[mlir] Put back virtual ~ConversionTarget(), some users started relying on it

diff --git a/mlir/include/mlir/Transforms/DialectConversion.h b/mlir/include/mlir/Transforms/DialectConversion.h
index c9e9f67..7354b55 100644 (file)
--- a/mlir/include/mlir/Transforms/DialectConversion.h
+++ b/mlir/include/mlir/Transforms/DialectConversion.h
@@ -622,6 +622,7 @@ public:
   using DynamicLegalityCallbackFn = std::function<bool(Operation *)>;
 
   ConversionTarget(MLIRContext &ctx) : ctx(ctx) {}
+  virtual ~ConversionTarget() = default;
 
   //===--------------------------------------------------------------------===//
   // Legality Registration