apache/beam · error

expected to end with . can't generate valid code

Error message

expected %v to end with %v. can't generate valid code

What it means

checkImportSuffix validates that generated shim code's beam import paths end with an expected package suffix (e.g. SchemaImport ends with "schema", SdfImport ends with "sdf"); otherwise the generated code would not compile, so it panics with 'can't generate valid code'.

Solutions

1. Correct the import path constant so it ends with the required suffix ("schema"/"sdf")
2. If the package moved, keep or alias the final path segment to match the expected suffix
3. Update the suffix expectation in generate.go if the suffix contract legitimately changed
4. Run the generator's tests to catch suffix mismatches before code generation

Example fix

// before
const SchemaImport = "github.com/myfork/beam/sdks/go/pkg/beam/x/data"
// after
const SchemaImport = "github.com/myfork/beam/sdks/go/pkg/beam/x/schema"

if !strings.HasSuffix(SchemaImport, "schema") {
	return fmt.Errorf("SchemaImport %q must end with 'schema'", SchemaImport)
}

func endsWith(path, suffix string) bool { return strings.HasSuffix(path, suffix) }

When it happens

Trigger: Calling validateBeamImports (or checkImportSuffix directly) with an import path whose final segment doesn't match the required suffix — e.g. after renaming/moving the beam schema or SDF packages or overriding import constants with a wrong path.

Common situations: Forking Beam and changing module paths so sdks/go/pkg/beam/x/schema no longer ends in "schema"; typos when updating import path constants; vendoring rewrites (e.g. replace directives) altering the path tail.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• AfterProcessingTime trigger set without a delay or…
• At least one subtrigger required for composite triggers.
• attempted to add namespace to missing coder id
• attempted to add namespace to missing windowing strategy id
• batch: failed to marshal worker UUID

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/8663918f9cb67378. Report an issue: GitHub.

Appendix: source

Thrown at sdks/go/pkg/beam/util/shimx/generate.go:68

	TypexImport    = "github.com/apache/beam/sdks/v2/go/pkg/beam/core/typex"
	ReflectxImport = "github.com/apache/beam/sdks/v2/go/pkg/beam/core/util/reflectx"
	RuntimeImport  = "github.com/apache/beam/sdks/v2/go/pkg/beam/core/runtime"
	SchemaImport   = "github.com/apache/beam/sdks/v2/go/pkg/beam/core/runtime/graphx/schema"
	SdfImport      = "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf"
)

func validateBeamImports() {
	checkImportSuffix(ExecImport, "exec")
	checkImportSuffix(TypexImport, "typex")
	checkImportSuffix(ReflectxImport, "reflectx")
	checkImportSuffix(RuntimeImport, "runtime")
	checkImportSuffix(SchemaImport, "schema")
	checkImportSuffix(SdfImport, "sdf")
}

func checkImportSuffix(path, suffix string) {
	if !strings.HasSuffix(path, suffix) {
		panic(fmt.Sprintf("expected %v to end with %v. can't generate valid code", path, suffix))
	}
}

// Top is the top level inputs into the template file for generating shims.
type Top struct {
	FileName, ToolName, Package string

	Imports   []string // the full import paths
	Functions []string // the plain names of the functions to be registered.
	Types     []string // the plain names of the types to be registered.
	Wraps     []Wrap
	Emitters  []Emitter
	Inputs    []Input
	Shims     []Func
}

// sort orders the shims consistently to minimize diffs in the generated code.
func (t *Top) sort() {

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