blt enable find mpi logic fix (#14)

* blt enable find mpi logic fix

Author: cyrush

azure-pipelines.yml

@@ -4,6 +4,12 @@
 # Ref:
 # https://aka.ms/yaml
 
+#####
+# TO USE A NEW CONTAINER, UPDATE TAG NAME HERE AS PART OF YOUR PR!
+#####
+variables:
+  main_tag : alpinedav/ascent-ci:ubuntu-18-devel
+
 # only build merge target pr to develop
 trigger: none
 pr:
@@ -19,14 +25,15 @@ stages:
   ###############################################################################
   # Ubuntu build and test, using spack to build tpls
   ###############################################################################
-  - job: Ubuntu_16
+  - job: Main_Ubuntu_18
     pool:
-      vmImage: 'ubuntu-16.04'
+      vmImage: 'ubuntu-latest'
+    container: ${{ variables.main_tag }}
     timeoutInMinutes: 0
     variables:
-      COMPILER_CC: gcc-5
-      COMPILER_CXX: g++-5
-      COMPILER_FC: gfortran-5
+      COMPILER_CC: gcc
+      COMPILER_CXX: g++
+      COMPILER_FC: gfortran
     strategy:
       matrix:
         shared_debug:
@@ -65,8 +72,8 @@ stages:
            sudo apt-get update
            # list pkgs we need
            export APT_PKGS=binutils
-           export APT_PKGS="$APT_PKGS gcc-5"
-           export APT_PKGS="$APT_PKGS g++-5"
+           export APT_PKGS="$APT_PKGS gcc"
+           export APT_PKGS="$APT_PKGS g++"
            export APT_PKGS="$APT_PKGS openmpi-bin"
            export APT_PKGS="$APT_PKGS libopenmpi-dev"
            export APT_PKGS="$APT_PKGS libncurses-dev"

src/cmake/SetupBLT.cmake

@@ -44,14 +44,23 @@ if(ENABLE_MPI)
         # the name mpi
         set(apcomp_blt_mpi_deps mpi CACHE STRING "")
     else()
-        if(TARGET MPI::MPI_CXX)
-            message(STATUS "Using MPI CMake imported target: MPI::MPI_CXX")
-            # newer cmake we use find mpi targets directly
-            set(apcomp_blt_mpi_deps MPI::MPI_CXX CACHE STRING "")
+        # if we are using BLT's enable mpi, then we must
+        # make sure the MPI targets exist
+        if(ENABLE_FIND_MPI)
+            if(TARGET MPI::MPI_CXX)
+                set(APCOMP_USE_CMAKE_MPI_TARGETS TRUE CACHE BOOL "")
+                message(STATUS "Using MPI CMake imported target: MPI::MPI_CXX")
+                # newer cmake we use find mpi targets directly
+                set(apcomp_blt_mpi_deps MPI::MPI_CXX CACHE STRING "")
+            else()
+                message(FATAL_ERROR "Cannot use CMake imported targets for MPI."
+                                    "(CMake > 3.15, ENABLE_MPI == ON, but "
+                                    "MPI::MPI_CXX CMake target is missing.)")
+            endif()
         else()
-            message(FATAL_ERROR "Cannot use CMake imported targets for MPI."
-                                "(CMake > 3.15, ENABLE_MPI == ON, but "
-                                "MPI::MPI_CXX CMake target is missing.)")
+            set(APCOMP_USE_CMAKE_MPI_TARGETS FALSE CACHE BOOL "")
+            # compiler will handle them implicitly
+            set(apcomp_blt_mpi_deps "" CACHE STRING "")
         endif()
     endif()
 endif()