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x/tools/go/analysis/passes/slog: False negitive when error type used as key. #65740

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aDotInTheVoid opened this issue Feb 16, 2024 · 1 comment
Open

x/tools/go/analysis/passes/slog: False negitive when error type used as key. #65740

aDotInTheVoid opened this issue Feb 16, 2024 · 1 comment
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@jba
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NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. Tools This label describes issues relating to any tools in the x/tools repository.
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@aDotInTheVoid
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Go version

go version go1.22.0 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/alona/.cache/go-build'
GOENV='/home/alona/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/alona/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/alona/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/alona/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.0.linux-amd64'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/alona/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.0.linux-amd64/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.22.0'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/tmp/goo/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build3366501523=/tmp/go-build -gno-record-gcc-switches'

What did you do?

I wrote code that assumed slog methods worked like fmt.Printf, instead of talking Attr/key-value pairs:

package main

import "log/slog"

func main() {
        var x error
        slog.Error("The error is %v", x)
}

playground

Running go vet -slog ./main.go

What did you see happen?

go vet -slog reports no errors, but the key isn't present.

$ go vet -slog ./main.go
$ go run ./main.go
2024/02/16 00:50:48 ERROR The error is %v !BADKEY=<nil>

What did you expect to see?

go vet -slog ./main.go should report an error like ./main.go:7:32: slog.Error arg "x" should be a string or a slog.Attr (possible missing key or value).

Interestingly, if you change the type of x to int, the error fires as you'd expect.

package main

import "log/slog"

func main() {
        var x int
        slog.Error("The error is %v", x)
}
$ go vet -slog ./main.go
# command-line-arguments
# [command-line-arguments]
./main.go:7:32: slog.Error arg "x" should be a string or a slog.Attr (possible missing key or value)
$ go run ./main.go
2024/02/16 00:52:58 ERROR The error is %v !BADKEY=0
@gopherbot gopherbot added the Tools This label describes issues relating to any tools in the x/tools repository. label Feb 16, 2024
@gopherbot gopherbot added this to the Unreleased milestone Feb 16, 2024
@seankhliao seankhliao changed the title x/tools/go/analysis/passes/slog/: False negitive when error type used as key. x/tools/go/analysis/passes/slog: False negitive when error type used as key. Feb 16, 2024
@thanm thanm added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Feb 16, 2024
@thanm
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thanm commented Feb 16, 2024

@jba per owners

@jba jba self-assigned this Feb 16, 2024
philip-peterson pushed a commit to philip-peterson/go that referenced this issue Apr 12, 2024
@jba
go/analysis/passes/slog: detect unsatifiable interface args
029c4ea 
Previously, if we saw an arg of interface type passed to a slog logging
function, we made no assumptions about it.

But we can do better when the argument is in key position:
- If neither string nor slog.Attr can implement the interface,
  we can immediately report an error.
- If only slog.Attr can implement the interface, then we can
  assume that the next position is a key and carry on.

Fixes golang#65740.

Change-Id: I1080c26b6cb46a46489f811e4cd73c9e505ce6b3
Reviewed-on: https://go-review.googlesource.com/c/tools/+/566895
Reviewed-by: Tim King <taking@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
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@gopherbot @thanm @jba @aDotInTheVoid