Fix isConstant (and other expression annotations) missing from Identifier nodes in AST JSON export

[Copilot]

Identifier nodes in the exported JSON AST were missing isConstant, isLValue, isPure, and lValueRequested — even though these annotations are correctly computed during analysis. As a result, constant variable references always appeared to have no annotation at all rather than "isConstant": true.

Root cause

visit(Identifier const& _node) in ASTJsonExporter.cpp was manually setting only typeDescriptions and argumentTypes, never calling appendExpressionAttributes() — unlike every other expression node visitor.

Changes

• libsolidity/ast/ASTJsonExporter.cpp: Refactor visit(Identifier const& _node) to call appendExpressionAttributes() instead of manually enumerating fields, matching the pattern used by all other expression visitors.
• ASTJSON test fixtures (18 files): Updated to include the now-emitted isConstant, isLValue, isPure, and lValueRequested fields on Identifier nodes.
• New test constant_identifier.sol / constant_identifier.json: Covers the exact reported case — identifiers referencing constant variables should emit "isConstant": true.

Example

uint constant X = 1234;
contract C {
    uint constant Y = 5678;
    function f() public returns (uint) { return X + Y; }
}

Before (Identifier nodes had no expression annotation fields):

{ "name": "X", "nodeType": "Identifier", "typeDescriptions": { ... } }

After:

{ "isConstant": true, "isLValue": false, "isPure": true, "lValueRequested": false,
  "name": "X", "nodeType": "Identifier", "typeDescriptions": { ... } }

Original prompt

---

This section details on the original issue you should resolve

<issue_title>isConstant annotation in the AST is always false</issue_title>
<issue_description>## Description

isConstant in the AST is supposed to be true when the node is an identifier (or member access) that refers to a constant variable. This appears to be true internally, but in the exported AST the annotation is false instead.

Environment

Reproducible on 0.8.33, develop and as far back as 0.5.0.

Steps to Reproduce

uint constant X = 1234;

contract C {
    uint constant Y = 5678;

    function f() public returns (uint) {
        return X + Y;
    }
}

solc test.sol --ast-compact-json --pretty-json --json-indent 4 | grep isConstant

                "isConstant": false,
                        "isConstant": false,
                                    "isConstant": false,

The bug is likely to be in the JSON exporter. I checked the place where we assign the value during analysis by placing an assertion there and the value is true but only false is present in the JSON output:

solidity/libsolidity/analysis/TypeChecker.cpp

Line 3698 in 64118f2

annotation.isPure = isConstant = variableDeclaration->isConstant();

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes isConstant annotation in the AST is always false #16419

---

[rodiazet]

LGTM. I updated cmdlineTests and remove .gitignore changes, as we already have build*path in .gitignore file. Also reorganised commits

[rodiazet]

Analysis Complete

Expression-derived types in AST:

Direct Expression derivatives:

1. ✅ Conditional - calls appendExpressionAttributes (line 858)
2. ✅ Assignment - calls appendExpressionAttributes (line 870)
3. ✅ TupleExpression - calls appendExpressionAttributes (line 881)
4. ✅ UnaryOperation - calls appendExpressionAttributes (line 896)
5. ✅ BinaryOperation - calls appendExpressionAttributes (line 912)
6. ✅ FunctionCall - calls appendExpressionAttributes (line 936)
7. ✅ FunctionCallOptions - calls appendExpressionAttributes (line 952)
8. ✅ NewExpression - calls appendExpressionAttributes (line 963)
9. ✅ MemberAccess - calls appendExpressionAttributes (line 976)
10. ✅ IndexAccess - calls appendExpressionAttributes (line 987)
11. ✅ IndexRangeAccess - calls appendExpressionAttributes (line 999)
12. ✅ PrimaryExpression - (abstract base class)
13. ❌ Builtin - NO visit method found in ASTJsonExporter

PrimaryExpression derivatives:
14. ✅ Identifier - calls appendExpressionAttributes (line 1014) ← fixed by current PR
15. ✅ ElementaryTypeNameExpression - calls appendExpressionAttributes (line 1024)
16. ✅ Literal - calls appendExpressionAttributes (line 1046)

Findings:

✅ All Expression-derived types with visit methods properly call appendExpressionAttributes

⚠️ Builtin class has no visit method: This class derives from Expression (AST.h:2637) but has no corresponding visit(Builtin const&) method in ASTJsonExporter.cpp. This might be intentional if Builtin is never exported to JSON, but should be verified.
Builtin is available only in experimental solidity only, hence it's probably intentional.

[cameel]

I'd use an AST property test for this. Those are less verbose and this is a case where are we're specifically interested in specific attributes and their values rather than the overall structure of the produced AST.

[cameel]

The PR needs a changelog entry.

[cameel]

Builtin is available only in experimental solidity only, hence it's probably intentional.

Yes, it's intentional.

[github-actions]

This pull request is stale because it has been open for 14 days with no activity.
It will be closed in 7 days unless the stale label is removed.

[github-actions]

This pull request was closed due to a lack of activity for 7 days after it was stale.