MSVC Compat 1 v2: Reconcile attributes and math macros by lbartoletti · Pull Request #805 · postgis/postgis

lbartoletti · 2025-05-16T06:53:37Z

This PR supersedes https://git.osgeo.org/gitea/postgis/postgis/pulls/208 and #777.

@ralian If I'm not mistaken, you don't need to include _USE_MATH_DEFINES in multiple files. It can be defined once globally. Could you test this PR?
If the AC_DEFINE approach is not sufficient, you can define it by adding CPPFLAGS="$CPPFLAGS -D_USE_MATH_DEFINES".

I'm also proposing an alternative version of the attribute macro that could be reused elsewhere in the codebase.

Introduce PRINTF_FORMAT(fmt, args) macro in new header `lwgeom_config.h` to handle GCC and Clang-specific printf format checking. This improves portability by avoiding direct usage of `__attribute__((format))` in function declarations. Affected functions: - lwnotice - lwerror - lwdebug - GEOSMessageHandler - lwgeom_geos_error

lbartoletti · 2025-05-16T06:55:46Z

@robe2 @strk as mentioned on IRC/Matrix months ago, I also tried to switch from gnu11 to c11 in another branch. It's OK for *BSD (FreeBSD and macOs tested) but not for Linux, because of a problem in PostgreSQL elog.h (sigjmp_buf not defined):

In file included from /usr/local/pgsql/include/server/postgres.h:47,
from lwgeom_pg.c:17:
/usr/local/pgsql/include/server/utils/elog.h:358:20: error: unknown type name 'sigjmp_buf'
358 | extern PGDLLIMPORT sigjmp_buf *PG_exception_stack;
| ^~~~~~~~~~
In file included from /usr/local/pgsql/include/server/postgres.h:47,
from lwgeom_transform.c:15:
/usr/local/pgsql/include/server/utils/elog.h:358:20: error: unknown type name 'sigjmp_buf'
358 | extern PGDLLIMPORT sigjmp_buf *PG_exception_stack;
| ^~~~~~~~~~
In file included from /usr/local/pgsql/include/server/postgres.h:47,
from lwgeom_cache.c:13:
/usr/local/pgsql/include/server/utils/elog.h:358:20: error: unknown type name 'sigjmp_buf'
358 | extern PGDLLIMPORT sigjmp_buf *PG_exception_stack;
| ^~~~~~~~~~
In file included from /usr/local/pgsql/include/server/postgres.h:47,
from gserialized_gist.c:17:
/usr/local/pgsql/include/server/utils/elog.h:358:20: error: unknown type name 'sigjmp_buf'
358 | extern PGDLLIMPORT sigjmp_buf *PG_exception_stack;
| ^~~~~~~~~~
In file included from /usr/local/pgsql/include/server/postgres.h:47,
from lwgeom_cache.h:15,
from shared_gserialized.c:48:
/usr/local/pgsql/include/server/utils/elog.h:358:20: error: unknown type name 'sigjmp_buf'
358 | extern PGDLLIMPORT sigjmp_buf *PG_exception_stack;
| ^~~~~~~~~~
make[1]: *** [Makefile:68: shared_gserialized.o] Error 1

Here's where I stand at the moment.

coderabbitai · 2025-05-16T06:55:58Z

📝 Walkthrough

Walkthrough

A macro for format string checking, PRINTF_FORMAT, was introduced in a new configuration header and applied to relevant variadic function declarations in logging and GEOS-related headers. The build configuration script was updated to define _USE_MATH_DEFINES for enabling math constants, with no changes to logic or control flow.

Changes

File(s)	Change Summary
configure.ac	Added unconditional definition of `_USE_MATH_DEFINES` for enabling math constants, mainly for MSVC support.
liblwgeom/lwgeom_config.h	New header defining `PRINTF_FORMAT` macro for compiler-specific format string checking attributes.
liblwgeom/lwgeom_geos.h	Replaced direct use of GCC format attribute with `PRINTF_FORMAT` macro; included `lwgeom_config.h`.
liblwgeom/lwgeom_log.h	Replaced direct use of GCC format attribute with `PRINTF_FORMAT` macro; included `lwgeom_config.h`.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant Application
    participant lwgeom_log.h
    participant lwgeom_config.h

