Fix and document static build (#6374)

* Set static stbi flag for static builds

* Add missing SYSTEM directive for external includes

* Add instructions for linking statically against slang

---------

Co-authored-by: Yong He <yonghe@outlook.com>

Author: expipiplus1

cmake/CompilerFlags.cmake

@@ -205,6 +205,7 @@ function(set_default_compile_options target)
             $<$<BOOL:${SLANG_ENABLE_FULL_DEBUG_VALIDATION}>:SLANG_ENABLE_FULL_IR_VALIDATION>
             $<$<BOOL:${SLANG_ENABLE_IR_BREAK_ALLOC}>:SLANG_ENABLE_IR_BREAK_ALLOC>
             $<$<BOOL:${SLANG_ENABLE_DX_ON_VK}>:SLANG_CONFIG_DX_ON_VK>
+            $<$<STREQUAL:${SLANG_LIB_TYPE},STATIC>:STB_IMAGE_STATIC>
     )
 
     if(SLANG_ENABLE_ASAN)

docs/building.md

@@ -321,6 +321,21 @@ cmake -B build -G Ninja
 cmake --build build -j
 ```
 
+## Static linking against libslang
+
+If linking against a static `libslang.a` you will need to link against some
+dependencies also if you're not already incorporating them into your project.
+
+You will need to link against:
+
+```
+${SLANG_DIR}/build/Release/lib/libslang.a
+${SLANG_DIR}/build/Release/lib/libcompiler-core.a
+${SLANG_DIR}/build/Release/lib/libcore.a
+${SLANG_DIR}/build/external/miniz/libminiz.a
+${SLANG_DIR}/build/external/lz4/build/cmake/liblz4.a
+```
+
 ## Notes
 
 [^1] below 3.25, CMake lacks the ability to mark directories as being

external/CMakeLists.txt

@@ -89,11 +89,19 @@ endif()
 
 # imgui
 add_library(imgui INTERFACE)
-target_include_directories(imgui INTERFACE "${CMAKE_CURRENT_LIST_DIR}/imgui")
+target_include_directories(
+    imgui
+    ${system}
+    INTERFACE "${CMAKE_CURRENT_LIST_DIR}/imgui"
+)
 
 # stb
 add_library(stb INTERFACE)
-target_include_directories(stb INTERFACE "${CMAKE_CURRENT_LIST_DIR}/stb")
+target_include_directories(
+    stb
+    ${system}
+    INTERFACE "${CMAKE_CURRENT_LIST_DIR}/stb"
+)
 
 # slang-rhi
 if(SLANG_ENABLE_SLANG_RHI)