EnC: It is possible to emit invalid delta if semantic info is inferred from documents that are not up to date

[tmat]

Semantic EnC analysis of documents that contain partial types or types moved across documents examines semantic information from the base project compilation.
Based on this information it may infer that a type does not exist in the base compilation but that type could be declared in a document that's out of date. As a result, the analysis may produce an insert edit for a type that already already exists in the compilation.

Possible solution would be to look up symbols from the baseline metadata for the first generation update in addition to the base source compilation (last committed solution).
Types can't be removed by EnC and therefore if the type exists in the baseline metadata it must exist in the base source compilation if it was up to date.