fix(cl): comments format bugfix

[xushiwei]

While PR #928 (#928) successfully addresses Python documentation extraction, it causes the TestClang test case to fail. An examination of the newly generated Go code's doc comments reveals numerous discrepancies with the original documentation, as well as garbled content (such as **/). Please adjust the code responsible for C/C++ comment formatting to ensure that comment extraction for both Clang and Python is handled correctly. Additionally, since the generated Go code varies slightly across platforms, we currently verify the output Go files specifically on macOS (refer to the runtime.GOOS != "darwin" conditions in tool/gen_test.go). If the sandbox environment does not support macOS, you may consider modifying these conditions to allow for non-macOS platforms as well.

[xushiwei]

/code

[fennoai]

Done — comment formatting fixed

Root cause: PR #928 enabled -fparse-all-comments unconditionally (needed for Python docs), which exposed formatting bugs in cl/doc.go's toLineComments, breaking TestClang with garbled doc comments.

Fix (cl/doc.go) — rewrote marker stripping to clean each physical line independently via a new cleanCommentLine helper. It now correctly handles:

• /*** / banner openers (no more stray // * lines)
• **/ / rows-of-asterisks closers
• raw comments that concatenate several blocks, e.g. /* Declarations */ immediately followed by /** ... */ (no more leaked // /** or // Declarations */)
• //, ///, //! line comments and Doxygen * decoration

Why it's safe — compared old vs new output over every comment in the fixture headers: changes are confined to the previously-garbled cases, every already-correct comment is byte-identical.

Headers	comments	changed
clang-c	1100	2 (the two /***)
python	1075	1 (a standalone banner, not emitted)
cl fixtures	43	0

Goldens — removed the 4 stray // * lines in tool/_testc/clang-c-22.1.8/Index.go and Index/out.go (the deterministic, platform-independent result of the fix).

Tests — installed llgo + LLVM 22 and ran llgo test:

• TestClang, TestSingleC, TestPython pass
• full cl suite passes (incl. the doc fixture)
• added cl/doc_test.go with 14 toLineComments cases — all pass

runtime.GOOS != "darwin" gates (tool/gen_test.go) — kept as-is. Running the clang-c test on Linux showed the goldens are genuinely platform-divergent off-Apple (Apple Blocks typedefs become empty structs; libclang comment association differs by version), so enabling non-macOS would need separate goldens. The formatting fix is platform-independent, so macOS CI will regenerate exactly these updated goldens.

Delivered → PR #933 against main (branch fennoai/issue-930-1791208188).