Add staticcheck tool

vendor/honnef.co/go/tools/simple/s1016/s1016.go

@@ -0,0 +1,193 @@
+package s1016
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"go/version"
+
+	"honnef.co/go/tools/analysis/code"
+	"honnef.co/go/tools/analysis/edit"
+	"honnef.co/go/tools/analysis/facts/generated"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "S1016",
+		Run:      run,
+		Requires: []*analysis.Analyzer{inspect.Analyzer, generated.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title: `Use a type conversion instead of manually copying struct fields`,
+		Text: `Two struct types with identical fields can be converted between each
+other. In older versions of Go, the fields had to have identical
+struct tags. Since Go 1.8, however, struct tags are ignored during
+conversions. It is thus not necessary to manually copy every field
+individually.`,
+		Before: `
+var x T1
+y := T2{
+    Field1: x.Field1,
+    Field2: x.Field2,
+}`,
+		After: `
+var x T1
+y := T2(x)`,
+		Since:   "2017.1",
+		MergeIf: lint.MergeIfAll,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+func run(pass *analysis.Pass) (any, error) {
+	// TODO(dh): support conversions between type parameters
+	fn := func(c inspector.Cursor) {
+		node := c.Node()
+		if unary, ok := c.Parent().Node().(*ast.UnaryExpr); ok && unary.Op == token.AND {
+			// Do not suggest type conversion between pointers
+			return
+		}
+
+		lit := node.(*ast.CompositeLit)
+		var typ1 types.Type
+		var named1 *types.Named
+		switch typ := pass.TypesInfo.TypeOf(lit.Type).(type) {
+		case *types.Named:
+			typ1 = typ
+			named1 = typ
+		case *types.Alias:
+			ua := types.Unalias(typ)
+			if n, ok := ua.(*types.Named); ok {
+				typ1 = typ
+				named1 = n
+			}
+		}
+		if typ1 == nil {
+			return
+		}
+		s1, ok := typ1.Underlying().(*types.Struct)
+		if !ok {
+			return
+		}
+
+		var typ2 types.Type
+		var named2 *types.Named
+		var ident *ast.Ident
+		getSelType := func(expr ast.Expr) (types.Type, *ast.Ident, bool) {
+			sel, ok := expr.(*ast.SelectorExpr)
+			if !ok {
+				return nil, nil, false
+			}
+			ident, ok := sel.X.(*ast.Ident)
+			if !ok {
+				return nil, nil, false
+			}
+			typ := pass.TypesInfo.TypeOf(sel.X)
+			return typ, ident, typ != nil
+		}
+		if len(lit.Elts) == 0 {
+			return
+		}
+		if s1.NumFields() != len(lit.Elts) {
+			return
+		}
+		for i, elt := range lit.Elts {
+			var t types.Type
+			var id *ast.Ident
+			var ok bool
+			switch elt := elt.(type) {
+			case *ast.SelectorExpr:
+				t, id, ok = getSelType(elt)
+				if !ok {
+					return
+				}
+				if i >= s1.NumFields() || s1.Field(i).Name() != elt.Sel.Name {
+					return
+				}
+			case *ast.KeyValueExpr:
+				var sel *ast.SelectorExpr
+				sel, ok = elt.Value.(*ast.SelectorExpr)
+				if !ok {
+					return
+				}
+
+				if elt.Key.(*ast.Ident).Name != sel.Sel.Name {
+					return
+				}
+				t, id, ok = getSelType(elt.Value)
+			}
+			if !ok {
+				return
+			}
+			// All fields must be initialized from the same object
+			if ident != nil && pass.TypesInfo.ObjectOf(ident) != pass.TypesInfo.ObjectOf(id) {
+				return
+			}
+			switch t := t.(type) {
+			case *types.Named:
+				typ2 = t
+				named2 = t
+			case *types.Alias:
+				if n, ok := types.Unalias(t).(*types.Named); ok {
+					typ2 = t
+					named2 = n
+				}
+			}
+			if typ2 == nil {
+				return
+			}
+			ident = id
+		}
+
+		if typ2 == nil {
+			return
+		}
+
+		if named1.Obj().Pkg() != named2.Obj().Pkg() {
+			// Do not suggest type conversions between different
+			// packages. Types in different packages might only match
+			// by coincidence. Furthermore, if the dependency ever
+			// adds more fields to its type, it could break the code
+			// that relies on the type conversion to work.
+			return
+		}
+
+		s2, ok := typ2.Underlying().(*types.Struct)
+		if !ok {
+			return
+		}
+		if typ1 == typ2 {
+			return
+		}
+		if version.Compare(code.LanguageVersion(pass, node), "go1.8") >= 0 {
+			if !types.IdenticalIgnoreTags(s1, s2) {
+				return
+			}
+		} else {
+			if !types.Identical(s1, s2) {
+				return
+			}
+		}
+
+		r := &ast.CallExpr{
+			Fun:  lit.Type,
+			Args: []ast.Expr{ident},
+		}
+		report.Report(pass, node,
+			fmt.Sprintf("should convert %s (type %s) to %s instead of using struct literal", ident.Name, types.TypeString(typ2, types.RelativeTo(pass.Pkg)), types.TypeString(typ1, types.RelativeTo(pass.Pkg))),
+			report.FilterGenerated(),
+			report.Fixes(edit.Fix("Use type conversion", edit.ReplaceWithNode(pass.Fset, node, r))))
+	}
+	for c := range code.Cursor(pass).Preorder((*ast.CompositeLit)(nil)) {
+		fn(c)
+	}
+	return nil, nil
+}