Fix ulp distance calculation for numbers with different signs

This is a simplification of the fix proposed in #2152, with the
critical function split out so that it can be tested directly,
without having to go through the ULP matcher.

Closes #2152

docs/matchers.md

@@ -161,6 +161,11 @@ away from the `target` value. The short version of what this means
 is that there is no more than `maxUlpDiff - 1` representeable floating
 point numbers between the argument for matching and the `target` value.
 
+**Important**: The WithinULP matcher requires the platform to use the
+[IEEE-754](https://en.wikipedia.org/wiki/IEEE_754) representation for
+floating point numbers.
+
+
 `WithinRel` creates a matcher that accepts floating point numbers that
 are _approximately equal_ with the `target` with tolerance of `eps.`
 Specifically, it matches if

src/CMakeLists.txt

@@ -65,6 +65,7 @@ set(INTERNAL_HEADERS
     ${SOURCES_DIR}/internal/catch_errno_guard.hpp
     ${SOURCES_DIR}/internal/catch_exception_translator_registry.hpp
     ${SOURCES_DIR}/internal/catch_fatal_condition_handler.hpp
+    ${SOURCES_DIR}/internal/catch_floating_point_helpers.hpp
     ${SOURCES_DIR}/internal/catch_unique_name.hpp
     ${SOURCES_DIR}/generators/catch_generator_exception.hpp
     ${SOURCES_DIR}/generators/catch_generators.hpp
@@ -160,6 +161,7 @@ set(IMPL_SOURCES
     ${SOURCES_DIR}/internal/catch_enum_values_registry.cpp
     ${SOURCES_DIR}/internal/catch_exception_translator_registry.cpp
     ${SOURCES_DIR}/internal/catch_fatal_condition_handler.cpp
+    ${SOURCES_DIR}/internal/catch_floating_point_helpers.cpp
     ${SOURCES_DIR}/generators/internal/catch_generators_combined_tu.cpp
     ${SOURCES_DIR}/interfaces/catch_interfaces_combined_tu.cpp
     ${SOURCES_DIR}/interfaces/catch_interfaces_reporter.cpp

src/catch2/catch_all.hpp

@@ -66,6 +66,7 @@
 #include <catch2/internal/catch_errno_guard.hpp>
 #include <catch2/internal/catch_exception_translator_registry.hpp>
 #include <catch2/internal/catch_fatal_condition_handler.hpp>
+#include <catch2/internal/catch_floating_point_helpers.hpp>
 #include <catch2/internal/catch_lazy_expr.hpp>
 #include <catch2/internal/catch_leak_detector.hpp>
 #include <catch2/internal/catch_list.hpp>

src/catch2/internal/catch_floating_point_helpers.cpp

@@ -0,0 +1,32 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE_1_0.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+#include <catch2/internal/catch_floating_point_helpers.hpp>
+
+#include <cstring>
+
+namespace Catch {
+    namespace Detail {
+
+        uint32_t convertToBits(float f) {
+            static_assert(sizeof(float) == sizeof(uint32_t), "Important ULP matcher assumption violated");
+            uint32_t i;
+            std::memcpy(&i, &f, sizeof(f));
+            return i;
+        }
+
+        uint64_t convertToBits(double d) {
+            static_assert(sizeof(double) == sizeof(uint64_t), "Important ULP matcher assumption violated");
+            uint64_t i;
+            std::memcpy(&i, &d, sizeof(d));
+            return i;
+        }
+
+    } // end namespace Detail
+} // end namespace Catch
+

src/catch2/internal/catch_floating_point_helpers.hpp

@@ -0,0 +1,88 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE_1_0.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+#ifndef CATCH_FLOATING_POINT_HELPERS_HPP_INCLUDED
+#define CATCH_FLOATING_POINT_HELPERS_HPP_INCLUDED
+
+#include <catch2/internal/catch_polyfills.hpp>
+
+#include <cmath>
+#include <cstdint>
+#include <utility>
+#include <limits>
+
+namespace Catch {
+    namespace Detail {
+
+        uint32_t convertToBits(float f);
+        uint64_t convertToBits(double d);
+
+    } // end namespace Detail
+
+
+    /**
+     * Calculates the ULP distance between two floating point numbers
+     *
+     * The ULP distance of two floating point numbers is the count of
+     * valid floating point numbers representable between them.
+     *
+     * There are some exceptions between how this function counts the
+     * distance, and the interpretation of the standard as implemented.
+     * by e.g. `nextafter`. For this function it always holds that:
+     * * `(x == y) => ulpDistance(x, y) == 0` (so `ulpDistance(-0, 0) == 0`)
+     * * `ulpDistance(maxFinite, INF) == 1`
+     * * `ulpDistance(x, -x) == 2 * ulpDistance(x, 0)`
+     *
+     * \pre `!isnan( lhs )`
+     * \pre `!isnan( rhs )`
+     * \pre floating point numbers are represented in IEEE-754 format
+     */
+    template <typename FP>
+    uint64_t ulpDistance( FP lhs, FP rhs ) {
+        assert( std::numeric_limits<FP>::is_iec559 &&
+            "ulpDistance assumes IEEE-754 format for floating point types" );
+        assert( !Catch::isnan( lhs ) &&
+                "Distance between NaN and number is not meaningful" );
+        assert( !Catch::isnan( rhs ) &&
+                "Distance between NaN and number is not meaningful" );
+
+        // We want X == Y to imply 0 ULP distance even if X and Y aren't
+        // bit-equal (-0 and 0), or X - Y != 0 (same sign infinities).
+        if ( lhs == rhs ) { return 0; }
+
+        // We need a properly typed positive zero for type inference.
+        static constexpr FP positive_zero{};
+
+        // We want to ensure that +/- 0 is always represented as positive zero
+        if ( lhs == positive_zero ) { lhs = positive_zero; }
+        if ( rhs == positive_zero ) { rhs = positive_zero; }
+
+        // If arguments have different signs, we can handle them by summing
+        // how far are they from 0 each.
+        if ( std::signbit( lhs ) != std::signbit( rhs ) ) {
+            return ulpDistance( std::abs( lhs ), positive_zero ) +
+                   ulpDistance( std::abs( rhs ), positive_zero );
+        }
+
+        // When both lhs and rhs are of the same sign, we can just
+        // read the numbers bitwise as integers, and then subtract them
+        // (assuming IEEE).
+        uint64_t lc = Detail::convertToBits( lhs );
+        uint64_t rc = Detail::convertToBits( rhs );
+
+        // The ulp distance between two numbers is symmetric, so to avoid
+        // dealing with overflows we want the bigger converted number on the lhs
+        if ( lc < rc ) {
+            std::swap( lc, rc );
+        }
+
+        return lc - rc;
+    }
+
+} // end namespace Catch
+
+#endif // CATCH_FLOATING_POINT_HELPERS_HPP_INCLUDED

