Merge pull request #1391 from boostorg/msvc

Add MSVC 14.5 runner

Author: mborland

.drone.jsonnet

@@ -433,4 +433,10 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
         "cppalliance/dronevs2022:1",
         { TOOLSET: 'msvc-14.3', CXXSTD: '14,17,20,latest' },
     ),
+
+    windows_pipeline(
+        "Windows VS2026 msvc-14.5",
+        "cppalliance/dronevs2026:1",
+        { TOOLSET: 'msvc-14.5', CXXSTD: '14,17,20,latest', ADDRMD: '32,64' },
+    ),
 ]

include/boost/decimal/decimal_fast128_t.hpp

@@ -87,7 +87,12 @@ constexpr auto write_payload(typename TargetDecimalType::significand_type payloa
 #  pragma warning(disable : 4324) // Structure was padded due to alignment specifier
 #endif
 
+// 32-bit MSVC mis-codegens reads of bool members in over-aligned structs; use natural alignment there.
+#if defined(_MSC_VER) && !defined(_M_X64) && !defined(_M_ARM64)
+BOOST_DECIMAL_EXPORT class decimal_fast128_t final
+#else
 BOOST_DECIMAL_EXPORT class alignas(16) decimal_fast128_t final
+#endif
 {
 public:
     using significand_type = int128::uint128_t;

include/boost/decimal/decimal_fast64_t.hpp

@@ -87,7 +87,12 @@ constexpr auto write_payload(typename TargetDecimalType::significand_type payloa
 #  pragma warning(disable : 4324) // Structure was padded due to alignment specifier
 #endif
 
+// 32-bit MSVC mis-codegens reads of bool members in over-aligned structs; use natural alignment there.
+#if defined(_MSC_VER) && !defined(_M_X64) && !defined(_M_ARM64)
+BOOST_DECIMAL_EXPORT class decimal_fast64_t final
+#else
 BOOST_DECIMAL_EXPORT class alignas(8) decimal_fast64_t final
+#endif
 {
 public:
     using significand_type = std::uint64_t;

include/boost/decimal/detail/u256.hpp

@@ -20,7 +20,12 @@ namespace boost {
 namespace decimal {
 namespace detail {
 
+// 32-bit MSVC 14.5 mis-codegens reads of bool members in over-aligned structs; use natural alignment there.
+#if defined(_MSC_VER) && !defined(_M_X64) && !defined(_M_ARM64)
+struct
+#else
 struct alignas(sizeof(std::uint64_t) * 4)
+#endif
 u256
 {
     std::uint64_t bytes[4] {};