
     test();
     let stop = precise_time_s();
 
-    printfln!("%s:\t\t%f ms", name, (stop - start) * 1000f);
+    println!("{}:\t\t{} ms", name, (stop - start) * 1000f);
 }
 
 fn shift_push() {
diff --git a/src/test/bench/msgsend-ring-mutex-arcs.rs b/src/test/bench/msgsend-ring-mutex-arcs.rs
index b52ba154f43..a676e01d927 100644
--- a/src/test/bench/msgsend-ring-mutex-arcs.rs
+++ b/src/test/bench/msgsend-ring-mutex-arcs.rs
@@ -118,7 +118,7 @@ fn main() {
     let elapsed = (stop - start);
     let rate = (num_msgs as float) / elapsed;
 
-    printfln!("Sent %? messages in %? seconds", num_msgs, elapsed);
-    printfln!("  %? messages / second", rate);
-    printfln!("  %? μs / message", 1000000. / rate);
+    println!("Sent {} messages in {} seconds", num_msgs, elapsed);
+    println!("  {} messages / second", rate);
+    println!("  {} μs / message", 1000000. / rate);
 }
diff --git a/src/test/bench/msgsend-ring-rw-arcs.rs b/src/test/bench/msgsend-ring-rw-arcs.rs
index e3d0b4912f9..1f95e4232ad 100644
--- a/src/test/bench/msgsend-ring-rw-arcs.rs
+++ b/src/test/bench/msgsend-ring-rw-arcs.rs
@@ -114,7 +114,7 @@ fn main() {
     let elapsed = (stop - start);
     let rate = (num_msgs as float) / elapsed;
 
-    printfln!("Sent %? messages in %? seconds", num_msgs, elapsed);
-    printfln!("  %? messages / second", rate);
-    printfln!("  %? μs / message", 1000000. / rate);
+    println!("Sent {} messages in {} seconds", num_msgs, elapsed);
+    println!("  {} messages / second", rate);
+    println!("  {} μs / message", 1000000. / rate);
 }
diff --git a/src/test/bench/shootout-ackermann.rs b/src/test/bench/shootout-ackermann.rs
index 3e7feb01c4a..9183bd5551a 100644
--- a/src/test/bench/shootout-ackermann.rs
+++ b/src/test/bench/shootout-ackermann.rs
@@ -35,5 +35,5 @@ fn main() {
         args
     };
     let n = from_str::<int>(args[1]).unwrap();
-    printfln!("Ack(3,%d): %d\n", n, ack(3, n));
+    println!("Ack(3,{}): {}\n", n, ack(3, n));
 }
diff --git a/src/test/bench/shootout-binarytrees.rs b/src/test/bench/shootout-binarytrees.rs
index e956beedaab..5d4ddec17f5 100644
--- a/src/test/bench/shootout-binarytrees.rs
+++ b/src/test/bench/shootout-binarytrees.rs
@@ -61,7 +61,7 @@ fn main() {
     let stretch_depth = max_depth + 1;
     let stretch_tree = bottom_up_tree(&stretch_arena, 0, stretch_depth);
 
-    printfln!("stretch tree of depth %d\t check: %d",
+    println!("stretch tree of depth {}\t check: {}",
               stretch_depth,
               item_check(stretch_tree));
 
@@ -79,11 +79,11 @@ fn main() {
             chk += item_check(temp_tree);
             i += 1;
         }
-        printfln!("%d\t trees of depth %d\t check: %d",
+        println!("{}\t trees of depth {}\t check: {}",
                   iterations * 2, depth, chk);
         depth += 2;
     }
-    printfln!("long lived tree of depth %d\t check: %d",
+    println!("long lived tree of depth {}\t check: {}",
               max_depth,
               item_check(long_lived_tree));
 }
diff --git a/src/test/bench/shootout-fannkuch-redux.rs b/src/test/bench/shootout-fannkuch-redux.rs
index 48372c6d03b..f93ce2e93b9 100644
--- a/src/test/bench/shootout-fannkuch-redux.rs
+++ b/src/test/bench/shootout-fannkuch-redux.rs
@@ -94,5 +94,5 @@ fn fannkuch_redux(n: i32) -> i32 {
 #[fixed_stack_segment]
 fn main() {
     let n: i32 = FromStr::from_str(os::args()[1]).unwrap();
-    printfln!("Pfannkuchen(%d) = %d", n as int, fannkuch_redux(n) as int);
+    println!("Pfannkuchen({}) = {}", n as int, fannkuch_redux(n) as int);
 }
diff --git a/src/test/bench/shootout-fibo.rs b/src/test/bench/shootout-fibo.rs
index f902a8b5339..616ec3fa694 100644
--- a/src/test/bench/shootout-fibo.rs
+++ b/src/test/bench/shootout-fibo.rs
@@ -31,5 +31,5 @@ fn main() {
         args
     };
     let n = from_str::<int>(args[1]).unwrap();
-    printfln!("%d\n", fib(n));
+    println!("{}\n", fib(n));
 }
diff --git a/src/test/bench/shootout-k-nucleotide.rs b/src/test/bench/shootout-k-nucleotide.rs
index ae3422540aa..5c2176e30ff 100644
--- a/src/test/bench/shootout-k-nucleotide.rs
+++ b/src/test/bench/shootout-k-nucleotide.rs
@@ -82,7 +82,7 @@ struct PrintCallback(&'static str);
 
