diff --git a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
--- a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
@@ -943,13 +943,21 @@
              << ");\n";
       }
       return;
-    case TypeParamKind::Collective:
-      body << "  "
-           << "assert(resultTypes.size() "
-           << (op.getNumVariableLengthResults() == 0 ? "==" : ">=") << " "
-           << (op.getNumResults() - op.getNumVariableLengthResults())
-           << "u && \"mismatched number of results\");\n";
+    case TypeParamKind::Collective: {
+      int numResults = op.getNumResults();
+      int numVariadicResults = op.getNumVariableLengthResults();
+      int numNonVariadicResults = numResults - numVariadicResults;
+      bool hasVariadicResult = numVariadicResults != 0;
+
+      // Avoid emitting "resultTypes.size() >= 0u" which is always true.
+      if (!(hasVariadicResult && numNonVariadicResults == 0))
+        body << "  "
+             << "assert(resultTypes.size() "
+             << (hasVariadicResult ? ">=" : "==") << " "
+             << numNonVariadicResults
+             << "u && \"mismatched number of results\");\n";
       body << "  " << builderOpState << ".addTypes(resultTypes);\n";
+    }
       return;
     }
     llvm_unreachable("unhandled TypeParamKind");