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simplify what was ported from the makefiles
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* remove some of the complicated logic.
  The additional warnings always make sense.
  CMake uses the state of `BUILD_SHARED_LIBS` to determine the library
  target type.
  Also remove the comment regarding building shared and static at the
  same time, as usually that's done as necessary by the user.
* append user-defined {C,LD}FLAGS instead of preprending - we expect
  them to know what they do, so they can override our defaults
* use target_{compile,link}_options() instead of setting variables

Signed-off-by: Steffen Jaeckel <[email protected]>
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@sjaeckel
sjaeckel committed Feb 21, 2022
1 parent c376761 commit 096aec2
Showing 1 changed file with 36 additions and 64 deletions.
100 changes: 36 additions & 64 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -20,49 +20,38 @@ option(BUILD_SHARED_LIBS "Build shared library and only the shared library if \"
# Compose CFLAGS
#-----------------------------------------------------------------------------

# check if there was one already set.
if(DEFINED ENV{LTM_CFLAGS})
set(LTM_C_FLAGS $ENV{LTM_CFLAGS})
endif()
if(DEFINED ENV{LTM_LDFLAGS})
set(LTM_LD_FLAGS $ENV{LTM_LDFLAGS})
endif()

# Some information copied from makefile_include.mk

# Basic set
set(LTM_C_FLAGS "${LTM_C_FLAGS} -Wall -Wsign-compare -Wextra -Wshadow")
set(LTM_C_FLAGS -Wall -Wsign-compare -Wextra -Wshadow)
set(LTM_C_FLAGS ${LTM_C_FLAGS} -Wdeclaration-after-statement -Wbad-function-cast -Wcast-align)
set(LTM_C_FLAGS ${LTM_C_FLAGS} -Wstrict-prototypes -Wpointer-arith)

# Do we run the sanitizer?
if(DEFINED ENV{SANITIZER})
set(LTM_C_FLAGS "${LTM_C_FLAGS} -fsanitize=undefined -fno-sanitize-recover=all -fno-sanitize=float-divide-by-zero")
endif()

if(NOT DEFINED ENV{NO_ADDTL_WARNINGS})
set(LTM_C_FLAGS "${LTM_C_FLAGS} -Wdeclaration-after-statement -Wbad-function-cast -Wcast-align")
set(LTM_C_FLAGS "${LTM_C_FLAGS} -Wstrict-prototypes -Wpointer-arith")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -fsanitize=undefined -fno-sanitize-recover=all -fno-sanitize=float-divide-by-zero)
endif()

if(DEFINED ENV{CONV_WARNINGS})
set(LTM_C_FLAGS "${LTM_C_FLAGS} -std=c89 -Wconversion -Wsign-conversion")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -std=c89 -Wconversion -Wsign-conversion)
if($ENV{CONV_WARNINGS} EQUAL "strict")
set(LTM_C_FLAGS "${LTM_C_FLAGS} -Wc++-compat")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -Wc++-compat)
endif()
else()
set(LTM_C_FLAGS "${LTM_C_FLAGS} -Wsystem-headers")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -Wsystem-headers)
endif()

if(DEFINED ENV{COMPILE_DEBUG})
set(LTM_C_FLAGS "${LTM_C_FLAGS} -g3")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -g3)
endif()

if(DEFINED ENV{COMPILE_SIZE})
set(LTM_C_FLAGS "${LTM_C_FLAGS} -Os")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -Os)
else()
if(NOT DEFINED ENV{IGNORE_SPEED})
set(LTM_C_FLAGS "${LTM_C_FLAGS} -O3 -funroll-loops")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -O3 -funroll-loops)
#x86 optimizations [should be valid for any GCC install though]
set(LTM_C_FLAGS "${LTM_C_FLAGS} -fomit-frame-pointer")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -fomit-frame-pointer)
endif()
# TODO:
# if(DEFINED ENV{COMPILE_LTO})
Expand All @@ -72,70 +61,56 @@ else()
# endif()
endif()

