Fix MSVC 14.29 errors:

- It doens't know which operator == to use when there is using
 EnumClassBitmask that looks like (a & b) == 0. Instead use just
 the form (a & b).
 - It doesn't do automatic capture of constexpr variables in lambdas so
 turn a couple constexpr into regular const.
 - It (correctly) warns that if constexpr (std::is_constant_evaluated())
 is always true, so remove the constexpr keyword.

 Bug: None

Change-Id: If7857abd1c30acb0736557844ff13f32a19d54cf
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/117888
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Corentin Wallez <cwallez@chromium.org>

src/tint/resolver/const_eval.cc

@@ -1854,7 +1854,7 @@ ConstEval::Result ConstEval::OpShiftRight(const type::Type* ty,
             using NumberT = decltype(e1);
             using T = UnwrapNumber<NumberT>;
             using UT = std::make_unsigned_t<T>;
-            constexpr size_t bit_width = BitWidth<NumberT>;
+            const size_t bit_width = BitWidth<NumberT>;
             const UT e1u = static_cast<UT>(e1);
             const UT e2u = static_cast<UT>(e2);
 

src/tint/transform/preserve_padding.cc

@@ -112,8 +112,8 @@ struct PreservePadding::State {
         //
         // Since this requires passing pointers to the storage address space, this will also enable
         // the chromium_experimental_full_ptr_parameters extension.
-        constexpr const char* kDestParamName = "dest";
-        constexpr const char* kValueParamName = "value";
+        const char* kDestParamName = "dest";
+        const char* kValueParamName = "value";
         auto call_helper = [&](auto&& body) {
             EnableExtension();
             auto helper = helpers.GetOrCreate(ty, [&]() {

src/tint/utils/math.h

@@ -46,7 +46,7 @@ inline constexpr uint32_t Log2(uint64_t value) {
 #elif defined(_MSC_VER) && !defined(__clang__) && __cplusplus >= 202002L  // MSVC and C++20+
     // note: std::is_constant_evaluated() added in C++20
     //       required here as _BitScanReverse64 is not constexpr
-    if constexpr (!std::is_constant_evaluated()) {
+    if (!std::is_constant_evaluated()) {
         // NOLINTNEXTLINE(runtime/int)
         if constexpr (sizeof(unsigned long) == 8) {  // 64-bit
             // NOLINTNEXTLINE(runtime/int)