auto merge of #11946 : alexcrichton/rust/no-io-error, r=brson

Turns out this was a little more far-reaching than I thought it was.

The first commit is the crux of this stack of commits. The `io::io_error` condition is completely removed and the `read` and `write` methods are altered to return `IoResult<T>`. This turned out to be an incredibly far-reaching change!

Overall, I'm very happy with how this turned out (in addition with the `unused_must_use` lint). I had to almost rewrite the pretty printer in `libsyntax` as well as the the formatting in `librustdoc` (as one would expect). These two modules do *tons* of I/O, and I believe that it's definitely improved.

This pull request also introduces the `if_ok!()` macro for returning-early from something that returns a result. I made quite liberal use of this in mostly the pretty printer and html renderer, and I found its usage generally quite pleasant and convenient to have. I didn't really feel like adding any other macro while I was using it, and I figured that pretty printing could be nicer, but it's nowhere near horrid today.

This may be a controversial issue closing, but I'm going to say it.

Closes #6163

src/compiletest/compiletest.rs

@@ -234,7 +234,13 @@ pub fn run_tests(config: &config) {
     // For context, see #8904
     io::test::raise_fd_limit();
     let res = test::run_tests_console(&opts, tests);
-    if !res { fail!("Some tests failed"); }
+    match res {
+        Ok(true) => {}
+        Ok(false) => fail!("Some tests failed"),
+        Err(e) => {
+            println!("I/O failure during tests: {}", e);
+        }
+    }
 }
 
 pub fn test_opts(config: &config) -> test::TestOpts {
@@ -255,7 +261,7 @@ pub fn make_tests(config: &config) -> ~[test::TestDescAndFn] {
     debug!("making tests from {}",
            config.src_base.display());
     let mut tests = ~[];
-    let dirs = fs::readdir(&config.src_base);
+    let dirs = fs::readdir(&config.src_base).unwrap();
     for file in dirs.iter() {
         let file = file.clone();
         debug!("inspecting file {}", file.display());

src/compiletest/procsrv.rs

@@ -58,9 +58,9 @@ pub fn run(lib_path: &str,
     });
 
     match opt_process {
-        Some(ref mut process) => {
+        Ok(ref mut process) => {
             for input in input.iter() {
-                process.input().write(input.as_bytes());
+                process.input().write(input.as_bytes()).unwrap();
             }
             let run::ProcessOutput { status, output, error } = process.finish_with_output();
 
@@ -70,7 +70,7 @@ pub fn run(lib_path: &str,
                 err: str::from_utf8_owned(error).unwrap()
             })
         },
-        None => None
+        Err(..) => None
     }
 }
 
@@ -90,13 +90,13 @@ pub fn run_background(lib_path: &str,
     });
 
     match opt_process {
-        Some(mut process) => {
+        Ok(mut process) => {
             for input in input.iter() {
-                process.input().write(input.as_bytes());
+                process.input().write(input.as_bytes()).unwrap();
             }
 
             Some(process)
         },
-        None => None
+        Err(..) => None
     }
 }

src/compiletest/runtest.rs

@@ -153,7 +153,7 @@ fn run_pretty_test(config: &config, props: &TestProps, testfile: &Path) {
     let rounds =
         match props.pp_exact { Some(_) => 1, None => 2 };
 
-    let src = File::open(testfile).read_to_end();
+    let src = File::open(testfile).read_to_end().unwrap();
     let src = str::from_utf8_owned(src).unwrap();
     let mut srcs = ~[src];
 
@@ -175,7 +175,7 @@ fn run_pretty_test(config: &config, props: &TestProps, testfile: &Path) {
     let mut expected = match props.pp_exact {
         Some(ref file) => {
             let filepath = testfile.dir_path().join(file);
-            let s = File::open(&filepath).read_to_end();
+            let s = File::open(&filepath).read_to_end().unwrap();
             str::from_utf8_owned(s).unwrap()
           }
           None => { srcs[srcs.len() - 2u].clone() }
@@ -318,8 +318,10 @@ fn run_debuginfo_test(config: &config, props: &TestProps, testfile: &Path) {
                 //waiting 1 second for gdbserver start
                 timer::sleep(1000);
                 let result = task::try(proc() {
-                    tcp::TcpStream::connect(
-                        SocketAddr { ip: Ipv4Addr(127, 0, 0, 1), port: 5039 });
+                    tcp::TcpStream::connect(SocketAddr {
+                        ip: Ipv4Addr(127, 0, 0, 1),
+                        port: 5039,
+                    }).unwrap();
                 });
                 if result.is_err() {
                     continue;
@@ -361,7 +363,7 @@ fn run_debuginfo_test(config: &config, props: &TestProps, testfile: &Path) {
                                stdout: out,
                                stderr: err,
                                cmdline: cmdline};
-            process.force_destroy();
+            process.force_destroy().unwrap();
         }
 
