diff options
| author | Andres Freund | 2022-12-29 20:47:29 +0000 |
|---|---|---|
| committer | Andres Freund | 2023-01-02 23:51:05 +0000 |
| commit | 99f8bc335cbed43d64ed1e440a7fa43a8746a683 (patch) | |
| tree | af7266d3237780123d8b87fe72daf5c3589bbf81 /src/include | |
| parent | 982b9b1eba8d809cd677009d15ca045cea890c69 (diff) | |
perl: Hide warnings inside perl.h when using gcc compatible compiler
New versions of perl trigger warnings within perl.h with our compiler
flags. At least -Wdeclaration-after-statement, -Wshadow=compatible-local are
known to be problematic.
To avoid these warnings, conditionally use #pragma GCC system_header before
including plperl.h.
Alternatively, we could add the include paths for problematic headers with
-isystem, but that is a larger hammer and is harder to search for.
A more granular alternative would be to use #pragma GCC diagnostic
push/ignored/pop, but gcc warns about unknown warnings being ignored, so every
to-be-ignored-temporarily compiler warning would require its own pg_config.h
symbol and #ifdef.
As the warnings are voluminous, it makes sense to backpatch this change. But
don't do so yet, we first want gather buildfarm coverage - it's e.g. possible
that some compiler claiming to be gcc compatible has issues with the pragma.
Author: Andres Freund <andres@anarazel.de>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: Discussion: https://postgr.es/m/20221228182455.hfdwd22zztvkojy2@awork3.anarazel.de
Diffstat (limited to 'src/include')
| -rw-r--r-- | src/include/c.h | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/src/include/c.h b/src/include/c.h index b21f9643a65..f5f2e2c90c9 100644 --- a/src/include/c.h +++ b/src/include/c.h @@ -257,6 +257,34 @@ #endif #endif +/* + * Does the compiler support #pragma GCC system_header? We optionally use it + * to avoid warnings that we can't fix (e.g. in the perl headers). + * See https://gcc.gnu.org/onlinedocs/cpp/System-Headers.html + * + * Headers for which we do not want to show compiler warnings can, + * conditionally, use #pragma GCC system_header to avoid warnings. Obviously + * this should only be used for external headers over which we do not have + * control. + * + * Support for the pragma is tested here, instead of during configure, as gcc + * also warns about the pragma being used in a .c file. It's surprisingly hard + * to get autoconf to use .h as the file-ending. Looks like gcc has + * implemented the pragma since the 2000, so this test should suffice. + * + * + * Alternatively, we could add the include paths for problematic headers with + * -isystem, but that is a larger hammer and is harder to search for. + * + * A more granular alternative would be to use #pragma GCC diagnostic + * push/ignored/pop, but gcc warns about unknown warnings being ignored, so + * every to-be-ignored-temporarily compiler warning would require its own + * pg_config.h symbol and #ifdef. + */ +#ifdef __GNUC__ +#define HAVE_PRAGMA_GCC_SYSTEM_HEADER 1 +#endif + /* ---------------------------------------------------------------- * Section 2: bool, true, false |