dolphin/Source/PCH/CMakeLists.txt

# The PCH that dolphin uses for MSVC is non-standard;
# Instead of having one PCH per module, dolphin has one PCH shared between all modules.
# So we need to implement PCH manually, rather than using the PCH support built into cmake

add_library(build_pch pch.h pch.cpp)

# fmt/format.h is included in the PCH
target_link_libraries(build_pch PUBLIC fmt::fmt)

# pch.cpp should be compiled with the /Yc command, which creates the precompiled header
target_compile_options(build_pch PRIVATE /Ycpch.h)

# /Fp sets the location of the PCH. By forcing it to a fixed location, all modules
# will share this one PCH. We give it a fixed name so we can depend on it later
target_compile_options(build_pch PUBLIC /Fp$<TARGET_FILE_DIR:build_pch>/dolphin.pch )

# Sharing a PCH breaks pdb files. So we use the /Z7 option to inline the pdb into
# the binary. That also requires us to disable minimal rebuilds.
target_compile_options(build_pch PUBLIC /Z7 /Gm-)

# To get this working with ninja, we need to tell it that compiling pch.cpp generates an extra output
set_source_files_properties(${CMAKE_CURRENT_SOURCE_DIR}/pch.cpp PROPERTIES
    OBJECT_OUTPUTS $<TARGET_FILE_DIR:build_pch>/dolphin.pch
)

# and then create a custom target that depends on the pch output
# so that ninja won't start building anything that depends on this
# target before the pch is built
add_custom_target(force_build_pch
    DEPENDS $<TARGET_FILE_DIR:build_pch>/dolphin.pch
)

# linking against this interface libary will cause targets to enable PCH
add_library(use_pch INTERFACE)
target_link_libraries(use_pch INTERFACE build_pch)

# targets which use the pch need these compile options
# /Yu - Use precompiled header named "pch.h"
# /FI - Force include "pch.h" at top of every source file
target_compile_options(use_pch INTERFACE /Yupch.h /FIpch.h)

# For ninja, we need to depend on force_build_pch
add_dependencies(use_pch force_build_pch)