{"go1.6", "go1.6.1", -1},
	{"go1.19", "go1.19.0", 0},
	{"go1.19rc1", "go1.19", -1},
	{"go1.20", "go1.20.0", 0},
	{"go1.20", "go1.20.0-bigcorp", 0},
	{"go1.20rc1", "go1.20", -1},
	{"go1.21", "go1.21.0", -1},
	{"go1.21", "go1.21.0-bigcorp", -1},
	{"go1.21", "go1.21rc1", -1},
	{"go1.21rc1", "go1.21.0", -1},
	{"go1.6", "go1.19", -1},
	{"go1.19", "go1.19.1", -1},
	{"go1.19rc1", "go1.19", -1},
	{"go1.19rc1", "go1.19", -1},

	{"1", "1.1", -1},
	{"1.5", "1.6", -1},
	{"1.5", "1.10", -1},
	{"1.6", "1.6.1", -1},
	{"1.19", "1.19.0", 0},
	{"1.19rc1", "1.19", -1},
	{"1.20", "1.20.0", 0},
	{"1.20rc1", "1.20", -1},
	{"1.21", "1.21.0", -1},
	{"1.21", "1.21rc1", -1},
	{"1.21rc1", "1.21.0", -1},
	{"1.6", "1.19", -1},
	{"1.19", "1.19.1", -1},
	{"1.19rc1", "1.19", -1},
	{"1.19rc1", "1.19.1", -1},
	{"1.19rc1", "1.19rc2", -1},
	{"1.19.0", "1.19.1", -1},

	{"1", "1.1", -1},
	{"1.5", "1.6", -1},
	{"1.5", "1.10", -1},
	{"1.6", "1.6.1", -1},
	{"1.19", "1.19.0", 0},
	{"1.19rc1", "1.19", -1},
	{"1.20", "1.20.0", 0},
	{"1.20rc1", "1.20", -1},
	{"1.21", "1.21.0", -1},
	{"1.21", "1.21rc1", -1},
	{"1.21rc1", "1.21.0", -1},
	{"1.6", "1.19", -1},
	{"1.19", "1.19.1", -1},
	{"1.19rc1", "1.19", -1},
	{"1.19rc1", "1.19.1", -1},
	{"1.19rc1", "1.19rc2", -1},
	{"1.19.0", "1.19.1", -1},

# go get go@1.22rc1 should use 1.22rc1 exactly, not a later release.
env GOTOOLCHAIN=local
cp go.mod.new go.mod
! go get go@1.22rc1
stderr '^go: updating go.mod requires go >= 1.22rc1 \(running go 1.21; GOTOOLCHAIN=local\)'

env GOTOOLCHAIN=auto
cp go.mod.new go.mod
go get go@1.22rc1
stderr '^go: updating go.mod requires go >= 1.22rc1; switching to go1.22.9$'

cat go.mod
go list -f '{{.Module.GoVersion}}'
stdout 1.22

# Adding a@v1.0.01 should upgrade to Go 1.23rc1.
cp go.mod go.mod1
go get example.com/a@v1.0.1
stderr '^go: upgraded go 1.22 => 1.23rc1\ngo: upgraded example.com/a v1.0.0 => v1.0.1\ngo: upgraded example.com/b v1.0.0 => v1.0.1$'
go list -f '{{.Module.GoVersion}}'
stdout 1.23rc1

# Repeating the update with go@1.24.0 should use that Go version.
cp go.mod1 go.mod

golang.org/toolchain v0.0.1-go1.22rc1.linux-amd64
written by hand
-- .info --
{"Version":"v0.0.1-go1.22rc1.linux-amd64"}
-- .mod --
golang.org/toolchain
-- go.mod --

golang.org/toolchain v0.0.1-go1.24rc1.linux-amd64
written by hand
-- .info --
{"Version":"v0.0.1-go1.24rc1.linux-amd64"}
-- .mod --
golang.org/toolchain
-- go.mod --

cp go.mod.orig go.mod
! go get go@1.24
stderr '^go: go@1.24: no matching versions for query "1.24"$'

# go get go@1.24rc1 works
cp go.mod.orig go.mod
go get go@1.24rc1
stderr '^go: upgraded go 1.21 => 1.24rc1$'
grep 'go 1.24rc1' go.mod
grep 'toolchain go1.99rc1' go.mod

# go get go@latest finds the latest Go 1.23
cp go.mod.orig go.mod
go get go@latest

// the overall language version; the first release is "1.x.0".
// The distinction is important because the relative ordering is
//
//	1.21 < 1.21rc1 < 1.21.0
//
// meaning that Go 1.21rc1 and Go 1.21.0 will both handle go.mod files that
// say "go 1.21", but Go 1.21rc1 will not handle files that say "go 1.21.0".
func IsLang(x string) bool {
	return gover.IsLang(x)
}

grep '^toolchain go1.22.9$' go.work

# work sync with newer modules should update go 1.22.1 -> 1.24rc1 and drop toolchain
go work edit -use=./m1_24_rc0
go work sync
stderr '^go: m1_24_rc0'${/}'go.mod requires go >= 1.24rc0; switching to go1.24rc1$'
cat go.work
grep '^go 1.24rc0$' go.work