[AST] Dump argument types for TypeTraitExpr. (#89370)

The argument types are not modeled as children of TypeTraitExpr,
therefore they are not dumped with the default implementation.

Dumping them is really useful for ad-hoc debugging, context #89358

Author: hokein

clang/include/clang/AST/ASTNodeTraverser.h

@@ -851,6 +851,12 @@ class ASTNodeTraverser
       Visit(R);
   }
 
+  void VisitTypeTraitExpr(const TypeTraitExpr *E) {
+    // Argument types are not children of the TypeTraitExpr.
+    for (auto *A : E->getArgs())
+      Visit(A->getType());
+  }
+
   void VisitLambdaExpr(const LambdaExpr *Node) {
     if (Traversal == TK_IgnoreUnlessSpelledInSource) {
       for (unsigned I = 0, N = Node->capture_size(); I != N; ++I) {

clang/test/AST/ast-dump-template-json-win32-mangler-crash.cpp

@@ -2725,7 +2725,25 @@ int main()
 // CHECK-NEXT:        "type": {
 // CHECK-NEXT:         "qualType": "bool"
 // CHECK-NEXT:        },
-// CHECK-NEXT:        "valueCategory": "prvalue"
+// CHECK-NEXT:        "valueCategory": "prvalue",
+// CHECK-NEXT:        "inner": [
+// CHECK-NEXT:         {
+// CHECK-NEXT:          "id": "0x{{.*}}",
+// CHECK-NEXT:          "kind": "TemplateTypeParmType",
+// CHECK-NEXT:          "type": {
+// CHECK-NEXT:           "qualType": "_Ty"
+// CHECK-NEXT:          },
+// CHECK-NEXT:          "isDependent": true,
+// CHECK-NEXT:          "isInstantiationDependent": true,
+// CHECK-NEXT:          "depth": 0,
+// CHECK-NEXT:          "index": 0,
+// CHECK-NEXT:          "decl": {
+// CHECK-NEXT:           "id": "0x{{.*}}",
+// CHECK-NEXT:           "kind": "TemplateTypeParmDecl",
+// CHECK-NEXT:           "name": "_Ty"
+// CHECK-NEXT:          }
+// CHECK-NEXT:         }
+// CHECK-NEXT:        ]
 // CHECK-NEXT:       }
 // CHECK-NEXT:      ]
 // CHECK-NEXT:     }
@@ -3003,7 +3021,25 @@ int main()
 // CHECK-NEXT:        "type": {
 // CHECK-NEXT:         "qualType": "bool"
 // CHECK-NEXT:        },
-// CHECK-NEXT:        "valueCategory": "prvalue"
+// CHECK-NEXT:        "valueCategory": "prvalue",
+// CHECK-NEXT:        "inner": [
+// CHECK-NEXT:         {
+// CHECK-NEXT:          "id": "0x{{.*}}",
+// CHECK-NEXT:          "kind": "TemplateTypeParmType",
+// CHECK-NEXT:          "type": {
+// CHECK-NEXT:           "qualType": "_Ty"
+// CHECK-NEXT:          },
+// CHECK-NEXT:          "isDependent": true,
+// CHECK-NEXT:          "isInstantiationDependent": true,
+// CHECK-NEXT:          "depth": 0,
+// CHECK-NEXT:          "index": 0,
+// CHECK-NEXT:          "decl": {
+// CHECK-NEXT:           "id": "0x{{.*}}",
+// CHECK-NEXT:           "kind": "TemplateTypeParmDecl",
+// CHECK-NEXT:           "name": "_Ty"
+// CHECK-NEXT:          }
+// CHECK-NEXT:         }
+// CHECK-NEXT:        ]
 // CHECK-NEXT:       }
 // CHECK-NEXT:      ]
 // CHECK-NEXT:     }

clang/test/AST/ast-dump-traits.cpp

@@ -40,10 +40,19 @@ void test_unary_expr_or_type_trait() {
 // CHECK-NEXT: |   | `-EnumDecl {{.*}} <col:3, col:11> col:8{{( imported)?}} referenced E
 // CHECK-NEXT: |   |-CStyleCastExpr {{.*}} <line:13:3, col:21> 'void' <ToVoid>
 // CHECK-NEXT: |   | `-TypeTraitExpr {{.*}} <col:10, col:21> 'bool' __is_enum
+// CHECK-NEXT: |   |   `-ElaboratedType {{.*}} 'E' sugar
+// CHECK-NEXT: |   |     `-EnumType {{.*}} 'E'
+// CHECK-NEXT: |   |       `-Enum {{.*}} 'E'
 // CHECK-NEXT: |   |-CStyleCastExpr {{.*}} <line:15:3, col:30> 'void' <ToVoid>
 // CHECK-NEXT: |   | `-TypeTraitExpr {{.*}} <col:10, col:30> 'bool' __is_same
+// CHECK-NEXT: |   |   |-BuiltinType {{.*}} 'int'
+// CHECK-NEXT: |   |   `-BuiltinType {{.*}} 'float'
 // CHECK-NEXT: |   `-CStyleCastExpr {{.*}} <line:17:3, col:47> 'void' <ToVoid>
 // CHECK-NEXT: |     `-TypeTraitExpr {{.*}} <col:10, col:47> 'bool' __is_constructible
+// CHECK-NEXT:         |-BuiltinType {{.*}} 'int'
+// CHECK-NEXT:         |-BuiltinType {{.*}} 'int'
+// CHECK-NEXT:         |-BuiltinType {{.*}} 'int'
+// CHECK-NEXT:         `-BuiltinType {{.*}} 'int'
 // CHECK-NEXT: |-FunctionDecl {{.*}} <line:20:1, line:23:1> line:20:6{{( imported)?}} test_array_type_trait 'void ()'
 // CHECK-NEXT: | `-CompoundStmt {{.*}} <col:30, line:23:1>
 // CHECK-NEXT: |   `-CStyleCastExpr {{.*}} <line:22:3, col:34> 'void' <ToVoid>