cmd/compile: inappropriate suggested token in case of syntax error in "if" statement

[gazerro]

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

$ go version
go version go1.16.5 darwin/amd64

Does this issue reproduce with the latest release?

Yes.

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

go env Output

$ go env
GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/marco/Library/Caches/go-build"
GOENV="/Users/marco/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/marco/go/pkg/mod"
GOOS="darwin"
GOPATH="/Users/marco/go"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.16.5"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
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/z9/xrln_qks56jbzxjbhs04fpm80000gn/T/go-build771492184=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Compile the following program

package main

func main() {
	if a := true: a { }
}

What did you expect to see?

syntax error: unexpected :, expecting ;

If a SimpleStmt is parsed, and the next token is not a semicolon, I expect the semicolon to be suggested in the error message.

What did you see instead?

syntax error: unexpected :, expecting {

[dmitshur]

Thanks for reporting.

Does this also happen in older versions of Go, like 1.14 and before, or is it a more recent regression?

[gazerro]

Does this also happen in older versions of Go, like 1.14 and before, or is it a more recent regression?

It also happens in older versions, for example in version 1.13.