From 70db1c1ff6aa7de8cea9ee96dd3769e25a3fe89a Mon Sep 17 00:00:00 2001
From: kyle <kyle@awesomeguy.co.za>
Date: Fri, 22 Oct 2021 16:00:44 +0200
Subject: [PATCH] Fixed support and documentation for Cmake CPLEX build on
 Linux

---
 cmake/FindCPLEX.cmake | 34 ++++++++++++++++++++++------------
 cmake/README.md       | 16 ++++++++++++++++
 2 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/cmake/FindCPLEX.cmake b/cmake/FindCPLEX.cmake
index 6f940f639d..f45fbcc23e 100644
--- a/cmake/FindCPLEX.cmake
+++ b/cmake/FindCPLEX.cmake
@@ -37,14 +37,12 @@ else()
   message(FATAL_ERROR "FindCPLEX only works if either C or CXX language is enabled")
 endif()
 
-if(APPLE)
-  message(FATAL_ERROR "CPLEX not yet supported on macOS")
-elseif(UNIX)
-  message(FATAL_ERROR "CPLEX not yet supported on Linux")
-endif()
-
 if(NOT CPLEX_ROOT)
-  set(CPLEX_ROOT $ENV{CPLEX_ROOT})
+  if(DEFINED ENV{UNIX_CPLEX_DIR})
+    set(CPLEX_ROOT $ENV{UNIX_CPLEX_DIR})
+  elseif(DEFINED ENV{CPLEX_ROOT})
+    set(CPLEX_ROOT $ENV{CPLEX_ROOT})
+  endif()
 endif()
 message(STATUS "CPLEX_ROOT: ${CPLEX_ROOT}")
 if(NOT CPLEX_ROOT)
@@ -53,12 +51,24 @@ else()
   set(CPLEX_FOUND TRUE)
 endif()
 
+# TODO(mizux) Bump support to CPLEX 20.1.0
+# ref: https://www.ibm.com/docs/en/icos/20.1.0?topic=cplex-setting-up-gnulinuxmacos
+# ref: https://www.ibm.com/docs/en/icos/20.1.0?topic=cplex-setting-up-windows
+
+# ref: https://www.ibm.com/docs/en/icos/12.10.0?topic=cplex-setting-up-gnulinuxmacos
 if(CPLEX_FOUND AND NOT TARGET CPLEX::CPLEX)
   add_library(CPLEX::CPLEX UNKNOWN IMPORTED)
+  target_include_directories(CPLEX::CPLEX SYSTEM INTERFACE "${CPLEX_ROOT}/cplex/include")
 
-  set_target_properties(CPLEX::CPLEX PROPERTIES
-    INTERFACE_INCLUDE_DIRECTORIES "${CPLEX_INCLUDE_DIRS}")
-
-  set_target_properties(CPLEX::CPLEX PROPERTIES
-    IMPORTED_LOCATION "${CPLEX_ROOT}/cplex/lib/x64_windows_msvc14/stat_mda/cplex12100.lib")
+  if(APPLE) # be aware that `UNIX` is `TRUE` on OS X, so this check must be first
+    # FIXME(mizux) need actual macOS library path
+    # target_link_libraries(CPLEX::CPLEX INTERFACE "${CPLEX_ROOT}/cplex/lib/libcplex.lib")
+    message(FATAL_ERROR "CPLEX not yet supported for CMake builds on ${CMAKE_SYSTEM}")
+  elseif(UNIX)
+    target_link_libraries(CPLEX::CPLEX INTERFACE "${CPLEX_ROOT}/cplex/lib/x86-64_linux/static_pic/libcplex.a")
+  elseif(MSVC)
+    target_link_libraries(CPLEX::CPLEX INTERFACE "${CPLEX_ROOT}/cplex/lib/x64_windows_msvc14/stat_mda/cplex12100.lib")
+  else()
+    message(FATAL_ERROR "CPLEX not supported for ${CMAKE_SYSTEM}")
+  endif()
 endif()
diff --git a/cmake/README.md b/cmake/README.md
index 3c050be034..aa946882f7 100644
--- a/cmake/README.md
+++ b/cmake/README.md
@@ -94,6 +94,22 @@ solvers:
 **warning: Since these solvers require license and are proprietary, we can't
 test it on public CI and support can be broken.**
 
+### Enabling CPLEX Support
+
+To enable CPLEX support, configure with `-DUSE_CPLEX=ON` and `-DCPLEX_ROOT=/absolute/path/to/CPLEX/root/dir`,
+replacing `/absolute/path/to/CPLEX/root/dir` with the path to your CPLEX installation.
+`CPLEX_ROOT` can also be defined as an environment variable rather than an option at configure time.
+
+For ease of migration from legacy `make third_party` builds, CMake will also read the CPLEX installation path from the
+`UNIX_CPLEX_DIR` environment variable, if defined.
+
+### Enabling XPRESS Support
+
+To enable XPRESS support, configure with `-DUSE_XPRESS=ON` and `-DXPRESS_ROOT=/absolute/path/to/XPRESS/root/dir`,
+replacing `/absolute/path/to/XPRESS/root/dir` with the path to your XPRESS
+installation. `XPRESS_ROOT` can also be defined as an environment variable rather than an option at configure time.
+
+
 <a name="options"></a>
 
 ## CMake Options