 impl TableCallback for PrintCallback {
     fn f(&self, entry: &mut Entry) {
-        printfln!("%d\t%s", entry.count as int, **self);
+        println!("{}\t{}", entry.count as int, **self);
     }
 }
 
@@ -279,9 +279,9 @@ fn print_frequencies(frequencies: &Table, frame: i32) {
     }
 
     for vector.each |&(key, count)| {
-        printfln!("%s %.3f",
-                  key.unpack(frame),
-                  (count as float * 100.0) / (total_count as float));
+        println!("{} {:.3f}",
+                 key.unpack(frame),
+                 (count as float * 100.0) / (total_count as float));
     }
 }
 
diff --git a/src/test/bench/shootout-mandelbrot.rs b/src/test/bench/shootout-mandelbrot.rs
index 72007d2b50a..83ffa058b32 100644
--- a/src/test/bench/shootout-mandelbrot.rs
+++ b/src/test/bench/shootout-mandelbrot.rs
@@ -16,7 +16,7 @@ fn main() {
         let mut byte_acc: i8 = 0;
         let mut bit_num: i32 = 0;
 
-        printfln!("P4\n%d %d", w as int, h as int);
+        println!("P4\n{} {}", w, h);
 
         let mode = "w";
         let stdout = fdopen(STDOUT_FILENO as c_int, transmute(&mode[0]));
diff --git a/src/test/bench/shootout-nbody.rs b/src/test/bench/shootout-nbody.rs
index 0f43d5027a9..ab5c7377bd8 100644
--- a/src/test/bench/shootout-nbody.rs
+++ b/src/test/bench/shootout-nbody.rs
@@ -143,9 +143,9 @@ fn main() {
     let mut bodies = BODIES;
 
     offset_momentum(&mut bodies);
-    printfln!("%.9f", energy(&bodies) as float);
+    println!("{:.9f}", energy(&bodies) as float);
 
     advance(&mut bodies, 0.01, n);
 
-    printfln!("%.9f", energy(&bodies) as float);
+    println!("{:.9f}", energy(&bodies) as float);
 }
diff --git a/src/test/bench/shootout-spectralnorm.rs b/src/test/bench/shootout-spectralnorm.rs
index d7f5e5781e0..105972591f3 100644
--- a/src/test/bench/shootout-spectralnorm.rs
+++ b/src/test/bench/shootout-spectralnorm.rs
@@ -63,5 +63,5 @@ fn main() {
         mult_AtAv(v, u, tmp);
     }
 
-    printfln!("%.9f", (dot(u,v) / dot(v,v)).sqrt() as float);
+    println!("{:.9f}", (dot(u,v) / dot(v,v)).sqrt() as float);
 }
diff --git a/src/test/bench/shootout-threadring.rs b/src/test/bench/shootout-threadring.rs
index ace008c1f95..0c0c5226dce 100644
--- a/src/test/bench/shootout-threadring.rs
+++ b/src/test/bench/shootout-threadring.rs
@@ -40,11 +40,11 @@ fn roundtrip(id: int, n_tasks: int, p: &Port<int>, ch: &Chan<int>) {
     while (true) {
         match p.recv() {
           1 => {
-            printfln!("%d\n", id);
+            println!("{}\n", id);
             return;
           }
           token => {
-            info!("thread: %d   got token: %d", id, token);
+            info2!("thread: {}   got token: {}", id, token);
             ch.send(token - 1);
             if token <= n_tasks {
                 return;
diff --git a/src/test/compile-fail/borrowck-auto-mut-ref-to-immut-var.rs b/src/test/compile-fail/borrowck-auto-mut-ref-to-immut-var.rs
index 9a82dd3f512..76e70060929 100644
--- a/src/test/compile-fail/borrowck-auto-mut-ref-to-immut-var.rs
+++ b/src/test/compile-fail/borrowck-auto-mut-ref-to-immut-var.rs
@@ -18,7 +18,7 @@ struct Foo {
 
 impl Foo {
     pub fn printme(&mut self) {
-        printfln!("%d", self.x);
+        println!("{}", self.x);
     }
 }
 
