diff options
| author | Tom Lane | 2025-12-10 22:09:10 +0000 |
|---|---|---|
| committer | Tom Lane | 2025-12-10 22:09:10 +0000 |
| commit | 0909380e4c9aa22b75dfe5a7e33393b48078db81 (patch) | |
| tree | 6ab139e874276eed48f8f768ec0f511a6559ffd8 /src | |
| parent | bfb335df58ea4274702039083c7e08fe3dba9e10 (diff) | |
Allow PG_PRINTF_ATTRIBUTE to be different in C and C++ code.
Although clang claims to be compatible with gcc's printf format
archetypes, this appears to be a falsehood: it likes __syslog__
(which gcc does not, on most platforms) and doesn't accept
gnu_printf. This means that if you try to use gcc with clang++
or clang with g++, you get compiler warnings when compiling
printf-like calls in our C++ code. This has been true for quite
awhile, but it's gotten more annoying with the recent appearance
of several buildfarm members that are configured like this.
To fix, run separate probes for the format archetype to use with the
C and C++ compilers, and conditionally define PG_PRINTF_ATTRIBUTE
depending on __cplusplus.
(We could alternatively insist that you not mix-and-match C and
C++ compilers; but if the case works otherwise, this is a poor
reason to insist on that.)
No back-patch for now, but we may want to do that if this
patch survives buildfarm testing.
Discussion: https://postgr.es/m/986485.1764825548@sss.pgh.pa.us
Diffstat (limited to 'src')
| -rw-r--r-- | src/include/c.h | 10 | ||||
| -rw-r--r-- | src/include/pg_config.h.in | 11 |
2 files changed, 18 insertions, 3 deletions
diff --git a/src/include/c.h b/src/include/c.h index 62cbf7a2eec..55effdda0fd 100644 --- a/src/include/c.h +++ b/src/include/c.h @@ -228,6 +228,16 @@ #define PG_USED_FOR_ASSERTS_ONLY pg_attribute_unused() #endif +/* + * Our C and C++ compilers may have different ideas about which printf + * archetype best represents what src/port/snprintf.c can do. + */ +#ifndef __cplusplus +#define PG_PRINTF_ATTRIBUTE PG_C_PRINTF_ATTRIBUTE +#else +#define PG_PRINTF_ATTRIBUTE PG_CXX_PRINTF_ATTRIBUTE +#endif + /* GCC supports format attributes */ #if defined(__GNUC__) #define pg_attribute_format_arg(a) __attribute__((format_arg(a))) diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in index 72434ce957e..3a7edb1f0a0 100644 --- a/src/include/pg_config.h.in +++ b/src/include/pg_config.h.in @@ -596,6 +596,14 @@ /* Define to the version of this package. */ #undef PACKAGE_VERSION +/* Define to best C++ printf format archetype, usually gnu_printf if + available. */ +#undef PG_CXX_PRINTF_ATTRIBUTE + +/* Define to best C printf format archetype, usually gnu_printf if available. + */ +#undef PG_C_PRINTF_ATTRIBUTE + /* Define to the name of a signed 128-bit integer type. */ #undef PG_INT128_TYPE @@ -612,9 +620,6 @@ /* PostgreSQL minor version number */ #undef PG_MINORVERSION_NUM -/* Define to best printf format archetype, usually gnu_printf if available. */ -#undef PG_PRINTF_ATTRIBUTE - /* PostgreSQL version as a string */ #undef PG_VERSION |