Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa1012/sa1012.go

@@ -0,0 +1,65 @@
+package sa1012
+
+import (
+	"go/ast"
+	"go/types"
+
+	"honnef.co/go/tools/analysis/code"
+	"honnef.co/go/tools/analysis/edit"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+	"honnef.co/go/tools/go/types/typeutil"
+	"honnef.co/go/tools/pattern"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA1012",
+		Run:      run,
+		Requires: code.RequiredAnalyzers,
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `A nil \'context.Context\' is being passed to a function, consider using \'context.TODO\' instead`,
+		Since:    "2017.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+var checkNilContextQ = pattern.MustParse(`(CallExpr fun@(Symbol _) (Builtin "nil"):_)`)
+
+func run(pass *analysis.Pass) (any, error) {
+	todo := &ast.CallExpr{
+		Fun: edit.Selector("context", "TODO"),
+	}
+	bg := &ast.CallExpr{
+		Fun: edit.Selector("context", "Background"),
+	}
+	for node, m := range code.Matches(pass, checkNilContextQ) {
+		call := node.(*ast.CallExpr)
+		fun, ok := m.State["fun"].(*types.Func)
+		if !ok {
+			// it might also be a builtin
+			continue
+		}
+		sig := fun.Type().(*types.Signature)
+		if sig.Params().Len() == 0 {
+			// Our CallExpr might've matched a method expression, like
+			// (*T).Foo(nil) – here, nil isn't the first argument of
+			// the Foo method, but the method receiver.
+			continue
+		}
+		if !typeutil.IsTypeWithName(sig.Params().At(0).Type(), "context.Context") {
+			continue
+		}
+		report.Report(pass, call.Args[0],
+			"do not pass a nil Context, even if a function permits it; pass context.TODO if you are unsure about which Context to use", report.Fixes(
+				edit.Fix("Use context.TODO", edit.ReplaceWithNode(pass.Fset, call.Args[0], todo)),
+				edit.Fix("Use context.Background", edit.ReplaceWithNode(pass.Fset, call.Args[0], bg))))
+	}
+	return nil, nil
+}