diff --git a/src/test/compile-fail/borrowck-vec-pattern-tail-element-loan.rs b/src/test/compile-fail/borrowck-vec-pattern-tail-element-loan.rs
index 87511c34172..e542238d035 100644
--- a/src/test/compile-fail/borrowck-vec-pattern-tail-element-loan.rs
+++ b/src/test/compile-fail/borrowck-vec-pattern-tail-element-loan.rs
@@ -9,5 +9,5 @@ fn a() -> &int {
 
 fn main() {
     let fifth = a();
-    printfln!("%d", *fifth);
+    println!("{}", *fifth);
 }
diff --git a/src/test/compile-fail/issue-3820.rs b/src/test/compile-fail/issue-3820.rs
index 04c3a062426..195585dd897 100644
--- a/src/test/compile-fail/issue-3820.rs
+++ b/src/test/compile-fail/issue-3820.rs
@@ -22,5 +22,4 @@ fn main() {
     let u = Thing {x: 2};
     let _v = u.mul(&3); // This is ok
     let w = u * 3; //~ ERROR binary operation * cannot be applied to type `Thing`
-    printfln!("%i", w.x);
 }
diff --git a/src/test/compile-fail/issue-4335.rs b/src/test/compile-fail/issue-4335.rs
index 9ec1f5cd441..5b6240d8ac8 100644
--- a/src/test/compile-fail/issue-4335.rs
+++ b/src/test/compile-fail/issue-4335.rs
@@ -14,5 +14,5 @@ fn f<'r, T>(v: &'r T) -> &'r fn()->T { id::<&'r fn()->T>(|| *v) } //~ ERROR cann
 
 fn main() {
     let v = &5;
-    printfln!("%d", f(v)());
+    println!("{}", f(v)());
 }
diff --git a/src/test/compile-fail/moves-based-on-type-no-recursive-stack-closure.rs b/src/test/compile-fail/moves-based-on-type-no-recursive-stack-closure.rs
index 19a3ce4f838..2762140be37 100644
--- a/src/test/compile-fail/moves-based-on-type-no-recursive-stack-closure.rs
+++ b/src/test/compile-fail/moves-based-on-type-no-recursive-stack-closure.rs
@@ -28,7 +28,7 @@ fn innocent_looking_victim() {
             match x {
                 Some(ref msg) => {
                     (f.c)(f, true);
-                    printfln!(msg);
+                    println!("{:?}", msg);
                 },
                 None => fail!("oops"),
             }
diff --git a/src/test/compile-fail/tuple-struct-nonexhaustive.rs b/src/test/compile-fail/tuple-struct-nonexhaustive.rs
index 4640957a9a8..1f14fbb27ad 100644
--- a/src/test/compile-fail/tuple-struct-nonexhaustive.rs
+++ b/src/test/compile-fail/tuple-struct-nonexhaustive.rs
@@ -13,7 +13,7 @@ struct Foo(int, int);
 fn main() {
     let x = Foo(1, 2);
     match x {   //~ ERROR non-exhaustive
-        Foo(1, b) => printfln!("%d", b),
-        Foo(2, b) => printfln!("%d", b)
+        Foo(1, b) => println!("{}", b),
+        Foo(2, b) => println!("{}", b)
     }
 }
diff --git a/src/test/run-fail/borrowck-wg-one-mut-one-imm-slice-method.rs b/src/test/run-fail/borrowck-wg-one-mut-one-imm-slice-method.rs
index 8ed3297e7d1..88ff00e86fa 100644
--- a/src/test/run-fail/borrowck-wg-one-mut-one-imm-slice-method.rs
+++ b/src/test/run-fail/borrowck-wg-one-mut-one-imm-slice-method.rs
@@ -33,5 +33,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(z.my_mut_slice(), z2.my_slice());
-    printfln!("%d", z[0]);
+    println!("{}", z[0]);
 }
diff --git a/src/test/run-fail/borrowck-wg-one-mut-one-imm-slices.rs b/src/test/run-fail/borrowck-wg-one-mut-one-imm-slices.rs
index d2971ad40ab..ef410fb5339 100644
--- a/src/test/run-fail/borrowck-wg-one-mut-one-imm-slices.rs
+++ b/src/test/run-fail/borrowck-wg-one-mut-one-imm-slices.rs
@@ -12,5 +12,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(z, z2);
-    printfln!("%d", z[0]);
+    println!("{}", z[0]);
 }
diff --git a/src/test/run-fail/borrowck-wg-one-mut-one-imm.rs b/src/test/run-fail/borrowck-wg-one-mut-one-imm.rs
index df096e8292f..9e52c3ae928 100644
--- a/src/test/run-fail/borrowck-wg-one-mut-one-imm.rs
+++ b/src/test/run-fail/borrowck-wg-one-mut-one-imm.rs
@@ -13,5 +13,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(&mut z[0], &z2[0]);
-    printfln!("%d", z[0]);
+    println!("{}", z[0]);
 }
diff --git a/src/test/run-fail/borrowck-wg-two-array-indices.rs b/src/test/run-fail/borrowck-wg-two-array-indices.rs
index 98bb72c9340..a41e529d062 100644
--- a/src/test/run-fail/borrowck-wg-two-array-indices.rs
+++ b/src/test/run-fail/borrowck-wg-two-array-indices.rs
@@ -13,5 +13,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(&mut z[0], &mut z2[0]);
-    printfln!("%d", z[0]);
+    println!("{}", z[0]);
 }
diff --git a/src/test/run-pass/auto-ref.rs b/src/test/run-pass/auto-ref.rs
index cc14af45c85..6dc67905427 100644
--- a/src/test/run-pass/auto-ref.rs
+++ b/src/test/run-pass/auto-ref.rs
@@ -18,7 +18,7 @@ trait Stuff {
 
