build: stop using a loop for finding dependencies

the loop and the helper variables do not help with the maintainability.
the intention was to split the data and code, but it hurts the
readability.

in this change, we

- remove the helper of `seastar_set_dep_args()`
- add a helper of `seastar_find_dep()`. it will be used for
  adapting to `find_dependency()` in `SeastarConfig.cmake.in`
- take this opportunity to add space before `(` to be consistent
  with the style in this file.

Signed-off-by: Kefu Chai <[email protected]>

cmake/SeastarDependencies.cmake

@@ -20,8 +20,6 @@
 # Copyright (C) 2019 Scylladb, Ltd.
 #
 
-include(CMakeParseArguments)
-
 #
 # CMake bundles `FindBoost.cmake`, which is coupled to the Boost version. If
 # we're on a system without a recent enough version of `FindBoost.cmake`, then
@@ -50,106 +48,58 @@ if (Boost_VERSION_STRING VERSION_LESS 1.81.0)
     INTERFACE_COMPILE_DEFINITIONS "BOOST_NO_CXX98_FUNCTION_BASE")
 endif ()
 
-# - set _seastar_dep_args_<package> for additional args for find_package().
-#   add REQUIRED if the corresponding option is explicitly enabled, so
-#   find_package() can stop the cmake generation.
-# - set _seastar_dep_skip_<package> if the option is explicitly disabled
-macro (seastar_set_dep_args package)
-  cmake_parse_arguments(args "REQUIRED" "VERSION;OPTION" "COMPONENTS" ${ARGN})
-  if (DEFINED args_VERSION)
-    list (APPEND _seastar_dep_args_${package} ${args_VERSION})
-  endif ()
-  if (args_REQUIRED)
-    list (APPEND _seastar_dep_args_${package} REQUIRED)
-  elseif (DEFINED args_OPTION)
-    if (args_OPTION)
-      list (APPEND _seastar_dep_args_${package} REQUIRED)
-    else ()
-      set (_seastar_dep_skip_${package} TRUE)
-    endif ()
-  endif ()
-  if (args_COMPONENTS)
-    list (APPEND _seastar_dep_args_${package} COMPONENTS
-      ${args_COMPONENTS})
-  endif ()
+macro (seastar_find_dep package)
+  find_package (${package} ${ARGN})
 endmacro ()
 
-#
-# Iterate through the dependency list defined below and execute `find_package`
-# with the corresponding configuration for each 3rd-party dependency.
-#
 macro (seastar_find_dependencies)
   #
   # List of Seastar dependencies that is meant to be used
   # both in Seastar configuration and by clients which
   # consume Seastar via SeastarConfig.cmake.
   #
-  set (_seastar_all_dependencies
-    # Public dependencies.
-    Boost
-    c-ares
-    dpdk # No version information published.
-    fmt
-    lz4
-    # Private and private/public dependencies.
-    GnuTLS
-    LibUring
-    LinuxMembarrier
-    # Protobuf is searched manually.
-    Sanitizers
-    SourceLocation
-    StdAtomic
-    SystemTap-SDT
-    hwloc
-    lksctp-tools # No version information published.
-    numactl # No version information published.
-    rt
-    ucontext
-    yaml-cpp)
-
-  # Arguments to `find_package` for each 3rd-party dependency.
-  # Note that the version specification is a "minimal" version requirement.
-
   # `unit_test_framework` is not required in the case we are building Seastar
   # without the testing library, however the component is always specified as required
   # to keep the CMake code minimalistic and easy-to-use.
-  seastar_set_dep_args (Boost REQUIRED
-    VERSION ${_seastar_boost_version}
+  seastar_find_dep (Boost ${_seastar_boost_version} REQUIRED
     COMPONENTS
       filesystem
       program_options
       thread
       unit_test_framework)
-  seastar_set_dep_args (c-ares REQUIRED
-    VERSION 1.13)
-  seastar_set_dep_args (dpdk
-    OPTION ${Seastar_DPDK})
-  seastar_set_dep_args (fmt REQUIRED
-    VERSION 8.1.1)
-  seastar_set_dep_args (lz4 REQUIRED
-    VERSION 1.7.3)
-  seastar_set_dep_args (GnuTLS REQUIRED
-    VERSION 3.3.26)
-  seastar_set_dep_args (LibUring
-    VERSION 2.0
-    OPTION ${Seastar_IO_URING})
-  seastar_set_dep_args (StdAtomic REQUIRED)
-  seastar_set_dep_args (hwloc
-    VERSION 1.11.2
-    OPTION ${Seastar_HWLOC})
-  seastar_set_dep_args (lksctp-tools REQUIRED)
-  seastar_set_dep_args (rt REQUIRED)
-  seastar_set_dep_args (numactl
-    OPTION ${Seastar_NUMA})
-  seastar_set_dep_args (ucontext REQUIRED)
-  seastar_set_dep_args (yaml-cpp REQUIRED
-    VERSION 0.5.1)
+  seastar_find_dep (c-ares 1.13 REQUIRED)
+  if (c-ares_VERSION VERSION_GREATER_EQUAL 1.33.0 AND c-ares_VERSION VERSION_LESS 1.34.1)
+    # https://github.com/scylladb/seastar/issues/2472
+    message (FATAL_ERROR
+      "c-ares ${c-ares_VERSION} is not supported. "
+      "Seastar requires c-ares version <1.33 or >=1.34.1 ")
+  endif ()
 
