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