Skip to content

refactor: consolidate duplicate byte/string AST predicates into linters astutil #46108

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
pelikhan merged 9 commits into from
Jul 17, 2026
Merged

refactor: consolidate duplicate byte/string AST predicates into linters astutil #46108

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
9 commits
Select commit Hold shift + click to select a range
57e88d3
Initial plan
Copilot Jul 17, 2026
bf4705d
chore: initial state - planning refactor
Copilot Jul 17, 2026
6771db9
refactor: consolidate duplicate byte/string AST predicates into astutil
Copilot Jul 17, 2026
51e6e23
Merge remote-tracking branch 'origin/main' into copilot/refactor-merg…
Copilot Jul 17, 2026
3b2c1d5
merge: resolve conflicts with origin/main workflow lock files
Copilot Jul 17, 2026
7085e75
chore: start pr finisher pass
Copilot Jul 17, 2026
77555eb
test: add coverage for shared astutil byte/string type helpers
Copilot Jul 17, 2026
2f525f5
test: stabilize astutil helper coverage expression selection
Copilot Jul 17, 2026
b2e6cdd
chore: start latest pr-finisher pass
Copilot Jul 17, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 2 additions & 1 deletion .github/workflows/release.lock.yml
View file
Open in desktop

Some generated files are not rendered by default. Learn more about how customized files appear on GitHub.

41 changes: 3 additions & 38 deletions pkg/linters/appendbytestring/appendbytestring.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@ package appendbytestring
import (
"fmt"
"go/ast"
"go/types"

"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/passes/inspect"
Expand Down Expand Up @@ -67,7 +66,7 @@ func run(pass *analysis.Pass) (any, error) {
}

// The first argument must be []byte.
if !isByteSlice(pass, call.Args[0]) {
if !astutil.IsByteSlice(pass, call.Args[0]) {
return
}

Expand All @@ -76,14 +75,14 @@ func run(pass *analysis.Pass) (any, error) {
if !ok {
return
}
if !isByteSliceConversion(pass, conv) {
if !astutil.IsByteSliceConversion(pass, conv) {
return
}
if len(conv.Args) != 1 {
return
}
strArg := conv.Args[0]
if !isStringType(pass, strArg) {
if !astutil.IsStringType(pass, strArg) {
return
}

Expand All @@ -103,40 +102,6 @@ func run(pass *analysis.Pass) (any, error) {
return nil, nil
}

// isByteSlice reports whether expr has type []byte.
func isByteSlice(pass *analysis.Pass, expr ast.Expr) bool {
t := pass.TypesInfo.TypeOf(expr)
if t == nil {
return false
}
sl, ok := t.Underlying().(*types.Slice)
if !ok {
return false
}
elem, ok := sl.Elem().(*types.Basic)
return ok && elem.Kind() == types.Byte
}

// isByteSliceConversion reports whether conv is a []byte/[]uint8 conversion expression.
func isByteSliceConversion(pass *analysis.Pass, conv *ast.CallExpr) bool {
// A type conversion has a type expression as the call function.
funTypeInfo, ok := pass.TypesInfo.Types[conv.Fun]
if !ok || !funTypeInfo.IsType() {
return false
}
return isByteSlice(pass, conv)
}

// isStringType reports whether expr has type string.
func isStringType(pass *analysis.Pass, expr ast.Expr) bool {
t := pass.TypesInfo.TypeOf(expr)
if t == nil {
return false
}
basic, ok := t.Underlying().(*types.Basic)
return ok && basic.Kind() == types.String
}

// buildFix returns a SuggestedFix rewriting append(b, []byte(s)...) to append(b, s...).
func buildFix(pass *analysis.Pass, conv *ast.CallExpr, strArg ast.Expr) []analysis.SuggestedFix {
sText := astutil.NodeText(pass.Fset, strArg)
Expand Down
16 changes: 1 addition & 15 deletions pkg/linters/bytescomparestring/bytescomparestring.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -276,23 +276,9 @@ func extractByteSliceStringConv(pass *analysis.Pass, expr ast.Expr) (ast.Expr, b

