Glslang third party build needs -fPIC (#1093)

Otherwise linking fails
google · Jul 3, 2020 · ffa1930 · ffa1930
1 parent f4025c1
commit ffa1930
Showing 1 changed file with 12 additions and 2 deletions.
diff --git a/third_party/CMakeLists.txt b/third_party/CMakeLists.txt
@@ -33,6 +33,7 @@ if(${SHADERC_ENABLE_TESTS})
 endif()
 
 set(OLD_PLATFORM_TOOLSET ${CMAKE_GENERATOR_TOOLSET})
+check_cxx_compiler_flag(-fPIC COMPILER_SUPPORTS_PIC)
 
 
 if (IS_DIRECTORY ${SHADERC_SPIRV_HEADERS_DIR})
@@ -64,7 +65,17 @@ endif()
 
 if (NOT TARGET glslang)
   if (IS_DIRECTORY ${SHADERC_GLSLANG_DIR})
-    add_subdirectory(${SHADERC_GLSLANG_DIR} glslang)
+    # Add -fPIC to glslang build, if supported
+    if (COMPILER_SUPPORTS_PIC)
+      set(CXX_BACK ${CMAKE_CXX_FLAGS})
+      set(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS} "-fPIC")
+      # cmake inserts a semicolon, change it to a space.
+      string(REGEX REPLACE ";" " " CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+      add_subdirectory(${SHADERC_GLSLANG_DIR} glslang)
+      set(CMAKE_CXX_FLAGS ${CXX_BACK})
+    else()
+      add_subdirectory(${SHADERC_GLSLANG_DIR} glslang)
+    endif()
   endif()
   if (NOT TARGET glslang)
     message(FATAL_ERROR "glslang was not found - required for compilation")
@@ -82,7 +93,6 @@ if (SHADERC_ENABLE_SPVC)
   if (NOT TARGET spirv-cross-core)
     if (IS_DIRECTORY ${SHADERC_SPIRV_CROSS_DIR})
       # Add -fPIC to SPIRV-Cross build, if supported
-      check_cxx_compiler_flag(-fPIC COMPILER_SUPPORTS_PIC)
       if (COMPILER_SUPPORTS_PIC)
         set(CXX_BACK ${CMAKE_CXX_FLAGS})
         set(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS} "-fPIC")