-  foreach (third_party ${_seastar_all_dependencies})
-    if (NOT _seastar_dep_skip_${third_party})
-      find_package ("${third_party}" ${_seastar_dep_args_${third_party}})
-    endif ()
-  endforeach ()
+  if (Seastar_DPDK)
+    seastar_find_dep (dpdk)
+  endif()
+  seastar_find_dep (fmt 8.1.1 REQUIRED)
+  seastar_find_dep (lz4 1.7.3 REQUIRED)
+  seastar_find_dep (GnuTLS 3.3.26 REQUIRED)
+  if (Seastar_IO_URING)
+    seastar_find_dep (LibUring 2.0 REQUIRED)
+  endif()
+  seastar_find_dep (LinuxMembarrier)
+  seastar_find_dep (Sanitizers)
+  seastar_find_dep (SourceLocation)
+  seastar_find_dep (StdAtomic REQUIRED)
+  seastar_find_dep (SystemTap-SDT)
+  if (Seastar_HWLOC)
+    seastar_find_dep (hwloc 1.11.2 REQUIRED)
+  endif()
+  seastar_find_dep (lksctp-tools REQUIRED)
+  seastar_find_dep (rt REQUIRED)
+  if (Seastar_NUMA)
+    seastar_find_dep (numactl REQUIRED)
+  endif ()
+  seastar_find_dep (ucontext REQUIRED)
+  seastar_find_dep (yaml-cpp REQUIRED
+    VERSION 0.5.1)
 
   # workaround for https://gitlab.kitware.com/cmake/cmake/-/issues/25079
   # since protobuf v22.0, it started using abseil, see
@@ -162,15 +112,9 @@ macro (seastar_find_dependencies)
   find_package (Protobuf QUIET CONFIG)
   if (Protobuf_FOUND AND Protobuf_VERSION VERSION_GREATER_EQUAL 2.5.0)
     # do it again, so the message is printed when the package is found
-    find_package(Protobuf CONFIG REQUIRED)
+    seastar_find_dep (Protobuf CONFIG REQUIRED)
   else ()
-    find_package(Protobuf 2.5.0 REQUIRED)
+    seastar_find_dep (Protobuf 2.5.0 REQUIRED)
   endif ()
 
-  if (c-ares_VERSION VERSION_GREATER_EQUAL 1.33.0 AND c-ares_VERSION VERSION_LESS 1.34.1)
-    # https://github.com/scylladb/seastar/issues/2472
-    message (FATAL_ERROR
-      "c-ares ${c-ares_VERSION} is not supported. "
-      "Seastar requires c-ares version <1.33 or >=1.34.1 ")
-  endif ()
 endmacro ()