fix(build): Correct tracking of intended target OS in premake (#10853) c7a0379ab3

We've been testing _TARGET_OS in a lot of places in our build, but that is not actually updated in Android/Emscripten builds (it would continue to report, say, Windows). Among other things, this meant that we would build D3D12 shaders for every Android build, even though they were not needed.

This adds a `rive_target_os` value to `rive_build_config.lua` which is updated manually for those two projects, so that scripts won't do the Windows/mac things when building for android/emscripten on those platforms.

Co-authored-by: Josh Jersild <joshua@rive.app>

.rive_head

@@ -1 +1 @@
-39741ac0c89ef4af6214bf2ec0f2130e489d8ed0
+c7a0379ab3bd3ec3fb9b2ed26d5b238b93a26976

build/rive_build_config.lua

@@ -403,10 +403,21 @@ end
 
 filter({})
 
+-- os.target() does not seem to be getting updated when system( ) is changed (for instance, when
+-- building on Windows, it stays 'windows' even after we do system('android') which means if we
+-- use it directly, we will include more things than are strictly necessary.
+--
+-- Instead, make an alias that we can use instead that we set manually based on calls to system()
+-- Additionally, premake deprecated `--os=android` which is why the custom system() call is 
+-- needed in the first place (otherwise the build script would just be passing it in)
+rive_target_os = os.target()
+
 -- Don't use filter() here because we don't want to generate the "android_ndk" toolset if not
 -- building for android.
 if _OPTIONS['for_android'] then
     system('android')
+    rive_target_os = 'android'
+
     pic('on') -- Position-independent code is required for NDK libraries.
 
     -- Detect the NDK.
@@ -766,6 +777,8 @@ if _OPTIONS['arch'] == 'wasm' or _OPTIONS['arch'] == 'js' then
     end
 
     system('emscripten')
+    rive_target_os = 'emscripten'
+
     toolset('emsdk')
 
     linkoptions({ '-sALLOW_MEMORY_GROWTH=1', '-sDYNAMIC_EXECUTION=0' })

renderer/premake5.lua

@@ -94,7 +94,7 @@ if not _OPTIONS['with-webgpu'] then
             externalincludedirs({ optick .. '/src'})
         end
 
-        if _TARGET_OS == 'windows' then
+        if rive_target_os == 'windows' then
             externalincludedirs({
                 dx12_headers .. '/include/directx',
             })

renderer/premake5_pls_renderer.lua

@@ -22,7 +22,7 @@ if _OPTIONS['with_vulkan'] then
     })
 end
 
-if _TARGET_OS == 'windows' then
+if rive_target_os == 'windows' then
     dx12_headers = dependency.github('microsoft/DirectX-Headers', 'v1.615.0')
 end
 
@@ -143,7 +143,7 @@ if os.host() == 'macosx' then
     end
 end
 
-if _TARGET_OS == 'windows' then
+if rive_target_os == 'windows' then
     makecommand = makecommand .. ' d3d'
 end
 
@@ -210,7 +210,7 @@ do
         files({ 'src/vulkan/*.cpp' })
     end
 
-    if _TARGET_OS == 'windows' then
+    if rive_target_os == 'windows' then
         externalincludedirs({
             dx12_headers .. '/include/directx',
         })

tests/rive_tools_project.lua

@@ -361,7 +361,7 @@ do
         RIVE_PLS_DIR .. '/shader_hotload/**.cpp',
     })
 
-    if _TARGET_OS == 'windows' then
+    if rive_target_os == 'windows' then
         externalincludedirs({
             dx12_headers .. '/include/directx',
         })