Go: imports of multi-file packages are dropped from --deps and --importers

[JordanCoin]

Summary

In a Go module, an import of a package that has two or more non-test .go files produces no edge. --deps lists every file in that package as standalone. --importers <file> says "No files import" and reports Coverage: complete. Imports of packages with exactly one non-test file resolve correctly.

Minimal repro

go.mod           module example.com/demo
single/single.go package single    (1 file)
single2/impl.go  package single2   (1 file, name differs from package)
multi/a.go       package multi     (2 files)
multi/b.go
named/named.go   package named     (2 files, one named after the package)
named/other.go
app/main.go      imports all four packages and calls into each

go build ./... succeeds.

$ codemap --deps .
  main ───▶ single/single, single2/impl
  +2 standalone files      # multi
  +2 standalone files      # named
7 files · 7 functions · 2 deps

$ codemap --importers multi/a.go .
No files import multi/a.go.
   Note: files in the same package never import each other ...
Coverage: complete

It's the same for multi/b.go, named/named.go and named/other.go. single2/impl.go resolves, so the file name doesn't matter. The only thing that decides it is the file count.

Same on this repo (v4.5.1)

$ grep -rl '"codemap/watch"' . | grep '\.go$' | grep -v '^./watch/' | wc -l
21
$ codemap --importers watch/events.go .
No files import watch/events.go.

analysis/contracts.go resolves (30 importers), because analysis/ has a single non-test file.

Impact

• Hub detection, blast radius and --importers undercount any package split across files, which is most real Go packages.
• The false negative is presented as complete coverage. "No files import X" is exactly the answer a caller acts on when deciding whether something is safe to change or delete.

Expected

An import of example.com/demo/multi links the importer to every non-test file in multi/, or to a package node that --importers expands. Either way, --importers multi/a.go lists app/main.go.

Related

#138 part 1 attributes "No files import" on Go files to same-package references not being modeled. This is a separate and larger gap: cross-package importers are also missed whenever the target package has more than one file.