cmake: don't find_package if target already present

Better for super build integration (#4543)

Author: Mizux

cmake/check_deps.cmake

@@ -109,11 +109,6 @@ if(USE_SCIP)
   set(SCIP_DEPS SCIP::libscip)
 endif()
 
-# Check optional Dependencies
-if(USE_CPLEX AND NOT TARGET CPLEX::CPLEX)
-  message(FATAL_ERROR "Target CPLEX::CPLEX not available.")
-endif()
-
 # CXX Test
 if(BUILD_TESTING)
   if(NOT TARGET GTest::gtest_main)

cmake/system_deps.cmake

@@ -22,93 +22,105 @@ find_package(Threads REQUIRED)
 set(CMAKE_FIND_PACKAGE_PREFER_CONFIG TRUE)
 
 # libprotobuf force us to depends on ZLIB::ZLIB target
-if(NOT BUILD_ZLIB)
+if(NOT BUILD_ZLIB AND NOT TARGET ZLIB::ZLIB)
  find_package(ZLIB REQUIRED)
 endif()
 
-if(NOT BUILD_absl)
+if(NOT BUILD_absl AND NOT TARGET absl::base)
   find_package(absl REQUIRED)
 endif()
 
-if(NOT BUILD_Protobuf)
+if(NOT BUILD_Protobuf AND NOT TARGET protobuf::libprotobuf)
   find_package(Protobuf REQUIRED)
 endif()
 
-if(NOT BUILD_Eigen3)
+if(NOT BUILD_Eigen3 AND NOT TARGET Eigen3::Eigen)
   find_package(Eigen3 REQUIRED)
 endif()
 
 if(NOT BUILD_re2 AND NOT TARGET re2::re2)
   find_package(re2 REQUIRED)
 endif()
 
+# Third Party Solvers
 if(USE_COINOR)
-  if(NOT BUILD_CoinUtils)
+  if(NOT BUILD_CoinUtils AND NOT TARGET Coin::CoinUtils)
     find_package(CoinUtils REQUIRED)
   endif()
 
-  if(NOT BUILD_Osi)
+  if(NOT BUILD_Osi AND NOT TARGET Coin::Osi)
     find_package(Osi REQUIRED)
   endif()
 
-  if(NOT BUILD_Clp)
+  if(NOT BUILD_Clp AND NOT TARGET Coin::ClpSolver)
     find_package(Clp REQUIRED)
   endif()
 
-  if(NOT BUILD_Cgl)
+  if(NOT BUILD_Cgl AND NOT TARGET Coin::Cgl)
     find_package(Cgl REQUIRED)
   endif()
 
-  if(NOT BUILD_Cbc)
+  if(NOT BUILD_Cbc AND NOT TARGET Coin::CbcSolver)
     find_package(Cbc REQUIRED)
   endif()
 endif()
 
-if(USE_GLPK AND NOT BUILD_GLPK)
-  find_package(GLPK REQUIRED)
+if(USE_CPLEX)
+  if(NOT TARGET CPLEX::CPLEX)
+    find_package(CPLEX REQUIRED)
+  endif()
 endif()
 
-if(USE_HIGHS AND NOT BUILD_HIGHS)
-  find_package(HIGHS REQUIRED)
+if(USE_GLPK)
+  if(NOT BUILD_GLPK AND NOT TARGET GLPK::GLPK)
+    find_package(GLPK REQUIRED)
+  endif()
 endif()
 
-if(USE_PDLP AND NOT BUILD_PDLP)
-  find_package(PDLP REQUIRED)
+if(USE_HIGHS)
+  if(NOT BUILD_HIGHS AND NOT TARGET highs::highs)
+    find_package(HIGHS REQUIRED)
+  endif()
 endif()
 
-if(USE_SCIP AND NOT BUILD_SCIP)
-  find_package(SCIP REQUIRED)
+if(USE_PDLP)
+  if(NOT BUILD_PDLP)
+    find_package(PDLP REQUIRED)
+  endif()
 endif()
 
-# Check optional Dependencies
-if(USE_CPLEX)
-  find_package(CPLEX REQUIRED)
+if(USE_SCIP)
+  if(NOT BUILD_SCIP AND NOT TARGET SCIP::libscip)
+    find_package(SCIP REQUIRED)
+  endif()
 endif()
 
 # CXX Test
-if(BUILD_TESTING AND NOT BUILD_googletest)
-  find_package(GTest REQUIRED)
-endif()
+if(BUILD_TESTING)
+  if(NOT BUILD_googletest AND NOT TARGET GTest::gtest_main)
+    find_package(GTest REQUIRED)
+  endif()
 
-if(BUILD_TESTING AND NOT BUILD_benchmark)
-  find_package(benchmark REQUIRED)
-endif()
+  if(NOT BUILD_benchmark AND NOT TARGET benchmark::benchmark)
+    find_package(benchmark REQUIRED)
+  endif()
 
-if(BUILD_TESTING AND NOT BUILD_fuzztest)
-  find_package(fuzztest REQUIRED)
+  if(NOT BUILD_fuzztest AND NOT TARGET fuzztest::fuzztest)
+    find_package(fuzztest REQUIRED)
+  endif()
 endif()
 
 # Check language Dependencies
 if(BUILD_PYTHON)
-  if(NOT BUILD_pybind11)
+  if(NOT BUILD_pybind11 AND NOT TARGET pybind11::pybind11_headers)
     find_package(pybind11 REQUIRED)
   endif()
 
-  if(NOT BUILD_pybind11_abseil)
+  if(NOT BUILD_pybind11_abseil AND NOT TARGET pybind11_abseil::absl_casters)
     find_package(pybind11_abseil REQUIRED)
   endif()
 
-  if(NOT BUILD_pybind11_protobuf)
+  if(NOT BUILD_pybind11_protobuf AND NOT TARGET pybind11_native_proto_caster)
     find_package(pybind11_protobuf REQUIRED)
   endif()
 endif()