funcs/generated: Support pre-releases

internal/funcs/generated/README.md

@@ -4,7 +4,12 @@ This package can generate function signature files for Terraform >= 1.4 automati
 
 It is intended to run whenever HashiCorp releases a new Terraform version. If the Terraform version contains updated function signatures, it generates a new file for that version. When no changes are detected, one should commit the version bump in `gen/gen.go`.
 
-It may only work with full releases and will likely fail for pre-releases or versions containing metadata.
+Pre-releases are accepted with the following caveats:
+
+ - The given pre-release version of Terraform is downloaded
+ - The pre-release part of the version is omitted in all other contexts (e.g. function name, file name, constraint etc.)
+
+... meaning that e.g. `1.5.0-alpha20230504` downloads Terraform `1.5.0-alpha20230504` but assumes compatibility with `1.5.0`. Therefore, generating signatures based on pre-releases should be used with the assumption that those signatures won't change before the final release.
 
 ## Running
 

internal/funcs/generated/gen/gen.go

@@ -26,8 +26,11 @@ import (
  tfjson "github.com/hashicorp/terraform-json"
 )
 
+var (
+ terraformVersion = version.Must(version.NewVersion("1.4.0"))
+)
+
 const (
- terraformVersion = "1.4.0"
  functionSignatureHash = "8877af98abc453ce29d43e390c71b97bceaf90563ed28cf575e0100288602e9d"
 )
 
@@ -47,7 +50,7 @@ func main() {
  return
  }
  log.Printf("generating new signatures for %q\n", newSignatureHash)
- functionsFile := fmt.Sprintf("%s.go", terraformVersion)
+ functionsFile := fmt.Sprintf("%s.go", terraformVersion.Core().String())
  err = writeFunctions(functionsFile, functions)
  if err != nil {
  log.Fatal(err)
@@ -79,7 +82,7 @@ func signaturesFromTerraform(ctx context.Context) (*tfjson.MetadataFunctions, er
  &releases.ExactVersion{
  Product: product.Terraform,
  InstallDir: installDir,
- Version: version.Must(version.NewVersion(terraformVersion)),
+ Version: terraformVersion,
  },
  })
  if err != nil {
@@ -171,7 +174,7 @@ func {{ .FunctionName }}() map[string]schema.FunctionSignature {
 
  var buf bytes.Buffer
  err = tpl.Execute(&buf, data{
- FunctionName: fmt.Sprintf("v%s_Functions", escapeVersion(terraformVersion)),
+ FunctionName: fmt.Sprintf("v%s_Functions", escapeVersion(terraformVersion.Core().String())),
  Signatures: functions.Signatures,
  })
  if err != nil {