Add staticcheck tool

vendor/honnef.co/go/tools/stylecheck/st1018/st1018.go

@@ -0,0 +1,157 @@
+package st1018
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"strconv"
+	"unicode"
+	"unicode/utf8"
+
+	"honnef.co/go/tools/analysis/code"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "ST1018",
+		Run:      run,
+		Requires: []*analysis.Analyzer{inspect.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title:   `Avoid zero-width and control characters in string literals`,
+		Since:   "2019.2",
+		MergeIf: lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+func run(pass *analysis.Pass) (any, error) {
+	fn := func(node ast.Node) {
+		lit := node.(*ast.BasicLit)
+		if lit.Kind != token.STRING {
+			return
+		}
+
+		type invalid struct {
+			r   rune
+			off int
+		}
+		var invalids []invalid
+		hasFormat := false
+		hasControl := false
+		prev := rune(-1)
+		const zwj = '\u200d'
+		for off, r := range lit.Value {
+			if unicode.Is(unicode.Cf, r) {
+				if r >= '\U000e0020' && r <= '\U000e007f' {
+					// These are used for spelling out country codes for flag emoji
+				} else if unicode.Is(unicode.Variation_Selector, r) {
+					// Always allow variation selectors
+				} else if r == zwj && (unicode.Is(unicode.S, prev) || unicode.Is(unicode.Variation_Selector, prev)) {
+					// Allow zero-width joiner in emoji, including those that use variation selectors.
+
+					// Technically some foreign scripts make valid use of zero-width joiners, too, but for now we'll err
+					// on the side of flagging all non-emoji uses of ZWJ.
+				} else {
+					switch r {
+					case '\u0600', '\u0601', '\u0602', '\u0603', '\u0604', '\u0605', '\u0890', '\u0891', '\u08e2':
+						// Arabic characters that are not actually invisible. If anyone knows why these are in the
+						// Other, Format category please let me know.
+					case '\u061c', '\u202A', '\u202B', '\u202D', '\u202E', '\u2066', '\u2067', '\u2068', '\u202C', '\u2069':
+						// Bidirectional formatting characters. At best they will render confusingly, at worst they're used
+						// to cause confusion.
+						fallthrough
+					default:
+						invalids = append(invalids, invalid{r, off})
+						hasFormat = true
+					}
+				}
+			} else if unicode.Is(unicode.Cc, r) && r != '\n' && r != '\t' && r != '\r' {
+				invalids = append(invalids, invalid{r, off})
+				hasControl = true
+			}
+			prev = r
+		}
+
+		switch len(invalids) {
+		case 0:
+			return
+		case 1:
+			var kind string
+			if hasFormat {
+				kind = "format"
+			} else if hasControl {
+				kind = "control"
+			} else {
+				panic("unreachable")
+			}
+
+			r := invalids[0]
+			msg := fmt.Sprintf("string literal contains the Unicode %s character %U, consider using the %q escape sequence instead", kind, r.r, r.r)
+
+			replacement := strconv.QuoteRune(r.r)
+			replacement = replacement[1 : len(replacement)-1]
+			edit := analysis.SuggestedFix{
+				Message: fmt.Sprintf("replace %s character %U with %q", kind, r.r, r.r),
+				TextEdits: []analysis.TextEdit{{
+					Pos:     lit.Pos() + token.Pos(r.off),
+					End:     lit.Pos() + token.Pos(r.off) + token.Pos(utf8.RuneLen(r.r)),
+					NewText: []byte(replacement),
+				}},
+			}
+			delete := analysis.SuggestedFix{
+				Message: fmt.Sprintf("delete %s character %U", kind, r.r),
+				TextEdits: []analysis.TextEdit{{
+					Pos: lit.Pos() + token.Pos(r.off),
+					End: lit.Pos() + token.Pos(r.off) + token.Pos(utf8.RuneLen(r.r)),
+				}},
+			}
+			report.Report(pass, lit, msg, report.Fixes(edit, delete))
+		default:
+			var kind string
+			if hasFormat && hasControl {
+				kind = "format and control"
+			} else if hasFormat {
+				kind = "format"
+			} else if hasControl {
+				kind = "control"
+			} else {
+				panic("unreachable")
+			}
+
+			msg := fmt.Sprintf("string literal contains Unicode %s characters, consider using escape sequences instead", kind)
+			var edits []analysis.TextEdit
+			var deletions []analysis.TextEdit
+			for _, r := range invalids {
+				replacement := strconv.QuoteRune(r.r)
+				replacement = replacement[1 : len(replacement)-1]
+				edits = append(edits, analysis.TextEdit{
+					Pos:     lit.Pos() + token.Pos(r.off),
+					End:     lit.Pos() + token.Pos(r.off) + token.Pos(utf8.RuneLen(r.r)),
+					NewText: []byte(replacement),
+				})
+				deletions = append(deletions, analysis.TextEdit{
+					Pos: lit.Pos() + token.Pos(r.off),
+					End: lit.Pos() + token.Pos(r.off) + token.Pos(utf8.RuneLen(r.r)),
+				})
+			}
+			edit := analysis.SuggestedFix{
+				Message:   fmt.Sprintf("replace all %s characters with escape sequences", kind),
+				TextEdits: edits,
+			}
+			delete := analysis.SuggestedFix{
+				Message:   fmt.Sprintf("delete all %s characters", kind),
+				TextEdits: deletions,
+			}
+			report.Report(pass, lit, msg, report.Fixes(edit, delete))
+		}
+	}
+	code.Preorder(pass, fn, (*ast.BasicLit)(nil))
+	return nil, nil
+}