Vacro Report

Better Panic Reporting for Procedural Macros

Introduction

vacro-report is a diagnostic enhancement tool designed to improve the debugging experience for Rust Procedural Macros.

It currently focuses on solving the opaque panic messages generated by syn::parse_quote! or parse_quote_spanned. When parse_quote! or parse_quote_spanned fails, it usually just says "failed to parse". vacro-report intercepts these calls and prints the actual generated token stream formatted as code, highlighting the syntax error.

Installation

[dependencies]
vacro-report = "0.1.2"

Usage

Simply decorate your function with #[vacro_report::scope].

Inside the scope, any usage of parse_quote! and parse_quote_spanned will be automatically instrumented. No other code changes are required.

use syn::{parse_quote, Expr, Token};
use vacro_report::scope;

#[scope]
fn generate_code() {
    // If this fails, vacro-report will print the exact tokens that caused the error.
    let _expr: Expr = parse_quote! {
        1 + 2 + // Missing operand, would normally panic silently or vaguely
    };
}

Features

• Automatic Interception: Rewrites parse_quote! and parse_quote_spanned! calls within the #[scope] function.
• Detailed Diagnostics: When a parsing error occurs, it displays the generated code (formatted) and the error location.
• Zero Overhead (Success): Adds minimal overhead only when an error actually occurs (panic path).

  ⚠️ Warning

  We use debug_assertions to make this judgment, which means that if you have enabled certain optimizations, the effect may not trigger.