 impl Stuff for Foo {
     fn printme(&self) {
-        printfln!("%d", self.x);
+        println!("{}", self.x);
     }
 }
 
diff --git a/src/test/run-pass/borrowck-wg-two-imm-borrows.rs b/src/test/run-pass/borrowck-wg-two-imm-borrows.rs
index 306141354ca..3d2988202f3 100644
--- a/src/test/run-pass/borrowck-wg-two-imm-borrows.rs
+++ b/src/test/run-pass/borrowck-wg-two-imm-borrows.rs
@@ -10,5 +10,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(&z[0], &z2[0]);
-    printfln!("%d", z[0]);
+    println!("{}", z[0]);
 }
diff --git a/src/test/run-pass/cci_impl_exe.rs b/src/test/run-pass/cci_impl_exe.rs
index 30adaf2dae4..b85d53991ea 100644
--- a/src/test/run-pass/cci_impl_exe.rs
+++ b/src/test/run-pass/cci_impl_exe.rs
@@ -19,7 +19,7 @@ pub fn main() {
     //info!("%?", bt0);
 
     do 3u.to(10u) |i| {
-        printfln!("%u", i);
+        println!("{}", i);
 
         //let bt1 = sys::frame_address();
         //info!("%?", bt1);
diff --git a/src/test/run-pass/cci_iter_exe.rs b/src/test/run-pass/cci_iter_exe.rs
index 50afcac4e3a..ea313a48bb3 100644
--- a/src/test/run-pass/cci_iter_exe.rs
+++ b/src/test/run-pass/cci_iter_exe.rs
@@ -17,7 +17,7 @@ pub fn main() {
     //let bt0 = sys::rusti::frame_address(1u32);
     //info!("%?", bt0);
     do cci_iter_lib::iter([1, 2, 3]) |i| {
-        printf!("%d", *i);
+        println!("{}", *i);
         //assert!(bt0 == sys::rusti::frame_address(2u32));
     }
 }
diff --git a/src/test/run-pass/cci_no_inline_exe.rs b/src/test/run-pass/cci_no_inline_exe.rs
index 6459239e469..53c67e4802b 100644
--- a/src/test/run-pass/cci_no_inline_exe.rs
+++ b/src/test/run-pass/cci_no_inline_exe.rs
@@ -23,7 +23,7 @@ pub fn main() {
     //let bt0 = sys::frame_address();
     //info!("%?", bt0);
     do iter(~[1u, 2u, 3u]) |i| {
-        printfln!("%u", i);
+        println!("{}", i);
 
         //let bt1 = sys::frame_address();
         //info!("%?", bt1);
diff --git a/src/test/run-pass/const-fields-and-indexing.rs b/src/test/run-pass/const-fields-and-indexing.rs
index b31dcc83428..e99b0ed185b 100644
--- a/src/test/run-pass/const-fields-and-indexing.rs
+++ b/src/test/run-pass/const-fields-and-indexing.rs
@@ -25,9 +25,9 @@ static k : K = K {a: 10, b: 20, c: D {d: 30, e: 40}};
 static m : int = k.c.e;
 
