Visual Studio 2017 Update 9 (15.9) Support

[shartte]

Describe the bug
Compilation fails when updating to the latest VS update (2017.9).
Visual Studio now requires Clang 7.
I am compiling for Windows x64.

To Reproduce
Install the latest update to Visual Studio and try to compile.
First you'll note that the MS STL now requires Clang 7.
After updating to Clang 7, the following errors occur.

Additional context

SPIRV
Three identical compile errors occurs in SPIRV:

D:\filament\third_party\glslang\SPIRV\GlslangToSpv.cpp(5469,49):  error: non-constant-expression cannot be narrowed from type 'spv::GroupOperation' to 'unsigned int' in initializer list [-Wc++11-narrowing]
            spv::IdImmediate groupOp = { false, groupOperation };
                                                ^~~~~~~~~~~~~~
D:\filament\third_party\glslang\SPIRV\GlslangToSpv.cpp(5469,49):  note: insert an explicit cast to silence this issue
            spv::IdImmediate groupOp = { false, groupOperation };
                                                ^~~~~~~~~~~~~~
                                                static_cast<unsigned int>( )

The error can be fixed by inserting the cast, but I am unsure it's correct.

Allocator

In file included from D:\filament\libs\utils\test\test_Allocators.cpp:25:
D:\filament\libs\utils\include\utils/Allocator.h(685,32):  error: no matching member function for call to 'alloc'
        return mArena.template alloc(size, alignment, 0);
               ~~~~~~~~~~~~~~~~^~~~~
D:\filament\libs\utils\test\test_Allocators.cpp(260,17):  note: in instantiation of member function 'utils::ArenaScope<utils::Arena<utils::LinearAllocator, utils::LockingPolicy::NoLock, utils::TrackingPolicy::Untracked> >::allocate' requested here
        p = ssa.allocate(1024);
                ^
D:\filament\libs\utils\include\utils/Allocator.h(533,8):  note: candidate template ignored: couldn't infer template argument 'T'
    T* alloc(size_t count, size_t alignment = alignof(T), size_t extra = 0) noexcept {
       ^

I "fix" this one by explicitly calling template alloc with <uint8_t> in the void* case like this:

    void* allocate(size_t size, size_t alignment = 1) noexcept {
        return mArena.template alloc<uint8_t>(size, alignment, 0);
    }

When I tried alloc<void>, clang cited that void is not trivially destructible.

This relates to #516 and #358

[romainguy]

Assigning to @pixelflinger for the Allocator issue.

@shartte The casts look correct but this would require maintaining a patch on top of glslang. You should also file a bug for glslang.

[shartte]

@romainguy Yeah I'll look into that. My gut says that the underlying type for that enum should be uint32_t to begin with, but I haven't looked into it yet.

edit, Done: KhronosGroup/glslang#1596
And yeah, I'd guess a better solution than inserting the cast would be setting the underlying enum type properly.

[shartte]

@romainguy So I checked with the upstream master, and that compiles without issues.
After updating glslang in the filament tree to their latest master, it also compiles in filament without further changes.

[romainguy]

Thanks for checking, we can just move to a newer glslang then.

@prideout or @bejado would you mind updating our glslang please?

[shartte]

Now that #526 is merged, this issue is fixed.