Add sanity check in MLIR ODS to catch case where two results have the same name

[mehdi_amini]

Summary

This is making a tablegen crash with a more friendly error.

[jpienaar]

I could have sworn I approved this already, sorry, must have not clicked submit.

[mehdi_amini]

Maybe you're thinking about https://reviews.llvm.org/D109449 ?

[rriddle]

We should check that no names overlap, i.e. no operand/result/region/successor/etc. can have the same name.

mlir/test/mlir-tblgen/op-error.td

 // RUN: not mlir-tblgen -gen-op-decls -I %S/../../include -DERROR1 %s 2>&1 | FileCheck --check-prefix=ERROR1 %s
 // RUN: not mlir-tblgen -gen-op-decls -I %S/../../include -DERROR2 %s 2>&1 | FileCheck --check-prefix=ERROR2 %s
 // RUN: not mlir-tblgen -gen-op-decls -I %S/../../include -DERROR3 %s 2>&1 | FileCheck --check-prefix=ERROR3 %s
+// RUN: not mlir-tblgen -gen-op-decls -I %S/../../include -DERROR4 %s 2>&1 | FileCheck --check-prefix=ERROR4 %s
+// RUN: not mlir-tblgen -gen-op-decls -I %S/../../include -DERROR5 %s 2>&1 | FileCheck --check-prefix=ERROR5 %s
 
 include "mlir/IR/OpBase.td"
 
 def Test_Dialect : Dialect {
   let name = "test_dialect";
 }
 
 #ifdef ERROR1

 #ifdef ERROR3
 // ERROR3: error: expected an argument with default value after other arguments with default values
 def OpDefaultValueNotTrailing : Op<Test_Dialect, "default_value"> {
   let builders = [
     OpBuilder<(ins CArg<"int", "42">, CArg<"int">)>
   ];
 }
 #endif
+
+#ifdef ERROR4
+// ERROR4: error: op has two operands with the same name: 'tensor'
+def OpWithDuplicatedArgNames : Op<Test_Dialect, "default_value"> {
+  let arguments = (ins AnyTensor:$tensor, AnyTensor:$tensor);
+}
+#endif
+
+#ifdef ERROR5
+// ERROR5: error: op has two results with the same name: 'tensor'
+def OpWithDuplicatedResultNames : Op<Test_Dialect, "default_value"> {
+  let results = (outs AnyTensor:$tensor, AnyTensor:$tensor);
+}
+#endif

mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp

static void generateNamedOperandGetters(const Operator &op, Class &opClass,
   // method.
   // Keep track of the operand names to find duplicates.
   SmallDenseSet<StringRef> operandNames;
   for (int i = 0; i != numOperands; ++i) {
     const auto &operand = op.getOperand(i);
     if (operand.name.empty())
       continue;
     if (!operandNames.insert(operand.name).second)
-      PrintFatalError(op.getLoc(), "op has two operands with the same name");
+      PrintFatalError(op.getLoc(), "op has two operands with the same name: '" +
+                                       operand.name + "'");
 
     if (operand.isOptional()) {
       m = opClass.addMethodAndPrune("::mlir::Value", operand.name);
       m->body()
           << "  auto operands = getODSOperands(" << i << ");\n"
           << "  return operands.empty() ? ::mlir::Value() : *operands.begin();";
     } else if (operand.isVariadicOfVariadic()) {
       StringRef segmentAttr =
generateValueRangeStartAndEnd(
       numNormalResults, "getOperation()->getNumResults()", attrSizedResults,
       attrSizeInitCode, op.getResults());
 
   auto *m = opClass.addMethodAndPrune("::mlir::Operation::result_range",
                                       "getODSResults", "unsigned", "index");
   m->body() << formatv(valueRangeReturnCode, "getOperation()->result_begin()",
                        "getODSResultIndexAndLength(index)");
 
+  SmallDenseSet<StringRef> resultNames;
   for (int i = 0; i != numResults; ++i) {
     const auto &result = op.getResult(i);
     if (result.name.empty())
       continue;
+    if (!resultNames.insert(result.name).second)
+      PrintFatalError(op.getLoc(), "op has two results with the same name: '" +
+                                       result.name + "'");
 
     if (result.isOptional()) {
       m = opClass.addMethodAndPrune("::mlir::Value", result.name);
       m->body()
           << "  auto results = getODSResults(" << i << ");\n"
           << "  return results.empty() ? ::mlir::Value() : *results.begin();";
     } else if (result.isVariadic()) {
       m = opClass.addMethodAndPrune("::mlir::Operation::result_range",