Motivation: add a check for a common issue I see humans and AI agents
making, so that we don't have to waste time on it in code reviews.
Resolves#42635
Note: This lint check has been mostly AI generated. I don't think it
needs a thorough review because it is not production code and not even
test code. Any issues will be obvious from usage by contributors.
Add a custom go/analysis analyzer that detects map[T]bool variables
used as sets (where only the literal `true` is ever assigned) and
suggests using map[T]struct{} instead, which is the idiomatic Go
approach for sets — zero memory for values and unambiguous semantics.
The analyzer minimizes false positives by:
- Only flagging when ALL indexed assignments use the literal `true`
- Skipping variables initialized from function calls (unknown source)
- Skipping variables reassigned from unknown sources
- Skipping function parameters and exported package-level variables
- Skipping range loop variables
Integrated as an incremental linter (new/changed code only) to avoid
breaking existing code.
Running this check on our whole codebase flags valid cases:
```
cmd/fleet/serve.go:306:2: map[string]bool used as a set; consider map[string]struct{} instead (setboolcheck)
allowedHostIdentifiers := map[string]bool{
^
cmd/fleetctl/fleetctl/generate_gitops.go:189:3: map[string]bool used as a set; consider map[string]struct{} instead (setboolcheck)
handled := make(map[string]bool, len(renames)*2)
^
cmd/fleetctl/fleetctl/generate_gitops.go:1593:2: map[uint]bool used as a set; consider map[uint]struct{} instead (setboolcheck)
m := make(map[uint]bool, len(ids))
```
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Chores**
* Added a new code analyzer to detect maps used as boolean sets and
recommend more efficient alternatives for better performance.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
---------
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Scott Gress <scottmgress@gmail.com>
Co-authored-by: Scott Gress <scott@fleetdm.com>
**Related issue:** Resolves#32999
- Enhanced internal code quality tooling by implementing a custom
linting build configuration.
- Updated continuous integration workflow to utilize the new custom
build process for improved code analysis and consistency checks.
### Confirmed that running local custom `golangci-lint` build with
`nilaway` plugin catches lots of issues when run on `fleet/`:
<img width="1555" height="939" alt="Screenshot 2026-01-29 at 2 47 50 PM"
src="https://github.com/user-attachments/assets/c6a18400-fdf0-4104-97d8-e117efc28ed6"
/>
<img width="301" height="109" alt="Screenshot 2026-01-29 at 2 48 36 PM"
src="https://github.com/user-attachments/assets/b459ee7b-b391-457a-9191-17d56a80c783"
/>
### Confirmed that new incremental CI step using custom `golangci-lint`
build with `nilaway` plugin _does not_ check any `.go` files when none
have been modified, and so passes successfully (incremental check works
as expected):
<img width="337" height="197" alt="Screenshot 2026-01-29 at 2 45 24 PM"
src="https://github.com/user-attachments/assets/c7ae585e-2e10-4ebf-a3a3-96c26063f1e4"
/>
### Confirmed that new incremental CI step using custom `golangci-lint`
build with `nilaway` plugin _does_ check modified lines of `.go` files,
and so successfully flags a potentially unsafe dereference and fails the
job (incremental check works as expected):
<img width="825" height="491" alt="Screenshot 2026-01-29 at 5 50 01 PM"
src="https://github.com/user-attachments/assets/82bc5616-6fb9-4357-b8bc-c7eebc42c2d8"
/>
### Honorable mention:
`nilaway` agrees that `listHostSoftware` is a wild beast:
<img width="1277" height="190" alt="Screenshot 2026-01-29 at 5 52 32 PM"
src="https://github.com/user-attachments/assets/dfade2a8-fbcc-4bae-98f9-6bf1089620d2"
/>
- [x] QA'd all new/changed functionality manually
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Fleet dev cycle reliability improvements**
<sub>✏️ Tip: You can customize this high-level summary in your review
settings.</sub>
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
---------
Co-authored-by: Victor Lyuboslavsky <2685025+getvictor@users.noreply.github.com>