src/catch2/matchers/catch_matchers_floating_point.cpp

@@ -10,12 +10,12 @@
 #include <catch2/internal/catch_polyfills.hpp>
 #include <catch2/internal/catch_to_string.hpp>
 #include <catch2/catch_tostring.hpp>
+#include <catch2/internal/catch_floating_point_helpers.hpp>
 
 #include <algorithm>
 #include <cmath>
 #include <cstdlib>
 #include <cstdint>
-#include <cstring>
 #include <sstream>
 #include <iomanip>
 #include <limits>
@@ -24,20 +24,6 @@
 namespace Catch {
 namespace {
 
-    int32_t convert(float f) {
-        static_assert(sizeof(float) == sizeof(int32_t), "Important ULP matcher assumption violated");
-        int32_t i;
-        std::memcpy(&i, &f, sizeof(f));
-        return i;
-    }
-
-    int64_t convert(double d) {
-        static_assert(sizeof(double) == sizeof(int64_t), "Important ULP matcher assumption violated");
-        int64_t i;
-        std::memcpy(&i, &d, sizeof(d));
-        return i;
-    }
-
     template <typename FP>
     bool almostEqualUlps(FP lhs, FP rhs, uint64_t maxUlpDiff) {
         // Comparison with NaN should always be false.
@@ -46,17 +32,10 @@ namespace {
             return false;
         }
 
-        auto lc = convert(lhs);
+        // This should also handle positive and negative zeros, infinities
-        auto rc = convert(rhs);
+        const auto ulpDist = ulpDistance(lhs, rhs);
 
-        if ((lc < 0) != (rc < 0)) {
+        return ulpDist <= maxUlpDiff;
-            // Potentially we can have +0 and -0
-            return lhs == rhs;
-        }
-
-        // static cast as a workaround for IBM XLC
-        auto ulpDiff = std::abs(static_cast<FP>(lc - rc));
-        return static_cast<uint64_t>(ulpDiff) <= maxUlpDiff;
     }
 
 #if defined(CATCH_CONFIG_GLOBAL_NEXTAFTER)
@@ -131,6 +110,9 @@ namespace Detail {
         CATCH_ENFORCE(m_type == Detail::FloatingPointKind::Double
                    || m_ulps < (std::numeric_limits<uint32_t>::max)(),
             "Provided ULP is impossibly large for a float comparison.");
+        CATCH_ENFORCE( std::numeric_limits<double>::is_iec559,
+                       "WithinUlp matcher only supports platforms with "
+                       "IEEE-754 compatible floating point representation" );
     }
 
 #if defined(__clang__)

tests/CMakeLists.txt

@@ -80,6 +80,7 @@ set(TEST_SOURCES
         ${SELF_TEST_DIR}/IntrospectiveTests/Clara.tests.cpp
         ${SELF_TEST_DIR}/IntrospectiveTests/CmdLine.tests.cpp
         ${SELF_TEST_DIR}/IntrospectiveTests/Details.tests.cpp
+        ${SELF_TEST_DIR}/IntrospectiveTests/FloatingPoint.tests.cpp
         ${SELF_TEST_DIR}/IntrospectiveTests/GeneratorsImpl.tests.cpp
         ${SELF_TEST_DIR}/IntrospectiveTests/InternalBenchmark.tests.cpp
         ${SELF_TEST_DIR}/IntrospectiveTests/PartTracker.tests.cpp

tests/SelfTest/Baselines/automake.sw.approved.txt

@@ -24,6 +24,8 @@ Nor would this
 :test-result: PASS #1954 - 7 arg template test case sig compiles - 1, 1, 1, 1, 1, 0, 0
 :test-result: PASS #1954 - 7 arg template test case sig compiles - 5, 1, 1, 1, 1, 0, 0
 :test-result: PASS #1954 - 7 arg template test case sig compiles - 5, 3, 1, 1, 1, 0, 0
+:test-result: PASS #2152 - ULP checks between differently signed values were wrong - double
+:test-result: PASS #2152 - ULP checks between differently signed values were wrong - float
 :test-result: XFAIL #748 - captures with unexpected exceptions
 :test-result: PASS #809
 :test-result: PASS #833
@@ -282,6 +284,7 @@ Message from section two
 :test-result: PASS classify_outliers
 :test-result: PASS comparisons between const int variables
 :test-result: PASS comparisons between int variables
+:test-result: PASS convertToBits
 :test-result: PASS empty tags are not allowed
 :test-result: PASS erfc_inv
 :test-result: PASS estimate_clock_resolution

