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x/tools: print check misses concatenated strings #344

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22 changes: 14 additions & 8 deletions go/analysis/passes/printf/printf.go
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Original file line number Diff line number Diff line change
Expand Up @@ -452,8 +452,15 @@ func stringConstantArg(pass *analysis.Pass, call *ast.CallExpr, idx int) (string
if idx >= len(call.Args) {
return "", false
}
arg := call.Args[idx]
lit := pass.TypesInfo.Types[arg].Value
return stringConstantExpr(pass, call.Args[idx])
}

// stringConstantExpr returns expression's string constant value.
//
// ("", false) is returned if expression isn't a string
// constant.
func stringConstantExpr(pass *analysis.Pass, expr ast.Expr) (string, bool) {
lit := pass.TypesInfo.Types[expr].Value
if lit != nil && lit.Kind() == constant.String {
return constant.StringVal(lit), true
}
Expand Down Expand Up @@ -1053,10 +1060,10 @@ func checkPrint(pass *analysis.Pass, call *ast.CallExpr, fn *types.Func) {
}

arg := args[0]
if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
// Ignore trailing % character in lit.Value.
if s, ok := stringConstantExpr(pass, arg); ok {
// Ignore trailing % character
// The % in "abc 0.0%" couldn't be a formatting directive.
s := strings.TrimSuffix(lit.Value, `%"`)
s = strings.TrimSuffix(s, "%")
if strings.Contains(s, "%") {
m := printFormatRE.FindStringSubmatch(s)
if m != nil {
Expand All @@ -1067,9 +1074,8 @@ func checkPrint(pass *analysis.Pass, call *ast.CallExpr, fn *types.Func) {
if strings.HasSuffix(fn.Name(), "ln") {
// The last item, if a string, should not have a newline.
arg = args[len(args)-1]
if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
str, _ := strconv.Unquote(lit.Value)
if strings.HasSuffix(str, "\n") {
if s, ok := stringConstantExpr(pass, arg); ok {
if strings.HasSuffix(s, "\n") {
pass.ReportRangef(call, "%s arg list ends with redundant newline", fn.FullName())
}
}
Expand Down
8 changes: 5 additions & 3 deletions go/analysis/passes/printf/testdata/src/a/a.go
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Original file line number Diff line number Diff line change
Expand Up @@ -153,6 +153,7 @@ func PrintfTests() {
fmt.Println("%s", "hi") // want "fmt.Println call has possible formatting directive %s"
fmt.Println("%v", "hi") // want "fmt.Println call has possible formatting directive %v"
fmt.Println("%T", "hi") // want "fmt.Println call has possible formatting directive %T"
fmt.Println("%s"+" there", "hi") // want "fmt.Println call has possible formatting directive %s"
fmt.Println("0.0%") // correct (trailing % couldn't be a formatting directive)
fmt.Printf("%s", "hi", 3) // want "fmt.Printf call needs 1 arg but has 2 args"
_ = fmt.Sprintf("%"+("s"), "hi", 3) // want "fmt.Sprintf call needs 1 arg but has 2 args"
Expand Down Expand Up @@ -768,9 +769,10 @@ func UnexportedStringerOrError() {
fmt.Printf("%s", uei) // want "Printf format %s has arg uei of wrong type a.unexportedErrorInterface"
fmt.Println("foo\n", "bar") // not an error

fmt.Println("foo\n") // want "Println arg list ends with redundant newline"
fmt.Println("foo\\n") // not an error
fmt.Println(`foo\n`) // not an error
fmt.Println("foo\n") // want "Println arg list ends with redundant newline"
fmt.Println("foo" + "\n") // want "Println arg list ends with redundant newline"
fmt.Println("foo\\n") // not an error
fmt.Println(`foo\n`) // not an error

intSlice := []int{3, 4}
fmt.Printf("%s", intSlice) // want `fmt.Printf format %s has arg intSlice of wrong type \[\]int`
Expand Down