feat: upgrade to go 1.21

[crandles]

Update all packages to 1.21, and update tests to cover 1.21 -> 1.23.

I was going to start with 1.23 -- I can update if preferred. At least with 1.21, you can build the later toolchains, so you can start to update individual packages as needed.

Additional changes:

• go mod tidy of all packages
• go work sync

---

There are many packages in the repository -- I'm not sure what your build tool of choice is, but here are some non-fancy makefile targets I've been using:

update-deps:
	GO_ARGS="mod tidy" $(MAKE) go
	GO_ARGS="work sync" $(MAKE) go
	GO_ARGS="test -v" $(MAKE) go
	GO_ARGS="build -v" $(MAKE) go

GO_ARGS ?= -h
go:
	find . -type d -not -path '*/.*' -exec sh -c 'cd {} && go $(GO_ARGS)' \;

[rhnvrm]

I was just trying to verify if this would break older go versions, and wrote this bash script and it seems to work. But I'm not a 100% sure. Wanted to understand if this is going to be a breaking change for those using v1.18-v1.20.

docker run --rm golang:1.18 bash -c "
    go version &&
    mkdir test &&
    cd test &&
    go mod init foo &&
    echo 'require github.com/knadh/koanf/v2 latest' >> go.mod &&
    echo 'replace github.com/knadh/koanf/v2 => github.com/crandles/koanf/v2 go-v1.21' >> go.mod &&
    cat <<EOL > main.go
package main

import (
    \"github.com/knadh/koanf/v2\"
    \"fmt\"
)

func main() {
    // Create a new koanf instance.
    k := koanf.New(\".\")
    k.Print()
    fmt.Println(\"done\")
}
EOL
    cat go.mod && go mod tidy && cat go.mod &&
    go run main.go
"

[crandles]

Perhaps worth adding back into the CI, then? I think things will break if you start depending on capabilities that don't exist yet in the older versions.

Starting in 1.21, there's more flexibility.

[rhnvrm]

Yeah, it might be better to keep v1.18 -> v1.21 in the matrix. Having a similar discussion in #313.

Let me think of other ways to test if anything is breaking in the meanwhile.