diff --git a/mlir/test/lib/Dialect/Test/TestOps.td b/mlir/test/lib/Dialect/Test/TestOps.td
--- a/mlir/test/lib/Dialect/Test/TestOps.td
+++ b/mlir/test/lib/Dialect/Test/TestOps.td
@@ -1660,6 +1660,24 @@
                           $x),
           (TestEitherOpB $arg2, $x)>;
 
+def TestEitherHelperOpA : TEST_Op<"either_helper_op_a"> {
+  let arguments = (ins I32:$arg0);
+  let results = (outs I32:$output);
+}
+
+def TestEitherHelperOpB : TEST_Op<"either_helper_op_b"> {
+  let arguments = (ins I32:$arg0);
+  let results = (outs I32:$output);
+}
+
+// This test case ensures `emitOpMatch` doesn't redefine `castedOp{0}` local
+// variables. To trigger this, we must ensure the matcher for
+// `TestEitherHelperOpA` and `TestEitherHelperOpB` are not lifted as a static
+// matcher.
+def : Pat<(TestEitherOpB (either (TestEitherHelperOpA I32:$either_helper_0),
+                                 (TestEitherHelperOpB I32:$either_helper_1))),
+          (TestEitherOpB $either_helper_0, $either_helper_1)>;
+
 //===----------------------------------------------------------------------===//
 // Test Patterns (Location)
 
diff --git a/mlir/tools/mlir-tblgen/RewriterGen.cpp b/mlir/tools/mlir-tblgen/RewriterGen.cpp
--- a/mlir/tools/mlir-tblgen/RewriterGen.cpp
+++ b/mlir/tools/mlir-tblgen/RewriterGen.cpp
@@ -715,11 +715,20 @@
 
       os << formatv("auto {0} = (*v{1}.begin()).getDefiningOp();\n", argName,
                     i);
+
+      // Indent emitMatchCheck and emitMatch because they declare local
+      // variables.
+      os << "{\n";
+      os.indent();
+
       emitMatchCheck(
           opName, /*matchStr=*/argName,
           formatv("\"There's no operation that defines operand {0} of {1}\"",
                   operandIndex++, opName));
       emitMatch(argTree, argName, depth + 1);
+
+      os.unindent() << "}\n";
+
       // `tblgen_ops` is used to collect the matched operations. In either, we
       // need to queue the operation only if the matching success. Thus we emit
       // the code at the end.