Fix expect.h

[Lightning11wins]

There were a couple bugs with #86, mostly caused by me not knowing how to write m4 macros that actually work. This should fix those issues.

[greptile-apps]

Greptile Summary

This PR fixes the bugs introduced in #86 by correcting a trailing comma in the AC_COMPILE_IFELSE m4 macro call inside centrallix-lib/aclocal.m4, and by properly consolidating HAVE_BUILTIN_EXPECT into centrallix-lib's public config header (cxlibconfig.h.in) so that the external expect.h can reference it. The CHECK_BUILTIN_EXPECT check is removed from the centrallix module since it is now exclusively owned by centrallix-lib.

Confidence Score: 5/5

Safe to merge — the changes correctly fix the m4 syntax bug and consolidate the build-detect define into the right public header.

Only finding is a P2 comment typo; no logic or correctness issues.

No files require special attention.

Important Files Changed

Filename	Overview
centrallix-lib/aclocal.m4	Removed trailing comma after the action-if-false argument of AC_COMPILE_IFELSE — the core bug fix from PR #86.
centrallix-lib/include/expect.h	Added HAVE_CONFIG_H/CXLIB_INTERNAL include guards to pull in cxlibconfig.h; indentation cleaned up; fallback macros now normalize to 0/1 via !!.
centrallix-lib/include/cxlibconfig.h.in	HAVE_BUILTIN_EXPECT moved here from centrallix/config.h.in so the public expect.h header can reference it; two typos in the new comment block.
centrallix-lib/include/cxlibconfig-internal.h.in	Added a clarifying comment block explaining that this file is for centrallix-lib-internal defines only.
centrallix/aclocal.m4	Removed the now-redundant CHECK_BUILTIN_EXPECT macro; the check lives exclusively in centrallix-lib/aclocal.m4.
centrallix/configure.ac	Removed the CHECK_BUILTIN_EXPECT call to match the macro removal in aclocal.m4.
centrallix/config.h.in	Removed HAVE_BUILTIN_EXPECT from centrallix's own config header; centrallix now gets the define via centrallix-lib's cxlibconfig.h.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[centrallix-lib/aclocal.m4
CHECK_BUILTIN_EXPECT macro] -->|AC_COMPILE_IFELSE fixed| B{builtin_expect
available?}
    B -->|yes| C[Define HAVE_BUILTIN_EXPECT
in cxlibconfig.h]
    B -->|no| D[No define set]
    C --> E[expect.h]
    D --> E
    E -->|CXLIB_INTERNAL defined| F[include cxlibconfig.h directly]
    E -->|external use| G[include cxlib/cxlibconfig.h]
    F --> H{HAVE_BUILTIN_EXPECT?}
    G --> H
    H -->|yes| I[LIKELY and UNLIKELY
use builtin_expect]
    H -->|no| J[LIKELY and UNLIKELY
fallback to normalized x]

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_{Reviews (4): Last reviewed commit: "Modify LIKELY() and UNLIKELY() to always..." | Re-trigger Greptile}

[Lightning11wins]

Not sure what this concern about "when a translation unit includes both config.h and CFLAGS=-DHAVE_BUILTIN_EXPECT" means. It sounds like it could be an issue but I don't understand what this means.

[Lightning11wins]

@greptileai The previous fix was badly designed, so I've fixed the fix. Please re-review.

[Lightning11wins]

@gbeeley @nboard
PR cleared for human review.

[Lightning11wins]

I realized today that guaranteeing that the return values is normalized is useful functionality, so I'm adding a TODO to make that change before we merge this.

[Lightning11wins]

Alright, the functions now always normalize values.

Once again, this PR cleared for human review.

[Lightning11wins]

Once again, this PR is still cleared for human review.

[gbeeley]

One small change needed - thanks!

[gbeeley]

Ideally these should be (!!(x))

[Lightning11wins]

Oops, you're right. Fixed.

[Lightning11wins]

I don't know why there was a merge conflict, but I fixed it.