Fix build failure with GCC 14+ (C23 bool keyword and -Wint-conversion) by messere1 · Pull Request #1385 · IvorySQL/IvorySQL

messere1 · 2026-07-09T09:02:25Z

Related Issue

Motivation

GCC 14 and 15 default to -std=gnu23, where bool, true, and false are C language keywords. This breaks the IvorySQL build in two places with IvorySQL-specific (non-upstream) code:

Error 1 — src/interfaces/libpq/libpq-fe.h:79:

libpq-fe.h:79:23: error: 'bool' cannot be defined via 'typedef'
   79 | typedef unsigned char bool;
      |                       ^~~~
libpq-fe.h:79:23: note: 'bool' is a keyword with '-std=c23' onwards

The existing guard #if !(defined(true) && defined(false)) is insufficient under C23: true/false may not be defined as macros even though bool is a built-in keyword, so the typedef is still emitted and fails.

Error 2 — contrib/ivorysql_ora/src/xml_functions/ora_xml_functions.c:2469:

ora_xml_functions.c:2469:16: error: returning 'void *' from a function with return type 'Datum' {aka 'long unsigned int'} makes integer from pointer without a cast [-Wint-conversion]
 2469 |         return NULL;
      |                ^~~~

ivy_xmlisvalid() is declared PG_FUNCTION_INFO_V1 returning Datum, but its #else (no libxml) fallback did return NULL;. GCC 14 promotes -Wint-conversion to an error by default.

Note: The uuid-ossp errors also shown in the issue are tracked separately in #979 and are not addressed here.

Changes

src/interfaces/libpq/libpq-fe.h — Extend the guard so the typedef unsigned char bool; is skipped under C23 (__STDC_VERSION__ >= 202311L) and C++ (__cplusplus), mirroring the pattern already used in src/include/c.h:
```
#if !defined(__cplusplus) && !(defined(true) && defined(false)) && \
    !(defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L)
typedef unsigned char bool;
#endif
```
contrib/ivorysql_ora/src/xml_functions/ora_xml_functions.c — In ivy_xmlisvalid(), replace return NULL; with return 0; in the !USE_LIBXML fallback, matching the upstream PostgreSQL src/backend/utils/adt/xml.c convention for Datum-returning SQL functions.

How Verified

Code review confirms both changes follow established PostgreSQL/IvorySQL patterns (c.h C23 guard; xml.c return 0 fallback).
Cannot compile-test GCC 14+ from the current Windows environment; CI on this PR (ubuntu-latest with recent GCC) will validate. The fix is minimal and mechanical.
The change is backward-compatible: under C11/C17 (__STDC_VERSION__ < 202311L) the original typedef behavior is preserved exactly.

Summary by CodeRabbit

Bug Fixes
- Improved XML validation behavior when XML support is unavailable, returning a clearer failure result instead of an unexpected value.
- Enhanced compatibility with newer C language versions and C++ builds, reducing build issues related to boolean type handling.

GCC 14 and 15 default to -std=gnu23, where 'bool' is a keyword. This causes two compile errors in IvorySQL-specific code: 1. src/interfaces/libpq/libpq-fe.h defines 'typedef unsigned char bool'. The existing guard '#if !(defined(true) && defined(false))' is not sufficient under C23, because true/false may not be defined as macros even though bool is a built-in keyword. Add a check for __STDC_VERSION__ >= 202311L (and __cplusplus) to skip the typedef, mirroring the pattern used in src/include/c.h. 2. contrib/ivorysql_ora/.../ora_xml_functions.c: ivy_xmlisvalid() returns Datum but the !USE_LIBXML fallback did 'return NULL'. With GCC 14's -Wint-conversion promoted to error, this fails. Replace with 'return 0' to match the upstream PostgreSQL xml.c pattern. Fixes IvorySQL#1351.

coderabbitai · 2026-07-09T09:03:01Z

No actionable comments were generated in the recent review. 🎉

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Run ID: 2ac5d078-21c8-4325-a296-0f3dd22dfd26

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Reviewing files that changed from the base of the PR and between 7fb2571 and 0b63396.

📒 Files selected for processing (2)

contrib/ivorysql_ora/src/xml_functions/ora_xml_functions.c
src/interfaces/libpq/libpq-fe.h

📝 Walkthrough

Walkthrough

Two independent build-compatibility fixes: the fallback return in ivy_xmlisvalid now returns 0 instead of NULL to match its Datum return type, and the libpq-fe.h fallback bool typedef guard now excludes C++ and C23-capable compilers to avoid redefinition errors.

Changes

C23 Build Compatibility Fixes

Layer / File(s)	Summary
Fix Datum return type mismatch `contrib/ivorysql_ora/src/xml_functions/ora_xml_functions.c`	`ivy_xmlisvalid`'s non-`USE_LIBXML` fallback now returns `0` instead of `NULL`, fixing an integer-from-pointer conversion error since the function returns `Datum`.
Guard bool typedef for C23/C++ `src/interfaces/libpq/libpq-fe.h`	The preprocessor condition for the fallback `typedef unsigned char bool;` now also excludes `__cplusplus` and `__STDC_VERSION__ >= 202311L`, preventing redefinition errors on C23-capable compilers.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Possibly related PRs

IvorySQL/IvorySQL#720: Prior PR that added the ivy_xmlisvalid fallback logic in the same function/module now modified here.

Suggested reviewers: yuanyl630

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the GCC 14+/C23 build fix and the two code paths changed.
Linked Issues check	✅ Passed	The PR addresses `#1351` by guarding the bool typedef in C23/C++ and fixing the Datum return in ivy_xmlisvalid.
Out of Scope Changes check	✅ Passed	All changes align with the reported GCC 14+/C23 build failure and no unrelated modifications are present.

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Pull request overview

This pull request fixes IvorySQL build failures with GCC 14+ (defaulting to -std=gnu23) by avoiding a C23/C++-conflicting bool typedef in libpq-fe.h and correcting a Datum-returning SQL function fallback that previously returned NULL (pointer) instead of an integer Datum.

Changes:

Skip typedef unsigned char bool; in src/interfaces/libpq/libpq-fe.h when compiling as C++ or C23 (__STDC_VERSION__ >= 202311L), preventing GCC 14+ errors where bool is a keyword.
Replace return NULL; with return 0; in the !USE_LIBXML fallback path of ivy_xmlisvalid() to avoid -Wint-conversion errors and match existing NO_XML_SUPPORT(); return 0; conventions.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/interfaces/libpq/libpq-fe.h	Extends the `bool` typedef guard to avoid redefining `bool` under C23 and C++.
contrib/ivorysql_ora/src/xml_functions/ora_xml_functions.c	Fixes `ivy_xmlisvalid()` fallback to return a valid `Datum` (`0`) after `NO_XML_SUPPORT()`.

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bigplaice · 2026-07-10T02:14:05Z

@hanjianqiao please follow up this pr.

hanjianqiao · 2026-07-10T02:18:24Z

@messere1 Welcome to contribute to the IvorySQL community! The regression checks has started and we will review the code soon.

Copilot AI review requested due to automatic review settings July 9, 2026 09:02

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Fix build failure with GCC 14+ (C23 bool keyword and -Wint-conversion)#1385

Fix build failure with GCC 14+ (C23 bool keyword and -Wint-conversion)#1385
messere1 wants to merge 1 commit into
IvorySQL:masterfrom
messere1:fix/issue-1351-gcc14-c23-bool

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messere1 commented Jul 9, 2026 •

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