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Remove validateFunctionVersions feature flag before v0.24 release (graduate to always-on) #342
Description
Context
PR #296 (function version validation) introduced the validateFunctionVersions feature flag to gate ValidateFunctionVersionSupport validation behind an opt-in context key. This validation checks that Terraform functions used through Fn.* are supported by the declared targetVersions at synth time.
The flag was intentionally behind a feature flag to avoid breaking existing projects in a minor release. New projects created via cdktn init automatically get the flag enabled through FUTURE_FLAGS.
Why now
The v0.23 → v0.24 release is a pre-v1 breaking-change-equivalent version bump. Per the feature flag lifecycle in CONTRIBUTING.md, v0.24 is the correct window to graduate the flag to always-on. If we miss this window, the flag stays gated until v0.25.
Must land BEFORE the v0.24 release is cut. Depends on PR #303.
What needs to change
- Always register validation —
terraform-stack.ts:134: remove theif (this.node.tryGetContext(VALIDATE_FUNCTION_VERSIONS))gate, always callthis.node.addValidation(new ValidateFunctionVersionSupport(this)) - Remove from
FUTURE_FLAGS—features.ts:43: dropVALIDATE_FUNCTION_VERSIONSfrom theFUTURE_FLAGSmap - Stop injecting into new projects —
cli-core/src/lib/init.ts:FUTURE_FLAGSiteration will naturally skip it - Update tests —
validations.test.ts: tests that pass[VALIDATE_FUNCTION_VERSIONS]: "true"need updating; default (no-flag) behavior becomes the validated behavior - Update integration test config —
test/typescript/function-version-validation/cdktf.json: drop the flag from context
Acceptance criteria
-
ValidateFunctionVersionSupportruns on everyTerraformStackregardless of context -
validateFunctionVersionsis removed fromFUTURE_FLAGS -
cdktn initno longer generates the flag incdktf.json - All tests pass with validation as the default behavior
- Tests cover both always-on validation and the no-targeted-functions path
Flagged during review of PR #296 by @so0k. /cc @jsteinich
Activity
so0k commentedon Jul 30, 2026
PR #362 implements this.
Approach: deleted outright, no no-op shim — following this repo's one existing precedent,
3c323e76d(which graduatedEXCLUDE_STACK_ID_FROM_LOGICAL_IDSandALLOW_SEP_CHARS_IN_LOGICAL_IDS)."Keep it accepted but ignored" turns out to already be what deletion gives us:
cdktf.json'scontextisreadonly context?: { [key: string]: any }(packages/@cdktn/commons/src/config.ts:296), passed straight through with no schema, allowlist, or unknown-key check anywhere in the CLI. An existingcdktf.jsonthat still sets"validateFunctionVersions": "true"keeps working — the key just becomes inert. There's no hard-fail to protect against, so a shim would be dead code.Confirmed no
.jsiiAPI diff:features.tsisn't re-exported frompackages/cdktn/src/index.ts, so the constant was never part of the public/JSII surface. Your item 3 is handled automatically —init.tsiteratesObject.entries(FUTURE_FLAGS)generically, socdktn initstops emitting the key without a code change.One consequence worth recording
Six tests in the
ValidateFunctionVersionSupportblock registered the validation manually on a resource, precisely because the constructor gate was off by default. With the gate always-on, everyTerraformStackalso registers a stack-scoped instance and both read the samestack._getUsedFunctions()— so each error gets reported twice, under[MyStack/testResource]and[MyStack].Dropping those manual registrations makes the tests exercise the real always-on path, and the inline snapshots re-prefix to
[MyStack]. The pre-existing interleaved-Apps test, which already relied on automatic registration, confirms that's the right prefix. This is why the test diff is bigger than a find/replace.Verification
Full
cdktnsuite compared against untouchedorigin/mainin a separate worktree: identical — 1 failed / 541 passed on both, the one failure being the pre-existingmatchers › toPlanSuccessfullytest that needs a realterraformbinary.Not verified locally: the
typescript/function-version-validationintegration test needspnpm package(somvn+dotnet), which wasn't available on the machine used. CI should cover it.feat(lib)!: validate Terraform function versions by default (open-con…
feat(lib)!: validate Terraform function versions by default (open-con…
github-actions commentedon Aug 30, 2026
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