Fix #716: Report error for incompatible task argument types

When an undimensioned (dynamic) array was passed to a task parameter
expecting a simple vector, the compiler would crash with an assertion
failure because the switch handling type casts didn't know how to
handle IVL_VT_DARRAY type.

Changed the assertion to emit a proper error message about type
incompatibility and continue processing, allowing the compiler to
report the error gracefully instead of crashing.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

elaborate.cc

@@ -4340,9 +4340,15 @@ NetProc* PCallTask::elaborate_build_call_(Design*des, NetScope*scope,
 			rv = cast_to_int4(rv, lv_width);
 			break;
 		      default:
-			  /* Don't yet know how to handle this. */
-			ivl_assert(*this, 0);
-			break;
+			  /* Cannot cast between these types. */
+			cerr << get_fileline() << ": error: "
+			     << "Type of task port " << (idx+1)
+			     << " is not compatible with the argument type."
+			     << endl;
+			des->errors += 1;
+			delete rv;
+			delete lv;
+			continue;
 		  }
 	    }
 	    rv = pad_to_width(rv, lv_width, *this);

ivtest/gold/br_gh716.gold

@@ -0,0 +1,2 @@
+./ivltests/br_gh716.v:11: error: Type of task port 1 is not compatible with the argument type.
+1 error(s) during elaboration.

ivtest/ivltests/br_gh716.v

@@ -0,0 +1,13 @@
+// Test for GitHub issue #716
+// Undimensioned array passed to task expecting single vector should error
+module test();
+  logic [7:0] mybuf [];
+
+  task t1(output logic [7:0] buffer);
+    buffer = 0;
+  endtask
+
+  initial begin
+    t1(mybuf);
+  end
+endmodule

ivtest/regress-sv.list

@@ -223,6 +223,7 @@ br_gh661a		normal,-g2009		ivltests
 br_gh661b		normal,-g2009		ivltests
 br_gh672		normal,-g2009		ivltests
 br_gh699		CE,-g2009		ivltests
+br_gh716		CE,-g2012		ivltests gold=br_gh716.gold
 br_gh756		normal,-g2009		ivltests
 br_gh782a		normal,-g2009		ivltests gold=br_gh782a.gold
 br_gh782b		normal,-g2009		ivltests gold=br_gh782b.gold