RFR: JDK-8253239: Disable VS warning C4307

[Aleksey Shipilev]

On Fri, 18 Sep 2020 08:22:56 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> hello, this fixes the build when using VS2017. VS2019 does not have the issue as far as I know.
> failure was
> 
>> ./test/hotspot/gtest/utilities/test_align.cpp(96): error C2220: warning treated as error - no 'object' file generated
>> ./test/hotspot/gtest/utilities/test_align.cpp(156): note: see reference to function template instantiation 'void
>> static_test_alignments<T,A>(void)' being compiled with
>> [
>> T=int64_t,
>> A=uint8_t
>> ]
>> ./test/hotspot/gtest/utilities/test_align.cpp(162): note: see reference to function template instantiation 'void
>> test_alignments<int64_t,uint8_t>(void)' being compiled ./test/hotspot/gtest/utilities/test_align.cpp(96): warning
>> C4307: '+': integral constant overflow
>>
>>
> 
> This might be related to an issue fixed at least in some versions of VS2019 , that is discussed here :
> 
> https://developercommunity.visualstudio.com/content/problem/211134/unsigned-integer-overflows-in-constexpr-functionsa.html
> 
> https://bugs.openjdk.java.net/browse/JDK-8253239

make/autoconf/flags-cflags.m4 line 138:

> 136:       DISABLED_WARNINGS="4800"
> 137:       if test "x$TOOLCHAIN_VERSION" = x2017; then
> 138:           DISABLED_WARNINGS+=" 4307"

Seems like this file uses 2 spaces as indenting, 4 spaces are used here.

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PR: https://git.openjdk.java.net/jdk/pull/237