 pub fn main() {
-    printfln!(p);
-    printfln!(q);
-    printfln!(t);
+    println!("{:?}", p);
+    println!("{:?}", q);
+    println!("{:?}", t);
     assert_eq!(p, 3);
     assert_eq!(q, 3);
     assert_eq!(t, 20);
diff --git a/src/test/run-pass/const-rec-and-tup.rs b/src/test/run-pass/const-rec-and-tup.rs
index 5b80988dcdf..c893a3ea8da 100644
--- a/src/test/run-pass/const-rec-and-tup.rs
+++ b/src/test/run-pass/const-rec-and-tup.rs
@@ -21,5 +21,5 @@ static y : AnotherPair = AnotherPair{ x: (0xf0f0f0f0_f0f0f0f0,
 pub fn main() {
     let (p, _) = y.x;
     assert_eq!(p, - 1085102592571150096);
-    printfln!("0x%x", p as uint);
+    println!("{:#x}", p);
 }
diff --git a/src/test/run-pass/const-region-ptrs.rs b/src/test/run-pass/const-region-ptrs.rs
index 3e79fad542e..c5884ae6e93 100644
--- a/src/test/run-pass/const-region-ptrs.rs
+++ b/src/test/run-pass/const-region-ptrs.rs
@@ -15,8 +15,8 @@ static x: &'static int = &10;
 static y: &'static Pair<'static> = &Pair {a: 15, b: x};
 
 pub fn main() {
-    printfln!("x = %?", *x);
-    printfln!("y = {a: %?, b: %?}", y.a, *(y.b));
+    println!("x = {}", *x);
+    println!("y = \\{a: {}, b: {}\\}", y.a, *(y.b));
     assert_eq!(*x, 10);
     assert_eq!(*(y.b), 10);
 }
diff --git a/src/test/run-pass/const-struct.rs b/src/test/run-pass/const-struct.rs
index 111fe3870ba..af6dd4029f5 100644
--- a/src/test/run-pass/const-struct.rs
+++ b/src/test/run-pass/const-struct.rs
@@ -32,6 +32,6 @@ pub fn main() {
     assert_eq!(z.b, 22);
     assert_eq!(w.a, 5);
     assert_eq!(w.c, 3);
-    printfln!("0x%x", x.b as uint);
-    printfln!("0x%x", z.c as uint);
+    println!("{:#x}", x.b);
+    println!("{:#x}", z.c);
 }
diff --git a/src/test/run-pass/const-vecs-and-slices.rs b/src/test/run-pass/const-vecs-and-slices.rs
index 8a1db762b44..3935bb241c7 100644
--- a/src/test/run-pass/const-vecs-and-slices.rs
+++ b/src/test/run-pass/const-vecs-and-slices.rs
@@ -12,8 +12,8 @@ static x : [int, ..4] = [1,2,3,4];
 static y : &'static [int] = &[1,2,3,4];
 
 pub fn main() {
-    printfln!(x[1]);
-    printfln!(y[1]);
+    println!("{:?}", x[1]);
+    println!("{:?}", y[1]);
     assert_eq!(x[1], 2);
     assert_eq!(x[3], 4);
     assert_eq!(x[3], y[3]);
diff --git a/src/test/run-pass/functional-struct-upd.rs b/src/test/run-pass/functional-struct-upd.rs
index 0cd9b2adf7c..10efc0b53f2 100644
--- a/src/test/run-pass/functional-struct-upd.rs
+++ b/src/test/run-pass/functional-struct-upd.rs
@@ -16,5 +16,5 @@ struct Foo {
 pub fn main() {
     let a = Foo { x: 1, y: 2 };
     let c = Foo { x: 4, .. a};
-    printfln!(c);
+    println!("{:?}", c);
 }
diff --git a/src/test/run-pass/issue-2185.rs b/src/test/run-pass/issue-2185.rs
index a1ea1b90809..fdf88f414ec 100644
--- a/src/test/run-pass/issue-2185.rs
+++ b/src/test/run-pass/issue-2185.rs
@@ -82,5 +82,5 @@ pub fn main() {
         a);
     let sum = foldl(filt, 0u, |accum, &&n: uint| accum + n );
 
-    printfln!("%u", sum);
+    println!("{}", sum);
 }
diff --git a/src/test/run-pass/issue-2989.rs b/src/test/run-pass/issue-2989.rs
index d4470dc34ff..9b667ab433b 100644
--- a/src/test/run-pass/issue-2989.rs
+++ b/src/test/run-pass/issue-2989.rs
@@ -40,7 +40,7 @@ pub fn main() {
     let bools2 = to_bools(Storage{storage: ~[0b01100100]});
 
     for i in range(0u, 8) {
-        printfln!("%u => %u vs %u", i, bools[i] as uint, bools2[i] as uint);
+        println!("{} => {} vs {}", i, bools[i], bools2[i]);
     }
 
     assert_eq!(bools, bools2);
diff --git a/src/test/run-pass/issue-3211.rs b/src/test/run-pass/issue-3211.rs
index 49ed6de0c99..5e89cb2dd36 100644
--- a/src/test/run-pass/issue-3211.rs
+++ b/src/test/run-pass/issue-3211.rs
@@ -4,5 +4,5 @@ pub fn main() {
         x += 1;
     }
     assert_eq!(x, 4096);
-    printfln!("x = %u", x);
+    println!("x = {}", x);
 }
diff --git a/src/test/run-pass/issue-3743.rs b/src/test/run-pass/issue-3743.rs
index f666571c2ad..be136160df4 100644
--- a/src/test/run-pass/issue-3743.rs
+++ b/src/test/run-pass/issue-3743.rs
@@ -40,11 +40,11 @@ pub fn main() {
 
