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Remove use of std::uniform_distribution<uint8_t>.

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A previous CL removed use of Google-specific random number generating
functionality, such as ACMRandom, and used the C++11 standard library
instead. The CL used std::uniform_distribution<uint8_t> to generate
random bytes, which seems to be unsupported by the standard [1, 2].

For better or for worse, our toolchain does not complain. However,
Visual Studio errors out with "invalid template argument for
uniform_int_distribution: N4659 29.6.1.1 [rand.req.genl]/1e requires one
of short, int, long, long long, unsigned short, unsigned int, unsigned
long, or unsigned long long".

This CL replaces std::uniform_distribution<uint8_t> with
std::uniform_distribution<int>(0, 255) and appropriate static_cast<>s.

[1] http://eel.is/c++draft/rand.req.genl#1.6
[2] be83c0b472/source/numerics.tex (L1807-L1817)
This commit is contained in:
costan 2019-01-06 11:47:58 -08:00 committed by Victor Costan
parent 3fcbc47f99
commit 9a6fa91217
1 changed files with 6 additions and 6 deletions
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12
snappy_unittest.cc
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@ -671,10 +671,10 @@ TEST(Snappy, SimpleTests) {
// Verify max blowup (lots of four-byte copies) // Verify max blowup (lots of four-byte copies)
TEST(Snappy, MaxBlowup) { TEST(Snappy, MaxBlowup) {
std::mt19937 rng; std::mt19937 rng;
std::uniform_int_distribution<uint8_t> random_byte; std::uniform_int_distribution<int> uniform_byte(0, 255);
string input; string input;
for (int i = 0; i < 80000; ++i) for (int i = 0; i < 80000; ++i)
input.push_back(static_cast<char>(random_byte(rng))); input.push_back(static_cast<char>(uniform_byte(rng)));
for (int i = 0; i < 80000; i += 4) { for (int i = 0; i < 80000; i += 4) {
string four_bytes(input.end() - i - 4, input.end() - i); string four_bytes(input.end() - i - 4, input.end() - i);
@ -687,7 +687,7 @@ TEST(Snappy, RandomData) {
std::minstd_rand0 rng(FLAGS_test_random_seed); std::minstd_rand0 rng(FLAGS_test_random_seed);
std::uniform_int_distribution<int> uniform_0_to_3(0, 3); std::uniform_int_distribution<int> uniform_0_to_3(0, 3);
std::uniform_int_distribution<int> uniform_0_to_8(0, 8); std::uniform_int_distribution<int> uniform_0_to_8(0, 8);
std::uniform_int_distribution<uint8_t> uniform_byte; std::uniform_int_distribution<int> uniform_byte(0, 255);
std::uniform_int_distribution<size_t> uniform_4k(0, 4095); std::uniform_int_distribution<size_t> uniform_4k(0, 4095);
std::uniform_int_distribution<size_t> uniform_64k(0, 65535); std::uniform_int_distribution<size_t> uniform_64k(0, 65535);
std::bernoulli_distribution one_in_ten(1.0 / 10); std::bernoulli_distribution one_in_ten(1.0 / 10);
@ -1062,14 +1062,14 @@ TEST(Snappy, FindMatchLengthRandom) {
constexpr int kNumTrials = 10000; constexpr int kNumTrials = 10000;
constexpr int kTypicalLength = 10; constexpr int kTypicalLength = 10;
std::minstd_rand0 rng(FLAGS_test_random_seed); std::minstd_rand0 rng(FLAGS_test_random_seed);
std::uniform_int_distribution<uint8_t> uniform_byte; std::uniform_int_distribution<int> uniform_byte(0, 255);
std::bernoulli_distribution one_in_two(1.0 / 2); std::bernoulli_distribution one_in_two(1.0 / 2);
std::bernoulli_distribution one_in_typical_length(1.0 / kTypicalLength); std::bernoulli_distribution one_in_typical_length(1.0 / kTypicalLength);
for (int i = 0; i < kNumTrials; i++) { for (int i = 0; i < kNumTrials; i++) {
string s, t; string s, t;
char a = uniform_byte(rng); char a = static_cast<char>(uniform_byte(rng));
char b = uniform_byte(rng); char b = static_cast<char>(uniform_byte(rng));
while (!one_in_typical_length(rng)) { while (!one_in_typical_length(rng)) {
s.push_back(one_in_two(rng) ? a : b); s.push_back(one_in_two(rng) ? a : b);
t.push_back(one_in_two(rng) ? a : b); t.push_back(one_in_two(rng) ? a : b);