tests/SelfTest/Baselines/compact.sw.approved.txt

@@ -80,6 +80,10 @@ PartTracker.tests.cpp:<line number>: passed: n for: 3
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
+Matchers.tests.cpp:<line number>: passed: smallest_non_zero, WithinULP( -smallest_non_zero, 2 ) for: 0.0 is within 2 ULPs of -4.9406564584124654e-324 ([-1.4821969375237396e-323, 4.9406564584124654e-324])
+Matchers.tests.cpp:<line number>: passed: smallest_non_zero, !WithinULP( -smallest_non_zero, 1 ) for: 0.0 not is within 1 ULPs of -4.9406564584124654e-324 ([-9.8813129168249309e-324, -0.0000000000000000e+00])
+Matchers.tests.cpp:<line number>: passed: smallest_non_zero, WithinULP( -smallest_non_zero, 2 ) for: 0.0f is within 2 ULPs of -1.40129846e-45f ([-4.20389539e-45, 1.40129846e-45])
+Matchers.tests.cpp:<line number>: passed: smallest_non_zero, !WithinULP( -smallest_non_zero, 1 ) for: 0.0f not is within 1 ULPs of -1.40129846e-45f ([-2.80259693e-45, -0.00000000e+00])
 Exception.tests.cpp:<line number>: failed: unexpected exception with message: 'answer := 42' with 1 message: 'expected exception'
 Exception.tests.cpp:<line number>: failed: unexpected exception with message: 'answer := 42'; expression was: thisThrows() with 1 message: 'expected exception'
 Exception.tests.cpp:<line number>: passed: thisThrows() with 1 message: 'answer := 42'
@@ -586,6 +590,7 @@ Matchers.tests.cpp:<line number>: passed: 10.f, !WithinAbs( 11.f, 0.5f ) for: 10
 Matchers.tests.cpp:<line number>: passed: -10.f, WithinAbs( -10.f, 0.5f ) for: -10.0f is within 0.5 of -10.0
 Matchers.tests.cpp:<line number>: passed: -10.f, WithinAbs( -9.6f, 0.5f ) for: -10.0f is within 0.5 of -9.6000003815
 Matchers.tests.cpp:<line number>: passed: 1.f, WithinULP( 1.f, 0 ) for: 1.0f is within 0 ULPs of 1.00000000e+00f ([1.00000000e+00, 1.00000000e+00])
+Matchers.tests.cpp:<line number>: passed: -1.f, WithinULP( -1.f, 0 ) for: -1.0f is within 0 ULPs of -1.00000000e+00f ([-1.00000000e+00, -1.00000000e+00])
 Matchers.tests.cpp:<line number>: passed: nextafter( 1.f, 2.f ), WithinULP( 1.f, 1 ) for: 1.0f is within 1 ULPs of 1.00000000e+00f ([9.99999940e-01, 1.00000012e+00])
 Matchers.tests.cpp:<line number>: passed: 0.f, WithinULP( nextafter( 0.f, 1.f ), 1 ) for: 0.0f is within 1 ULPs of 1.40129846e-45f ([0.00000000e+00, 2.80259693e-45])
 Matchers.tests.cpp:<line number>: passed: 1.f, WithinULP( nextafter( 1.f, 0.f ), 1 ) for: 1.0f is within 1 ULPs of 9.99999940e-01f ([9.99999881e-01, 1.00000000e+00])
@@ -2065,6 +2070,16 @@ Condition.tests.cpp:<line number>: passed: long_var == unsigned_char_var for: 1
 Condition.tests.cpp:<line number>: passed: long_var == unsigned_short_var for: 1 == 1
 Condition.tests.cpp:<line number>: passed: long_var == unsigned_int_var for: 1 == 1
 Condition.tests.cpp:<line number>: passed: long_var == unsigned_long_var for: 1 == 1
+FloatingPoint.tests.cpp:<line number>: passed: convertToBits( 0.f ) == 0 for: 0 == 0
+FloatingPoint.tests.cpp:<line number>: passed: convertToBits( -0.f ) == ( 1ULL << 31 ) for: 2147483648 (0x<hex digits>)
+==
+2147483648 (0x<hex digits>)
+FloatingPoint.tests.cpp:<line number>: passed: convertToBits( 0. ) == 0 for: 0 == 0
+FloatingPoint.tests.cpp:<line number>: passed: convertToBits( -0. ) == ( 1ULL << 63 ) for: 9223372036854775808 (0x<hex digits>)
+==
+9223372036854775808 (0x<hex digits>)
+FloatingPoint.tests.cpp:<line number>: passed: convertToBits( std::numeric_limits<float>::denorm_min() ) == 1 for: 1 == 1
+FloatingPoint.tests.cpp:<line number>: passed: convertToBits( std::numeric_limits<double>::denorm_min() ) == 1 for: 1 == 1
 Tag.tests.cpp:<line number>: passed: Catch::TestCaseInfo("", { "test with an empty tag", "[]" }, dummySourceLineInfo)
 InternalBenchmark.tests.cpp:<line number>: passed: erfc_inv(1.103560) == Approx(-0.09203687623843015) for: -0.0920368762 == Approx( -0.0920368762 )
 InternalBenchmark.tests.cpp:<line number>: passed: erfc_inv(1.067400) == Approx(-0.05980291115763361) for: -0.0598029112 == Approx( -0.0598029112 )

tests/SelfTest/Baselines/console.std.approved.txt

@@ -1386,6 +1386,6 @@ due to unexpected exception with message:
   Why would you throw a std::string?
 