# TODO
# Are the coming three checks really the best way?

# What compiler do we have and what are their...uhm... peculiarities
# TODO: is the check for a C++ compiler necessary?
if( (CMAKE_C_COMPILER_ID MATCHES "(C|c?)lang") OR (CMAKE_CXX_COMPILER_ID MATCHES "(C|c?)lang"))
set(LTM_C_FLAGS "${LTM_C_FLAGS} -Wno-typedef-redefinition -Wno-tautological-compare -Wno-builtin-requires-header")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -Wno-typedef-redefinition -Wno-tautological-compare -Wno-builtin-requires-header)
endif()

if( (CMAKE_C_COMPILER_ID MATCHES "mingw") OR (CMAKE_CXX_COMPILER_ID MATCHES "mingw"))
set(LTM_C_FLAGS "${LTM_C_FLAGS} -Wno-shadow")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -Wno-shadow)
endif()

if(DEFINED ENV{PLATFORM})
if($ENV{PLATFORM} MATCHES "Darwin")
set(LTM_C_FLAGS "${LTM_C_FLAGS} -Wno-nullability-completeness")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -Wno-nullability-completeness)
endif()
if($ENV{PLATFORM} MATCHES "CYGWIN")
set(LTM_C_FLAGS "${LTM_C_FLAGS} -no-undefined")
set(LTM_C_FLAGS ${LTM_C_FLAGS} -no-undefined)
endif()
endif()

# TODO: coverage (lgcov)

# We have several private functions in the library and the "demo/test" programm
# needs a littkle note to be able to switch them off. Please use the static build
# to get a full test.
if(BUILD_SHARED_LIBS)
set(LTM_C_FLAGS "${LTM_C_FLAGS} -DLTM_TEST_DYNAMIC")
# If the user set the environment variables at generate-time, append them
# in order to allow overriding our defaults.
if(DEFINED ENV{LTM_CFLAGS})
set(LTM_C_FLAGS ${LTM_C_FLAGS} $ENV{LTM_CFLAGS})
endif()
if(DEFINED ENV{LTM_LDFLAGS})
set(LTM_LD_FLAGS ${LTM_LD_FLAGS} $ENV{LTM_LDFLAGS})
endif()

# Bring it home
set(CMAKE_C_FLAGS "${LTM_C_FLAGS}")
set(CMAKE_C_FLAGS_DEBUG "${LTM_C_FLAGS}")
set(CMAKE_C_FLAGS_RELEASE "${LTM_C_FLAGS}")

#-----------------------------------------------------------------------------
# library target
#-----------------------------------------------------------------------------

# TODO: There may be a way but I found none to build both at once without complication.
# It is possible with e.g. Linux where the static library is named libtommath.a
# and the dynamic library libtommath.so*, two different names.
# That is not the case with e.g. Windows where both types have the same name.
# See also:
# https://stackoverflow.com/questions/2152077/is-it-possible-to-get-cmake-to-build-both-a-static-and-shared-library-at-the-sam
if(BUILD_SHARED_LIBS)
add_library(${PROJECT_NAME} SHARED
${SOURCES}
)
else()
add_library(${PROJECT_NAME} STATIC
${SOURCES}
)
endif()

# Clear cache manually
unset(BUILD_SHARED_LIBS CACHE)
add_library(${PROJECT_NAME}
${SOURCES}
)

target_include_directories(${PROJECT_NAME} PUBLIC
$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/${PROJECT_NAME}>
)

target_include_directories(${PROJECT_NAME} PUBLIC
$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/${PROJECT_NAME}>
target_compile_options(${PROJECT_NAME} BEFORE PRIVATE
${LTM_C_FLAGS}
)
target_link_options(${PROJECT_NAME} BEFORE PRIVATE
${LTM_LD_FLAGS}
)

set_target_properties(${PROJECT_NAME} PROPERTIES VERSION ${PROJECT_VERSION})
Expand All @@ -159,17 +134,13 @@ target_link_libraries(test-target PRIVATE
${PROJECT_NAME}
)

# for the SHARED_LIBRARY build we need some special flags enabled
# We also allow our users to override our selection by defining their own
# `CMAKE_C_FLAGS` on generation-phase. CMake itself doesn't allow a user
# to override settings defined in the CMakeLists.txt so we append it manually
# again even though CMake prepended it already.
target_compile_options(test-target BEFORE PRIVATE
$<$<STREQUAL:$<TARGET_PROPERTY:${PROJECT_NAME},TYPE>,SHARED_LIBRARY>:-O1 -DLTM_TEST_DYNAMIC>
${CMAKE_C_FLAGS}
${LTM_C_FLAGS}
)
target_link_options(test-target BEFORE PRIVATE
$<$<STREQUAL:$<TARGET_PROPERTY:${PROJECT_NAME},TYPE>,SHARED_LIBRARY>:-O1>
${LTM_LD_FLAGS}
)

#-----------------------------------------------------------------------------
Expand All @@ -191,6 +162,7 @@ set(TARGETS_EXPORT_NAME "${PROJECT_NAME}Targets")

install(TARGETS ${PROJECT_NAME}
EXPORT ${TARGETS_EXPORT_NAME}
LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
)

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