[mlir][IR] Improve error message when parsing incorrect type (#134984)

Improve error messages when parsing an incorrect type.

Before:
```
invalid kind of type specified
```

After:
```
invalid kind of type specified: expected builtin.tensor, but found 'tensor<*xi32>'
```

This error message is produced when a certain operand/result type is
expected according to an op's TableGen definition, but a different type
is parsed. Type constraints (which may have nice error messages) are
checked after parsing a type. If an incorrect type is parsed, we never
get to the point of printing type constraint error messages. This may
discourage users from specifying C++ classes with type constraints.
(Explicitly specifying C++ classes is beneficial because the
auto-generated C++ code will have richer type information; explicit
casts are unnecessary, etc.) See #134981 for an example where specifying
additional type information with type constraints (e.g.,
`LLVM_AnyVector`) lead to worse error messages.

Note: In order to generate a better error message, the parser must
retrieve a type's name from the C++ class. TableGen-generated type
classes always have a `name` field, but hand-written C++ type classes
may not. The `HasStaticName` template was copied from
`DialectImplementation.h` (`HasStaticDialectName`).

Author: matthias-springer

mlir/include/mlir/IR/OpImplementation.h

@@ -21,6 +21,19 @@
 #include "llvm/Support/SMLoc.h"
 #include <optional>
 
+namespace {
+// reference https://stackoverflow.com/a/16000226
+template <typename T, typename = void>
+struct HasStaticName : std::false_type {};
+
+template <typename T>
+struct HasStaticName<T,
+                     typename std::enable_if<
+                         std::is_same<::llvm::StringLiteral,
+                                      std::decay_t<decltype(T::name)>>::value,
+                         void>::type> : std::true_type {};
+} // namespace
+
 namespace mlir {
 class AsmParsedResourceEntry;
 class AsmResourceBuilder;
@@ -1238,8 +1251,13 @@ class AsmParser {
 
     // Check for the right kind of type.
     result = llvm::dyn_cast<TypeT>(type);
-    if (!result)
-      return emitError(loc, "invalid kind of type specified");
+    if (!result) {
+      InFlightDiagnostic diag =
+          emitError(loc, "invalid kind of type specified");
+      if constexpr (HasStaticName<TypeT>::value)
+        diag << ": expected " << TypeT::name << ", but found " << type;
+      return diag;
+    }
 
     return success();
   }
@@ -1270,8 +1288,13 @@ class AsmParser {
 
     // Check for the right kind of Type.
     result = llvm::dyn_cast<TypeT>(type);
-    if (!result)
-      return emitError(loc, "invalid kind of Type specified");
+    if (!result) {
+      InFlightDiagnostic diag =
+          emitError(loc, "invalid kind of type specified");
+      if constexpr (HasStaticName<TypeT>::value)
+        diag << ": expected " << TypeT::name << ", but found " << type;
+      return diag;
+    }
     return success();
   }
 
@@ -1307,8 +1330,13 @@ class AsmParser {
 
     // Check for the right kind of type.
     result = llvm::dyn_cast<TypeType>(type);
-    if (!result)
-      return emitError(loc, "invalid kind of type specified");
+    if (!result) {
+      InFlightDiagnostic diag =
+          emitError(loc, "invalid kind of type specified");
+      if constexpr (HasStaticName<TypeType>::value)
+        diag << ": expected " << TypeType::name << ", but found " << type;
+      return diag;
+    }
 
     return success();
   }

mlir/test/Dialect/EmitC/invalid_ops.mlir

@@ -281,7 +281,7 @@ func.func @test_assign_type_mismatch(%arg1: f32) {
 
 func.func @test_assign_to_array(%arg1: !emitc.array<4xi32>) {
   %v = "emitc.variable"() <{value = #emitc.opaque<"">}> : () -> !emitc.array<4xi32>
-  // expected-error @+1 {{invalid kind of Type specified}}
+  // expected-error @+1 {{invalid kind of type specified: expected emitc.lvalue, but found '!emitc.array<4xi32>'}}
   emitc.assign %arg1 : !emitc.array<4xi32> to %v : !emitc.array<4xi32>
   return
 }

mlir/test/Dialect/LLVMIR/invalid.mlir

@@ -121,7 +121,7 @@ func.func @gep_missing_result_type(%pos : i64, %base : !llvm.ptr) {
 // -----
 
 func.func @gep_non_function_type(%pos : i64, %base : !llvm.ptr) {
-  // expected-error@+1 {{invalid kind of type specified}}
+  // expected-error@+1 {{invalid kind of type specified: expected builtin.function, but found '!llvm.ptr'}}
   llvm.getelementptr %base[%pos] : !llvm.ptr
 }
 

mlir/test/Dialect/SparseTensor/invalid.mlir

@@ -347,7 +347,7 @@ func.func @sparse_wrong_arity_compression(%arg0: memref<?xf64>,
 // -----
 
