Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa4017/sa4017.go

@@ -0,0 +1,86 @@
+package sa4017
+
+import (
+	"fmt"
+	"go/types"
+
+	"honnef.co/go/tools/analysis/code"
+	"honnef.co/go/tools/analysis/facts/purity"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+	"honnef.co/go/tools/go/ir"
+	"honnef.co/go/tools/go/ir/irutil"
+	"honnef.co/go/tools/go/types/typeutil"
+	"honnef.co/go/tools/internal/passes/buildir"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA4017",
+		Run:      run,
+		Requires: []*analysis.Analyzer{buildir.Analyzer, purity.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `Discarding the return values of a function without side effects, making the call pointless`,
+		Since:    "2017.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAll,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+func run(pass *analysis.Pass) (any, error) {
+	pure := pass.ResultOf[purity.Analyzer].(purity.Result)
+
+fnLoop:
+	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
+		if code.IsInTest(pass, fn) {
+			params := fn.Signature.Params()
+			for param := range params.Variables() {
+				if typeutil.IsPointerToTypeWithName(param.Type(), "testing.B") {
+					// Ignore discarded pure functions in code related
+					// to benchmarks. Instead of matching BenchmarkFoo
+					// functions, we match any function accepting a
+					// *testing.B. Benchmarks sometimes call generic
+					// functions for doing the actual work, and
+					// checking for the parameter is a lot easier and
+					// faster than analyzing call trees.
+					continue fnLoop
+				}
+			}
+		}
+
+		for _, b := range fn.Blocks {
+			for _, ins := range b.Instrs {
+				ins, ok := ins.(*ir.Call)
+				if !ok {
+					continue
+				}
+				refs := ins.Referrers()
+				if refs == nil || len(irutil.FilterDebug(*refs)) > 0 {
+					continue
+				}
+
+				callee := ins.Common().StaticCallee()
+				if callee == nil {
+					continue
+				}
+				if callee.Object() == nil {
+					// TODO(dh): support anonymous functions
+					continue
+				}
+				if _, ok := pure[callee.Object().(*types.Func)]; ok {
+					if pass.Pkg.Path() == "fmt_test" && callee.Object().(*types.Func).FullName() == "fmt.Sprintf" {
+						// special case for benchmarks in the fmt package
+						continue
+					}
+					report.Report(pass, ins, fmt.Sprintf("%s doesn't have side effects and its return value is ignored", callee.Object().Name()))
+				}
+			}
+		}
+	}
+	return nil, nil
+}