 ===============================================================================
-test cases:  365 |  289 passed |  70 failed |  6 failed as expected
+test cases:  368 |  292 passed |  70 failed |  6 failed as expected
-assertions: 2092 | 1940 passed | 129 failed | 23 failed as expected
+assertions: 2103 | 1951 passed | 129 failed | 23 failed as expected
 

tests/SelfTest/Baselines/console.sw.approved.txt

@@ -744,6 +744,41 @@ Misc.tests.cpp:<line number>
 
 Misc.tests.cpp:<line number>: PASSED:
 
+-------------------------------------------------------------------------------
+#2152 - ULP checks between differently signed values were wrong - double
+-------------------------------------------------------------------------------
+Matchers.tests.cpp:<line number>
+...............................................................................
+
+Matchers.tests.cpp:<line number>: PASSED:
+  CHECK_THAT( smallest_non_zero, WithinULP( -smallest_non_zero, 2 ) )
+with expansion:
+  0.0 is within 2 ULPs of -4.9406564584124654e-324 ([-1.4821969375237396e-323,
+  4.9406564584124654e-324])
+
+Matchers.tests.cpp:<line number>: PASSED:
+  CHECK_THAT( smallest_non_zero, !WithinULP( -smallest_non_zero, 1 ) )
+with expansion:
+  0.0 not is within 1 ULPs of -4.9406564584124654e-324 ([-9.8813129168249309e-
+  324, -0.0000000000000000e+00])
+
+-------------------------------------------------------------------------------
+#2152 - ULP checks between differently signed values were wrong - float
+-------------------------------------------------------------------------------
+Matchers.tests.cpp:<line number>
+...............................................................................
+
+Matchers.tests.cpp:<line number>: PASSED:
+  CHECK_THAT( smallest_non_zero, WithinULP( -smallest_non_zero, 2 ) )
+with expansion:
+  0.0f is within 2 ULPs of -1.40129846e-45f ([-4.20389539e-45, 1.40129846e-45])
+
+Matchers.tests.cpp:<line number>: PASSED:
+  CHECK_THAT( smallest_non_zero, !WithinULP( -smallest_non_zero, 1 ) )
+with expansion:
+  0.0f not is within 1 ULPs of -1.40129846e-45f ([-2.80259693e-45, -0.
+  00000000e+00])
+
 -------------------------------------------------------------------------------
 #748 - captures with unexpected exceptions
   outside assertions
@@ -4490,6 +4525,12 @@ Matchers.tests.cpp:<line number>: PASSED:
 with expansion:
   1.0f is within 0 ULPs of 1.00000000e+00f ([1.00000000e+00, 1.00000000e+00])
 
+Matchers.tests.cpp:<line number>: PASSED:
+  REQUIRE_THAT( -1.f, WithinULP( -1.f, 0 ) )
+with expansion:
+  -1.0f is within 0 ULPs of -1.00000000e+00f ([-1.00000000e+00, -1.00000000e+
+  00])
+
 Matchers.tests.cpp:<line number>: PASSED:
   REQUIRE_THAT( nextafter( 1.f, 2.f ), WithinULP( 1.f, 1 ) )
 with expansion:
@@ -14597,6 +14638,46 @@ Condition.tests.cpp:<line number>: PASSED:
 with expansion:
   1 == 1
 
+-------------------------------------------------------------------------------
+convertToBits
+-------------------------------------------------------------------------------
+FloatingPoint.tests.cpp:<line number>
+...............................................................................
+
+FloatingPoint.tests.cpp:<line number>: PASSED:
+  CHECK( convertToBits( 0.f ) == 0 )
+with expansion:
+  0 == 0
+
+FloatingPoint.tests.cpp:<line number>: PASSED:
+  CHECK( convertToBits( -0.f ) == ( 1ULL << 31 ) )
+with expansion:
+  2147483648 (0x<hex digits>)
+  ==
+  2147483648 (0x<hex digits>)
+
+FloatingPoint.tests.cpp:<line number>: PASSED:
+  CHECK( convertToBits( 0. ) == 0 )
+with expansion:
+  0 == 0
+
+FloatingPoint.tests.cpp:<line number>: PASSED:
+  CHECK( convertToBits( -0. ) == ( 1ULL << 63 ) )
+with expansion:
+  9223372036854775808 (0x<hex digits>)
+  ==
+  9223372036854775808 (0x<hex digits>)
+
+FloatingPoint.tests.cpp:<line number>: PASSED:
+  CHECK( convertToBits( std::numeric_limits<float>::denorm_min() ) == 1 )
+with expansion:
+  1 == 1
+
+FloatingPoint.tests.cpp:<line number>: PASSED:
+  CHECK( convertToBits( std::numeric_limits<double>::denorm_min() ) == 1 )
+with expansion:
+  1 == 1
+
 -------------------------------------------------------------------------------
 empty tags are not allowed
 -------------------------------------------------------------------------------
@@ -16852,6 +16933,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  365 |  273 passed |  86 failed |  6 failed as expected
+test cases:  368 |  276 passed |  86 failed |  6 failed as expected
-assertions: 2109 | 1940 passed | 146 failed | 23 failed as expected
+assertions: 2120 | 1951 passed | 146 failed | 23 failed as expected
 

tests/SelfTest/Baselines/console.swa4.approved.txt

@@ -744,6 +744,41 @@ Misc.tests.cpp:<line number>
 
 Misc.tests.cpp:<line number>: PASSED:
 
