Export of internal Abseil changes.

--
9c4ef32276054fba6a116c01cd4b3fd278f59ece by Andy Soffer <asoffer@google.com>:

Remove support for unused arbitrary-width output in FastUniformBits. Width
should be inferred from the requested return UIntType.

PiperOrigin-RevId: 257189319

--
e3326329d02171a301cc3d6ae617ed448472b728 by Abseil Team <absl-team@google.com>:

Update comments to make clear that absl::Format(std::string *, ...) appends to the provided string.

PiperOrigin-RevId: 257058043

--
e2096b06d714fba3ea2c885d670a42efd872765c by Xiaoyi Zhang <zhangxy@google.com>:

Fix compilation error on MSVC 2017. The root cause seems to be a compiler bug
in VS 2017 about pack expansion with multiple parameter packs, specifically `MakeVisitationMatrixImpl::Run` is triggering compiler error "error C3528: 'BoundIndices': the number of elements in this pack expansion does not match the number of elements in 'EndIndices'".
Work around this issue by using only one parameter pack `CurrIndices` in `MakeVisitationMatrixImpl::Run`.

PiperOrigin-RevId: 257040381

--
9ab75ff27b2513583fffc1233e6568aa96be36f7 by Matt Calabrese <calabrese@google.com>:

Internal change.

PiperOrigin-RevId: 257039041
GitOrigin-RevId: 9c4ef32276054fba6a116c01cd4b3fd278f59ece
Change-Id: I5f708bb03aff93948502394a413260af2a8a273b

1 files changed, 0 insertions, 155 deletions

diff --git a/absl/random/internal/fast_uniform_bits_test.cc b/absl/random/internal/fast_uniform_bits_test.cc
index f4b9cd5..1837794 100644
--- a/absl/random/internal/fast_uniform_bits_test.cc
+++ b/absl/random/internal/fast_uniform_bits_test.cc
@@ -45,57 +45,6 @@ TYPED_TEST(FastUniformBitsTypedTest, BasicTest) {
   }
 }
 
-TEST(FastUniformBitsTest, TypeBoundaries32) {
-  // Tests that FastUniformBits can adapt to 32-bit boundaries.
-  absl::random_internal::FastUniformBits<uint32_t, 1> a;
-  absl::random_internal::FastUniformBits<uint32_t, 31> b;
-  absl::random_internal::FastUniformBits<uint32_t, 32> c;
-
-  {
-    std::mt19937 gen;  // 32-bit
-    a(gen);
-    b(gen);
-    c(gen);
-  }
-
-  {
-    std::mt19937_64 gen;  // 64-bit
-    a(gen);
-    b(gen);
-    c(gen);
-  }
-}
-
-TEST(FastUniformBitsTest, TypeBoundaries64) {
-  // Tests that FastUniformBits can adapt to 64-bit boundaries.
-  absl::random_internal::FastUniformBits<uint64_t, 1> a;
-  absl::random_internal::FastUniformBits<uint64_t, 31> b;
-  absl::random_internal::FastUniformBits<uint64_t, 32> c;
-  absl::random_internal::FastUniformBits<uint64_t, 33> d;
-  absl::random_internal::FastUniformBits<uint64_t, 63> e;
-  absl::random_internal::FastUniformBits<uint64_t, 64> f;
-
-  {
-    std::mt19937 gen;  // 32-bit
-    a(gen);
-    b(gen);
-    c(gen);
-    d(gen);
-    e(gen);
-    f(gen);
-  }
-
-  {
-    std::mt19937_64 gen;  // 64-bit
-    a(gen);
-    b(gen);
-    c(gen);
-    d(gen);
-    e(gen);
-    f(gen);
-  }
-}
-
 class UrngOddbits {
  public:
   using result_type = uint8_t;
@@ -135,18 +84,6 @@ TEST(FastUniformBitsTest, FastUniformBitsDetails) {
     static_assert(constants::kRangeMask == 0x0f,
                   "constants::kRangeMask == false");
   }
-  {
-    using looping = FastUniformBitsLoopingConstants<uint32_t, 31, Urng4bits>;
-    // To get 31 bits from a 4-bit generator, issue 8 calls and extract 4 bits
-    // per call on all except the first.
-    static_assert(looping::kN0 == 1, "looping::kN0");
-    static_assert(looping::kW0 == 3, "looping::kW0");
-    static_assert(looping::kM0 == 0x7, "looping::kM0");
-    // (The second set of calls, kN1, will not do anything.)
-    static_assert(looping::kN1 == 8, "looping::kN1");
-    static_assert(looping::kW1 == 4, "looping::kW1");
-    static_assert(looping::kM1 == 0xf, "looping::kM1");
-  }
 
