[libc++][test] Avoid truncation warnings from double to float
#74184
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It might look repetitive, but T(value) is what avoids this warning. I usually prefer to use static_cast instead of functional-style casts, but I chose to remain consistent with the surrounding code.
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@llvm/pr-subscribers-libcxx Author: Stephan T. Lavavej (StephanTLavavej) ChangesFound while running libc++'s test suite with MSVC's STL, where we use both MSVC's compiler and Clang/LLVM. MSVC really enjoys emitting "warning C4305: 'initializing': truncation from 'double' to 'float'". It might look repetitive, but I usually prefer to use By the way, you might notice that Full diff: https://github.com/llvm/llvm-project/pull/74184.diff 15 Files Affected:
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/assign.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/assign.pass.cpp
index 3daf3aba71fc9f2..66f6c91b802cb0c 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/assign.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/assign.pass.cpp
@@ -31,7 +31,7 @@ void test_impl() {
// assignment
{
- MaybeVolatile<std::atomic<T>> a(3.1);
+ MaybeVolatile<std::atomic<T>> a(T(3.1));
std::same_as<T> decltype(auto) r = (a = T(1.2));
assert(a.load() == T(1.2));
assert(r == T(1.2));
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_strong.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_strong.pass.cpp
index b010e7c7a4d79d9..711b49ddc233028 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_strong.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_strong.pass.cpp
@@ -44,8 +44,8 @@ void testBasic(MemoryOrder... memory_order) {
// compare pass
{
MaybeVolatile<std::atomic<T>> a(T(1.2));
- T expected(1.2);
- const T desired(2.3);
+ T expected(T(1.2));
+ const T desired(T(2.3));
std::same_as<bool> decltype(auto) r = a.compare_exchange_strong(expected, desired, memory_order...);
assert(r);
@@ -57,7 +57,7 @@ void testBasic(MemoryOrder... memory_order) {
{
MaybeVolatile<std::atomic<T>> a(T(1.2));
T expected(1.5);
- const T desired(2.3);
+ const T desired(T(2.3));
std::same_as<bool> decltype(auto) r = a.compare_exchange_strong(expected, desired, memory_order...);
assert(!r);
@@ -168,7 +168,7 @@ void test_impl() {
auto store = [](MaybeVolatile<std::atomic<T>>& x, T, T new_val) { x.store(new_val, std::memory_order::release); };
auto load = [](MaybeVolatile<std::atomic<T>>& x) {
auto result = x.load(std::memory_order::relaxed);
- T unexpected(-9999.99);
+ T unexpected(T(-9999.99));
bool r = x.compare_exchange_strong(unexpected, unexpected, std::memory_order_relaxed, std::memory_order_acquire);
assert(!r);
return result;
@@ -177,7 +177,7 @@ void test_impl() {
auto load_one_arg = [](MaybeVolatile<std::atomic<T>>& x) {
auto result = x.load(std::memory_order::relaxed);
- T unexpected(-9999.99);
+ T unexpected(T(-9999.99));
bool r = x.compare_exchange_strong(unexpected, unexpected, std::memory_order_acquire);
assert(!r);
return result;
@@ -187,7 +187,7 @@ void test_impl() {
// acq_rel replaced by acquire
auto load_one_arg_acq_rel = [](MaybeVolatile<std::atomic<T>>& x) {
auto result = x.load(std::memory_order::relaxed);
- T unexpected(-9999.99);
+ T unexpected(T(-9999.99));
bool r = x.compare_exchange_strong(unexpected, unexpected, std::memory_order_acq_rel);
assert(!r);
return result;
@@ -200,7 +200,7 @@ void test_impl() {
auto store = [](MaybeVolatile<std::atomic<T>>& x, T, T new_val) { x.store(new_val, std::memory_order::seq_cst); };
auto load = [](MaybeVolatile<std::atomic<T>>& x) {
auto result = x.load(std::memory_order::relaxed);
- T unexpected(-9999.99);
+ T unexpected(T(-9999.99));
bool r = x.compare_exchange_strong(unexpected, unexpected, std::memory_order_relaxed, std::memory_order::seq_cst);
assert(!r);
return result;
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_weak.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_weak.pass.cpp
index 27853ef08c7482c..ee1a00c284276c8 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_weak.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_weak.pass.cpp
@@ -44,8 +44,8 @@ void testBasic(MemoryOrder... memory_order) {
// compare pass
{
MaybeVolatile<std::atomic<T>> a(T(1.2));
- T expected(1.2);
- const T desired(2.3);
+ T expected(T(1.2));
+ const T desired(T(2.3));
std::same_as<bool> decltype(auto) r = a.compare_exchange_weak(expected, desired, memory_order...);
// could be false spuriously
@@ -61,7 +61,7 @@ void testBasic(MemoryOrder... memory_order) {
{
MaybeVolatile<std::atomic<T>> a(T(1.2));
T expected(1.5);
- const T desired(2.3);
+ const T desired(T(2.3));
