fix: type aliases

[ldez]

Fixes #46

[Antonboom]

Thank you, @ldez

Can I ask you to copy-paste your example from issue in new testcase (pkg/analyzer/testdata/src)? And check change through TDD

Thanks 🙏

[ldez]

The examples come from the test cases of golangci-lint, I thought they were here too.

[ldez]

They are already inside your repo.

ex:

nilnil/pkg/analyzer/testdata/src/examples/positive.go

Lines 81 to 83 in 1d33958

	func m3() (mapAlias, error) {
	return nil, nil // want "return both a `nil` error and an invalid value: use a sentinel error instead"
	}

nilnil/pkg/analyzer/testdata/src/examples/positive_external_types.go

Lines 34 to 36 in 1d33958

	func ifaceTypeAliasedExtPkg() (closerAlias, error) {
	return nil, nil // want "return both a `nil` error and an invalid value: use a sentinel error instead"
	}

[ldez]

To reproduce:

• modify the min Go version inside the go.mod to go1.23.0
• run the tests

$ go test ./...
?       github.com/Antonboom/nilnil     [no test files]
--- FAIL: TestNilNil (0.93s)
    analysistest.go:614: examples/positive.go:68: no diagnostic was reported matching "return both a `nil` error and an invalid value: use a sentinel error instead"
    analysistest.go:614: examples/positive.go:82: no diagnostic was reported matching "return both a `nil` error and an invalid value: use a sentinel error instead"
    analysistest.go:614: examples/positive_external_types.go:35: no diagnostic was reported matching "return both a `nil` error and an invalid value: use a sentinel error instead"
    analysistest.go:614: examples/positive_own_types.go:34: no diagnostic was reported matching "return both a `nil` error and an invalid value: use a sentinel error instead"
FAIL
FAIL    github.com/Antonboom/nilnil/pkg/analyzer        0.947s
FAIL

I tried to set:

godebug (
    gotypesalias=1
)

with a min Go version 1.22 but this doesn't produce the error.

But the env var approach works:

$ GODEBUG=gotypesalias=1 go test ./...
?       github.com/Antonboom/nilnil     [no test files]
--- FAIL: TestNilNil (0.90s)
    analysistest.go:614: examples/positive.go:68: no diagnostic was reported matching "return both a `nil` error and an invalid value: use a sentinel error instead"
    analysistest.go:614: examples/positive.go:82: no diagnostic was reported matching "return both a `nil` error and an invalid value: use a sentinel error instead"
    analysistest.go:614: examples/positive_external_types.go:35: no diagnostic was reported matching "return both a `nil` error and an invalid value: use a sentinel error instead"
    analysistest.go:614: examples/positive_own_types.go:34: no diagnostic was reported matching "return both a `nil` error and an invalid value: use a sentinel error instead"
FAIL
FAIL    github.com/Antonboom/nilnil/pkg/analyzer        0.917s
FAIL

EDIT: I know why the godebug directive doesn't work inside the go.mod

To override these defaults, starting in Go 1.23, the work module’s go.mod or the workspace’s go.work can list one or more godebug lines:
https://go.dev/doc/godebug

So the godebug directive inside the go.mod doesn't work with go1.22

[Antonboom]

They are already inside your repo.

Oh, thanks, I completely forgot about it 🤦
Thanks for MR and digging