 func.func @sparse_convert_unranked(%arg0: tensor<*xf32>) -> tensor<10xf32> {
-  // expected-error@+1 {{invalid kind of type specified}}
+  // expected-error@+1 {{invalid kind of type specified: expected builtin.tensor, but found 'tensor<*xf32>'}}
   %0 = sparse_tensor.convert %arg0 : tensor<*xf32> to tensor<10xf32>
   return %0 : tensor<10xf32>
 }

mlir/test/Dialect/Tensor/invalid.mlir

@@ -81,7 +81,7 @@ func.func @insert_too_many_indices(%arg0: f32, %arg1: tensor<?xf32>) {
 // -----
 
 func.func @tensor.from_elements_wrong_result_type() {
-  // expected-error@+2 {{'tensor.from_elements' invalid kind of type specified}}
+  // expected-error@+2 {{'tensor.from_elements' invalid kind of type specified: expected builtin.tensor, but found 'tensor<*xi32>'}}
   %c0 = arith.constant 0 : i32
   %0 = tensor.from_elements %c0 : tensor<*xi32>
   return
@@ -459,7 +459,7 @@ func.func @pad_yield_type(%arg0: tensor<?x4xi32>, %arg1: i8) -> tensor<?x9xi32>
 // -----
 
 func.func @invalid_splat(%v : f32) {
-  // expected-error@+1 {{invalid kind of type specified}}
+  // expected-error@+1 {{invalid kind of type specified: expected builtin.tensor, but found 'memref<8xf32>'}}
   tensor.splat %v : memref<8xf32>
   return
 }

mlir/test/Dialect/Vector/invalid.mlir

@@ -1,7 +1,7 @@
 // RUN: mlir-opt %s -split-input-file -verify-diagnostics
 
 func.func @broadcast_to_scalar(%arg0: f32) -> f32 {
-  // expected-error@+1 {{custom op 'vector.broadcast' invalid kind of type specified}}
+  // expected-error@+1 {{custom op 'vector.broadcast' invalid kind of type specified: expected builtin.vector, but found 'f32'}}
   %0 = vector.broadcast %arg0 : f32 to f32
 }
 
@@ -144,7 +144,7 @@ func.func @extract_element(%arg0: vector<4x4xf32>) {
 // -----
 
 func.func @extract_vector_type(%arg0: index) {
-  // expected-error@+1 {{invalid kind of type specified}}
+  // expected-error@+1 {{invalid kind of type specified: expected builtin.vector, but found 'index'}}
   %1 = vector.extract %arg0[] : index from index
 }
 
@@ -1174,7 +1174,7 @@ func.func @shape_cast_scalability_flag_is_dropped(%arg0 : vector<2x[15]x[2]xf32>
 // -----
 
 func.func @bitcast_not_vector(%arg0 : vector<5x1x3x2xf32>) {
-  // expected-error@+1 {{'vector.bitcast' invalid kind of type specified}}
+  // expected-error@+1 {{'vector.bitcast' invalid kind of type specified: expected builtin.vector, but found 'f32'}}
   %0 = vector.bitcast %arg0 : vector<5x1x3x2xf32> to f32
 }
 
@@ -1628,7 +1628,7 @@ func.func @scan_unsupported_kind(%arg0: vector<2x3xf32>, %arg1: vector<3xf32>) -
 // -----
 
 func.func @invalid_splat(%v : f32) {
-  // expected-error@+1 {{invalid kind of type specified}}
+  // expected-error@+1 {{invalid kind of type specified: expected builtin.vector, but found 'memref<8xf32>'}}
   vector.splat %v : memref<8xf32>
   return
 }

mlir/test/Target/LLVMIR/llvmir-invalid.mlir

@@ -246,7 +246,7 @@ llvm.func @matrix_transpose_intr_wrong_type(%matrix : f32) -> vector<48xf32> {
 // -----
 
 llvm.func @active_lane_intr_wrong_type(%base : i64, %n : vector<7xi64>) -> vector<7xi1> {
-  // expected-error @below{{invalid kind of type specified}}
+  // expected-error @below{{invalid kind of type specified: expected builtin.integer, but found 'vector<7xi64>'}}
   %0 = llvm.intr.get.active.lane.mask %base, %n : i64, vector<7xi64> to vector<7xi1>
   llvm.return %0 : vector<7xi1>
 }

mlir/test/mlir-tblgen/attr-or-type-format.mlir

@@ -129,7 +129,7 @@ func.func private @test_verifier_fails() -> () attributes {
 // -----
 
 func.func private @test_attr_with_type_failed_to_parse_type() -> () attributes {
-  // expected-error@+2 {{invalid kind of type specified}}
+  // expected-error@+2 {{invalid kind of type specified: expected builtin.integer, but found 'vector<4xi32>'}}
   // expected-error@+1 {{failed to parse TestAttrWithTypeParam parameter 'int_type'}}
   attr = #test.attr_with_type<vector<4xi32>, vector<4xi32>>
 }