// The argument must be []byte (or []uint8).
arg := call.Args[0]
if !isByteSlice(pass, arg) {
if !astutil.IsByteSlice(pass, arg) {
return nil, false
}

return arg, true
}

// isByteSlice reports whether expr has underlying type []byte ([]uint8).
func isByteSlice(pass *analysis.Pass, expr ast.Expr) bool {
t := pass.TypesInfo.TypeOf(expr)
if t == nil {
return false
}
sl, ok := t.Underlying().(*types.Slice)
if !ok {
return false
}
elem, ok := sl.Elem().(*types.Basic)
return ok && elem.Kind() == types.Byte
}
33 changes: 33 additions & 0 deletions pkg/linters/internal/astutil/astutil.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -345,6 +345,39 @@ func QualifierShadowed(pkg *types.Package, pos token.Pos, name, importPath strin
return pkgName.Imported().Path() != importPath
}

// IsByteSlice reports whether expr has underlying type []byte ([]uint8).
func IsByteSlice(pass *analysis.Pass, expr ast.Expr) bool {
t := pass.TypesInfo.TypeOf(expr)
if t == nil {
return false
}
sl, ok := t.Underlying().(*types.Slice)
if !ok {
return false
}
elem, ok := sl.Elem().(*types.Basic)
return ok && elem.Kind() == types.Byte
}

// IsByteSliceConversion reports whether conv is a []byte or []uint8 conversion expression.
func IsByteSliceConversion(pass *analysis.Pass, conv *ast.CallExpr) bool {
funTypeInfo, ok := pass.TypesInfo.Types[conv.Fun]
if !ok || !funTypeInfo.IsType() {
return false
}
return IsByteSlice(pass, conv)
}

// IsStringType reports whether expr has underlying type string (or a named string type).
func IsStringType(pass *analysis.Pass, expr ast.Expr) bool {
t := pass.TypesInfo.TypeOf(expr)
if t == nil {
return false
}
basic, ok := t.Underlying().(*types.Basic)
return ok && basic.Kind() == types.String
}

// ConstIntValue returns the integer constant value of expr, if it is a
// constant integer.
func ConstIntValue(pass *analysis.Pass, expr ast.Expr) (int64, bool) {

@github-actions github-actions Bot Jul 17, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[/tdd] The three new exported helpers have no tests — a gap that matters now they are shared API surface.

💡 Suggested test skeleton 
// astutil_test.go
func TestIsByteSlice(t *testing.T) {
    // arrange: build a *analysis.Pass with TypesInfo pointing at a []byte expr
    // act:     call IsByteSlice(pass, expr)
    // assert:  returns true for []byte / []uint8, false for string / int
}

func TestIsByteSliceConversion(t *testing.T) {
    // assert: true only when the call function is a []byte type expression
    // assert: false when it is a plain function call
}

func TestIsStringType(t *testing.T) {
    // assert: true for predeclared string and named-string types
    // assert: false for []byte / int
}

Because these predicates are now called from three linters, a single misunderstanding about what counts as "underlying type" will silently affect all three.

@copilot please address this.

Copilot AI Jul 17, 2026

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Added focused unit coverage for IsByteSlice, IsByteSliceConversion, and IsStringType in pkg/linters/internal/astutil/astutil_test.go (including positive/negative cases and named string type handling) in 77555eb.

Expand Down
115 changes: 115 additions & 0 deletions pkg/linters/internal/astutil/astutil_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,37 @@ package astutil
import (
"go/ast"
"go/constant"
"go/importer"
"go/parser"
"go/token"
"go/types"
"testing"

"golang.org/x/tools/go/analysis"
)

func typecheckSnippet(t *testing.T, src string) (*analysis.Pass, *ast.File) {
t.Helper()

fset := token.NewFileSet()
file, err := parser.ParseFile(fset, "snippet.go", src, parser.SkipObjectResolution)
if err != nil {
t.Fatalf("ParseFile() error = %v", err)
}

info := &types.Info{
Types: make(map[ast.Expr]types.TypeAndValue),
Defs: make(map[*ast.Ident]types.Object),
Uses: make(map[*ast.Ident]types.Object),
}
cfg := types.Config{Importer: importer.Default()}
if _, err := cfg.Check("example.com/p", fset, []*ast.File{file}, info); err != nil {
t.Fatalf("type checking failed: %v", err)
}

return &analysis.Pass{TypesInfo: info}, file
}

func TestRhsExprForIndex(t *testing.T) {
t.Parallel()