         _=> {
@@ -727,7 +729,7 @@ fn compose_and_run_compiler(
 
 fn ensure_dir(path: &Path) {
     if path.is_dir() { return; }
-    fs::mkdir(path, io::UserRWX);
+    fs::mkdir(path, io::UserRWX).unwrap();
 }
 
 fn compose_and_run(config: &config, testfile: &Path,
@@ -852,7 +854,7 @@ fn dump_output(config: &config, testfile: &Path, out: &str, err: &str) {
 fn dump_output_file(config: &config, testfile: &Path,
                     out: &str, extension: &str) {
     let outfile = make_out_name(config, testfile, extension);
-    File::create(&outfile).write(out.as_bytes());
+    File::create(&outfile).write(out.as_bytes()).unwrap();
 }
 
 fn make_out_name(config: &config, testfile: &Path, extension: &str) -> Path {
@@ -1003,7 +1005,7 @@ fn _arm_exec_compiled_test(config: &config, props: &TestProps,
 fn _arm_push_aux_shared_library(config: &config, testfile: &Path) {
     let tdir = aux_output_dir_name(config, testfile);
 
-    let dirs = fs::readdir(&tdir);
+    let dirs = fs::readdir(&tdir).unwrap();
     for file in dirs.iter() {
         if file.extension_str() == Some("so") {
             // FIXME (#9639): This needs to handle non-utf8 paths
@@ -1099,7 +1101,7 @@ fn disassemble_extract(config: &config, _props: &TestProps,
 
 
 fn count_extracted_lines(p: &Path) -> uint {
-    let x = File::open(&p.with_extension("ll")).read_to_end();
+    let x = File::open(&p.with_extension("ll")).read_to_end().unwrap();
     let x = str::from_utf8_owned(x).unwrap();
     x.lines().len()
 }

src/doc/guide-conditions.md

@@ -47,15 +47,15 @@ An example program that does this task reads like this:
 # #[allow(unused_imports)];
 use std::io::{BufferedReader, File};
 # mod BufferedReader {
-#     use std::io::File;
+#     use std::io::{File, IoResult};
 #     use std::io::MemReader;
 #     use std::io::BufferedReader;
 #     static s : &'static [u8] = bytes!("1 2\n\
 #                                        34 56\n\
 #                                        789 123\n\
 #                                        45 67\n\
 #                                        ");
-#     pub fn new(_inner: Option<File>) -> BufferedReader<MemReader> {
+#     pub fn new(_inner: IoResult<File>) -> BufferedReader<MemReader> {
 #           BufferedReader::new(MemReader::new(s.to_owned()))
 #     }
 # }
@@ -71,7 +71,6 @@ fn read_int_pairs() -> ~[(int,int)] {
     let mut pairs = ~[];
 
     // Path takes a generic by-value, rather than by reference
-#    let _g = std::io::ignore_io_error();
     let path = Path::new(&"foo.txt");
     let mut reader = BufferedReader::new(File::open(&path));
 
@@ -245,15 +244,15 @@ and trapping its exit status using `task::try`:
 use std::io::{BufferedReader, File};
 use std::task;
 # mod BufferedReader {
-#     use std::io::File;
+#     use std::io::{File, IoResult};
 #     use std::io::MemReader;
 #     use std::io::BufferedReader;
 #     static s : &'static [u8] = bytes!("1 2\n\
 #                                        34 56\n\
 #                                        789 123\n\
 #                                        45 67\n\
 #                                        ");
-#     pub fn new(_inner: Option<File>) -> BufferedReader<MemReader> {
+#     pub fn new(_inner: IoResult<File>) -> BufferedReader<MemReader> {
 #           BufferedReader::new(MemReader::new(s.to_owned()))
 #     }
 # }
@@ -277,7 +276,6 @@ fn main() {
 
 fn read_int_pairs() -> ~[(int,int)] {
     let mut pairs = ~[];
-#    let _g = std::io::ignore_io_error();
     let path = Path::new(&"foo.txt");
 
     let mut reader = BufferedReader::new(File::open(&path));
@@ -347,15 +345,15 @@ but similarly clear as the version that used `fail!` in the logic where the erro
 # #[allow(unused_imports)];
 use std::io::{BufferedReader, File};
 # mod BufferedReader {
-#     use std::io::File;
+#     use std::io::{File, IoResult};
 #     use std::io::MemReader;
 #     use std::io::BufferedReader;
 #     static s : &'static [u8] = bytes!("1 2\n\
 #                                        34 56\n\
 #                                        789 123\n\
 #                                        45 67\n\
 #                                        ");
-#     pub fn new(_inner: Option<File>) -> BufferedReader<MemReader> {
+#     pub fn new(_inner: IoResult<File>) -> BufferedReader<MemReader> {
 #           BufferedReader::new(MemReader::new(s.to_owned()))
 #     }
 # }
@@ -374,7 +372,6 @@ fn main() {
 
