Remove vendored terraform RPC diagnostics code

Makefile

@@ -95,6 +95,7 @@ terraform_gen:
     	-exec sed -i".bak" 's#github\.com/hashicorp/terraform/version#github.com/fugue/regula/v2/pkg/terraform/version#' '{}' \;
 	find pkg/terraform/ -name '*.bak' -delete
 	find pkg/terraform/ -name '*_test.go' -delete
+	git apply patches/terraform.patch
 	rm -rf terraform.zip terraform-$(TERRAFORM_VERSION)
 
 #############

patches/terraform.patch

@@ -0,0 +1,109 @@
+diff --git a/pkg/terraform/configs/configload/loader_snapshot.go b/pkg/terraform/configs/configload/loader_snapshot.go
+index 243939f..6ca8b4f 100644
+--- a/pkg/terraform/configs/configload/loader_snapshot.go
++++ b/pkg/terraform/configs/configload/loader_snapshot.go
+@@ -325,6 +325,10 @@ func (fs snapshotFS) Chmod(name string, mode os.FileMode) error {
+ 	return fmt.Errorf("cannot set file mode inside configuration snapshot")
+ }
+
++func (fs snapshotFS) Chown(string, int, int) error {
++	return fmt.Errorf("cannot set file owner inside configuration snapshot")
++}
++
+ func (fs snapshotFS) Chtimes(name string, atime, mtime time.Time) error {
+ 	return fmt.Errorf("cannot set file times inside configuration snapshot")
+ }
+diff --git a/pkg/terraform/tfdiags/diagnostics.go b/pkg/terraform/tfdiags/diagnostics.go
+index 30476ee..25cd135 100644
+--- a/pkg/terraform/tfdiags/diagnostics.go
++++ b/pkg/terraform/tfdiags/diagnostics.go
+@@ -107,24 +107,6 @@ func (diags Diagnostics) HasErrors() bool {
+ 	return false
+ }
+
+-// ForRPC returns a version of the receiver that has been simplified so that
+-// it is friendly to RPC protocols.
+-//
+-// Currently this means that it can be serialized with encoding/gob and
+-// subsequently re-inflated. It may later grow to include other serialization
+-// formats.
+-//
+-// Note that this loses information about the original objects used to
+-// construct the diagnostics, so e.g. the errwrap API will not work as
+-// expected on an error-wrapped Diagnostics that came from ForRPC.
+-func (diags Diagnostics) ForRPC() Diagnostics {
+-	ret := make(Diagnostics, len(diags))
+-	for i := range diags {
+-		ret[i] = makeRPCFriendlyDiag(diags[i])
+-	}
+-	return ret
+-}
+-
+ // Err flattens a diagnostics list into a single Go error, or to nil
+ // if the diagnostics list does not include any error-level diagnostics.
+ //
+diff --git a/pkg/terraform/tfdiags/rpc_friendly.go b/pkg/terraform/tfdiags/rpc_friendly.go
+deleted file mode 100644
+index 485063b..0000000
+--- a/pkg/terraform/tfdiags/rpc_friendly.go
++++ /dev/null
+@@ -1,59 +0,0 @@
+-package tfdiags
+-
+-import (
+-	"encoding/gob"
+-)
+-
+-type rpcFriendlyDiag struct {
+-	Severity_ Severity
+-	Summary_  string
+-	Detail_   string
+-	Subject_  *SourceRange
+-	Context_  *SourceRange
+-}
+-
+-// rpcFriendlyDiag transforms a given diagnostic so that is more friendly to
+-// RPC.
+-//
+-// In particular, it currently returns an object that can be serialized and
+-// later re-inflated using gob. This definition may grow to include other
+-// serializations later.
+-func makeRPCFriendlyDiag(diag Diagnostic) Diagnostic {
+-	desc := diag.Description()
+-	source := diag.Source()
+-	return &rpcFriendlyDiag{
+-		Severity_: diag.Severity(),
+-		Summary_:  desc.Summary,
+-		Detail_:   desc.Detail,
+-		Subject_:  source.Subject,
+-		Context_:  source.Context,
+-	}
+-}
+-
+-func (d *rpcFriendlyDiag) Severity() Severity {
+-	return d.Severity_
+-}
+-
+-func (d *rpcFriendlyDiag) Description() Description {
+-	return Description{
+-		Summary: d.Summary_,
+-		Detail:  d.Detail_,
+-	}
+-}
+-
+-func (d *rpcFriendlyDiag) Source() Source {
+-	return Source{
+-		Subject: d.Subject_,
+-		Context: d.Context_,
+-	}
+-}
+-
+-func (d rpcFriendlyDiag) FromExpr() *FromExpr {
+-	// RPC-friendly diagnostics cannot preserve expression information because
+-	// expressions themselves are not RPC-friendly.
+-	return nil
+-}
+-
+-func init() {
+-	gob.Register((*rpcFriendlyDiag)(nil))
+-}

pkg/terraform/tfdiags/diagnostics.go

@@ -107,24 +107,6 @@ func (diags Diagnostics) HasErrors() bool {
 	return false
 }
 
-// ForRPC returns a version of the receiver that has been simplified so that
-// it is friendly to RPC protocols.
-//
-// Currently this means that it can be serialized with encoding/gob and
-// subsequently re-inflated. It may later grow to include other serialization
-// formats.
-//
-// Note that this loses information about the original objects used to
-// construct the diagnostics, so e.g. the errwrap API will not work as
-// expected on an error-wrapped Diagnostics that came from ForRPC.
-func (diags Diagnostics) ForRPC() Diagnostics {
-	ret := make(Diagnostics, len(diags))
-	for i := range diags {
-		ret[i] = makeRPCFriendlyDiag(diags[i])
-	}
-	return ret
-}
-
 // Err flattens a diagnostics list into a single Go error, or to nil
 // if the diagnostics list does not include any error-level diagnostics.
 //