[libc++][numeric][NFC] Cleanup *Saturation arithmetic* tests

This simplifies the tests a little bit:

Fixed -> TODO(LLVM20): remove [[maybe_unused]] and `{}` scope since all supported compilers support "Placeholder variables with no name"

Author: H-G-Hristov

libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/add_sat.pass.cpp

@@ -25,8 +25,7 @@ constexpr bool test_signed() {
   constexpr auto minVal = std::numeric_limits<IntegerT>::min();
   constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
 
-  // TODO(LLVM-20) remove [[maybe_unused]]  since all supported compilers support "Placeholder variables with no name"
-  [[maybe_unused]] std::same_as<IntegerT> decltype(auto) _ = std::add_sat(minVal, maxVal);
+  std::same_as<IntegerT> decltype(auto) _ = std::add_sat(minVal, maxVal);
 
   static_assert(noexcept(std::add_sat(minVal, maxVal)));
 
@@ -97,8 +96,7 @@ constexpr bool test_unsigned() {
   constexpr auto minVal = std::numeric_limits<IntegerT>::min();
   constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
 
-  // TODO(LLVM-20) remove [[maybe_unused]]  since all supported compilers support "Placeholder variables with no name"
-  [[maybe_unused]] std::same_as<IntegerT> decltype(auto) _ = std::add_sat(minVal, maxVal);
+  std::same_as<IntegerT> decltype(auto) _ = std::add_sat(minVal, maxVal);
 
   static_assert(noexcept(std::add_sat(minVal, maxVal)));
 

libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.pass.cpp

@@ -26,8 +26,7 @@ constexpr bool test_signed() {
   constexpr auto minVal = std::numeric_limits<IntegerT>::min();
   constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
 
-  // TODO(LLVM-20) remove [[maybe_unused]] and `{}` scope since all supported compilers support "Placeholder variables with no name"
-  [[maybe_unused]] std::same_as<IntegerT> decltype(auto) _ = std::div_sat(minVal, maxVal);
+  std::same_as<IntegerT> decltype(auto) _ = std::div_sat(minVal, maxVal);
 
   static_assert(noexcept(std::div_sat(minVal, maxVal)));
 
@@ -89,8 +88,7 @@ constexpr bool test_unsigned() {
   constexpr auto minVal = std::numeric_limits<IntegerT>::min();
   constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
 
-  // TODO(LLVM-20) remove [[maybe_unused]] since all supported compilers support "Placeholder variables with no name"
-  [[maybe_unused]] std::same_as<IntegerT> decltype(auto) _ = std::div_sat(minVal, maxVal);
+  std::same_as<IntegerT> decltype(auto) _ = std::div_sat(minVal, maxVal);
   static_assert(noexcept(std::div_sat(minVal, maxVal)));
 
   // clang-format off

libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/mul_sat.pass.cpp

@@ -26,8 +26,7 @@ constexpr bool test_signed() {
   constexpr auto minVal = std::numeric_limits<IntegerT>::min();
   constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
 
-  // TODO(LLVM-20) remove [[maybe_unused]] since all supported compilers support "Placeholder variables with no name"
-  [[maybe_unused]] std::same_as<IntegerT> decltype(auto) _ = std::mul_sat(minVal, maxVal);
+  std::same_as<IntegerT> decltype(auto) _ = std::mul_sat(minVal, maxVal);
 
   static_assert(noexcept(std::mul_sat(minVal, maxVal)));
 
@@ -103,8 +102,7 @@ constexpr bool test_unsigned() {
   constexpr auto minVal = std::numeric_limits<IntegerT>::min();
   constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
 
-  // TODO(LLVM-20) remove [[maybe_unused]] since all supported compilers support "Placeholder variables with no name"
-  [[maybe_unused]] std::same_as<IntegerT> decltype(auto) _ = std::mul_sat(minVal, maxVal);
+  std::same_as<IntegerT> decltype(auto) _ = std::mul_sat(minVal, maxVal);
 
   static_assert(noexcept(std::mul_sat(minVal, maxVal)));