CNA-BUG-269: cna_validate_renderer_identity_selection says it checks the per-identity CNA_RENDERER_<X> switches, but only retired names are checked: a misspelled or unknown switch is never read and the platform's default renderer is configured silently

CNA snapshot 009d40f5  ·  Known Issues › Current bugs  ·  source links pinned to 009d40f5

The validator's comment promises to check the CNA_RENDERER_<X> switches, but it only loops over retired names; -DCNA_RENDERER_D3D9=ON or a typo is neither an error nor honoured, and the platform's default renderer is configured without a diagnostic.

Identifier

CNA-BUG-269

Category

Bug

Subsystem

Build & CI

Status

Open

Verified against

CNA 009d40f5 (009d40f5dd085c4e674d3479675fac84b12b3e0a)

Severity

Low (a triage suggestion, not a project priority)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

Yes: see Current tests

Affected contract

cmake/RendererIdentities.cmake::cna_validate_renderer_identity_selection and the per-identity CNA_RENDERER_<X> configure switches

Expected behaviour

The comment above the function says it “checks every route that can name a renderer: CNA_GRAPHICS_RENDERER, each member of CNA_GRAPHICS_RENDERERS, and the per-identity CNA_RENDERER_<X> switches”, and the other two routes report an unknown name at configure time (cna_require_public_renderer_identity: “unknown graphics renderer … (requested through …)”). A misspelled switch should get the same error instead of a silent fallback.

Actual behaviour at TARGET

RendererIdentities.cmake tests CNA_RENDERER_<X> only inside a loop over the list of retired identities, and for those it requires a public one. For any other name, such as an old renderer spelling or a typo, the variable is never read: RendererSelection.cmake consults a switch only for the names in the public identity list, so the configure succeeds and the platform's default renderer is selected. The only diagnostic is CMake's own generic 'Manually-specified variables were not used by the project' warning, printed after the configure summary and only for values given with -D or a preset; it names the variable but not the cause, and CNA's own header, plan and tests treat an unread selector as the silent fallback this file exists to close.

Source locations

• cmake/RendererIdentities.cmake — cna_validate_renderer_identity_selection: the CNA_RENDERER_<X> route is checked only for retired names
• cmake/RendererSelection.cmake — the switch loop over CNA_RENDERER_PUBLIC_IDENTITIES
• cmake/Tests/RendererRetiredIdentityCase.cmake — the retired-name case is tested; an unknown name is not

Evidence

Read at 009d40f5; nothing was configured. Found by the C13 conservation reviewer (glossary appendix) and re-verified by the orchestrator against the validator, the selection loop and the tests under cmake/Tests.

Focused reproduction

No focused reproduction is known. Nothing has been invented here; the evidence above is what exists.

Current tests

cmake/Tests/RendererRetiredIdentityCase.cmake pins the error for a retired name; nothing exercises an unknown or misspelled CNA_RENDERER_<X> switch.

Regression test

Configure with -DCNA_RENDERER_NOSUCH=ON and expect a configure-time error naming the switch and the supported identities, next to the existing retired-identity case.

Blast radius

Builds that select a renderer with an -DCNA_RENDERER_<X>=ON switch and misspell or use a stale name (for example a pre-rename spelling): the build succeeds with the host's default renderer instead of the intended one.

Workaround

Select the renderer with CNA_GRAPHICS_RENDERER (or CNA_GRAPHICS_RENDERERS), which reject unknown names at configure time.