     // the following compiles and works properly
     let v1: Vec2 = a * 3f;
-    printfln!("%f %f", v1.x, v1.y);
+    println!("{} {}", v1.x, v1.y);
 
     // the following compiles but v2 will not be Vec2 yet and
     // using it later will cause an error that the type of v2
     // must be known
     let v2 = a * 3f;
-    printfln!("%f %f", v2.x, v2.y); // error regarding v2's type
+    println!("{} {}", v2.x, v2.y); // error regarding v2's type
 }
diff --git a/src/test/run-pass/issue-3753.rs b/src/test/run-pass/issue-3753.rs
index 12ec501788d..0a35120cd1e 100644
--- a/src/test/run-pass/issue-3753.rs
+++ b/src/test/run-pass/issue-3753.rs
@@ -35,5 +35,5 @@ impl Shape {
 
 pub fn main(){
     let s = Circle(Point { x: 1f, y: 2f }, 3f);
-    printfln!("%f", s.area(s));
+    println!("{}", s.area(s));
 }
diff --git a/src/test/run-pass/issue-3794.rs b/src/test/run-pass/issue-3794.rs
index fdd0955bbed..61e6bd264e2 100644
--- a/src/test/run-pass/issue-3794.rs
+++ b/src/test/run-pass/issue-3794.rs
@@ -18,7 +18,7 @@ struct S {
 
 impl T for S {
     fn print(&self) {
-        printfln!(self);
+        println!("{:?}", self);
     }
 }
 
diff --git a/src/test/run-pass/issue-3904.rs b/src/test/run-pass/issue-3904.rs
index 98b7741461e..6b678ffdb1c 100644
--- a/src/test/run-pass/issue-3904.rs
+++ b/src/test/run-pass/issue-3904.rs
@@ -12,7 +12,7 @@
 type ErrPrinter = &fn(&str, &str);
 
 fn example_err(prog: &str, arg: &str) {
-    printfln!("%s: %s", prog, arg)
+    println!("{}: {}", prog, arg)
 }
 
 fn exit(+print: ErrPrinter, prog: &str, arg: &str) {
diff --git a/src/test/run-pass/issue-4241.rs b/src/test/run-pass/issue-4241.rs
index 6df859d938b..b53036d091f 100644
--- a/src/test/run-pass/issue-4241.rs
+++ b/src/test/run-pass/issue-4241.rs
@@ -114,7 +114,6 @@ fn query(cmd: ~[~str], sb: TcpSocketBuf) -> Result {
   //io::println(cmd);
   sb.write_str(cmd);
   let res = parse_response(@sb as @io::Reader);
-  //printfln!(res);
   res
 }
 
@@ -122,7 +121,7 @@ fn query2(cmd: ~[~str]) -> Result {
   let _cmd = cmd_to_str(cmd);
     do io::with_str_reader(~"$3\r\nXXX\r\n") |sb| {
     let res = parse_response(@sb as @io::Reader);
-    printfln!(res);
+    println!("{:?}", res);
     res
     }
 }
diff --git a/src/test/run-pass/issue-4401.rs b/src/test/run-pass/issue-4401.rs
index 99250c4c8a2..ab38d7650da 100644
--- a/src/test/run-pass/issue-4401.rs
+++ b/src/test/run-pass/issue-4401.rs
@@ -4,5 +4,5 @@ pub fn main() {
         count += 1;
     }
     assert_eq!(count, 999_999);
-    printfln!("%u", count);
+    println!("{}", count);
 }
diff --git a/src/test/run-pass/link-section.rs b/src/test/run-pass/link-section.rs
index a5ea32e5157..0a1d28b2ef1 100644
--- a/src/test/run-pass/link-section.rs
+++ b/src/test/run-pass/link-section.rs
@@ -29,6 +29,6 @@ static mut frobulator: uint = 0xdeadbeef;
 pub fn main() {
     unsafe {
         frobulator = 0xcafebabe;
-        printfln!("%? %? %?", i_live_in_more_text(), magic, frobulator);
+        println!("{} {} {}", i_live_in_more_text(), magic, frobulator);
     }
 }
diff --git a/src/test/run-pass/max-min-classes.rs b/src/test/run-pass/max-min-classes.rs
index 685a11c79ee..e3c375f8b0f 100644
--- a/src/test/run-pass/max-min-classes.rs
+++ b/src/test/run-pass/max-min-classes.rs
@@ -35,5 +35,5 @@ fn Foo(x: int, y: int) -> Foo {
 
