Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa4019/sa4019.go

@@ -0,0 +1,82 @@
+package sa4019
+
+import (
+	"fmt"
+	"go/ast"
+	"sort"
+	"strings"
+
+	"honnef.co/go/tools/analysis/facts/generated"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+	"honnef.co/go/tools/go/ast/astutil"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA4019",
+		Run:      run,
+		Requires: []*analysis.Analyzer{generated.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `Multiple, identical build constraints in the same file`,
+		Since:    "2017.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+func buildTagsIdentical(s1, s2 []string) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	s1s := make([]string, len(s1))
+	copy(s1s, s1)
+	sort.Strings(s1s)
+	s2s := make([]string, len(s2))
+	copy(s2s, s2)
+	sort.Strings(s2s)
+	for i, s := range s1s {
+		if s != s2s[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func run(pass *analysis.Pass) (any, error) {
+	for _, f := range pass.Files {
+		constraints := buildTags(f)
+		for i, constraint1 := range constraints {
+			for j, constraint2 := range constraints {
+				if i >= j {
+					continue
+				}
+				if buildTagsIdentical(constraint1, constraint2) {
+					msg := fmt.Sprintf("identical build constraints %q and %q",
+						strings.Join(constraint1, " "),
+						strings.Join(constraint2, " "))
+					report.Report(pass, f, msg, report.FilterGenerated(), report.ShortRange())
+				}
+			}
+		}
+	}
+	return nil, nil
+}
+
+func buildTags(f *ast.File) [][]string {
+	var out [][]string
+	for line := range strings.SplitSeq(astutil.Preamble(f), "\n") {
+		if !strings.HasPrefix(line, "+build ") {
+			continue
+		}
+		line = strings.TrimSpace(strings.TrimPrefix(line, "+build "))
+		fields := strings.Fields(line)
+		out = append(out, fields)
+	}
+	return out
+}