[duplicate-code] Discarded-Error Linter Scaffolding Duplicated Across strconv/glob/json Analyzers #65436

🔍 Duplicate Code Detected: Discarded-Error Linter Scaffolding

Analysis of commit 31e5fda

Assignee: @copilot

Summary

Three "ignored/discarded error" analyzers in pkg/linters/ — strconvparseignorederror, globwalkignorederror, and jsonmarshalignoredeerror — implement nearly identical AST traversal and pattern-matching logic to detect val, _ := pkg.Func(...) assignments where the error return is discarded. The run setup and the core "2-LHS / blank second ident / selector call / resolve PkgName / match import path" block are structurally duplicated across all three files.

assign, ok := n.(*ast.AssignStmt)
if !ok {
    return
}
if len(assign.Lhs) != 2 || len(assign.Rhs) != 1 {
    return
}
blank, ok := assign.Lhs[1].(*ast.Ident)
if !ok || blank.Name != "_" {
    return
}
call, ok := assign.Rhs[0].(*ast.CallExpr)
if !ok {
    return
}
sel, ok := call.Fun.(*ast.SelectorExpr)
if !ok {
    return
}
ident, ok := sel.X.(*ast.Ident)
if !ok {
    return
}
obj := pass.TypesInfo.Uses[ident]
pkgName, ok := obj.(*types.PkgName)
if !ok /* || path mismatch */ {
    return
}

Impact Analysis

• Maintainability: A change to how discarded-error detection handles aliases, dot-imports, or multi-assignment must be applied in three places.
• Bug Risk: The three copies have already diverged slightly (e.g. strconvparse uses map[string]bool, globwalk uses map[string]map[string]struct{}, jsonmarshal hardcodes names), so fixes risk being applied inconsistently.
• Code Bloat: ~60-80 duplicated lines of matching logic across the three files.

Refactoring Recommendations

1. Extract a shared "discarded error call" matcher

   • Add a helper to pkg/linters/internal/astutil (e.g. MatchDiscardedErrorCall(pass, assign) (call *ast.CallExpr, pkgPath, funcName string, ok bool)) encapsulating the LHS/blank/selector/PkgName resolution.
   • Each analyzer supplies only a map[pkgPath]set(funcName) and a message template.
   • Estimated effort: 3-4 hours
   • Benefits: single tested implementation of the fiddly type-resolution logic; analyzers shrink to declarations.

2. Share the run + Indexes + Preorder boilerplate

   • Provide an analyzerutil helper that wires a per-assignment callback, removing the repeated run function.

Implementation Checklist

• Review duplication findings
• Prioritize refactoring tasks
• Create refactoring plan
• Implement shared matcher in astutil
• Migrate the three analyzers
• Update tests
• Verify no functionality broken

Generated by 🔍 Duplicate Code Detector · pi · opus48 · 361.7 AIC · ⌖ 46.9 AIC · ⊞ 4.4K · ◷

• expires on Oct 5, 2026, 2:50 PM UTC-08:00