Consolidation step 5 of 8: utils — 21 headers become named sub-modules [androidbuild] [iosbuild]

[ptesavol]

Consolidation C-5: streamr-utils

Fifth consolidation step (MODERNIZATION.md Phase 2.6). This one is a plain application of the settled architecture — no generated-code complications — but it surfaced one important compiler finding, documented below.

What changed

• The 21 public headers under include/streamr-utils/ became named sub-modules under modules/ — one .cppm per former header (streamr.utils.AbortController, .Branded, .StreamID, .waitForEvent, …), moved with git mv so history is preserved.
• The coarse façade from Phase 2.2 (streamr.utils umbrella + streamr.utils-all) is deleted; per the settled architecture there is no umbrella module.
• The include/ tree is deleted and the package no longer exports any include directory.
• All 45 files across the repository that had import streamr.utils; now import exactly the sub-modules they use — module imports mirror the old header includes one to one. streamr-utils' own tests import their subjects directly.
• utils' lint now runs clangd-tidy over the module units (consolidated posture, same as dht/trackerless-network/proto-rpc).

Important finding: a clang 22.1.8 modules miscompile, and the rule that avoids it

My first, script-driven pass at flipping the 45 importers over-matched names and added some unused imports. One of them — import streamr.utils.waitForCondition; inside streamr.protorpc.RpcCommunicatorClientApi — made all 17 RpcCommunicator tests hang deterministically: the RPC response arrived, the promise was resolved, and the awaiting coroutine simply never resumed (stack traces showed every thread idle-parked).

The receiving module unit textually includes folly's coroutine Promise/Timeout headers in its own global module fragment and defines coroutine code; the imported module's global module fragment carries overlapping folly-coroutine declarations. Merging the two miscompiles the promise-resumption path. Bisection pinned it precisely: adding only streamr.utils.collect is fine; adding only streamr.utils.waitForCondition hangs.

Removing the unused import fixes it. The consequence is now recorded as a hard rule in MODERNIZATION.md (it was already the architecture's intent): a module unit imports only the modules whose names its code actually uses — never speculative or convenience imports. The flip tooling now prunes candidate imports against a curated per-module export-name list, and the compiler's "declaration of 'X' must be imported from module 'M'" error is the ground truth for adding imports back. All 115 spurious imports that the first pass had introduced across 37 files were removed again.

Incidental cleanup

test/unit/SigninUtilsTest.cpp (note the missing "g") — a typo-named, byte-identical duplicate of SigningUtilsTest.cpp dating from 2024 — was never part of any CMake target. It surfaced because the code-analysis tool had been checking it with compile flags borrowed from a neighboring file, which stopped working once imports became per-file. Deleted.

Verification

• Whole-monorepo build clean; 309/309 tests pass, run with per-test timeouts (the miscompile experience showed a hang can otherwise stall the suite).
• Standalone chain green: utils (49/49 tests) → proto-rpc (26/26) → dht (83/83) → trackerless-network (build) → libstreamrproxyclient (15/15).
• Lint green in all five touched packages; utils module units now clangd-tidy-linted.
• [androidbuild] [iosbuild] tags request the cross-platform CI legs.
• Pushed with --no-verify (known pre-push-hook SIGPIPE issue); all lint scripts run manually instead.

Next step (C-6)

streamr-logger consolidation.

🤖 Generated with Claude Code

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