Index: mlir/include/mlir/Dialect/EmitC/IR/EmitC.td
===================================================================
--- mlir/include/mlir/Dialect/EmitC/IR/EmitC.td
+++ mlir/include/mlir/Dialect/EmitC/IR/EmitC.td
@@ -143,7 +143,6 @@
   let results = (outs AnyType);
 
   let hasFolder = 1;
-  // TODO: Disallow empty constants.
   let hasVerifier = 1;
 }
 
Index: mlir/lib/Dialect/EmitC/IR/EmitC.cpp
===================================================================
--- mlir/lib/Dialect/EmitC/IR/EmitC.cpp
+++ mlir/lib/Dialect/EmitC/IR/EmitC.cpp
@@ -121,6 +121,11 @@
   if (getValueAttr().isa<emitc::OpaqueAttr>())
     return success();
 
+  // Value must not be empty
+  StringAttr strAttr = getValueAttr().dyn_cast<StringAttr>();
+  if (strAttr && strAttr.getValue().empty())
+    return emitOpError() << "value must not be empty";
+
   TypedAttr value = getValueAttr();
   Type type = getType();
   if (!value.getType().isa<NoneType>() && type != value.getType())
@@ -129,9 +134,7 @@
   return success();
 }
 
-OpFoldResult emitc::ConstantOp::fold(FoldAdaptor adaptor) {
-  return getValue();
-}
+OpFoldResult emitc::ConstantOp::fold(FoldAdaptor adaptor) { return getValue(); }
 
 //===----------------------------------------------------------------------===//
 // IncludeOp
Index: mlir/test/Dialect/EmitC/invalid_ops.mlir
===================================================================
--- mlir/test/Dialect/EmitC/invalid_ops.mlir
+++ mlir/test/Dialect/EmitC/invalid_ops.mlir
@@ -16,6 +16,14 @@
 
 // -----
 
+func.func @empty_constant() {
+    // expected-error @+1 {{'emitc.constant' op value must not be empty}}
+    %c0 = "emitc.constant"(){value = ""} : () -> i32
+    return
+}
+
+// -----
+
 func.func @index_args_out_of_range_1() {
     // expected-error @+1 {{'emitc.call' op index argument is out of range}}
     emitc.call "test" () {args = [0 : index]} : () -> ()