Load input failed: unknown package error with aliased imports

[jDomantas]

Actual behavior

File contents:

// file subpkg/alphabetically_first.go
package subpkg

import (
	"time"
)

var _ time.Time


// file subpkg/alphabetically_second.go
package subpkg

import (
	aliased_time_import "time"
)

type I1 interface {
	Foo(t aliased_time_import.Time)
}


// file x.go
package mockgen_repro

import "mockgen_repro/subpkg"

type I2 interface {
	subpkg.I1
}


// file go.mod
module mockgen_repro

go 1.24.0

Mockgen in source mode on x.go fails:

# mockgen -source x.go
2025/05/20 11:53:46 Loading input failed: .../mockgen_repro/subpkg/alphabetically_second.go:8:5: failed parsing arguments: .../mockgen_repro/subpkg/alphabetically_second.go:8:8: unknown package "aliased_time_import"

Expected behavior

Mock generation should succeed (like it does if I rename alphabetically_first.go and alphabetically_second.go to be ordered the other way around).

Additional Information

• gomock mode (reflect or source): source
• gomock version or git ref: v0.5.2
• golang version: 1.24.0

Triage Notes for the Maintainers

There is some existing discussion about this bug in #166, but the original reported bug there was different and the issue got closed, so I'm reporting it here again with the reproduction specifically for the issue that I encountered.

[hdimer]

Root cause: in source mode, parsePackage reads the imported package's imports from ast.MergePackageFiles(..., FilterImportDuplicates). That filter dedupes imports by path, so when one file imports a package plainly and another aliases it, the alias gets dropped and referencing it later fails with unknown package. Reading imports per-file instead of from the merged file keeps the alias. Opened #311 with the fix and a regression test.