    User->>Application: Calls logging function (e.g., lwnotice)
    Application->>lwgeom_log.h: Uses PRINTF_FORMAT macro in declaration
    lwgeom_log.h->>lwgeom_config.h: Expands PRINTF_FORMAT for compiler
    lwgeom_config.h-->>lwgeom_log.h: Provides attribute or nothing
    Application-->>User: Logging proceeds with format string checking (if supported)

Poem

In the realm of code, a macro appears,
PRINTF_FORMAT hops in, dispelling old fears.
Math constants enabled, logs now precise,
With headers and scripts all playing nice.
A rabbit applauds with a jubilant cheer—
“To safer formats and math constants this year!”
🐇✨

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Reviewing files that changed from the base of the PR and between 8bc70be and 7833d91.

📒 Files selected for processing (4)

configure.ac (1 hunks)
liblwgeom/lwgeom_config.h (1 hunks)
liblwgeom/lwgeom_geos.h (2 hunks)
liblwgeom/lwgeom_log.h (4 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (12)

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GitHub Check: 14.2-RELEASE
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GitHub Check: CI (latest, tests)
GitHub Check: CI (pg13-geos38-gdal31-proj71, tests)
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🔇 Additional comments (8)

liblwgeom/lwgeom_config.h (2)

1-24: Well-structured license and copyright header.

The standard PostGIS license header and copyright information is appropriately included.

26-30: Good implementation of a compiler-agnostic format attribute macro.

The PRINTF_FORMAT macro is well-designed to handle compiler differences, using the __attribute__ mechanism for GCC and Clang while gracefully degrading for other compilers like MSVC.

This approach improves cross-platform compatibility while maintaining the benefits of format string checking where supported. The use of preprocessor conditionals is appropriate for this use case.

configure.ac (1)

189-192: Good approach for defining MSVC math constants globally.

Adding _USE_MATH_DEFINES once in the build configuration is cleaner than including it in multiple source files, as mentioned in the PR objectives.

This definition enables access to math constants like M_PI in MSVC builds, improving cross-platform compatibility.

liblwgeom/lwgeom_geos.h (3)

26-27: Appropriate include of the new configuration header.

Including lwgeom_config.h provides access to the PRINTF_FORMAT macro needed later in this file.

30-30: Successfully replaced GCC-specific attribute with portable macro.

The typedef for GEOSMessageHandler now uses the portable PRINTF_FORMAT macro instead of a direct compiler-specific attribute.

55-55: Consistent use of the portable format attribute macro.

The function declaration for lwgeom_geos_error now uses the portable PRINTF_FORMAT macro, ensuring consistency with the other changes.

liblwgeom/lwgeom_log.h (2)

33-33: Appropriate include of the new configuration header.

Including lwgeom_config.h provides access to the PRINTF_FORMAT macro needed for the function declarations in this file.

130-130: Consistent application of the portable format attribute macro.

All three logging function declarations (lwnotice, lwerror, and lwdebug) now use the portable PRINTF_FORMAT macro instead of compiler-specific attributes.

This change maintains the format string checking capability for supported compilers while improving compatibility with MSVC.

Also applies to: 140-140, 149-149

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robe2 · 2025-10-13T05:34:12Z

@lbartoletti sorry haven't had a chance to look at this. Regarding https://gitea.osgeo.org/gitea/postgis/postgis/pulls/208 I had pushed this pull request over there so we could have more thorough testing.

robe2 · 2025-10-13T05:36:07Z

Oh wait I didn't notice there were 2 so I'll update https://gitea.osgeo.org/gitea/postgis/postgis/pulls/208 with this one

robe2 · 2025-10-13T05:49:48Z

Oh wait I didn't notice there were 2 so I'll update https://gitea.osgeo.org/gitea/postgis/postgis/pulls/208 with this one

Okay repointed the gitea one to what you have here so far.

pramsey · 2026-01-27T16:40:16Z

Being worked at gitea

lbartoletti added 2 commits May 16, 2025 08:30

build(MSVC): add include _USE_MATH_DEFINES

481b348

lbartoletti requested review from robe2 and strk May 16, 2025 06:53

pramsey closed this Jan 27, 2026

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MSVC Compat 1 v2: Reconcile attributes and math macros - #805

MSVC Compat 1 v2: Reconcile attributes and math macros#805
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