Filtering expression involving comparison with unknown symbol generates "This is a bug in the OpenTelemetry Transformation Language"

[tilowiklundSensmetry]

Component(s)

processor/filter

What happened?

Description

Using the filter processor with an expression involving a comparison against an undefined symbol starting with an upper-case letter generates an error message the wording of which suggests a bug in the collector

Error: invalid configuration: processors::filter: unable to parse OTTL condition [...]: no value field set.
This is a bug in the OpenTelemetry Transformation Language

Steps to Reproduce

Run the collector with a filter comparing against an undefined symbol, such as value_double != NaN (NaN is undefined at the time of writing), value_int == IAmUndefined, or IAmUndefined == IAmUndefined.

Note that the behaviour is different for symbols not starting with upper-case letters (which generate either parsing errors or is not a valid path errors).

See attached config for full example.

Expected Result

Error message not indicating the error is a bug in the collector, such the one generated for lower-case symbols

[...] is not a valid path nor a valid OTTL keyword [...]

or mixed case symbols

[...] invalid syntax: 1:29: unexpected token [...]

Actual Result

An error message indicating the issue is due to a bug in the collector

This is a bug in the OpenTelemetry Transformation Language

Collector version

v0.100.0

Environment information

Environment

Precompiled binary with md5sum

41a4690a6ec5834a05a6615a8fdf1494  otelcol-contrib_0.100.0_linux_amd64.tar.gz

OS: Gentoo Linux

OpenTelemetry Collector configuration

receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317
      http:
        endpoint: 0.0.0.0:4318

exporters:
  debug:
    verbosity: detailed

processors:
  filter:
    metrics:
      datapoint:
          - 'value_double != NaN'

service:
  pipelines:
    metrics:
      receivers: [otlp]
      processors: [filter]
      exporters: [debug]

Log output

Error: invalid configuration: processors::filter: unable to parse OTTL condition "value_double != NaN": no value field set. This is a bug in the OpenTelemetry Transformation Language
2024/05/14 16:38:05 collector server run finished with error: invalid configuration: processors::filter: unable to parse OTTL condition "value_double != NaN": no value field set. This is a bug in the OpenTelemetry Transformation Language

Additional context

No response

[github-actions]

Pinging code owners:

• processor/filter: @TylerHelmuth @boostchicken

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[github-actions]

Pinging code owners for pkg/ottl: @TylerHelmuth @kentquirk @bogdandrutu @evan-bradley. See Adding Labels via Comments if you do not have permissions to add labels yourself.