[SR-3908] Extension methods visible without importing module in a file

[aciidgh]

Previous ID	SR-3908
Radar	rdar://problem/16154294
Original Reporter	@aciidb0mb3r
Type	Bug

Attachment: Download

Additional Detail from JIRA

Votes	9
Component/s	Compiler
Labels	Bug
Assignee	None
Priority	Medium

md5: 7cc3dd991a1637efb2f2ca9e6d75b83d

is duplicated by:

• [SR-4521] Framework extensions are accessible inside file without import #47098
• [SR-4654] Struct extension implicitly imported from framework #47231
• [SR-8353] Public extensions of shared types in a framework are visible without importing it #50881
• [SR-9913] Transitive dependencies and extensions of standard types #52319

Issue Description:

The attached package contains three targets:

1. foo - defines a Version struct which can be initialized by a string param.
2. bar - depends on foo and defines an extension with an initializer to Version with no parameters
3. exe - depends on foo and bar and has two files.

• other.swift - imports bar
• main.swift - imports foo and calls Version()

This should not compile or run because Version() is defined in bar and bar is not imported in main.swift.
It works as expected after removing import bar from other.swift (needs a swift package clean though).

[belkadan]

Old, old bug. :-)

[swift-ci]

Comment by Fabio Mignogna (JIRA)

Any news on this bug?

[notapplicableio]

Looks like this is still a thing in Xcode 14.3/Swift 5.8

[piotrsmajek]

XCode 15.0/Swift 5.9 same problem

[KeithBauerANZ]

Made a longwinded thread that eventually tracked back here: https://forums.swift.org/t/find-how-a-symbol-was-imported/68052

[tshortli]

This is addressed by #72974 in the Swift 6.0 compiler, but behind a feature flag for now.

[tshortli]

I posted a Swift Evolution pitch: https://forums.swift.org/t/pitch-fixing-member-import-visibility/71432