With the advanced grammar, only the last `- to` clause is respected

Metadata

Project: snapcraft
Number: #5255
Type: issue
State: open
Author: simondeziel
Labels: Status: Triaged Type: Bug
Created: 2025-02-11 09:48 PM UTC
Updated: 2025-06-12 12:58 PM UTC
Closed: —

Current evaluation

Advanced grammar bug: when a list has multiple `- to <arch>` clauses plus `else`, only the last `to` clause is respected, so e.g. armhf still pulls packages meant for other arches. Triaged, tracked upstream at craft-grammar#89, and added to a snapcraft pulse (June 2025) pending scoping; no fix yet.

Suggested action: keep open

Reason: Maintainers have triaged this (Status: Triaged, Type: Bug labels), filed the upstream bug at canonical/craft-grammar#89, and in June 2025 sergiusens asked to get it fixed next pulse and mr-cal confirmed it was added to the pulse pending scoping. The upstream craft-grammar#89 is still open and the current craft-grammar code still processes `to` clauses one at a time with no fix commit found, so the issue remains valid and actively tracked.

Impact: 65 Quick Win: 29.25 Staleness: 45 Complexity: 55 Confidence: 80 Support Request: 5

Issue body

### Bug Description In the LXD snap, we have some parts that are meant to be supported on some arches only. For example, we don't want to ship QEMU for `armhf` nor `riscv64`. As such, the `qemu` part is constructed to avoid installing the `build-packages` and the `stage-packages` when building for `armhf`/`riscv64`: ``` qemu: build-packages: - to armhf: - cmake # placeholder pkg (actually used by lxd part) to avoid installing build-packages on unsupported arches - to riscv64: - cmake # placeholder pkg (actually used by lxd part) to avoid installing build-packages on unsupported arches - else: - bison - ... - librbd-dev stage-packages: - to armhf: - acl # placeholder pkg (actually used by lxd part) to avoid installing stage-packages on unsupported arches - to riscv64: - acl # placeholder pkg (actually used by lxd part) to avoid installing stage-packages on unsupported arches - else: - genisoimage - ... - qemu-system-data # This is needed due to --disable-install-blobs. ... ``` However, only the last `- to $ARCH:` clause seems to be respected as on `armhf`, the builds on LP builders always fail complaining that `librbd-dev` is not available. `librbd-dev` is indeed not available for `armhf` which is the whole reason why we try to exclude it with the `- to`/`- else` clauses. The exclusion works for the `- to riscv64:` as neither `librbd-dev` nor `qemu-system-data` are found in the `riscv64` build logs. **important**: Inverting the `- to armhf:` and `- to riscv64:` made the `armhf` build work as it then stops trying to pull `librbd-dev` ### To Reproduce `snapcraft remote-build --platform amd64,armhf,riscv64` on a cloned repo from https://github.com/canonical/lxd-pkg-snap ### Environment ``` $ snap list snapcraft Name Version Rev Tracking Publisher Notes snapcraft 8.6.1 13459 latest/stable canonical✓ classic ``` ### snapcraft.yaml ```yaml https://github.com/canonical/lxd-pkg-snap/blob/f3327146996d52e66f8726a88766021f678e2575/snapcraft.yaml ``` ### Relevant log output ```shell Running pull phase... Initialising lifecycle Installing build-packages Cannot find package listed in 'build-packages': librbd-dev ``` ### Additional context _No response_

Evaluation history

Date	Model	Scores	Action	Summary
2026-09-01 02:52 AM UTC	qwen/qwen3.8-27b	Impact: 65 Quick Win: 29.25 Staleness: 45 Complexity: 55 Confidence: 80 Support Request: 5	keep open	Advanced grammar bug: when a list has multiple `- to <arch>` clauses plus `else`, only the last `to` clause is respected, so e.g. armhf still pulls packages meant for other arches. Triaged, tracked upstream at craft-grammar#89, and added to a snapcraft pulse (June 2025) pending scoping; no fix yet.
2026-07-22 12:14 PM UTC	qwen/qwen3.6-35b-a3b	Staleness: 65 Complexity: 45 Confidence: 90 Support Request: 5	keep open	Bug where multiple `- to <arch>` clauses in build/stage-packages only respect the last one. Triaged, upstream craft-grammar issue created, currently awaiting scoping for next pulse.
2026-07-08 05:04 PM UTC	qwen3.6-35b-a3b-mtp-q6	Staleness: 75 Complexity: 50 Confidence: 90 Support Request: 10	keep open	Bug in Snapcraft's advanced grammar where multiple - to <arch> clauses in package lists only respect the last one, causing incorrect package resolution on specific architectures. Currently triaged, with an upstream fix tracked and added to a development pulse for scoping.
2026-06-16 09:24 PM UTC	qwen3.6-35b-a3b-mtp-q6	Staleness: 15 Complexity: 40 Confidence: 90 Support Request: 0	keep open	Snapcraft grammar bug where only the last - to $ARCH: clause is respected, causing incorrect architecture-specific package installation. Triaged,

Update history

No update history recorded yet.

Related work

Blocked By: canonical/craft-grammar#89 (confidence 90%)
mr-cal explicitly filed this upstream bug for the same multiple-`to`-statement behavior; the fix belongs in the craft-grammar parser, so this snapcraft issue is blocked on that work.

Related issues

No related issues found above the similarity threshold.