2 files changed, 210 insertions, 0 deletions
diff --git a/vendor/github.com/ashanbrown/makezero/LICENSE b/vendor/github.com/ashanbrown/makezero/LICENSE
new file mode 100644
index 000000000..dc1d47ad5
--- /dev/null
+++ b/vendor/github.com/ashanbrown/makezero/LICENSE
@@ -0,0 +1,13 @@
+Copyright 2019 Andrew Shannon Brown
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
diff --git a/vendor/github.com/ashanbrown/makezero/makezero/makezero.go b/vendor/github.com/ashanbrown/makezero/makezero/makezero.go
new file mode 100644
index 000000000..6bf230b12
--- /dev/null
+++ b/vendor/github.com/ashanbrown/makezero/makezero/makezero.go
@@ -0,0 +1,197 @@
+// makezero provides a linter for appends to slices initialized with non-zero length.
+package makezero
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/printer"
+	"go/token"
+	"go/types"
+	"log"
+	"regexp"
+)
+
+type Issue interface {
+	Details() string
+	Position() token.Position
+	String() string
+}
+
+type AppendIssue struct {
+	name     string
+	position token.Position
+}
+
+func (a AppendIssue) Details() string {
+	return fmt.Sprintf("append to slice `%s` with non-zero initialized length", a.name)
+}
+
+func (a AppendIssue) Position() token.Position {
+	return a.position
+}
+
+func (a AppendIssue) String() string { return toString(a) }
+
+type MustHaveNonZeroInitLenIssue struct {
+	name     string
+	position token.Position
+}
+
+func (i MustHaveNonZeroInitLenIssue) Details() string {
+	return fmt.Sprintf("slice `%s` does not have non-zero initial length", i.name)
+}
+
+func (i MustHaveNonZeroInitLenIssue) Position() token.Position {
+	return i.position
+}
+
+func (i MustHaveNonZeroInitLenIssue) String() string { return toString(i) }
+
+func toString(i Issue) string {
+	return fmt.Sprintf("%s at %s", i.Details(), i.Position())
+}
+
+type visitor struct {
+	initLenMustBeZero bool
+
+	comments []*ast.CommentGroup // comments to apply during this visit
+	info     *types.Info
+
+	nonZeroLengthSliceDecls map[interface{}]struct{}
+	fset                    *token.FileSet
+	issues                  []Issue
+}
+
+type Linter struct {
+	initLenMustBeZero bool
+}
+
+func NewLinter(initialLengthMustBeZero bool) *Linter {
+	return &Linter{
+		initLenMustBeZero: initialLengthMustBeZero,
+	}
+}
+
+func (l Linter) Run(fset *token.FileSet, info *types.Info, nodes ...ast.Node) ([]Issue, error) {
+	var issues []Issue // nolint:prealloc // don't know how many there will be
+	for _, node := range nodes {
+		var comments []*ast.CommentGroup
+		if file, ok := node.(*ast.File); ok {
+			comments = file.Comments
+		}
+		visitor := visitor{
+			nonZeroLengthSliceDecls: make(map[interface{}]struct{}),
+			initLenMustBeZero:       l.initLenMustBeZero,
+			info:                    info,
+			fset:                    fset,
+			comments:                comments,
+		}
+		ast.Walk(&visitor, node)
+		issues = append(issues, visitor.issues...)
+	}
+	return issues, nil
+}
+
+func (v *visitor) Visit(node ast.Node) ast.Visitor {
+	switch node := node.(type) {
+	case *ast.CallExpr:
+		fun, ok := node.Fun.(*ast.Ident)
+		if !ok || fun.Name != "append" {
+			break
+		}
+		if sliceIdent, ok := node.Args[0].(*ast.Ident); ok &&
+			v.hasNonZeroInitialLength(sliceIdent) &&
+			!v.hasNoLintOnSameLine(fun) {
+			v.issues = append(v.issues, AppendIssue{name: sliceIdent.Name, position: v.fset.Position(fun.Pos())})
+		}
+	case *ast.AssignStmt:
+		for i, right := range node.Rhs {
+			if right, ok := right.(*ast.CallExpr); ok {
+				fun, ok := right.Fun.(*ast.Ident)
+				if !ok || fun.Name != "make" {
+					continue
+				}
+				left := node.Lhs[i]
+				if len(right.Args) == 2 {
+					// ignore if not a slice or it has explicit zero length
+					if !v.isSlice(right.Args[0]) {
+						break
+					} else if lit, ok := right.Args[1].(*ast.BasicLit); ok && lit.Kind == token.INT && lit.Value == "0" {
+						break
+					}
+					if v.initLenMustBeZero && !v.hasNoLintOnSameLine(fun) {
+						v.issues = append(v.issues, MustHaveNonZeroInitLenIssue{
+							name:     v.textFor(left),
+							position: v.fset.Position(node.Pos()),
+						})
+					}
+					v.recordNonZeroLengthSlices(left)
+				}
+			}
+		}
+	}
+	return v
+}
+
+func (v *visitor) textFor(node ast.Node) string {
+	typeBuf := new(bytes.Buffer)
+	if err := printer.Fprint(typeBuf, v.fset, node); err != nil {
+		log.Fatalf("ERROR: unable to print type: %s", err)
+	}
+	return typeBuf.String()
+}
+
+func (v *visitor) hasNonZeroInitialLength(ident *ast.Ident) bool {
+	if ident.Obj == nil {
+		log.Printf("WARNING: could not determine with %q at %s is a slice (missing object type)",
+			ident.Name, v.fset.Position(ident.Pos()).String())
+		return false
+	}
+	_, exists := v.nonZeroLengthSliceDecls[ident.Obj.Decl]
+	return exists
+}
+
+func (v *visitor) recordNonZeroLengthSlices(node ast.Node) {
+	ident, ok := node.(*ast.Ident)
+	if !ok {
+		return
+	}
+	v.nonZeroLengthSliceDecls[ident.Obj.Decl] = struct{}{}
+}
+
+func (v *visitor) isSlice(node ast.Node) bool {
+	// determine type if this is a user-defined type
+	if ident, ok := node.(*ast.Ident); ok {
+		obj := ident.Obj
+		if obj == nil {
+			if v.info != nil {
+				_, ok := v.info.ObjectOf(ident).Type().(*types.Slice)
+				return ok
+			}
+			return false
+		}
+		spec, ok := obj.Decl.(*ast.TypeSpec)
+		if !ok {
+			return false
+		}
+		node = spec.Type
+	}
+
+	if node, ok := node.(*ast.ArrayType); ok {
+		return node.Len == nil // only slices have zero length
+	}
+	return false
+}
+
+func (v *visitor) hasNoLintOnSameLine(node ast.Node) bool {
+	var nolint = regexp.MustCompile(`^\s*nozero\b`)
+	nodePos := v.fset.Position(node.Pos())
+	for _, c := range v.comments {
+		commentPos := v.fset.Position(c.Pos())
+		if commentPos.Line == nodePos.Line && nolint.MatchString(c.Text()) {
+			return true
+		}
+	}
+	return false
+}