+-------------------------------------------------------------------------------
+#2152 - ULP checks between differently signed values were wrong - double
+-------------------------------------------------------------------------------
+Matchers.tests.cpp:<line number>
+...............................................................................
+
+Matchers.tests.cpp:<line number>: PASSED:
+  CHECK_THAT( smallest_non_zero, WithinULP( -smallest_non_zero, 2 ) )
+with expansion:
+  0.0 is within 2 ULPs of -4.9406564584124654e-324 ([-1.4821969375237396e-323,
+  4.9406564584124654e-324])
+
+Matchers.tests.cpp:<line number>: PASSED:
+  CHECK_THAT( smallest_non_zero, !WithinULP( -smallest_non_zero, 1 ) )
+with expansion:
+  0.0 not is within 1 ULPs of -4.9406564584124654e-324 ([-9.8813129168249309e-
+  324, -0.0000000000000000e+00])
+
+-------------------------------------------------------------------------------
+#2152 - ULP checks between differently signed values were wrong - float
+-------------------------------------------------------------------------------
+Matchers.tests.cpp:<line number>
+...............................................................................
+
+Matchers.tests.cpp:<line number>: PASSED:
+  CHECK_THAT( smallest_non_zero, WithinULP( -smallest_non_zero, 2 ) )
+with expansion:
+  0.0f is within 2 ULPs of -1.40129846e-45f ([-4.20389539e-45, 1.40129846e-45])
+
+Matchers.tests.cpp:<line number>: PASSED:
+  CHECK_THAT( smallest_non_zero, !WithinULP( -smallest_non_zero, 1 ) )
+with expansion:
+  0.0f not is within 1 ULPs of -1.40129846e-45f ([-2.80259693e-45, -0.
+  00000000e+00])
+
 -------------------------------------------------------------------------------
 #748 - captures with unexpected exceptions
   outside assertions
@@ -924,6 +959,6 @@ Condition.tests.cpp:<line number>: FAILED:
   CHECK( true != true )
 
 ===============================================================================
-test cases: 31 | 26 passed | 3 failed | 2 failed as expected
+test cases:  33 | 28 passed | 3 failed | 2 failed as expected
-assertions: 99 | 92 passed | 4 failed | 3 failed as expected
+assertions: 103 | 96 passed | 4 failed | 3 failed as expected
 

tests/SelfTest/Baselines/junit.sw.approved.txt

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuitesloose text artifact
 >
-  <testsuite name="<exe-name>" errors="17" failures="130" tests="2110" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="130" tests="2121" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="filters" value="~[!nonportable]~[!benchmark]~[approvals] *"/>
       <property name="random-seed" value="1"/>
@@ -47,6 +47,8 @@ Nor would this
     <testcase classname="<exe-name>.global" name="#1954 - 7 arg template test case sig compiles - 1, 1, 1, 1, 1, 0, 0" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="#1954 - 7 arg template test case sig compiles - 5, 1, 1, 1, 1, 0, 0" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="#1954 - 7 arg template test case sig compiles - 5, 3, 1, 1, 1, 0, 0" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="#2152 - ULP checks between differently signed values were wrong - double" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="#2152 - ULP checks between differently signed values were wrong - float" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="#748 - captures with unexpected exceptions/outside assertions" time="{duration}" status="run">
       <error type="TEST_CASE">
 FAILED:
@@ -1548,6 +1550,7 @@ Misc.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="classify_outliers/mixed" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="comparisons between const int variables" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="comparisons between int variables" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="convertToBits" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="empty tags are not allowed" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="erfc_inv" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="estimate_clock_resolution" time="{duration}" status="run"/>

tests/SelfTest/Baselines/sonarqube.sw.approved.txt

@@ -77,6 +77,9 @@
     <testCase name="Process can be configured on command line/Benchmark options/warmup-time" duration="{duration}"/>
     <testCase name="Test with special, characters &quot;in name" duration="{duration}"/>
   </file>
+  <file path="tests/<exe-name>/IntrospectiveTests/FloatingPoint.tests.cpp">
+    <testCase name="convertToBits" duration="{duration}"/>
+  </file>
   <file path="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp">
     <testCase name="Generators internals/Single value" duration="{duration}"/>
     <testCase name="Generators internals/Preset values" duration="{duration}"/>
@@ -988,6 +991,8 @@ Exception.tests.cpp:<line number>
     <testCase name="tables" duration="{duration}"/>
   </file>
   <file path="tests/<exe-name>/UsageTests/Matchers.tests.cpp">
+    <testCase name="#2152 - ULP checks between differently signed values were wrong - double" duration="{duration}"/>
+    <testCase name="#2152 - ULP checks between differently signed values were wrong - float" duration="{duration}"/>
     <testCase name="Arbitrary predicate matcher/Function pointer" duration="{duration}"/>
     <testCase name="Arbitrary predicate matcher/Lambdas + different type" duration="{duration}"/>
     <testCase name="Combining MatchAllOfGeneric does not nest" duration="{duration}"/>