 pub fn main() {
     let foo = Foo(3, 20);
-    printfln!("%d %d", foo.sum(), foo.product());
+    println!("{} {}", foo.sum(), foo.product());
 }
diff --git a/src/test/run-pass/new-style-constants.rs b/src/test/run-pass/new-style-constants.rs
index a00bfceab0f..e2402080bc3 100644
--- a/src/test/run-pass/new-style-constants.rs
+++ b/src/test/run-pass/new-style-constants.rs
@@ -13,5 +13,5 @@ use std::io::println;
 static FOO: int = 3;
 
 pub fn main() {
-    printfln!("%d", FOO);
+    println!("{}", FOO);
 }
diff --git a/src/test/run-pass/new-style-fixed-length-vec.rs b/src/test/run-pass/new-style-fixed-length-vec.rs
index 488bd65f548..a689fb0cf7c 100644
--- a/src/test/run-pass/new-style-fixed-length-vec.rs
+++ b/src/test/run-pass/new-style-fixed-length-vec.rs
@@ -8,10 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::io::println;
-
 static FOO: [int, ..3] = [1, 2, 3];
 
 pub fn main() {
-    printfln!("%d %d %d", FOO[0], FOO[1], FOO[2]);
+    println!("{} {} {}", FOO[0], FOO[1], FOO[2]);
 }
diff --git a/src/test/run-pass/newtype.rs b/src/test/run-pass/newtype.rs
index 3e2308bfcaf..f7c879759df 100644
--- a/src/test/run-pass/newtype.rs
+++ b/src/test/run-pass/newtype.rs
@@ -16,6 +16,6 @@ fn compute(i: mytype) -> int { return i.val + 20; }
 
 pub fn main() {
     let myval = mytype(Mytype{compute: compute, val: 30});
-    printfln!("%d", compute(myval));
+    println!("{}", compute(myval));
     assert_eq!((myval.compute)(myval), 50);
 }
diff --git a/src/test/run-pass/placement-new-arena.rs b/src/test/run-pass/placement-new-arena.rs
index f2063b583e4..238ea7485c9 100644
--- a/src/test/run-pass/placement-new-arena.rs
+++ b/src/test/run-pass/placement-new-arena.rs
@@ -17,6 +17,6 @@ pub fn main() {
     let mut arena = Arena::new();
     let p = &mut arena;
     let x = p.alloc(|| 4u);
-    printf!("%u", *x);
+    println!("{}", *x);
     assert_eq!(*x, 4u);
 }
diff --git a/src/test/run-pass/recursion.rs b/src/test/run-pass/recursion.rs
index 07a5c10ab1f..5ecd09f8bbb 100644
--- a/src/test/run-pass/recursion.rs
+++ b/src/test/run-pass/recursion.rs
@@ -30,5 +30,5 @@ fn test<T:Dot> (n:int, i:int, first:T, second:T) ->int {
 }
 pub fn main() {
   let n = test(1, 0, Nil, Nil);
-  printfln!("%d", n);
+  println!("{}", n);
 }
diff --git a/src/test/run-pass/reflect-visit-data.rs b/src/test/run-pass/reflect-visit-data.rs
index cf6f12a06e5..919fd351161 100644
--- a/src/test/run-pass/reflect-visit-data.rs
+++ b/src/test/run-pass/reflect-visit-data.rs
@@ -647,9 +647,9 @@ pub fn main() {
 
         let r = u.vals.clone();
         for s in r.iter() {
-            printfln!("val: %s", *s);
+            println!("val: {}", *s);
         }
-        error!("%?", u.vals.clone());
+        error2!("{:?}", u.vals.clone());
         assert_eq!(u.vals.clone(),
                    ~[ ~"1", ~"2", ~"3", ~"true", ~"false", ~"5", ~"4", ~"3", ~"12"]);
     }
diff --git a/src/test/run-pass/reflect-visit-type.rs b/src/test/run-pass/reflect-visit-type.rs
index b3d81d9c511..258afaa3f8d 100644
--- a/src/test/run-pass/reflect-visit-type.rs
+++ b/src/test/run-pass/reflect-visit-type.rs
@@ -161,7 +161,7 @@ pub fn main() {
     visit_ty::<~[int]>(&mut v);
 
