core: Detect and reject self-referencing local values

We already catch indirect cycles through the normal cycle detector, but
we never create self-edges in the graph so we need to handle a direct
self-reference separately here.

The prior behavior was simply to produce an incorrect result (since the
local value wasn't assigned a new value yet).

This fixes #18503.
This commit is contained in:
Martin Atkins 2018-12-19 12:38:18 -08:00
parent 8ca7cc0237
commit 176ae6e95f
2 changed files with 34 additions and 4 deletions

View File

@ -4,8 +4,11 @@ import (
"fmt"
"github.com/hashicorp/hcl2/hcl"
"github.com/hashicorp/terraform/addrs"
"github.com/zclconf/go-cty/cty"
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/lang"
"github.com/hashicorp/terraform/tfdiags"
)
// EvalLocal is an EvalNode implementation that evaluates the
@ -17,11 +20,32 @@ type EvalLocal struct {
}
func (n *EvalLocal) Eval(ctx EvalContext) (interface{}, error) {
val, diags := ctx.EvaluateExpr(n.Expr, cty.DynamicPseudoType, nil)
var diags tfdiags.Diagnostics
// We ignore diags here because any problems we might find will be found
// again in EvaluateExpr below.
refs, _ := lang.ReferencesInExpr(n.Expr)
for _, ref := range refs {
if ref.Subject == n.Addr {
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Self-referencing local value",
Detail: fmt.Sprintf("Local value %s cannot use its own result as part of its expression.", n.Addr),
Subject: ref.SourceRange.ToHCL().Ptr(),
Context: n.Expr.Range().Ptr(),
})
}
}
if diags.HasErrors() {
return nil, diags.Err()
}
val, moreDiags := ctx.EvaluateExpr(n.Expr, cty.DynamicPseudoType, nil)
diags = diags.Append(moreDiags)
if moreDiags.HasErrors() {
return nil, diags.Err()
}
state := ctx.State()
if state == nil {
return nil, fmt.Errorf("cannot write local value to nil state")

View File

@ -34,6 +34,11 @@ func TestEvalLocal(t *testing.T) {
"",
false,
},
{
"Hello, ${local.foo}",
nil,
true, // self-referencing
},
}
for _, test := range tests {
@ -64,8 +69,9 @@ func TestEvalLocal(t *testing.T) {
ms := ctx.StateState.Module(addrs.RootModuleInstance)
gotLocals := ms.LocalValues
wantLocals := map[string]cty.Value{
"foo": hcl2shim.HCL2ValueFromConfigValue(test.Want),
wantLocals := map[string]cty.Value{}
if test.Want != nil {
wantLocals["foo"] = hcl2shim.HCL2ValueFromConfigValue(test.Want)
}
if !reflect.DeepEqual(gotLocals, wantLocals) {