tests/SelfTest/Baselines/tap.sw.approved.txt

@@ -158,6 +158,14 @@ ok {test-number} -
 ok {test-number} -
 # #1954 - 7 arg template test case sig compiles - 5, 3, 1, 1, 1, 0, 0
 ok {test-number} -
+# #2152 - ULP checks between differently signed values were wrong - double
+ok {test-number} - smallest_non_zero, WithinULP( -smallest_non_zero, 2 ) for: 0.0 is within 2 ULPs of -4.9406564584124654e-324 ([-1.4821969375237396e-323, 4.9406564584124654e-324])
+# #2152 - ULP checks between differently signed values were wrong - double
+ok {test-number} - smallest_non_zero, !WithinULP( -smallest_non_zero, 1 ) for: 0.0 not is within 1 ULPs of -4.9406564584124654e-324 ([-9.8813129168249309e-324, -0.0000000000000000e+00])
+# #2152 - ULP checks between differently signed values were wrong - float
+ok {test-number} - smallest_non_zero, WithinULP( -smallest_non_zero, 2 ) for: 0.0f is within 2 ULPs of -1.40129846e-45f ([-4.20389539e-45, 1.40129846e-45])
+# #2152 - ULP checks between differently signed values were wrong - float
+ok {test-number} - smallest_non_zero, !WithinULP( -smallest_non_zero, 1 ) for: 0.0f not is within 1 ULPs of -1.40129846e-45f ([-2.80259693e-45, -0.00000000e+00])
 # #748 - captures with unexpected exceptions
 not ok {test-number} - unexpected exception with message: 'answer := 42' with 1 message: 'expected exception'
 # #748 - captures with unexpected exceptions
@@ -1155,6 +1163,8 @@ ok {test-number} - -10.f, WithinAbs( -9.6f, 0.5f ) for: -10.0f is within 0.5 of
 # Floating point matchers: float
 ok {test-number} - 1.f, WithinULP( 1.f, 0 ) for: 1.0f is within 0 ULPs of 1.00000000e+00f ([1.00000000e+00, 1.00000000e+00])
 # Floating point matchers: float
+ok {test-number} - -1.f, WithinULP( -1.f, 0 ) for: -1.0f is within 0 ULPs of -1.00000000e+00f ([-1.00000000e+00, -1.00000000e+00])
+# Floating point matchers: float
 ok {test-number} - nextafter( 1.f, 2.f ), WithinULP( 1.f, 1 ) for: 1.0f is within 1 ULPs of 1.00000000e+00f ([9.99999940e-01, 1.00000012e+00])
 # Floating point matchers: float
 ok {test-number} - 0.f, WithinULP( nextafter( 0.f, 1.f ), 1 ) for: 0.0f is within 1 ULPs of 1.40129846e-45f ([0.00000000e+00, 2.80259693e-45])
@@ -3703,6 +3713,18 @@ ok {test-number} - long_var == unsigned_short_var for: 1 == 1
 ok {test-number} - long_var == unsigned_int_var for: 1 == 1
 # comparisons between int variables
 ok {test-number} - long_var == unsigned_long_var for: 1 == 1
+# convertToBits
+ok {test-number} - convertToBits( 0.f ) == 0 for: 0 == 0
+# convertToBits
+ok {test-number} - convertToBits( -0.f ) == ( 1ULL << 31 ) for: 2147483648 (0x<hex digits>) == 2147483648 (0x<hex digits>)
+# convertToBits
+ok {test-number} - convertToBits( 0. ) == 0 for: 0 == 0
+# convertToBits
+ok {test-number} - convertToBits( -0. ) == ( 1ULL << 63 ) for: 9223372036854775808 (0x<hex digits>) == 9223372036854775808 (0x<hex digits>)
+# convertToBits
+ok {test-number} - convertToBits( std::numeric_limits<float>::denorm_min() ) == 1 for: 1 == 1
+# convertToBits
+ok {test-number} - convertToBits( std::numeric_limits<double>::denorm_min() ) == 1 for: 1 == 1
 # empty tags are not allowed
 ok {test-number} - Catch::TestCaseInfo("", { "test with an empty tag", "[]" }, dummySourceLineInfo)
 # erfc_inv
@@ -4220,5 +4242,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2109
+1..2120
 

tests/SelfTest/Baselines/teamcity.sw.approved.txt

@@ -50,6 +50,10 @@ Tricky.tests.cpp:<line number>|nexplicit failure with message:|n  "1514"']
 ##teamcity[testFinished name='#1954 - 7 arg template test case sig compiles - 5, 1, 1, 1, 1, 0, 0' duration="{duration}"]
 ##teamcity[testStarted name='#1954 - 7 arg template test case sig compiles - 5, 3, 1, 1, 1, 0, 0']
 ##teamcity[testFinished name='#1954 - 7 arg template test case sig compiles - 5, 3, 1, 1, 1, 0, 0' duration="{duration}"]
+##teamcity[testStarted name='#2152 - ULP checks between differently signed values were wrong - double']
+##teamcity[testFinished name='#2152 - ULP checks between differently signed values were wrong - double' duration="{duration}"]
+##teamcity[testStarted name='#2152 - ULP checks between differently signed values were wrong - float']
+##teamcity[testFinished name='#2152 - ULP checks between differently signed values were wrong - float' duration="{duration}"]
 ##teamcity[testStarted name='#748 - captures with unexpected exceptions']
 Exception.tests.cpp:<line number>|nunexpected exception with messages:|n  "answer := 42"|n  "expected exception"- failure ignore as test marked as |'ok to fail|'|n']
 Exception.tests.cpp:<line number>|nunexpected exception with messages:|n  "answer := 42"|n  "expected exception"|n  REQUIRE_NOTHROW( thisThrows() )|nwith expansion:|n  thisThrows()|n- failure ignore as test marked as |'ok to fail|'|n']
@@ -690,6 +694,8 @@ Misc.tests.cpp:<line number>|nexpression failed|n  REQUIRE( testCheckedIf( false
 ##teamcity[testFinished name='comparisons between const int variables' duration="{duration}"]
 ##teamcity[testStarted name='comparisons between int variables']
 ##teamcity[testFinished name='comparisons between int variables' duration="{duration}"]
+##teamcity[testStarted name='convertToBits']
+##teamcity[testFinished name='convertToBits' duration="{duration}"]
 ##teamcity[testStarted name='empty tags are not allowed']
 ##teamcity[testFinished name='empty tags are not allowed' duration="{duration}"]
 ##teamcity[testStarted name='erfc_inv']

