Golang x/tools/go/analysis/passes/printf: function with conditional sprintf detected as a wrapper

Go version

go version go1.24.5 linux/amd64

Output of go env in your module/workspace:

AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/home/ubuntu/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/ubuntu/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build3272950330=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/tmp/example/go.mod'
GOMODCACHE='/home/ubuntu/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/ubuntu/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/ubuntu/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/ubuntu/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/ubuntu/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.24.5'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

I tried running go vet on the following code and expected no errors:

// example1.go
package example

import "fmt"

func ConditionallyFormattedMessage(message string, args ...interface{}) string {
        if len(args) == 0 {
                return message
        } else {
                return fmt.Sprintf(message, args...)
        }
}

func Example1(arg string) string {
        return ConditionallyFormattedMessage(arg)
}

What did you see happen?

Running go vet on the above code results in a printf problem being reported despite there being none:

$ go vet
# example.com/m
./example1.go:15:46: non-constant format string in call to example.com/m.ConditionallyFormattedMessage

What did you expect to see?

I expected no errors.

Additional context

The above is a minimal reproduction of an issue I'm seeing with methods in the (quite popular) errorx package such as (*github.com/joomcode/errorx.Type).New and (*github.com/joomcode/errorx.Type).Wrap. The errorx package has a method that is very similar to the ConditionallyFormattedMessage() function above - ErrorBuilder.WithConditionallyFormattedMessage(): https://github.com/joomcode/errorx/blob/3280086cb5400e2900300ba010ddf658fa717fc4/builder.go#L84-L95 which is used by the aforementioned New and Wrap methods: https://github.com/joomcode/errorx/blob/3280086cb5400e2900300ba010ddf658fa717fc4/type.go#L41-L45 https://github.com/joomcode/errorx/blob/3280086cb5400e2900300ba010ddf658fa717fc4/type.go#L60-L65

An alternative reproduction using github.com/joomcode/errorx@v1.2.0 can be seen below:

// example2.go
package example

import "github.com/joomcode/errorx"

func Example2(arg string) *errorx.Error {
        return errorx.InternalError.New(arg)
}

$ go vet
# example.com/m
./example2.go:7:34: non-constant format string in call to (*github.com/joomcode/errorx.Type).New

Comment From: gabyhelp

Related Issues

• x/tools/passes/printf: conditionally printf-like functions are treated as printf-like, causing false positives #73485 (closed)
• cmd/vet: printf analyzer cannot analyze anonymous functions #44350
• x/tools/go/analysis/passes/printf: `%#x` recursion is not recognized #73825 (closed)
• x/tools/gopls: doesn't seem to vet text output formatting errors in non-core packages #34059 (closed)
• x/tools/analysis: printf pass should only allow %w in fmt.Errorf #37792 (closed)
• go vet incorrectly recognizes format verb in string #38131 (closed)
• cmd/vet: Formatting string check cannot see through type assertions or varargs #70814 (closed)
• go1.13 errors package #34060 (closed)
• cmd/doc: garbled -src output #37028 (closed)
• cmd/vet: doesn't handle formatting strings in variables #44063

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}