   // ~7-bit URBG
   {
@@ -158,31 +95,6 @@ TEST(FastUniformBitsTest, FastUniformBitsDetails) {
     static_assert(constants::kRangeMask == 0x7f,
                   "constants::kRangeMask == 0x7f");
   }
-  {
-    using looping = FastUniformBitsLoopingConstants<uint64_t, 60, UrngOddbits>;
-    // To get 60 bits from a 7-bit generator, issue 10 calls and extract 6 bits
-    // per call, discarding the excess entropy.
-    static_assert(looping::kN0 == 10, "looping::kN0");
-    static_assert(looping::kW0 == 6, "looping::kW0");
-    static_assert(looping::kM0 == 0x3f, "looping::kM0");
-    // (The second set of calls, kN1, will not do anything.)
-    static_assert(looping::kN1 == 10, "looping::kN1");
-    static_assert(looping::kW1 == 7, "looping::kW1");
-    static_assert(looping::kM1 == 0x7f, "looping::kM1");
-  }
-  {
-    using looping = FastUniformBitsLoopingConstants<uint64_t, 63, UrngOddbits>;
-    // To get 63 bits from a 7-bit generator, issue 10 calls--the same as we
-    // would issue for 60 bits--however this time we use two groups.  The first
-    // group (kN0) will issue 7 calls, extracting 6 bits per call.
-    static_assert(looping::kN0 == 7, "looping::kN0");
-    static_assert(looping::kW0 == 6, "looping::kW0");
-    static_assert(looping::kM0 == 0x3f, "looping::kM0");
-    // The second group (kN1) will issue 3 calls, extracting 7 bits per call.
-    static_assert(looping::kN1 == 10, "looping::kN1");
-    static_assert(looping::kW1 == 7, "looping::kW1");
-    static_assert(looping::kM1 == 0x7f, "looping::kM1");
-  }
 }
 
 TEST(FastUniformBitsTest, Urng4_VariousOutputs) {
@@ -193,33 +105,6 @@ TEST(FastUniformBitsTest, Urng4_VariousOutputs) {
 
   // 8-bit types
   {
-    absl::random_internal::FastUniformBits<uint8_t, 1> fast1;
-    EXPECT_EQ(0x1, fast1(urng4));
-    EXPECT_EQ(0x1, fast1(urng32));
-  }
-  {
-    absl::random_internal::FastUniformBits<uint8_t, 2> fast2;
-    EXPECT_EQ(0x1, fast2(urng4));
-    EXPECT_EQ(0x1, fast2(urng32));
-  }
-
-  {
-    absl::random_internal::FastUniformBits<uint8_t, 4> fast4;
-    EXPECT_EQ(0x1, fast4(urng4));
-    EXPECT_EQ(0x1, fast4(urng32));
-  }
-  {
-    absl::random_internal::FastUniformBits<uint8_t, 6> fast6;
-    EXPECT_EQ(0x9, fast6(urng4));  // b001001 (2x3)
-    EXPECT_EQ(0x1, fast6(urng32));
-  }
-  {
-    absl::random_internal::FastUniformBits<uint8_t, 6> fast7;
-    EXPECT_EQ(0x9, fast7(urng4));  // b00001001 (1x4 + 1x3)
-    EXPECT_EQ(0x1, fast7(urng32));
-  }
-
-  {
     absl::random_internal::FastUniformBits<uint8_t> fast8;
     EXPECT_EQ(0x11, fast8(urng4));
     EXPECT_EQ(0x1, fast8(urng32));
@@ -227,22 +112,6 @@ TEST(FastUniformBitsTest, Urng4_VariousOutputs) {
 
   // 16-bit types
   {
-    absl::random_internal::FastUniformBits<uint16_t, 10> fast10;
-    EXPECT_EQ(0x91, fast10(urng4));  // b 0010010001 (2x3 + 1x4)
-    EXPECT_EQ(0x1, fast10(urng32));
-  }
-  {
-    absl::random_internal::FastUniformBits<uint16_t, 11> fast11;
-    EXPECT_EQ(0x111, fast11(urng4));
-    EXPECT_EQ(0x1, fast11(urng32));
-  }
-  {
-    absl::random_internal::FastUniformBits<uint16_t, 12> fast12;
-    EXPECT_EQ(0x111, fast12(urng4));
-    EXPECT_EQ(0x1, fast12(urng32));
-  }
-
-  {
     absl::random_internal::FastUniformBits<uint16_t> fast16;
     EXPECT_EQ(0x1111, fast16(urng4));
     EXPECT_EQ(0x1, fast16(urng32));
@@ -250,17 +119,6 @@ TEST(FastUniformBitsTest, Urng4_VariousOutputs) {
 
   // 32-bit types
   {
-    absl::random_internal::FastUniformBits<uint32_t, 21> fast21;
-    EXPECT_EQ(0x49111, fast21(urng4));  // b 001001001 000100010001 (3x3 + 3x4)
-    EXPECT_EQ(0x1, fast21(urng32));
-  }
-  {
-    absl::random_internal::FastUniformBits<uint32_t, 24> fast24;
-    EXPECT_EQ(0x111111, fast24(urng4));
-    EXPECT_EQ(0x1, fast24(urng32));
-  }
-
-  {
     absl::random_internal::FastUniformBits<uint32_t> fast32;
     EXPECT_EQ(0x11111111, fast32(urng4));
     EXPECT_EQ(0x1, fast32(urng32));
@@ -268,19 +126,6 @@ TEST(FastUniformBitsTest, Urng4_VariousOutputs) {
 
   // 64-bit types
   {
-    absl::random_internal::FastUniformBits<uint64_t, 5> fast5;
-    EXPECT_EQ(0x9, fast5(urng4));
-    EXPECT_EQ(0x1, fast5(urng32));
-  }
-
-  {
-    absl::random_internal::FastUniformBits<uint64_t, 48> fast48;
-    EXPECT_EQ(0x111111111111, fast48(urng4));
-    // computes in 2 steps, should be 24 << 24
-    EXPECT_EQ(0x000001000001, fast48(urng32));
-  }
-
-  {
     absl::random_internal::FastUniformBits<uint64_t> fast64;
     EXPECT_EQ(0x1111111111111111, fast64(urng4));
     EXPECT_EQ(0x0000000100000001, fast64(urng32));