tests/SelfTest/Baselines/xml.sw.approved.txt

@@ -650,6 +650,44 @@ Nor would this
     <TestCase name="#1954 - 7 arg template test case sig compiles - 5, 3, 1, 1, 1, 0, 0" tags="[.][compilation][regression]" filename="tests/<exe-name>/UsageTests/Misc.tests.cpp" >
       <OverallResult success="true"/>
     </TestCase>
+    <TestCase name="#2152 - ULP checks between differently signed values were wrong - double" tags="[floating-point][matchers][ulp]" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
+      <Expression success="true" type="CHECK_THAT" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
+        <Original>
+          smallest_non_zero, WithinULP( -smallest_non_zero, 2 )
+        </Original>
+        <Expanded>
+          0.0 is within 2 ULPs of -4.9406564584124654e-324 ([-1.4821969375237396e-323, 4.9406564584124654e-324])
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="CHECK_THAT" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
+        <Original>
+          smallest_non_zero, !WithinULP( -smallest_non_zero, 1 )
+        </Original>
+        <Expanded>
+          0.0 not is within 1 ULPs of -4.9406564584124654e-324 ([-9.8813129168249309e-324, -0.0000000000000000e+00])
+        </Expanded>
+      </Expression>
+      <OverallResult success="true"/>
+    </TestCase>
+    <TestCase name="#2152 - ULP checks between differently signed values were wrong - float" tags="[floating-point][matchers][ulp]" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
+      <Expression success="true" type="CHECK_THAT" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
+        <Original>
+          smallest_non_zero, WithinULP( -smallest_non_zero, 2 )
+        </Original>
+        <Expanded>
+          0.0f is within 2 ULPs of -1.40129846e-45f ([-4.20389539e-45, 1.40129846e-45])
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="CHECK_THAT" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
+        <Original>
+          smallest_non_zero, !WithinULP( -smallest_non_zero, 1 )
+        </Original>
+        <Expanded>
+          0.0f not is within 1 ULPs of -1.40129846e-45f ([-2.80259693e-45, -0.00000000e+00])
+        </Expanded>
+      </Expression>
+      <OverallResult success="true"/>
+    </TestCase>
     <TestCase name="#748 - captures with unexpected exceptions" tags="[!shouldfail][!throws][.][failing]" filename="tests/<exe-name>/UsageTests/Exception.tests.cpp" >
       <Section name="outside assertions" filename="tests/<exe-name>/UsageTests/Exception.tests.cpp" >
         <Info>
@@ -5087,6 +5125,14 @@ Nor would this
             1.0f is within 0 ULPs of 1.00000000e+00f ([1.00000000e+00, 1.00000000e+00])
           </Expanded>
         </Expression>
+        <Expression success="true" type="REQUIRE_THAT" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
+          <Original>
+            -1.f, WithinULP( -1.f, 0 )
+          </Original>
+          <Expanded>
+            -1.0f is within 0 ULPs of -1.00000000e+00f ([-1.00000000e+00, -1.00000000e+00])
+          </Expanded>
+        </Expression>
         <Expression success="true" type="REQUIRE_THAT" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
           <Original>
             nextafter( 1.f, 2.f ), WithinULP( 1.f, 1 )
@@ -5135,7 +5181,7 @@ Nor would this
             -0.0f is within 0 ULPs of 0.00000000e+00f ([0.00000000e+00, 0.00000000e+00])
           </Expanded>
         </Expression>
-        <OverallResults successes="7" failures="0" expectedFailures="0"/>
+        <OverallResults successes="8" failures="0" expectedFailures="0"/>
       </Section>
       <Section name="Composed" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
         <Expression success="true" type="REQUIRE_THAT" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
@@ -17257,6 +17303,61 @@ There is no extra whitespace here
       </Expression>
       <OverallResult success="true"/>
     </TestCase>
+    <TestCase name="convertToBits" tags="[conversion][floating-point]" filename="tests/<exe-name>/IntrospectiveTests/FloatingPoint.tests.cpp" >
+      <Expression success="true" type="CHECK" filename="tests/<exe-name>/IntrospectiveTests/FloatingPoint.tests.cpp" >
+        <Original>
+          convertToBits( 0.f ) == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="CHECK" filename="tests/<exe-name>/IntrospectiveTests/FloatingPoint.tests.cpp" >
+        <Original>
+          convertToBits( -0.f ) == ( 1ULL &lt;&lt; 31 )
+        </Original>
+        <Expanded>
+          2147483648 (0x<hex digits>)
+==
+2147483648 (0x<hex digits>)
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="CHECK" filename="tests/<exe-name>/IntrospectiveTests/FloatingPoint.tests.cpp" >
+        <Original>
+          convertToBits( 0. ) == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="CHECK" filename="tests/<exe-name>/IntrospectiveTests/FloatingPoint.tests.cpp" >
+        <Original>
+          convertToBits( -0. ) == ( 1ULL &lt;&lt; 63 )
+        </Original>
+        <Expanded>
+          9223372036854775808 (0x<hex digits>)
+==
+9223372036854775808 (0x<hex digits>)
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="CHECK" filename="tests/<exe-name>/IntrospectiveTests/FloatingPoint.tests.cpp" >
+        <Original>
+          convertToBits( std::numeric_limits&lt;float>::denorm_min() ) == 1
+        </Original>
+        <Expanded>
+          1 == 1
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="CHECK" filename="tests/<exe-name>/IntrospectiveTests/FloatingPoint.tests.cpp" >
+        <Original>
+          convertToBits( std::numeric_limits&lt;double>::denorm_min() ) == 1
+        </Original>
+        <Expanded>
+          1 == 1
+        </Expanded>
+      </Expression>
+      <OverallResult success="true"/>
+    </TestCase>
     <TestCase name="empty tags are not allowed" tags="[tags]" filename="tests/<exe-name>/IntrospectiveTests/Tag.tests.cpp" >
       <Expression success="true" type="REQUIRE_THROWS" filename="tests/<exe-name>/IntrospectiveTests/Tag.tests.cpp" >
         <Original>
@@ -19826,9 +19927,9 @@ loose text artifact
       </Section>
       <OverallResult success="true"/>
     </TestCase>
-    <OverallResults successes="1940" failures="147" expectedFailures="23"/>
+    <OverallResults successes="1951" failures="147" expectedFailures="23"/>
-    <OverallResultsCases successes="273" failures="86" expectedFailures="6"/>
+    <OverallResultsCases successes="276" failures="86" expectedFailures="6"/>
   </Group>
-  <OverallResults successes="1940" failures="146" expectedFailures="23"/>
+  <OverallResults successes="1951" failures="146" expectedFailures="23"/>
-  <OverallResultsCases successes="273" failures="86" expectedFailures="6"/>
+  <OverallResultsCases successes="276" failures="86" expectedFailures="6"/>
 </Catch>

