cmake: Fix GLPK support (Fix #3312)

* Eigen was spuriously enabling fortran
* Missing GLKP helpers functions

cmake/cpp.cmake

@@ -30,6 +30,7 @@ if(USE_COINOR)
 endif()
 if(USE_GLPK)
   list(APPEND OR_TOOLS_COMPILE_DEFINITIONS "USE_GLPK")
+  set(GLPK_DIR glpk)
 endif()
 if(USE_PDLP)
   list(APPEND OR_TOOLS_COMPILE_DEFINITIONS "USE_PDLP")
@@ -227,6 +228,7 @@ foreach(SUBPROJECT IN ITEMS
  base
  bop
  constraint_solver
+ ${GLPK_DIR}
  ${PDLP_DIR}
  ${GSCIP_DIR}
  glop

cmake/dependencies/CMakeLists.txt

@@ -39,6 +39,7 @@ set(FETCHCONTENT_UPDATES_DISCONNECTED ON)
 set(BUILD_SHARED_LIBS OFF)
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 set(BUILD_TESTING OFF)
+set(CMAKE_Fortran_COMPILER OFF)
 
 # ##############################################################################
 # ZLIB
@@ -132,7 +133,6 @@ if(BUILD_Eigen3)
   set(EIGEN_BUILD_PKGCONFIG OFF)
   set(EIGEN_BUILD_DOC OFF)
   set(EIGEN_BUILD_TESTING OFF)
-  set(EIGEN_BUILD_DOC OFF)
   FetchContent_Declare(
     eigen3
     GIT_REPOSITORY "https://gitlab.com/libeigen/eigen.git"

ortools/glpk/CMakeLists.txt

@@ -0,0 +1,31 @@
+if(NOT USE_GLPK)
+  return()
+endif()
+
+file(GLOB _SRCS "*.h" "*.cc")
+
+set(NAME ${PROJECT_NAME}_glpk)
+
+if(MSVC)
+  set(STANDARD 20)
+else()
+  set(STANDARD 17)
+endif()
+
+# Will be merge in libortools.so
+#add_library(${NAME} STATIC ${_SRCS})
+add_library(${NAME} OBJECT ${_SRCS})
+set_target_properties(${NAME} PROPERTIES
+  CXX_STANDARD ${STANDARD}
+  CXX_STANDARD_REQUIRED ON
+  CXX_EXTENSIONS OFF
+  POSITION_INDEPENDENT_CODE ON
+  )
+target_include_directories(${NAME} PUBLIC
+  $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}>
+  $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}>)
+target_link_libraries(${NAME} PRIVATE
+  absl::strings
+  absl::str_format
+  $<$<BOOL:${USE_GLPK}>:GLPK::GLPK>)
+#add_library(${PROJECT_NAME}::glpk ALIAS ${NAME})