 fn read_int_pairs() -> ~[(int,int)] {
     let mut pairs = ~[];
-#    let _g = std::io::ignore_io_error();
     let path = Path::new(&"foo.txt");
 
     let mut reader = BufferedReader::new(File::open(&path));
@@ -415,15 +412,15 @@ and replaces bad input lines with the pair `(-1,-1)`:
 # #[allow(unused_imports)];
 use std::io::{BufferedReader, File};
 # mod BufferedReader {
-#     use std::io::File;
+#     use std::io::{File, IoResult};
 #     use std::io::MemReader;
 #     use std::io::BufferedReader;
 #     static s : &'static [u8] = bytes!("1 2\n\
 #                                        34 56\n\
 #                                        789 123\n\
 #                                        45 67\n\
 #                                        ");
-#     pub fn new(_inner: Option<File>) -> BufferedReader<MemReader> {
+#     pub fn new(_inner: IoResult<File>) -> BufferedReader<MemReader> {
 #           BufferedReader::new(MemReader::new(s.to_owned()))
 #     }
 # }
@@ -447,7 +444,6 @@ fn main() {
 
 fn read_int_pairs() -> ~[(int,int)] {
     let mut pairs = ~[];
-#    let _g = std::io::ignore_io_error();
     let path = Path::new(&"foo.txt");
 
     let mut reader = BufferedReader::new(File::open(&path));
@@ -489,15 +485,15 @@ Changing the condition's return type from `(int,int)` to `Option<(int,int)>` wil
 # #[allow(unused_imports)];
 use std::io::{BufferedReader, File};
 # mod BufferedReader {
-#     use std::io::File;
+#     use std::io::{IoResult, File};
 #     use std::io::MemReader;
 #     use std::io::BufferedReader;
 #     static s : &'static [u8] = bytes!("1 2\n\
 #                                        34 56\n\
 #                                        789 123\n\
 #                                        45 67\n\
 #                                        ");
-#     pub fn new(_inner: Option<File>) -> BufferedReader<MemReader> {
+#     pub fn new(_inner: IoResult<File>) -> BufferedReader<MemReader> {
 #           BufferedReader::new(MemReader::new(s.to_owned()))
 #     }
 # }
@@ -522,7 +518,6 @@ fn main() {
 
 fn read_int_pairs() -> ~[(int,int)] {
     let mut pairs = ~[];
-#    let _g = std::io::ignore_io_error();
     let path = Path::new(&"foo.txt");
 
     let mut reader = BufferedReader::new(File::open(&path));
@@ -573,15 +568,15 @@ This can be encoded in the handler API by introducing a helper type: `enum Malfo
 # #[allow(unused_imports)];
 use std::io::{BufferedReader, File};
 # mod BufferedReader {
-#     use std::io::File;
+#     use std::io::{File, IoResult};
 #     use std::io::MemReader;
 #     use std::io::BufferedReader;
 #     static s : &'static [u8] = bytes!("1 2\n\
 #                                        34 56\n\
 #                                        789 123\n\
 #                                        45 67\n\
 #                                        ");
-#     pub fn new(_inner: Option<File>) -> BufferedReader<MemReader> {
+#     pub fn new(_inner: IoResult<File>) -> BufferedReader<MemReader> {
 #           BufferedReader::new(MemReader::new(s.to_owned()))
 #     }
 # }
@@ -615,7 +610,6 @@ fn main() {
 
 fn read_int_pairs() -> ~[(int,int)] {
     let mut pairs = ~[];
-#    let _g = std::io::ignore_io_error();
     let path = Path::new(&"foo.txt");
 
     let mut reader = BufferedReader::new(File::open(&path));
@@ -696,15 +690,15 @@ a second condition and a helper function will suffice:
 # #[allow(unused_imports)];
 use std::io::{BufferedReader, File};
 # mod BufferedReader {
-#     use std::io::File;
+#     use std::io::{File, IoResult};
 #     use std::io::MemReader;
 #     use std::io::BufferedReader;
 #     static s : &'static [u8] = bytes!("1 2\n\
 #                                        34 56\n\
 #                                        789 123\n\
 #                                        45 67\n\
 #                                        ");
-#     pub fn new(_inner: Option<File>) -> BufferedReader<MemReader> {
+#     pub fn new(_inner: IoResult<File>) -> BufferedReader<MemReader> {
 #           BufferedReader::new(MemReader::new(s.to_owned()))
 #     }
 # }
@@ -752,7 +746,6 @@ fn parse_int(x: &str) -> int {
 
 fn read_int_pairs() -> ~[(int,int)] {
     let mut pairs = ~[];
-#    let _g = std::io::ignore_io_error();
     let path = Path::new(&"foo.txt");
 
     let mut reader = BufferedReader::new(File::open(&path));

src/etc/combine-tests.py

@@ -69,6 +69,7 @@ def scrub(b):
 use run_pass_stage2::*;
 use std::io;
 use std::io::Writer;
+#[allow(warnings)]
 fn main() {
     let mut out = io::stdout();
 """