tests/SelfTest/IntrospectiveTests/FloatingPoint.tests.cpp

@@ -0,0 +1,66 @@
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/catch_template_test_macros.hpp>
+#include <catch2/internal/catch_floating_point_helpers.hpp>
+
+
+TEST_CASE("convertToBits", "[floating-point][conversion]") {
+    using Catch::Detail::convertToBits;
+
+    CHECK( convertToBits( 0.f ) == 0 );
+    CHECK( convertToBits( -0.f ) == ( 1ULL << 31 ) );
+    CHECK( convertToBits( 0. ) == 0 );
+    CHECK( convertToBits( -0. ) == ( 1ULL << 63 ) );
+    CHECK( convertToBits( std::numeric_limits<float>::denorm_min() ) == 1 );
+    CHECK( convertToBits( std::numeric_limits<double>::denorm_min() ) == 1 );
+}
+
+TEMPLATE_TEST_CASE("type-shared ulpDistance tests", "[floating-point][ulp][approvals]", float, double) {
+    using FP = TestType;
+    using Catch::ulpDistance;
+
+    // Distance between zeros is zero
+    CHECK( ulpDistance( FP{}, FP{} ) == 0 );
+    CHECK( ulpDistance( FP{}, -FP{} ) == 0 );
+    CHECK( ulpDistance( -FP{}, -FP{} ) == 0 );
+
+    // Distance between same-sign infinities is zero
+    static constexpr FP infinity = std::numeric_limits<FP>::infinity();
+    CHECK( ulpDistance( infinity, infinity ) == 0 );
+    CHECK( ulpDistance( -infinity, -infinity ) == 0 );
+
+    // Distance between max-finite-val and same sign infinity is 1
+    static constexpr FP max_finite = std::numeric_limits<FP>::max();
+    CHECK( ulpDistance( max_finite, infinity ) == 1 );
+    CHECK( ulpDistance( -max_finite, -infinity ) == 1 );
+
+    // Distance between X and 0 is half of distance between X and -X
+    CHECK( ulpDistance( -infinity, infinity ) ==
+           2 * ulpDistance( infinity, FP{} ) );
+    CHECK( 2 * ulpDistance( FP{ -2. }, FP{} ) ==
+           ulpDistance( FP{ -2. }, FP{ 2. } ) );
+    CHECK( 2 * ulpDistance( FP{ 2. }, FP{} ) ==
+           ulpDistance( FP{ -2. }, FP{ 2. } ) );
+
+    // Denorms are supported
+    CHECK( ulpDistance( std::numeric_limits<FP>::denorm_min(), FP{} ) == 1 );
+    CHECK( ulpDistance( std::numeric_limits<FP>::denorm_min(), -FP{} ) == 1 );
+    CHECK( ulpDistance( -std::numeric_limits<FP>::denorm_min(), FP{} ) == 1 );
+    CHECK( ulpDistance( -std::numeric_limits<FP>::denorm_min(), -FP{} ) == 1 );
+    CHECK( ulpDistance( std::numeric_limits<FP>::denorm_min(),
+                        -std::numeric_limits<FP>::denorm_min() ) == 2 );
+
+    // Machine epsilon
+    CHECK( ulpDistance( FP{ 1. },
+                        FP{ 1. } + std::numeric_limits<FP>::epsilon() ) == 1 );
+    CHECK( ulpDistance( -FP{ 1. },
+                        -FP{ 1. } - std::numeric_limits<FP>::epsilon() ) == 1 );
+}
+
+TEST_CASE("UlpDistance", "[floating-point][ulp][approvals]") {
+    using Catch::ulpDistance;
+
+    CHECK( ulpDistance( 1., 2. ) == 0x10'00'00'00'00'00'00 );
+    CHECK( ulpDistance( -2., 2. ) == 0x80'00'00'00'00'00'00'00 );
+    CHECK( ulpDistance( 1.f, 2.f ) == 0x80'00'00 );
+    CHECK( ulpDistance( -2.f, 2.f ) == 0x80'00'00'00 );
+}

tests/SelfTest/UsageTests/Matchers.tests.cpp

@@ -4,6 +4,7 @@
  */
 
 #include <catch2/catch_test_macros.hpp>
+#include <catch2/catch_template_test_macros.hpp>
 #include <catch2/matchers/catch_matchers_exception.hpp>
 #include <catch2/matchers/catch_matchers_floating_point.hpp>
 #include <catch2/matchers/catch_matchers_predicate.hpp>
@@ -465,6 +466,7 @@ TEST_CASE( "Floating point matchers: float", "[matchers][floating-point]" ) {
     }
     SECTION( "ULPs" ) {
         REQUIRE_THAT( 1.f, WithinULP( 1.f, 0 ) );
+        REQUIRE_THAT(-1.f, WithinULP( -1.f, 0 ) );
 
         REQUIRE_THAT( nextafter( 1.f, 2.f ), WithinULP( 1.f, 1 ) );
         REQUIRE_THAT( 0.f, WithinULP( nextafter( 0.f, 1.f ), 1 ) );
@@ -1081,3 +1083,17 @@ TEST_CASE( "Matchers can take references",
 #ifdef __clang__
 #    pragma clang diagnostic pop
 #endif
+
+TEMPLATE_TEST_CASE(
+    "#2152 - ULP checks between differently signed values were wrong",
+    "[matchers][floating-point][ulp]",
+    float,
+    double ) {
+    using Catch::Matchers::WithinULP;
+
+    static constexpr TestType smallest_non_zero =
+        std::numeric_limits<TestType>::denorm_min();
+
+    CHECK_THAT( smallest_non_zero, WithinULP( -smallest_non_zero, 2 ) );
+    CHECK_THAT( smallest_non_zero, !WithinULP( -smallest_non_zero, 1 ) );
+}