Expand Down Expand Up @@ -424,3 +448,94 @@ func TestBuildContainsFix(t *testing.T) {
t.Fatalf("negated Message = %q, want %q", fixes[0].Message, "negated message")
}
}

func TestByteStringTypeHelpers(t *testing.T) {
t.Parallel()

const src = `package p

func g(s string) []byte { return nil }

func f(s string, b []byte) {
type myString string
var ms myString

_ = []byte(s)
_ = g(s)
_ = b
_ = s
_ = ms
}
`

pass, file := typecheckSnippet(t, src)

var fn *ast.FuncDecl
for _, decl := range file.Decls {
decl, ok := decl.(*ast.FuncDecl)
if ok && decl.Name.Name == "f" {
fn = decl
break
}
}
if fn == nil || fn.Body == nil {
t.Fatal("failed to find function f in test snippet")
}

var rhsExprs []ast.Expr
for _, stmt := range fn.Body.List {
assign, ok := stmt.(*ast.AssignStmt)
if !ok || len(assign.Rhs) != 1 {
continue
}
rhsExprs = append(rhsExprs, assign.Rhs[0])
}
if len(rhsExprs) != 5 {
t.Fatalf("found %d assignment expressions in f, want 5", len(rhsExprs))
}

byteConv, ok := rhsExprs[0].(*ast.CallExpr)
if !ok {
t.Fatalf("rhs[0] type = %T, want *ast.CallExpr", rhsExprs[0])
}
gCall, ok := rhsExprs[1].(*ast.CallExpr)
if !ok {
t.Fatalf("rhs[1] type = %T, want *ast.CallExpr", rhsExprs[1])
}
bIdent, ok := rhsExprs[2].(*ast.Ident)
if !ok {
t.Fatalf("rhs[2] type = %T, want *ast.Ident", rhsExprs[2])
}
sIdent, ok := rhsExprs[3].(*ast.Ident)
if !ok {
t.Fatalf("rhs[3] type = %T, want *ast.Ident", rhsExprs[3])
}
msIdent, ok := rhsExprs[4].(*ast.Ident)
if !ok {
t.Fatalf("rhs[4] type = %T, want *ast.Ident", rhsExprs[4])
}

if !IsByteSlice(pass, bIdent) {
t.Fatal("IsByteSlice(b) = false, want true")
}
if IsByteSlice(pass, sIdent) {
t.Fatal("IsByteSlice(s) = true, want false")
}

if !IsByteSliceConversion(pass, byteConv) {
t.Fatal("IsByteSliceConversion([]byte(s)) = false, want true")
}
if IsByteSliceConversion(pass, gCall) {
t.Fatal("IsByteSliceConversion(g(s)) = true, want false")
}

if !IsStringType(pass, sIdent) {
t.Fatal("IsStringType(s) = false, want true")
}
if !IsStringType(pass, msIdent) {
t.Fatal("IsStringType(ms) = false, want true for named string")
}
if IsStringType(pass, bIdent) {
t.Fatal("IsStringType(b) = true, want false")
}
}
37 changes: 2 additions & 35 deletions pkg/linters/writebytestring/writebytestring.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -98,11 +98,11 @@ func run(pass *analysis.Pass) (any, error) {
if !ok {
return
}
if !isByteSliceConversion(pass, conv) {
if !astutil.IsByteSliceConversion(pass, conv) {
return
}
strArg := conv.Args[0]
if !isStringType(pass, strArg) {
if !astutil.IsStringType(pass, strArg) {
return
}

Expand Down Expand Up @@ -146,39 +146,6 @@ func run(pass *analysis.Pass) (any, error) {
return nil, nil
}

// isByteSliceConversion reports whether conv is a []byte or []uint8 conversion expression.
func isByteSliceConversion(pass *analysis.Pass, conv *ast.CallExpr) bool {
funTypeInfo, ok := pass.TypesInfo.Types[conv.Fun]
if !ok || !funTypeInfo.IsType() {
return false
}
return isByteSlice(pass, conv)
}

// isByteSlice reports whether expr has type []byte ([]uint8).
func isByteSlice(pass *analysis.Pass, expr ast.Expr) bool {
t := pass.TypesInfo.TypeOf(expr)
if t == nil {
return false
}
sl, ok := t.Underlying().(*types.Slice)
if !ok {
return false
}
elem, ok := sl.Elem().(*types.Basic)
return ok && elem.Kind() == types.Byte
}

// isStringType reports whether expr has type string (or named string type).
func isStringType(pass *analysis.Pass, expr ast.Expr) bool {
t := pass.TypesInfo.TypeOf(expr)
if t == nil {
return false
}
basic, ok := t.Underlying().(*types.Basic)
return ok && basic.Kind() == types.String
}

// isExactString reports whether t is the predeclared string type, not a named
// type whose underlying type is string. io.WriteString(w Writer, s string)
// requires a predeclared string; named string types need an explicit string(...)
Expand Down