     for s in v.types.iter() {
-        printfln!("type: %s", (*s).clone());
+        println!("type: {}", (*s).clone());
     }
     assert_eq!((*v.types).clone(), ~[~"bool", ~"int", ~"i8", ~"i16", ~"[", ~"int", ~"]"]);
 }
diff --git a/src/test/run-pass/struct-pattern-matching.rs b/src/test/run-pass/struct-pattern-matching.rs
index 3d8c2b7f56a..d2b038fab0e 100644
--- a/src/test/run-pass/struct-pattern-matching.rs
+++ b/src/test/run-pass/struct-pattern-matching.rs
@@ -16,6 +16,6 @@ struct Foo {
 pub fn main() {
     let a = Foo { x: 1, y: 2 };
     match a {
-        Foo { x: x, y: y } => printfln!("yes, %d, %d", x, y)
+        Foo { x: x, y: y } => println!("yes, {}, {}", x, y)
     }
 }
diff --git a/src/test/run-pass/trait-inheritance-num2.rs b/src/test/run-pass/trait-inheritance-num2.rs
index 4003a83e80b..babe1a18fa1 100644
--- a/src/test/run-pass/trait-inheritance-num2.rs
+++ b/src/test/run-pass/trait-inheritance-num2.rs
@@ -99,7 +99,7 @@ impl FloatExt for f64 {}
 impl FloatExt for float {}
 
 
-fn test_float_ext<T:FloatExt>(n: T) { printfln!(n < n) }
+fn test_float_ext<T:FloatExt>(n: T) { println!("{}", n < n) }
 
 pub fn main() {
     test_float_ext(1f32);
diff --git a/src/test/run-pass/trait-inheritance-num3.rs b/src/test/run-pass/trait-inheritance-num3.rs
index 2d6b5e11325..b7150e873a5 100644
--- a/src/test/run-pass/trait-inheritance-num3.rs
+++ b/src/test/run-pass/trait-inheritance-num3.rs
@@ -16,7 +16,7 @@ pub trait NumExt: Eq + Ord + Num + NumCast {}
 impl NumExt for f32 {}
 
 fn num_eq_one<T:NumExt>(n: T) {
-    printfln!(n == NumCast::from(1))
+    println!("{}", n == NumCast::from(1))
 }
 
 pub fn main() {
diff --git a/src/test/run-pass/tuple-struct-construct.rs b/src/test/run-pass/tuple-struct-construct.rs
index 9f1b930f168..3c15bc0bd6b 100644
--- a/src/test/run-pass/tuple-struct-construct.rs
+++ b/src/test/run-pass/tuple-struct-construct.rs
@@ -12,5 +12,5 @@ struct Foo(int, int);
 
 pub fn main() {
     let x = Foo(1, 2);
-    printfln!(x);
+    println!("{:?}", x);
 }
diff --git a/src/test/run-pass/tuple-struct-destructuring.rs b/src/test/run-pass/tuple-struct-destructuring.rs
index a1b1f36dc41..ec7675abf83 100644
--- a/src/test/run-pass/tuple-struct-destructuring.rs
+++ b/src/test/run-pass/tuple-struct-destructuring.rs
@@ -13,7 +13,7 @@ struct Foo(int, int);
 pub fn main() {
     let x = Foo(1, 2);
     let Foo(y, z) = x;
-    printfln!("%d %d", y, z);
+    println!("{} {}", y, z);
     assert_eq!(y, 1);
     assert_eq!(z, 2);
 }
diff --git a/src/test/run-pass/tuple-struct-matching.rs b/src/test/run-pass/tuple-struct-matching.rs
index 36467189bbd..f50b0405953 100644
--- a/src/test/run-pass/tuple-struct-matching.rs
+++ b/src/test/run-pass/tuple-struct-matching.rs
@@ -16,7 +16,7 @@ pub fn main() {
         Foo(a, b) => {
             assert_eq!(a, 1);
             assert_eq!(b, 2);
-            printfln!("%d %d", a, b);
+            println!("{} {}", a, b);
         }
     }
 }
diff --git a/src/test/run-pass/vec-fixed-length.rs b/src/test/run-pass/vec-fixed-length.rs
index e4c6bcf6791..8e22be1b432 100644
--- a/src/test/run-pass/vec-fixed-length.rs
+++ b/src/test/run-pass/vec-fixed-length.rs
@@ -10,5 +10,5 @@
 
 pub fn main() {
     let x: [int, ..4] = [1, 2, 3, 4];
-    printfln!("%d", x[0]);
+    println!("{}", x[0]);
 }
diff --git a/src/test/run-pass/vec-matching-legal-tail-element-borrow.rs b/src/test/run-pass/vec-matching-legal-tail-element-borrow.rs
index ad2440f1e4f..d90abe31b27 100644
--- a/src/test/run-pass/vec-matching-legal-tail-element-borrow.rs
+++ b/src/test/run-pass/vec-matching-legal-tail-element-borrow.rs
@@ -5,6 +5,6 @@ pub fn main() {
             [1, ..ref tail] => &tail[0],
             _ => unreachable!()
         };
-        printfln!("%d", *el);
+        println!("{}", *el);
     }
 }