120 lines
2.6 KiB
Go
120 lines
2.6 KiB
Go
package rule
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import (
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"fmt"
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"go/ast"
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"go/types"
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"github.com/mgechev/revive/lint"
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)
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// UnhandledErrorRule lints given else constructs.
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type UnhandledErrorRule struct{}
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type ignoreListType map[string]struct{}
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// Apply applies the rule to given file.
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func (r *UnhandledErrorRule) Apply(file *lint.File, args lint.Arguments) []lint.Failure {
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var failures []lint.Failure
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ignoreList := make(ignoreListType, len(args))
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for _, arg := range args {
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argStr, ok := arg.(string)
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if !ok {
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panic(fmt.Sprintf("Invalid argument to the unhandled-error rule. Expecting a string, got %T", arg))
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}
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ignoreList[argStr] = struct{}{}
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}
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walker := &lintUnhandledErrors{
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ignoreList: ignoreList,
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pkg: file.Pkg,
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onFailure: func(failure lint.Failure) {
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failures = append(failures, failure)
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},
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}
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file.Pkg.TypeCheck()
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ast.Walk(walker, file.AST)
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return failures
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}
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// Name returns the rule name.
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func (r *UnhandledErrorRule) Name() string {
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return "unhandled-error"
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}
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type lintUnhandledErrors struct {
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ignoreList ignoreListType
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pkg *lint.Package
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onFailure func(lint.Failure)
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}
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// Visit looks for statements that are function calls.
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// If the called function returns a value of type error a failure will be created.
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func (w *lintUnhandledErrors) Visit(node ast.Node) ast.Visitor {
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switch n := node.(type) {
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case *ast.ExprStmt:
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fCall, ok := n.X.(*ast.CallExpr)
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if !ok {
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return nil // not a function call
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}
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funcType := w.pkg.TypeOf(fCall)
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if funcType == nil {
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return nil // skip, type info not available
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}
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switch t := funcType.(type) {
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case *types.Named:
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if !w.isTypeError(t) {
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return nil // func call does not return an error
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}
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w.addFailure(fCall)
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default:
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retTypes, ok := funcType.Underlying().(*types.Tuple)
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if !ok {
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return nil // skip, unable to retrieve return type of the called function
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}
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if w.returnsAnError(retTypes) {
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w.addFailure(fCall)
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}
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}
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}
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return w
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}
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func (w *lintUnhandledErrors) addFailure(n *ast.CallExpr) {
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funcName := gofmt(n.Fun)
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if _, mustIgnore := w.ignoreList[funcName]; mustIgnore {
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return
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}
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w.onFailure(lint.Failure{
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Category: "bad practice",
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Confidence: 1,
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Node: n,
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Failure: fmt.Sprintf("Unhandled error in call to function %v", funcName),
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})
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}
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func (*lintUnhandledErrors) isTypeError(t *types.Named) bool {
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const errorTypeName = "_.error"
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return t.Obj().Id() == errorTypeName
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}
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func (w *lintUnhandledErrors) returnsAnError(tt *types.Tuple) bool {
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for i := 0; i < tt.Len(); i++ {
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nt, ok := tt.At(i).Type().(*types.Named)
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if ok && w.isTypeError(nt) {
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return true
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}
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}
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return false
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}
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