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go.tools/cmd/vet: check for missing printf verb

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A trailing % resulted in a bad error message.
Also clean up a couple of dregs left over from the
refactoring to add indexed formats.

R=dsymonds
CC=golang-dev
https://golang.org/cl/10336044
This commit is contained in:
Rob Pike 2013-06-18 08:21:06 -07:00
parent 16c6244c27
commit df787c2073
2 changed files with 45 additions and 27 deletions
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52
cmd/vet/print.go
View File

@ -8,6 +8,7 @@ package main
import (
"flag"
"fmt"
"go/ast"
"go/token"
"strconv"
@ -109,14 +110,15 @@ func (f *File) literal(value ast.Expr) *ast.BasicLit {
type formatState struct {
verb rune // the format verb: 'd' for "%d"
format string // the full format string
name string // Printf, Sprintf etc.
flags []byte // the list of # + etc.
argNums []int // the successive argument numbers that are consumed, adjusted to refer to actual arg in call
nbytes int // number of bytes of the format string consumed.
indexed bool // whether an indexing expression appears: %[1]d.
firstArg int // Index of first argument after the format in the Printf call.
// Used only during parse.
file *File
call *ast.CallExpr
firstArg int // Index of first argument after the format in the Printf call.
argNum int // Which argument we're expecting to format now.
indexPending bool // Whether we have an indexed argument that has not resolved.
}
@ -155,7 +157,7 @@ func (f *File) checkPrintf(call *ast.CallExpr, name string, formatIndex int) {
for i, w := 0, 0; i < len(format); i += w {
w = 1
if format[i] == '%' {
state := f.parsePrintfVerb(call, format[i:], firstArg, argNum)
state := f.parsePrintfVerb(call, name, format[i:], firstArg, argNum)
if state == nil {
return
}
@ -163,7 +165,9 @@ func (f *File) checkPrintf(call *ast.CallExpr, name string, formatIndex int) {
if state.indexed {
indexed = true
}
f.checkPrintfArg(call, state)
if !f.okPrintfArg(call, state) { // One error per format is enough.
return
}
if len(state.argNums) > 0 {
// Continue with the next sequential argument.
argNum = state.argNums[len(state.argNums)-1] + 1
@ -267,9 +271,10 @@ func (s *formatState) parsePrecision() bool {
// parsePrintfVerb looks the formatting directive that begins the format string
// and returns a formatState that encodes what the directive wants, without looking
// at the actual arguments present in the call. The result is nil if there is an error.
func (f *File) parsePrintfVerb(call *ast.CallExpr, format string, firstArg, argNum int) *formatState {
func (f *File) parsePrintfVerb(call *ast.CallExpr, name, format string, firstArg, argNum int) *formatState {
state := &formatState{
format: format,
name: name,
flags: make([]byte, 0, 5),
argNum: argNum,
argNums: make([]int, 0, 1),
@ -298,6 +303,10 @@ func (f *File) parsePrintfVerb(call *ast.CallExpr, format string, firstArg, argN
if !indexPending && !state.parseIndex() {
return nil
}
if state.nbytes == len(state.format) {
f.Badf(call.Pos(), "missing verb at end of format string in %s call", name)
return nil
}
verb, w := utf8.DecodeRuneInString(state.format[state.nbytes:])
state.verb = verb
state.nbytes += w
@ -365,10 +374,10 @@ var printVerbs = []printVerb{
{'X', sharpNumFlag, argRune | argInt | argString},
}
// checkPrintfArg compares the formatState to the arguments actually present,
// okPrintfArg compares the formatState to the arguments actually present,
// reporting any discrepancies it can discern. If the final argument is ellipsissed,
// there's little it can do for that.
func (f *File) checkPrintfArg(call *ast.CallExpr, state *formatState) {
func (f *File) okPrintfArg(call *ast.CallExpr, state *formatState) (ok bool) {
var v printVerb
found := false
// Linear scan is fast enough for a small list.
@ -380,12 +389,12 @@ func (f *File) checkPrintfArg(call *ast.CallExpr, state *formatState) {
}
if !found {
f.Badf(call.Pos(), "unrecognized printf verb %q", state.verb)
return
return false
}
for _, flag := range state.flags {
if !strings.ContainsRune(v.flags, rune(flag)) {
f.Badf(call.Pos(), "unrecognized printf flag for verb %q: %q", state.verb, flag)
return
return false
}
}
// Verb is good. If len(state.argNums)>trueArgs, we have something like %.*s and all
@ -397,20 +406,21 @@ func (f *File) checkPrintfArg(call *ast.CallExpr, state *formatState) {
nargs := len(state.argNums)
for i := 0; i < nargs-trueArgs; i++ {
argNum := state.argNums[i]
if !f.argCanBeChecked(call, argNum, true, state.verb) {
continue
if !f.argCanBeChecked(call, i, true, state) {
return
}
arg := call.Args[argNum]
if !f.matchArgType(argInt, arg) {
f.Badf(call.Pos(), "arg %s for * in printf format not of type int", f.gofmt(arg))
return false
}
}
if state.verb == '%' {
return
return true
}
argNum := state.argNums[len(state.argNums)-1]
if !f.argCanBeChecked(call, argNum, false, state.verb) {
return
if !f.argCanBeChecked(call, len(state.argNums)-1, false, state) {
return false
}
arg := call.Args[argNum]
if !f.matchArgType(v.typ, arg) {
@ -419,13 +429,16 @@ func (f *File) checkPrintfArg(call *ast.CallExpr, state *formatState) {
typeString = typ.String()
}
f.Badf(call.Pos(), "arg %s for printf verb %%%c of wrong type: %s", f.gofmt(arg), state.verb, typeString)
return false
}
return true
}
// argCanBeChecked reports whether the specified argument is statically present;
// it may be beyond the list of arguments or in a terminal slice... argument, which
// means we can't see it.
func (f *File) argCanBeChecked(call *ast.CallExpr, argNum int, isStar bool, verb rune) bool {
func (f *File) argCanBeChecked(call *ast.CallExpr, formatArg int, isStar bool, state *formatState) bool {
argNum := state.argNums[formatArg]
if argNum < 0 {
// Shouldn't happen, so catch it with prejudice.
panic("negative arg num")
@ -439,11 +452,14 @@ func (f *File) argCanBeChecked(call *ast.CallExpr, argNum int, isStar bool, verb
if argNum < len(call.Args) {
return true
}
if verb == '*' {
f.Badf(call.Pos(), "argument number %d for * for verb %%%c out of range", argNum, verb)
} else {
f.Badf(call.Pos(), "wrong number of args for format in Printf call")
// There are bad indexes in the format or there are fewer arguments than the format needs.
verb := fmt.Sprintf("verb %%%c", state.verb)
if isStar {
verb = "indirect *"
}
// This is the argument number relative to the format: Printf("%s", "hi") will give 1 for the "hi".
arg := argNum - state.firstArg + 1 // People think of arguments as 1-indexed.
f.Badf(call.Pos(), "missing argument for %s %s: need %d, only have %d", state.name, verb, arg, len(call.Args)-state.firstArg)
return false
}

