1 files changed, 137 insertions, 0 deletions
diff --git a/vendor/github.com/mgechev/revive/rule/defer.go b/vendor/github.com/mgechev/revive/rule/defer.go
new file mode 100644
index 0000000000..2ec7ef47c2
--- /dev/null
+++ b/vendor/github.com/mgechev/revive/rule/defer.go
@@ -0,0 +1,137 @@
+package rule
+
+import (
+	"fmt"
+	"go/ast"
+
+	"github.com/mgechev/revive/lint"
+)
+
+// DeferRule lints unused params in functions.
+type DeferRule struct{}
+
+// Apply applies the rule to given file.
+func (r *DeferRule) Apply(file *lint.File, arguments lint.Arguments) []lint.Failure {
+	allow := r.allowFromArgs(arguments)
+
+	var failures []lint.Failure
+	onFailure := func(failure lint.Failure) {
+		failures = append(failures, failure)
+	}
+
+	w := lintDeferRule{onFailure: onFailure, allow: allow}
+
+	ast.Walk(w, file.AST)
+
+	return failures
+}
+
+// Name returns the rule name.
+func (r *DeferRule) Name() string {
+	return "defer"
+}
+
+func (r *DeferRule) allowFromArgs(args lint.Arguments) map[string]bool {
+	if len(args) < 1 {
+		allow := map[string]bool{
+			"loop":        true,
+			"call-chain":  true,
+			"method-call": true,
+			"return":      true,
+			"recover":     true,
+		}
+
+		return allow
+	}
+
+	aa, ok := args[0].([]interface{})
+	if !ok {
+		panic(fmt.Sprintf("Invalid argument '%v' for 'defer' rule. Expecting []string, got %T", args[0], args[0]))
+	}
+
+	allow := make(map[string]bool, len(aa))
+	for _, subcase := range aa {
+		sc, ok := subcase.(string)
+		if !ok {
+			panic(fmt.Sprintf("Invalid argument '%v' for 'defer' rule. Expecting string, got %T", subcase, subcase))
+		}
+		allow[sc] = true
+	}
+
+	return allow
+}
+
+type lintDeferRule struct {
+	onFailure  func(lint.Failure)
+	inALoop    bool
+	inADefer   bool
+	inAFuncLit bool
+	allow      map[string]bool
+}
+
+func (w lintDeferRule) Visit(node ast.Node) ast.Visitor {
+	switch n := node.(type) {
+	case *ast.ForStmt:
+		w.visitSubtree(n.Body, w.inADefer, true, w.inAFuncLit)
+		return nil
+	case *ast.RangeStmt:
+		w.visitSubtree(n.Body, w.inADefer, true, w.inAFuncLit)
+		return nil
+	case *ast.FuncLit:
+		w.visitSubtree(n.Body, w.inADefer, false, true)
+		return nil
+	case *ast.ReturnStmt:
+		if len(n.Results) != 0 && w.inADefer && w.inAFuncLit {
+			w.newFailure("return in a defer function has no effect", n, 1.0, "logic", "return")
+		}
+	case *ast.CallExpr:
+		if isIdent(n.Fun, "recover") && !w.inADefer {
+			// confidence is not 1 because recover can be in a function that is deferred elsewhere
+			w.newFailure("recover must be called inside a deferred function", n, 0.8, "logic", "recover")
+		}
+	case *ast.DeferStmt:
+		w.visitSubtree(n.Call.Fun, true, false, false)
+
+		if w.inALoop {
+			w.newFailure("prefer not to defer inside loops", n, 1.0, "bad practice", "loop")
+		}
+
+		switch fn := n.Call.Fun.(type) {
+		case *ast.CallExpr:
+			w.newFailure("prefer not to defer chains of function calls", fn, 1.0, "bad practice", "call-chain")
+		case *ast.SelectorExpr:
+			if id, ok := fn.X.(*ast.Ident); ok {
+				isMethodCall := id != nil && id.Obj != nil && id.Obj.Kind == ast.Typ
+				if isMethodCall {
+					w.newFailure("be careful when deferring calls to methods without pointer receiver", fn, 0.8, "bad practice", "method-call")
+				}
+			}
+		}
+		return nil
+	}
+
+	return w
+}
+
+func (w lintDeferRule) visitSubtree(n ast.Node, inADefer, inALoop, inAFuncLit bool) {
+	nw := &lintDeferRule{
+		onFailure:  w.onFailure,
+		inADefer:   inADefer,
+		inALoop:    inALoop,
+		inAFuncLit: inAFuncLit,
+		allow:      w.allow}
+	ast.Walk(nw, n)
+}
+
+func (w lintDeferRule) newFailure(msg string, node ast.Node, confidence float64, cat string, subcase string) {
+	if !w.allow[subcase] {
+		return
+	}
+
+	w.onFailure(lint.Failure{
+		Confidence: confidence,
+		Node:       node,
+		Category:   cat,
+		Failure:    msg,
+	})
+}