std::same_as<bool> decltype(auto) r = a.compare_exchange_weak(expected, desired, memory_order...);
assert(!r);
@@ -183,7 +183,7 @@ void test_impl() {
auto store = [](MaybeVolatile<std::atomic<T>>& x, T, T new_val) { x.store(new_val, std::memory_order::release); };
auto load = [](MaybeVolatile<std::atomic<T>>& x) {
auto result = x.load(std::memory_order::relaxed);
- T unexpected(-9999.99);
+ T unexpected(T(-9999.99));
bool r = x.compare_exchange_weak(unexpected, unexpected, std::memory_order_relaxed, std::memory_order_acquire);
assert(!r);
return result;
@@ -192,7 +192,7 @@ void test_impl() {
auto load_one_arg = [](MaybeVolatile<std::atomic<T>>& x) {
auto result = x.load(std::memory_order::relaxed);
- T unexpected(-9999.99);
+ T unexpected(T(-9999.99));
bool r = x.compare_exchange_weak(unexpected, unexpected, std::memory_order_acquire);
assert(!r);
return result;
@@ -202,7 +202,7 @@ void test_impl() {
// acq_rel replaced by acquire
auto load_one_arg_acq_rel = [](MaybeVolatile<std::atomic<T>>& x) {
auto result = x.load(std::memory_order::relaxed);
- T unexpected(-9999.99);
+ T unexpected(T(-9999.99));
bool r = x.compare_exchange_weak(unexpected, unexpected, std::memory_order_acq_rel);
assert(!r);
return result;
@@ -215,7 +215,7 @@ void test_impl() {
auto store = [](MaybeVolatile<std::atomic<T>>& x, T, T new_val) { x.store(new_val, std::memory_order::seq_cst); };
auto load = [](MaybeVolatile<std::atomic<T>>& x) {
auto result = x.load(std::memory_order::relaxed);
- T unexpected(-9999.99);
+ T unexpected(T(-9999.99));
bool r = x.compare_exchange_weak(unexpected, unexpected, std::memory_order_relaxed, std::memory_order::seq_cst);
assert(!r);
return result;
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/exchange.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/exchange.pass.cpp
index 9c67d7e671cfa71..c0d1eb686db7a08 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/exchange.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/exchange.pass.cpp
@@ -34,7 +34,7 @@ void test_impl() {
// exchange
{
- MaybeVolatile<std::atomic<T>> a(3.1);
+ MaybeVolatile<std::atomic<T>> a(T(3.1));
std::same_as<T> decltype(auto) r = a.exchange(T(1.2), std::memory_order::relaxed);
assert(a.load() == T(1.2));
assert(r == T(3.1));
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_add.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_add.pass.cpp
index 664185fc243f9a2..c31243053e69fba 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_add.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_add.pass.cpp
@@ -42,7 +42,7 @@ void test_impl() {
// fetch_add
{
- MaybeVolatile<std::atomic<T>> a(3.1);
+ MaybeVolatile<std::atomic<T>> a(T(3.1));
std::same_as<T> decltype(auto) r = a.fetch_add(T(1.2), std::memory_order::relaxed);
assert(r == T(3.1));
assert(a.load() == T(3.1) + T(1.2));
@@ -78,7 +78,7 @@ void test_impl() {
return res;
};
- assert(at.load() == times(1.234, number_of_threads * loop));
+ assert(at.load() == times(T(1.234), number_of_threads * loop));
}
#endif
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_sub.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_sub.pass.cpp
index c4e33538de74178..d26d21dec1b3346 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_sub.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_sub.pass.cpp
@@ -43,7 +43,7 @@ void test_impl() {
// fetch_sub
{
- MaybeVolatile<std::atomic<T>> a(3.1);
+ MaybeVolatile<std::atomic<T>> a(T(3.1));
std::same_as<T> decltype(auto) r = a.fetch_sub(T(1.2), std::memory_order::relaxed);
assert(r == T(3.1));
assert(a.load() == T(3.1) - T(1.2));
@@ -79,7 +79,7 @@ void test_impl() {
return res;
};
- assert(at.load() == accu_neg(1.234, number_of_threads * loop));
+ assert(at.load() == accu_neg(T(1.234), number_of_threads * loop));
}
#endif
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/load.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/load.pass.cpp
index b495d04989e2007..b567af457dcaecd 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/load.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/load.pass.cpp
@@ -41,7 +41,7 @@ void test_impl() {
// load
{
- MaybeVolatile<std::atomic<T>> a(3.1);
+ MaybeVolatile<std::atomic<T>> a(T(3.1));
a.store(T(1.2));
std::same_as<T> decltype(auto) r = a.load(std::memory_order::relaxed);
assert(r == T(1.2));
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/notify_all.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/notify_all.pass.cpp
index eca7a19e5c57da0..b50c0ad9ee92efb 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/notify_all.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/notify_all.pass.cpp
@@ -37,7 +37,7 @@ void test_impl() {
// should x87 80bit long double work at all?
