diag: probe whether rmumps.dll exports dmumps_c on Windows

Author: bnaras

scripts/diag_uno.R

@@ -14,6 +14,20 @@ cat("\n===== rmumps loadable? =====\n")
 cat("requireNamespace('rmumps'):",
     requireNamespace("rmumps", quietly = TRUE), "\n")
 
+cat("\n===== does rmumps.dll export dmumps_c on this platform? =====\n")
+# This is the exact lookup Uno's dmumps_shim.c performs at runtime via
+# R_FindSymbol("dmumps_c","rmumps"). configure.win disables MUMPS BECAUSE this
+# was historically false on Windows. Verify the current reality.
+loadNamespace("rmumps")
+cat("is.loaded('dmumps_c'):", is.loaded("dmumps_c"), "\n")
+sym <- tryCatch(getNativeSymbolInfo("dmumps_c", PACKAGE = "rmumps"),
+                error = function(e) conditionMessage(e))
+cat("getNativeSymbolInfo('dmumps_c', PACKAGE='rmumps'):\n")
+print(sym)
+dll <- tryCatch(getLoadedDLLs()[["rmumps"]][["path"]],
+                error = function(e) NA_character_)
+cat("rmumps DLL path:", dll, "\n")
+
 library(CVXR)
 
 cat("\n===== convex solve via UNO (verbose = TRUE) =====\n")