Ambiguous symbol import error is too restrictive

[Akirathan]

PR #6868 introduces an ambiguous symbol import error that is thrown once some import statement imports a symbol that has already been imported by a different import and points to a different entity. This seems too restrictive. We should report this error only if the symbol is used.

The following example unnecessarily results in an ambiguous symbol import error:
Lib1/src/Main.enso:

type S
export project.S

Lib2/src/Main.enso:

type S
export project.S

New_Project/Main.enso:

from Lib1 import all
from Lib2 import all

# Never use symbol S

Currently, this will result in a compiler error about ambiguous symbol S - this first import points to Lib1.S and the second one to Lib2.S. This is too restrictive. We want to defer this error until the symbol S is actually used for the first time.

Currently, both our Standard.Base and Standard.Table have Data directories that can potentially be exported. If they are exported, we will have this ambiguous error.

The solution should probably be to modify AliasAnalysis to include symbols from imports. More specifically, to attach metadata to imported symbols?

[JaroslavTulach]

Don't we have hidding to resolve the clashes?

[Akirathan]

Don't we have hidding to resolve the clashes?

@JaroslavTulach Yes. hiding is an obvious fix. Closing this issue as not relevant at the moment.