if constexpr (!std::same_as<T, long double>) {
for (auto i = 0; i < 100; ++i) {
- const T old = 3.1;
+ const T old = T(3.1);
MaybeVolatile<std::atomic<T>> a(old);
bool done = false;
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/notify_one.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/notify_one.pass.cpp
index 183cf18b820e746..aee4af186b9ffe3 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/notify_one.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/notify_one.pass.cpp
@@ -37,7 +37,7 @@ void test_impl() {
// should x87 80bit long double work at all?
if constexpr (!std::same_as<T, long double>) {
for (auto i = 0; i < 100; ++i) {
- const T old = 3.1;
+ const T old = T(3.1);
MaybeVolatile<std::atomic<T>> a(old);
std::atomic_bool started = false;
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.float.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.float.pass.cpp
index 58c8da6c1042b26..5d957ca68404a23 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.float.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.float.pass.cpp
@@ -28,7 +28,7 @@ void test_impl() {
// operator float
{
- MaybeVolatile<std::atomic<T>> a(3.1);
+ MaybeVolatile<std::atomic<T>> a(T(3.1));
T r = a;
assert(r == T(3.1));
}
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.minus_equals.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.minus_equals.pass.cpp
index b1ef276d870cf50..269eb819524f9d4 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.minus_equals.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.minus_equals.pass.cpp
@@ -39,7 +39,7 @@ void test_impl() {
// -=
{
- MaybeVolatile<std::atomic<T>> a(3.1);
+ MaybeVolatile<std::atomic<T>> a(T(3.1));
std::same_as<T> decltype(auto) r = a -= T(1.2);
assert(r == T(3.1) - T(1.2));
assert(a.load() == T(3.1) - T(1.2));
@@ -75,7 +75,7 @@ void test_impl() {
return res;
};
- assert(at.load() == accu_neg(1.234, number_of_threads * loop));
+ assert(at.load() == accu_neg(T(1.234), number_of_threads * loop));
}
#endif
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.plus_equals.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.plus_equals.pass.cpp
index 0b1781bf8e571b9..9a2298ea46d660b 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.plus_equals.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.plus_equals.pass.cpp
@@ -39,7 +39,7 @@ void test_impl() {
// +=
{
- MaybeVolatile<std::atomic<T>> a(3.1);
+ MaybeVolatile<std::atomic<T>> a(T(3.1));
std::same_as<T> decltype(auto) r = a += T(1.2);
assert(r == T(3.1) + T(1.2));
assert(a.load() == T(3.1) + T(1.2));
@@ -75,7 +75,7 @@ void test_impl() {
return res;
};
- assert(at.load() == times(1.234, number_of_threads * loop));
+ assert(at.load() == times(T(1.234), number_of_threads * loop));
}
// memory_order::seq_cst
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/store.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/store.pass.cpp
index 81d17cd32a6c502..b0888aac67dbbf5 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/store.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/store.pass.cpp
@@ -41,7 +41,7 @@ void test_impl() {
// store
{
- MaybeVolatile<std::atomic<T>> a(3.1);
+ MaybeVolatile<std::atomic<T>> a(T(3.1));
a.store(T(1.2), std::memory_order::relaxed);
assert(a.load() == T(1.2));
}
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/test_helper.h b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/test_helper.h
index b831b774fbd3073..d0da1f20f550507 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/test_helper.h
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/test_helper.h
@@ -23,7 +23,7 @@
template <class T>
bool approximately_equals(T x, T y) {
- T epsilon = 0.001;
+ T epsilon = T(0.001);
return std::abs(x - y) < epsilon;
}
diff --git a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/wait.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/wait.pass.cpp
index d95801e25d35e03..8e003a7e365da1a 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/wait.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/wait.pass.cpp
@@ -51,7 +51,7 @@ void test_impl() {
// should x87 80bit long double work at all?
if constexpr (!std::same_as<T, long double>) {
for (auto i = 0; i < 100; ++i) {
- const T old = 3.1;
+ const T old = T(3.1);
MaybeVolatile<std::atomic<T>> a(old);
std::atomic_bool started = false;
|
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https://llvm.org/docs/CodingStandards.html#prefer-c-style-casts |
philnik777
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Dec 2, 2023
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Checks are green modulo spurious git failures, merging... |
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Found while running libc++'s test suite with MSVC's STL, where we use both MSVC's compiler and Clang/LLVM.
MSVC really enjoys emitting "warning C4305: 'initializing': truncation from 'double' to 'float'". It might look repetitive, but
T(value)avoids this warning. (According to my understanding, the compiler looks at the immediate context, and if it's a functional-style cast, it's satisfied that the truncation was intentional. Not even the direct-initialization context ofT unexpected(-9999.99)is enough to activate that "ok, the programmer knows what they're getting" codepath.)I usually prefer to use
static_castinstead of functional-style casts, but I chose to remain consistent with the surrounding code.By the way, you might notice that
1.5doesn't need these changes. This is because it's exactly representable as both adoubleand afloat. Values like3.125instead of3.1would similarly avoid truncation warnings without the need for casts, but I didn't want to intrusively change the test code.