go build ignores GoVersion in go.mod file

[jgimenez]

What version of Go are you using (go version)?

$ go version
go version go1.19.5 darwin/amd64

Does this issue reproduce with the latest release?

I can not test this, since the bug only happens when you're not using the non-latest version.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/gimix/Library/Caches/go-build"
GOENV="/Users/gimix/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/gimix/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/gimix/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.19.5/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.19.5/libexec/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.19.5"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/gimix/tmp/go/go.mod"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/q3/6yf46y5j3cb3wb_sxymhgd980000gn/T/go-build128337086=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

go.mod file:

module example.com/test

go 1.20

main.go file:

package main

func main() {

}

Then run:

go build

What did you expect to see?

An error like go: go.mod file indicates go 1.20, but maximum version supported by build is 1.19

What did you see instead?

The compilation worked, even if I am using the go 1.19 build tool.

This can lead to code that is syntactially correct in both versions but semantically different, be compiled with the wrong version. For example, if I were using math/rand pacakge, the behavior would be different because of the different seeding method.

[seankhliao]

working as intended (for now).

see also #57001