8
cmd/vet/testdata/print.go vendored
View File

@ -101,7 +101,7 @@ func PrintfTests() {
fmt.Println() // not an error
fmt.Println("%s", "hi") // ERROR "possible formatting directive in Println call"
fmt.Printf("%s", "hi", 3) // ERROR "wrong number of args for format in Printf call"
fmt.Printf("%"+("s"), "hi", 3) // ERROR "wrong number of args for format in Printf call"
fmt.Sprintf("%"+("s"), "hi", 3) // ERROR "wrong number of args for format in Sprintf call"
fmt.Printf("%s%%%d", "hi", 3) // correct
fmt.Printf("%08s", "woo") // correct
fmt.Printf("% 8s", "woo") // correct
@ -118,12 +118,13 @@ func PrintfTests() {
Printf("hi") // ok
const format = "%s %s\n"
Printf(format, "hi", "there")
Printf(format, "hi") // ERROR "wrong number of args for format in Printf call"
Printf(format, "hi") // ERROR "missing argument for Printf verb %s: need 2, only have 1"
f := new(stringer)
f.Warn(0, "%s", "hello", 3) // ERROR "possible formatting directive in Warn call"
f.Warnf(0, "%s", "hello", 3) // ERROR "wrong number of args for format in Warnf call"
f.Warnf(0, "%r", "hello") // ERROR "unrecognized printf verb"
f.Warnf(0, "%#s", "hello") // ERROR "unrecognized printf flag"
Printf("d%", 2) // ERROR "missing verb at end of format string in Printf call"
// Good argument reorderings.
Printf("%[1]d", 3)
Printf("%[1]*d", 3, 1)
@ -133,7 +134,8 @@ func PrintfTests() {
// Bad argument reorderings.
Printf("%[xd", 3) // ERROR "illegal syntax for printf argument index"
Printf("%[x]d", 3) // ERROR "illegal syntax for printf argument index"
Printf("%[2]d", 3) // ERROR "wrong number of args for format in Printf call"
Printf("%[3]*s", "hi", 2) // ERROR "missing argument for Printf indirect \*: need 3, only have 2"
fmt.Sprintf("%[3]d", 2) // ERROR "missing argument for Sprintf verb %d: need 3, only have 1"
Printf("%[2]*.[1]*[3]d", 2, "hi", 4) // ERROR "arg .hi. for \* in printf format not of type int"
// Something that satisfies the error interface.
var e error