https://github.com/adia-dev/zlg_bug_hover

https://github.com/adia-dev/zlg_bug_hover

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• Host: GitHub
• URL: https://github.com/adia-dev/zlg_bug_hover
• Owner: adia-dev
• Created: 2024-02-11T13:29:00.000Z (9 months ago)
• Default Branch: main
• Last Pushed: 2024-02-11T13:29:03.000Z (9 months ago)
• Last Synced: 2024-04-20T16:53:10.627Z (7 months ago)
• Language: Zig
• Size: 387 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# ZLS Hover Information Bug Reproduction

## Overview

This repository contains a minimal Zig code example that demonstrates an issue with Zig Language Server (ZLS) providing incorrect type information on hover for a specific case involving union downcasting.

The bug has been spotted on zig version `0.12.0-dev.2500+c085c6ecd` and zls version `0.12.0-dev.365+a8a83b6`.

## Issue Description

In the provided Zig code, when attempting to downcast from `UnaryExpression.Right` to `NumberLiteralExpression`, the expected type on hover should be `*NumberLiteralExpression`. However, ZLS incorrectly displays it as `*UnaryExpression`.

See image below:

![Screenshot of the hover event](./images/hover.png)

As shown in the screenshot above, the hover information incorrectly indicates the type as `*UnaryExpression` instead of `*NumberLiteralExpression`.

## Steps to Reproduce

1. Clone this repository.

2. Open the project in your preferred Zig development environment that utilizes ZLS.

3. Hover over the variable `number` in the `main` function to observe the type information provided by ZLS.

4. You can execute the code to see that zig is evaluating the downcast accordingly.

## Expected Behavior

The hover information for `number` should indicate its type as `*NumberLiteralExpression`.

## Actual Behavior

The hover information for `number` incorrectly indicates its type as `*UnaryExpression`.

## Environment

- Zig version: 0.12.0-dev.2500+c085c6ecd

- ZLS version: 0.12.0-dev.365+a8a83b6

- OS: MacOS M1 Pro 2020 Sonoma 14.2.1

## Code Snippet

```zig

// ✅ Downcast from Statement to ExpressionStatement

if (statement.downcast(ExpressionStatement)) |expr_stmt| {

    // ✅ Downcast from ExpressionStatement.Expression to UnaryExpression

    if (expr_stmt.expression.downcast(UnaryExpression)) |unary| {

        // ❌ Downcast from UnaryExpression.Right to NumberLiteralExpression

        if (unary.right.downcast(NumberLiteralExpression)) |number| {

            std.debug.print("I am a NumberLiteralExpression and not a UnaryExpression: {}\n", .{number});

        }

    }

}

```