Add optional, external tests for floating point parsing.

Running these tests takes hours, so they are not run by @bors.

src/etc/test-float-parse/_common.rs

@@ -0,0 +1,26 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::io;
+use std::io::prelude::*;
+use std::mem::transmute;
+
+// Nothing up my sleeve: Just (PI - 3) in base 16.
+#[allow(dead_code)]
+pub const SEED: [u32; 3] = [0x243f_6a88, 0x85a3_08d3, 0x1319_8a2e];
+
+pub fn validate(text: String) {
+    let mut out = io::stdout();
+    let x: f64 = text.parse().unwrap();
+    let f64_bytes: u64 = unsafe { transmute(x) };
+    let x: f32 = text.parse().unwrap();
+    let f32_bytes: u32 = unsafe { transmute(x) };
+    writeln!(&mut out, "{:016x} {:08x} {}", f64_bytes, f32_bytes, text).unwrap();
+}

src/etc/test-float-parse/few-ones.rs

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+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+mod _common;
+
+use _common::validate;
+
+fn main() {
+    let mut pow = vec![];
+    for i in 0..63 {
+        pow.push(1u64 << i);
+    }
+    for a in &pow {
+        for b in &pow {
+            for c in &pow {
+                validate((a | b | c).to_string());
+            }
+        }
+    }
+}

src/etc/test-float-parse/huge-pow10.rs

@@ -0,0 +1,21 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+mod _common;
+
+use _common::validate;
+
+fn main() {
+    for e in 300..310 {
+        for i in 0..100000 {
+            validate(format!("{}e{}", i, e));
+        }
+    }
+}

src/etc/test-float-parse/many-digits.rs

@@ -0,0 +1,39 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(rand)]
+
+extern crate rand;
+
+mod _common;
+
+use std::char;
+use rand::{IsaacRng, Rng, SeedableRng};
+use rand::distributions::{Range, Sample};
+use _common::{validate, SEED};
+
+fn main() {
+    let mut rnd = IsaacRng::from_seed(&SEED);
+    let mut range = Range::new(0, 10);
+    for _ in 0..5_000_000u64 {
+        let num_digits = rnd.gen_range(100, 300);
+        let digits = gen_digits(num_digits, &mut range, &mut rnd);
+        validate(digits);
+    }
+}
+
+fn gen_digits<R: Rng>(n: u32, range: &mut Range<u32>, rnd: &mut R) -> String {
+    let mut s = String::new();
+    for _ in 0..n {
+        let digit = char::from_digit(range.sample(rnd), 10).unwrap();
+        s.push(digit);
+    }
+    s
+}

src/etc/test-float-parse/rand-f64.rs

@@ -0,0 +1,32 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(rand)]
+
+extern crate rand;
+
+mod _common;
+
+use _common::{validate, SEED};
+use rand::{IsaacRng, Rng, SeedableRng};
+use std::mem::transmute;
+
+fn main() {
+    let mut rnd = IsaacRng::from_seed(&SEED);
+    let mut i = 0;
+    while i < 10_000_000 {
+        let bits = rnd.next_u64();
+        let x: f64 = unsafe { transmute(bits) };
+        if x.is_finite() {
+            validate(format!("{:e}", x));
+            i += 1;
+        }
+    }
+}