(core): `stack.exportValue()` does not work with `ref` parameters

[juanqui]

The new stack.exportValue() feature introduced in #12778 does not seem to work with resource parameters that would be referenced by Ref rather than GetAtt.

Reproduction Steps

const someSampleRole = new iam.Role(this, 'SomeSampleRole', {});
this.exportValue(someSampleRole.roleName);

Results in: Error: exportValue: either supply 'name' or make sure to export a resource attribute (like 'bucket.bucketName')

What did you expect to happen?

Trying to break a deadly embrace where I used the roleName and roleArn in another stack. The roleArn is a GetAtt and the roleName is actually a Ref. The roleArn worked great, but roleName will not synthesize without me specifying the full export name which looks something like STACK_NAME:ExportsOutputRefSomeSampleRole1D3A83A01C1B4250.

What actually happened?

Error: Error: exportValue: either supply 'name' or make sure to export a resource attribute (like 'bucket.bucketName')

Environment

• CDK CLI Version : 1.88.0
• Framework Version: 1.88.0
• Node.js Version: v10.23.2
• OS : Amazon Linux 2
• Language (Version): TypeScript (3.8.3)

Other

N/A

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This is 🐛 Bug Report

[skinny85]

Confirming I was able to reproduce it, using an @aws-cdk/aws-s3 Bucket's bucketName attribute, which fails with this pretty ironic message:

exportValue: either supply 'name' or make sure to export a resource attribute (like 'bucket.bucketName')

[skinny85]

Actually, same error happens when trying to use bucketArn.

[rix0rrr]

Cool. It's the physicalName system that's messing us up here, which is wrapping the Reference token in a Lazy 😡

[github-actions]

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