[golang/go] proposal: x/tools/go/analysis/passes/modernize: vars for atomic, errorsastype, plusbuild, stringscut, stditerators

### ROOT CAUSE The issue proposes adding a new analyzer to the modernize package in the Go tooling. This analyzer would suggest replacing the use of primitive `sync/atomic` functions (e.g., `atomic.AddInt32`) with the strongly typed atomic wrapper types introduced in Go 1.19 (e.g., `atomic.Int32`). The root cause is the unsafe and error-prone nature of the primitive atomic functions, which can lead to memory alignment issues and non-atomic access problems. The new atomic types provide type safety, alignment guarantees, and a more idiomatic way to handle atomic operations. ### CODE FIX To implement this analyzer, follow these steps: 1. **Create a New Analyzer**: - Add a new file `atomic/analyzer.go` in the `x/tools/go/analysis/passes/modernize` directory. - Define a new `Analyzer` struct that implements the `analysis.Pass` interface. 2. **Traverse the AST**: - Use Go's `go/ast` package to traverse the code and identify variable declarations and function calls involving `sync/atomic` operations on primitive types. 3. **Check Go Version**: - Ensure the analyzer only runs on code targeting Go 1.19 or later by checking the `go` directive or `go.mod` file. 4. **Suggest Transformations**: - For each variable used with atomic operations, suggest replacing it with the corresponding atomic type (e.g., `int32` → `atomic.Int32`). - Replace direct `atomic` function calls with member function calls (e.g., `atomic.AddInt32(&x, 1)` → `x.Add(1)`). 5. **Register the Analyzer**: - Update the `modernize` package to include the new analyzer in its list of passes. Example code snippet from `atomic/analyzer.go`: ```go package modernize import ( "go/ast" "go/types" "golang.org/x/tools/go/analysis/analysistest" ) var Analyzer = &analysis.Analyzer{ Name: "atomic", Doc: "atomic suggests replacing primitive atomic operations with typed atomic types", Run: run, } func run(pass *analysis.Pass) (any, error) { // Traverse the AST and suggest replacements for _, decl := range pass.AST.Decls { if genDecl, ok := decl.(*ast.GenDecl); ok && genDecl.Typedefs() { for _, spec := range genDecl.Specs { if typeSpec, ok := spec.(*ast.TypeSpec); ok { // Check if the type is a primitive and used with atomic // (simplified logic) } } } } return nil, nil } ``` 6. **Update Documentation**: - Document the analyzer in the `README.md` of the `modernize` package. This analyzer would help developers modernize their code by leveraging safer atomic operations introduced in Go 1.19.