fatcontext/pkg/analyzer/analyzer.go

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2024-03-27 19:24:38 +01:00
package analyzer
import (
"bytes"
"errors"
"fmt"
"go/ast"
"go/printer"
"go/token"
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/passes/inspect"
"golang.org/x/tools/go/ast/inspector"
)
var Analyzer = &analysis.Analyzer{
Name: "foreshadow",
Doc: "Enforces context shadowing inside loops.",
Run: run,
Requires: []*analysis.Analyzer{inspect.Analyzer},
}
var errUnknown = errors.New("unknown node type")
func run(pass *analysis.Pass) (interface{}, error) {
inspctr := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
nodeFilter := []ast.Node{
(*ast.ForStmt)(nil),
(*ast.RangeStmt)(nil),
}
inspctr.Preorder(nodeFilter, func(node ast.Node) {
body, err := getBody(node)
if err != nil {
return
}
for _, stmt := range body.List {
assignStmt, ok := stmt.(*ast.AssignStmt)
if !ok {
continue
}
t := pass.TypesInfo.TypeOf(assignStmt.Lhs[0])
if t == nil {
continue
}
if t.String() != "context.Context" {
continue
}
if assignStmt.Tok == token.DEFINE {
break
}
assignStmt.Tok = token.DEFINE
suggested := render(pass.Fset, assignStmt)
pass.Report(analysis.Diagnostic{
Pos: assignStmt.Pos(),
Message: "context not shadowed in loop",
SuggestedFixes: []analysis.SuggestedFix{
{
Message: fmt.Sprintf("replace `=` with `:=`"),
TextEdits: []analysis.TextEdit{
{
Pos: assignStmt.Pos(),
End: assignStmt.End(),
NewText: []byte(suggested),
},
},
},
},
})
break
}
})
return nil, nil
}
func getBody(node ast.Node) (*ast.BlockStmt, error) {
forStmt, ok := node.(*ast.ForStmt)
if ok {
return forStmt.Body, nil
}
rangeStmt, ok := node.(*ast.RangeStmt)
if ok {
return rangeStmt.Body, nil
}
return nil, errUnknown
}
// render returns the pretty-print of the given node
func render(fset *token.FileSet, x interface{}) string {
var buf bytes.Buffer
if err := printer.Fprint(&buf, fset, x); err != nil {
panic(err)
}
return buf.String()
}