ARM64/ARM64EC runtime assertions in `P0811R3_midpoint_lerp`

[StephanTLavavej]

With the latest available Windows 11 SDK (10.0.26100.4188), P0811R3_midpoint_lerp fails assert(check_feexcept(0)) at runtime on ARM64:

STL/tests/std/tests/P0811R3_midpoint_lerp/test.cpp

Lines 1048 to 1053 in a2686a0

	{
	ExceptGuard except;
	assert(bit_cast<float_bit_type>(lerp(2e+38f, 1e+38f, 4.0f)) == bit_cast<float_bit_type>(-2e+38f));
	assert(check_feexcept(0));
	}

Click to expand test logs for the 2 failing configurations:

C:\GitHub\STL\out\ARM64>python %STL%\tools\scripts\print_failures.py testing_ARM64.log
code: FAIL
name: std :: tests/P0811R3_midpoint_lerp:34
output: Build setup steps:
Build steps:
Command: "C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\bin\HostARM64\ARM64\cl.EXE" "C:\GitHub\STL\tests\std\tests\P0811R3_midpoint_lerp\test.cpp" "-IC:\GitHub\STL\out\ARM64\out\inc" "-IC:\GitHub\STL\llvm-project\libcxx\test\support" "-IC:\GitHub\STL\tests\std\include" "/nologo" "/Od" "/W4" "/w14061" "/w14242" "/w14265" "/w14582" "/w14583" "/w14587" "/w14588" "/w14749" "/w14841" "/w14842" "/w15038" "/w15214" "/w15215" "/w15216" "/w15217" "/w15262" "/sdl" "/WX" "/D_ENABLE_STL_INTERNAL_CHECK" "/bigobj" "/FIforce_include.hpp" "/w14365" "/w14668" "/w15267" "/D_ENFORCE_FACET_SPECIALIZATIONS=1" "/w14640" "/Zc:threadSafeInit-" "/EHsc" "/MTd" "/D_ITERATOR_DEBUG_LEVEL=0" "/std:c++latest" "/permissive-" "/fp:strict" "/Od" "-FeC:\GitHub\STL\out\ARM64\tests\std\tests\P0811R3_midpoint_lerp\Output\34\P0811R3_midpoint_lerp.exe" "-link" "-LIBPATH:C:\GitHub\STL\out\ARM64\out\lib\arm64" "-LIBPATH:C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\lib\arm64" "/MANIFEST:EMBED"
Exit Code: 0 (0x0)
Standard Output:
--
test.cpp
--

Intellisense response file steps:
Test setup steps:
Test steps:
Test step failed unexpectedly.
Command: "C:\GitHub\STL\out\ARM64\tests\std\tests\P0811R3_midpoint_lerp\Output\34\P0811R3_midpoint_lerp.exe"
Exit Code: 3 (0x3)
Standard Error:
--
Assertion failed: check_feexcept(0), file C:\GitHub\STL\tests\std\tests\P0811R3_midpoint_lerp\test.cpp, line 1052
abort() has been called--


==================================================
code: FAIL
name: std :: tests/P0811R3_midpoint_lerp:35
output: Build setup steps:
Build steps:
Command: "C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\bin\HostARM64\ARM64\cl.EXE" "C:\GitHub\STL\tests\std\tests\P0811R3_midpoint_lerp\test.cpp" "-IC:\GitHub\STL\out\ARM64\out\inc" "-IC:\GitHub\STL\llvm-project\libcxx\test\support" "-IC:\GitHub\STL\tests\std\include" "/nologo" "/Od" "/W4" "/w14061" "/w14242" "/w14265" "/w14582" "/w14583" "/w14587" "/w14588" "/w14749" "/w14841" "/w14842" "/w15038" "/w15214" "/w15215" "/w15216" "/w15217" "/w15262" "/sdl" "/WX" "/D_ENABLE_STL_INTERNAL_CHECK" "/bigobj" "/FIforce_include.hpp" "/w14365" "/w14668" "/w15267" "/D_ENFORCE_FACET_SPECIALIZATIONS=1" "/w14640" "/Zc:threadSafeInit-" "/EHsc" "/MTd" "/D_ITERATOR_DEBUG_LEVEL=0" "/std:c++latest" "/permissive-" "/fp:strict" "/O2" "-FeC:\GitHub\STL\out\ARM64\tests\std\tests\P0811R3_midpoint_lerp\Output\35\P0811R3_midpoint_lerp.exe" "-link" "-LIBPATH:C:\GitHub\STL\out\ARM64\out\lib\arm64" "-LIBPATH:C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\lib\arm64" "/MANIFEST:EMBED"
Exit Code: 0 (0x0)
Standard Output:
--
test.cpp
--
Standard Error:
--
cl : Command line warning D9025 : overriding '/Od' with '/O2'
--

Intellisense response file steps:
Test setup steps:
Test steps:
Test step failed unexpectedly.
Command: "C:\GitHub\STL\out\ARM64\tests\std\tests\P0811R3_midpoint_lerp\Output\35\P0811R3_midpoint_lerp.exe"
Exit Code: 3 (0x3)
Standard Error:
--
Assertion failed: check_feexcept(0), file C:\GitHub\STL\tests\std\tests\P0811R3_midpoint_lerp\test.cpp, line 1052
abort() has been called--

I'm going to skip these asserts for ARM64, but we should investigate the root cause.