[mlir] Print bad size in AttrSizedOperandSegments

When printing verification errors for ops with the incorrect number of
operand segments, print the required number as well as the actual
number. Split off from D93005.

Differential Revision: https://reviews.llvm.org/D93145

Author: modocache

mlir/test/IR/traits.mlir

@@ -448,7 +448,7 @@ func @failedResultSizeAttrWrongTotalSize() {
 // -----
 
 func @failedResultSizeAttrWrongCount() {
-  // expected-error @+1 {{'result_segment_sizes' attribute for specifying result segments must have 4 elements}}
+  // expected-error @+1 {{'result_segment_sizes' attribute for specifying result segments must have 4 elements, but got 3}}
   %0:4 = "test.attr_sized_results"() {result_segment_sizes = dense<[2, 1, 1]>: vector<3xi32>} : () -> (i32, i32, i32, i32)
 }
 

mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp

@@ -2211,7 +2211,7 @@ void OpOperandAdaptorEmitter::addVerification() {
     auto numElements = sizeAttr.getType().cast<::mlir::ShapedType>().getNumElements();
     if (numElements != {1})
       return emitError(loc, "'{0}' attribute for specifying {2} segments "
-                       "must have {1} elements");
+                       "must have {1} elements, but got ") << numElements;
   }
   )";