Add staticcheck tool

vendor/honnef.co/go/tools/simple/s1020/s1020.go

@@ -0,0 +1,74 @@
+package s1020
+
+import (
+	"fmt"
+	"go/ast"
+	"go/types"
+
+	"honnef.co/go/tools/analysis/code"
+	"honnef.co/go/tools/analysis/facts/generated"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+	"honnef.co/go/tools/pattern"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "S1020",
+		Run:      run,
+		Requires: append([]*analysis.Analyzer{generated.Analyzer}, code.RequiredAnalyzers...),
+	},
+	Doc: &lint.RawDocumentation{
+		Title:   `Omit redundant nil check in type assertion`,
+		Before:  `if _, ok := i.(T); ok && i != nil {}`,
+		After:   `if _, ok := i.(T); ok {}`,
+		Since:   "2017.1",
+		MergeIf: lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+var (
+	checkAssertNotNilFn1Q = pattern.MustParse(`
+		(IfStmt
+			(AssignStmt [(Ident "_") ok@(Object _)] _ [(TypeAssertExpr assert@(Object _) _)])
+			(Or
+				(BinaryExpr ok "&&" (BinaryExpr assert "!=" (Builtin "nil")))
+				(BinaryExpr (BinaryExpr assert "!=" (Builtin "nil")) "&&" ok))
+			_
+			_)`)
+	checkAssertNotNilFn2Q = pattern.MustParse(`
+		(IfStmt
+			nil
+			(BinaryExpr lhs@(Object _) "!=" (Builtin "nil"))
+			[
+				ifstmt@(IfStmt
+					(AssignStmt [(Ident "_") ok@(Object _)] _ [(TypeAssertExpr lhs _)])
+					ok
+					_
+					nil)
+			]
+			nil)`)
+)
+
+func run(pass *analysis.Pass) (any, error) {
+	for node, m := range code.Matches(pass, checkAssertNotNilFn1Q) {
+		assert := m.State["assert"].(types.Object)
+		assign := m.State["ok"].(types.Object)
+		report.Report(pass, node, fmt.Sprintf("when %s is true, %s can't be nil", assign.Name(), assert.Name()),
+			report.ShortRange(),
+			report.FilterGenerated())
+	}
+	for _, m := range code.Matches(pass, checkAssertNotNilFn2Q) {
+		ifstmt := m.State["ifstmt"].(*ast.IfStmt)
+		lhs := m.State["lhs"].(types.Object)
+		assignIdent := m.State["ok"].(types.Object)
+		report.Report(pass, ifstmt, fmt.Sprintf("when %s is true, %s can't be nil", assignIdent.Name(), lhs.Name()),
+			report.ShortRange(),
+			report.FilterGenerated())
+	}
+	return nil, nil
+}