go-cty-yaml parse error

Temporary repo to illustrate and test YAML parse error occurring in Terraform and OpenTofu when decoding YAML containing strings values of just +

This originates from go-cty-yaml

terraform plan

Error example:

   on main.tf line 28, in output "yaml_decode_test":
│   28:       inline_error            = yamldecode(local.yaml_inline_sample_error)
│     ├────────────────
│     │ while calling yamldecode(src)
│     │ local.yaml_inline_sample_error is "element: +\nsome_list:\n- foo\n- +\n"
│
│ Call to function "yamldecode" failed: cannot parse "+" as tag:yaml.org,2002:int.
╵

Showing validly parsed YAML:

terraform plan -var 'include_errors=false'

Validating YAML

Checking spec: https://yaml.org/spec/1.2.2/#indicator-characters

Using any of the online validators, e.g.: https://yamlchecker.com/

Using https://yamllint.readthedocs.io/en/stable/index.html

python3 -m yamllint .

Merely some warnings, + values pass validation

./sample-ok.yaml
  1:1       warning  missing document start "---"  (document-start)

./sample-error-list-value.yaml
  1:1       warning  missing document start "---"  (document-start)

./sample-error-single-value.yaml
  1:1       warning  missing document start "---"  (document-start)

Possible cause

Interpreted as integer based on +, then turning out not to be an integer by absence of any digits.

Reference: https://yaml.org/spec/1.2.2/#tags

TBeijen/terraform-go-cty-yaml-decode-error

go-cty-yaml parse error

Validating YAML

Possible cause