preprocessor: stop macro-argument scan on an unexpected/EOF token

[EylonKrause]

Problem

VerilogPreprocess::ConsumeAndParseMacroCall hangs (infinite loop) on an unterminated macro call.

Root cause

The while (parameters_size > 0) argument-scan loop (verilog/preprocessor/verilog-preprocess.cc:252) only handles three token kinds: MacroArg, ,, and ). An unterminated call such as `FOO( at end of input leaves the current token as the EOF token, which matches none of the three branches — so neither token_iter nor parameters_size advances and the loop spins forever. This is reached from untrusted/truncated .sv via AnalyzeAutomaticPreprocessFallback (expand_macros=true) in both the linter and the LSP.

Fix

Break out of the loop on any other token; the existing trailing loop already back-fills the remaining parameters with default TokenInfo (the same terminal state an early ) produces), so the fix routes into a path the tests already exercise.

Related (not fixed here)

On the macro-expansion paths (ExpandMacro/ExpandText), the lexed sequence is built without a trailing EOF sentinel, so GenerateBypassWhiteSpaces can dereference an exhausted generator (crash) on similar input. That needs a separate structural fix (append an EOF sentinel / add an end-guard) — happy to follow up in a second PR.

Verification

Static reasoning; the `MACRO3 () test already exercises the all-defaults back-fill path this fix routes into. (Bazel build not set up locally.)

[linux-foundation-easycla]

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• ✅ login: EylonKrause / name: Eylon Krause (1ac0e86, e626007)

[EylonKrause]

Disclosure: this contribution was authored with an AI coding assistant (Claude) and reviewed before submission.

[hzeller]

I wonder if instead of silently accepting the issue, we should may return absl::InvalidArgumentError() ?

[EylonKrause]

Good idea — done. ConsumeAndParseMacroCall now returns absl::InvalidArgumentError when the argument scan hits an unexpected token (in particular the EOF of an unterminated call), and the caller (HandleMacroIdentifier) records it as a preprocessor error at the call site, so a malformed call surfaces a real diagnostic instead of being silently back-filled. An early ) remains the legal way to pass fewer arguments than parameters. The test now asserts the error is reported.

(ConsumeAndParseMacroCall is static, so it can't push to preprocess_data_.errors itself; the caller records the returned message — mirroring the existing undefined-macro path.)