Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa9001/sa9001.go

@@ -0,0 +1,69 @@
+package sa9001
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"honnef.co/go/tools/analysis/code"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+	"honnef.co/go/tools/go/types/typeutil"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA9001",
+		Run:      run,
+		Requires: []*analysis.Analyzer{inspect.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `Defers in range loops may not run when you expect them to`,
+		Since:    "2017.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+func run(pass *analysis.Pass) (any, error) {
+	fn := func(node ast.Node) {
+		loop := node.(*ast.RangeStmt)
+		typ := pass.TypesInfo.TypeOf(loop.X)
+		_, ok := typeutil.CoreType(typ).(*types.Chan)
+		if !ok {
+			return
+		}
+
+		stmts := []*ast.DeferStmt{}
+		exits := false
+		fn2 := func(node ast.Node) bool {
+			switch stmt := node.(type) {
+			case *ast.DeferStmt:
+				stmts = append(stmts, stmt)
+			case *ast.FuncLit:
+				// Don't look into function bodies
+				return false
+			case *ast.ReturnStmt:
+				exits = true
+			case *ast.BranchStmt:
+				exits = node.(*ast.BranchStmt).Tok == token.BREAK
+			}
+			return true
+		}
+		ast.Inspect(loop.Body, fn2)
+
+		if exits {
+			return
+		}
+		for _, stmt := range stmts {
+			report.Report(pass, stmt, "defers in this range loop won't run unless the channel gets closed")
+		}
+	}
+	code.Preorder(pass, fn, (*ast.RangeStmt)(nil))
+	return nil, nil
+}