xai-org/x-algorithm · error · SemanticCheckFailure

StructTuple expects pairs of name and values, but a %s recei

Error message

StructTuple expects pairs of name and values, but a %s received

What it means

When constructing a StructTuple node, every child must be a ToPair (name, value) mapping a field name to its value. Any other child node type (a bare constant, function call, etc.) is rejected with this error.

Source

Thrown at botmaker/src/java/com/twitter/botmaker/compiler/CompilerUnit.java:276

      @Override
      public BotMakerDoc botMakerDoc() {
        return description;
      }

      @Override
      public Fingerprint fingerprint() {
        return Fingerprint.EMPTY;
      }

      @Override
      public ASTNode createASTNode(ImmutableList<ASTNode> children) throws SemanticCheckFailure {

        ImmutableList<String> fieldNames = structTupleType.fieldNames;
        ASTNode[] fieldValues = new ASTNode[fieldNames.size()];

        for (ASTNode child : children) {
          if (!(child instanceof ToPair)) {
            throw new SemanticCheckFailure(
                String.format(
                    "StructTuple expects pairs of name and values, but a %s received", child)
            );
          }

          String fieldName = ((Constant) child.getChildren().get(0)).getValue().toString();
          if (!fieldNames.contains(fieldName)) {
            throw new SemanticCheckFailure(
                String.format("Field %s does not belong to %s", fieldName, toString())
            );
          }
          fieldValues[fieldNames.indexOf(fieldName)] = (ASTNode) child.getChildren().get(1);
        }
        return new ToStructTuple(fn, fieldNames, ImmutableList.copyOf(fieldValues)) {
          @Override
          public Signature getSignature() {
            return signature;
          }

View on GitHub (pinned to 24c60942c5)

Solutions

Rewrite the struct literal using field=value pairs for every field
Check the struct's expected fields and provide each as a named pair
If generating code, emit ToPair nodes for each field

Example fix

// before
MyStruct(a, b)
// after
MyStruct(field1 = a, field2 = b)

Defensive patterns

Strategy: validation

Validate before calling

for (ASTNode c : children) if (!(c instanceof ToPair)) throw new IllegalArgumentException("StructTuple children must be name=value pairs");

Type guard

boolean isFieldPair(ASTNode n) { return n instanceof ToPair; }

Try / catch

catch (SemanticCheckFailure e) { /* rewrite struct literal as field=value pairs */ }

Prevention

Always construct struct literals with explicit field names
Lint generated code for bare children in struct constructors

When it happens

Trigger: Passing non-pair children to a struct-tuple constructor in the DSL, e.g. 'StructType(value1, value2)' instead of 'StructType(field = value1, other = value2)', so a child ASTNode is not an instance of ToPair.

Common situations: Writing struct literals positionally instead of by field name; DSL syntax changes; generated code emitting bare expressions inside struct constructors.

Related errors

AI-assisted analysis of xai-org/x-algorithm@24c60942c5 (2026-08-28). Data as JSON: /api/errors/2c22c349bb8bdada. Report an issue: GitHub.