Terraform: Terraform is crashing when null is passed to compact function

[vermdeep]

Terraform Version

Terraform v0.12.3

Terraform Configuration Files

locals {
  a = compact(["a", "", "b", "c", null])
}

output "a" {
value = local.a
}

Debug Output

Crash Output

Call to function "compact" failed: panic in function implementation: value is
null
goroutine 29 [running]:
runtime/debug.Stack(0xc000340208, 0x19dddc0, 0x2190d30)
/opt/goenv/versions/1.12.4/src/runtime/debug/stack.go:24 +0x9d
github.com/zclconf/go-cty/cty/function.errorForPanic(...)
/opt/teamcity-agent/work/9e329aa031982669/pkg/mod/github.com/zclconf/[email protected]/cty/function/error.go:44
github.com/zclconf/go-cty/cty/function.Function.Call.func1(0xc000340568,
0xc000340588)
/opt/teamcity-agent/work/9e329aa031982669/pkg/mod/github.com/zclconf/[email protected]/cty/function/function.go:239
+0x8f
panic(0x19dddc0, 0x2190d30)
/opt/goenv/versions/1.12.4/src/runtime/panic.go:522 +0x1b5
github.com/zclconf/go-cty/cty.Value.AsString(...)
/opt/teamcity-agent/work/9e329aa031982669/pkg/mod/github.com/zclconf/[email protected]/cty/value_ops.go:1029
github.com/hashicorp/terraform/lang/funcs.glob..func12(0xc0004d5bc0, 0x1, 0x1,
0x2206c80, 0xc000362da0, 0xc000362da0, 0x0, 0x0, 0x76302f, 0x2206d80, ...)
/opt/teamcity-agent/work/9e329aa031982669/src/github.com/hashicorp/terraform/lang/funcs/collection.go:249
+0x53d
github.com/zclconf/go-cty/cty/function.Function.Call(0xc000326ed0,
0xc0004d5bc0, 0x1, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
/opt/teamcity-agent/work/9e329aa031982669/pkg/mod/github.com/zclconf/[email protected]/cty/function/function.go:243
+0x2f8
github.com/hashicorp/hcl2/hcl/hclsyntax.(FunctionCallExpr).Value(0xc000548000,
0xc0004d5ba0, 0x0, 0xc000341700, 0x1, 0x1, 0x0, 0x0, 0x0)
/opt/teamcity-agent/work/9e329aa031982669/pkg/mod/github.com/hashicorp/[email protected]/hcl/hclsyntax/expression.go:385
+0x10c8
github.com/hashicorp/terraform/lang.(Scope).EvalExpr(0xc0000b4b40, 0x2205900,
0xc000548000, 0x2206c40, 0x3311ca0, 0x0, 0x1ba37e0, 0x0, 0xc0004d4e60,
0xc0001458e0, ...)
/opt/teamcity-agent/work/9e329aa031982669/src/github.com/hashicorp/terraform/lang/eval.go:95
+0x1b3
github.com/hashicorp/terraform/terraform.(BuiltinEvalContext).EvaluateExpr(0xc00013d5f0,
0x2205900, 0xc000548000, 0x2206c40, 0x3311ca0, 0x0, 0x0, 0x0, 0xc00036f9f0,
0x434d6c, ...)
/opt/teamcity-agent/work/9e329aa031982669/src/github.com/hashicorp/terraform/terraform/eval_context_builtin.go:284
+0x1e4
github.com/hashicorp/terraform/terraform.(EvalLocal).Eval(0xc0004d4e00,
0x22388c0, 0xc00013d5f0, 0x2, 0x2, 0xf46ded, 0x1aeddc0)
/opt/teamcity-agent/work/9e329aa031982669/src/github.com/hashicorp/terraform/terraform/eval_local.go:43
+0x73a
github.com/hashicorp/terraform/terraform.EvalRaw(0x21c5580, 0xc0004d4e00,
0x22388c0, 0xc00013d5f0, 0x1a70ce0, 0x31c7105, 0x19dddc0, 0xc00012f5b0)
/opt/teamcity-agent/work/9e329aa031982669/src/github.com/hashicorp/terraform/terraform/eval.go:57
+0x131
github.com/hashicorp/terraform/terraform.Eval(0x21c5580, 0xc0004d4e00,
0x22388c0, 0xc00013d5f0, 0xc0004d4e00, 0x21c5580, 0xc0004d4e00, 0x0)
/opt/teamcity-agent/work/9e329aa031982669/src/github.com/hashicorp/terraform/terraform/eval.go:35
+0x4d
github.com/hashicorp/terraform/terraform.(Graph).walk.func1(0x1bfdd20,
0xc000466f60, 0x0, 0x0, 0x0)
/opt/teamcity-agent/work/9e329aa031982669/src/github.com/hashicorp/terraform/terraform/graph.go:90
+0xf40
github.com/hashicorp/terraform/dag.(Walker).walkVertex(0xc000124280,
0x1bfdd20, 0xc000466f60, 0xc000260640)
/opt/teamcity-agent/work/9e329aa031982669/src/github.com/hashicorp/terraform/dag/walk.go:392
+0x353
created by github.com/hashicorp/terraform/dag.(*Walker).Update
/opt/teamcity-agent/work/9e329aa031982669/src/github.com/hashicorp/terraform/dag/walk.go:314
+0xa9b
.

Expected Behavior

Output should be:

["a", "b", "c"]

Actual Behavior

Terraform crashed

Steps to Reproduce

Please list the full steps required to reproduce the issue, for example:

1. terraform init
2. terraform apply

Additional Context

References

[saveriomiroddi]

I'm not sure if this is intended or not; while looking at the code, I see that there is a mention that null values in functions (I guess, with the implicit exclusion of coalesce()) are supposed to panic.

Nonetheless, I've fixed the issue in the associated PR, so if the maintainers decide to allow null value, the PR is ready (at least for review).

[hashibot[bot]]

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