From 2a88896365cdfd0b86e9c4c26940378d2cff51da Mon Sep 17 00:00:00 2001
From: Soren Rasmussen <s.c.rasmussen@gmail.com>
Date: Wed, 22 Oct 2025 12:05:15 -0600
Subject: [PATCH] OUTPUT_CHAN_CONN uses nudging io but not nudging. In the
 build system nudging io module has been moved to its own directory to make
 seperate build cleaner

---
 CMakeLists.txt                             |  2 ++
 src/CMakeLists.txt                         | 11 +++++++++++
 src/Routing/CMakeLists.txt                 |  7 +++++++
 src/nudging/CMakeLists.txt                 |  2 +-
 src/nudging/io/CMakeLists.txt              | 10 ++++++++++
 src/nudging/{ => io}/module_nudging_io.F90 |  0
 6 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 src/nudging/io/CMakeLists.txt
 rename src/nudging/{ => io}/module_nudging_io.F90 (100%)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5818bdc65..36e472c00 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -185,6 +185,8 @@ endif()
 message("OUTPUT_CHAN_CONN = " ${OUTPUT_CHAN_CONN} )
 if (OUTPUT_CHAN_CONN STREQUAL "1" )
         add_definitions(-DOUTPUT_CHAN_CONN)
+        # requires nudging io module
+        set(WRF_HYDRO_NUDGING_IO "1")
 endif()
 
 #set -DPRECIP_DOUBLE from env
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 8c7e2f74e..c6575f5df 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -27,6 +27,12 @@ if(${PROJECT_NAME} STREQUAL "WRF")
         add_subdirectory("CPL/WRF_cpl")
 endif()
 
+if (WRF_HYDRO_NUDGING_IO STREQUAL "1" OR
+    WRF_HYDRO_NUDGING STREQUAL "1")
+        add_subdirectory("nudging/io")
+        add_dependencies(hydro_routing hydro_nudging_io)
+endif()
+
 if (WRF_HYDRO_NUDGING STREQUAL "1")
         add_subdirectory("nudging")
         add_dependencies(hydro_routing hydro_nudging)
@@ -126,6 +132,11 @@ if (HYDRO_LSM MATCHES "NoahMP")
                 # hydro_routing_groundwater_simple
         )
 
+        if (WRF_HYDRO_NUDGING_IO STREQUAL "1")
+          target_link_libraries(wrfhydro hydro_nudging_io)
+          add_dependencies(wrfhydro hydro_nudging_io)
+        endif()
+
         if (WRF_HYDRO_NUDGING STREQUAL "1")
                 target_link_libraries(wrfhydro hydro_nudging)
                 target_link_libraries(wrfhydro hydro_routing_diversions)
diff --git a/src/Routing/CMakeLists.txt b/src/Routing/CMakeLists.txt
index 8ca1af4d3..748b941e8 100644
--- a/src/Routing/CMakeLists.txt
+++ b/src/Routing/CMakeLists.txt
@@ -32,3 +32,10 @@ target_link_libraries(hydro_routing
        hydro_routing_reservoirs_rfc
        hydro_routing_diversions
 )
+
+if (WRF_HYDRO_NUDGING_IO STREQUAL "1")
+  target_link_libraries(hydro_routing
+    PRIVATE
+    hydro_nudging_io
+  )
+endif()
diff --git a/src/nudging/CMakeLists.txt b/src/nudging/CMakeLists.txt
index 142fce6ec..e7b385667 100644
--- a/src/nudging/CMakeLists.txt
+++ b/src/nudging/CMakeLists.txt
@@ -1,12 +1,12 @@
 # build the version static library
 add_library(hydro_nudging STATIC
         module_date_utils_nudging.F90
-        module_nudging_io.F90
         module_nudging_utils.F90
         module_stream_nudging.F90
 )
 
 target_link_libraries(hydro_nudging PRIVATE
+        hydro_nudging_io
         hydro_mpp
         hydro_data_rec
         hydro_orchestrator
diff --git a/src/nudging/io/CMakeLists.txt b/src/nudging/io/CMakeLists.txt
new file mode 100644
index 000000000..e7fdc6a1e
--- /dev/null
+++ b/src/nudging/io/CMakeLists.txt
@@ -0,0 +1,10 @@
+# build the version static library
+add_library(hydro_nudging_io STATIC
+        module_nudging_io.F90
+)
+
+target_link_libraries(hydro_nudging_io PRIVATE
+        hydro_orchestrator
+        hydro_data_rec
+        hydro_mpp
+)
diff --git a/src/nudging/module_nudging_io.F90 b/src/nudging/io/module_nudging_io.F90
similarity index 100%
rename from src/nudging/module_nudging_io.F90
rename to src/nudging/io/module_nudging_io.F90