From 97525bc5c8ffb31475d23955d08e9ec9c1408f33 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Thu, 28 Nov 2024 11:48:07 +1300 Subject: [PATCH] Require sizeof(bool) == 1. The C standard says that sizeof(bool) is implementation-defined, but we know of no current systems where it is not 1. The last known systems seem to have been Apple macOS/PowerPC 10.5 and Microsoft Visual C++ 4, both long defunct. PostgreSQL has always required sizeof(bool) == 1 for the definition of bool that it used, but previously it would define its own type if the system-provided bool had a different size. That was liable to cause memory layout problems when interacting with system and third-party libraries on (by now hypothetical) computers with wider _Bool, and now C23 has introduced a new problem by making bool a built-in datatype (like C++), so the fallback code doesn't even compile. We could probably work around that, but then we'd be writing new untested code for a computer that doesn't exist. Instead, delete the unreachable and C23-uncompilable fallback code, and let existing static assertions fail if the system-provided bool is too wide. If we ever get a problem report from a real system, then it will be time to figure out what to do about it in a way that also works on modern compilers. Note on C++: Previously we avoided including or trying to define a new bool type in headers that might be included by C++ code. These days we might as well just include unconditionally: it should be visible to C++11 but do nothing, just as in C23. We already include without C++ guards in c.h, and that falls under the same C99-compatibility section of the C++11 standard as , so let's remove the guards here too. Reviewed-by: Tom Lane Discussion: https://postgr.es/m/3198438.1731895163%40sss.pgh.pa.us --- configure | 41 -------------------- configure.ac | 9 ----- meson.build | 7 ---- src/backend/jit/llvm/llvmjit_types.c | 8 ++-- src/backend/utils/fmgr/dfmgr.c | 10 ----- src/include/c.h | 30 +------------- src/include/pg_config.h.in | 6 --- src/interfaces/ecpg/include/ecpg_config.h.in | 3 -- src/interfaces/ecpg/include/ecpglib.h | 30 +------------- src/interfaces/ecpg/include/meson.build | 1 - src/pl/plperl/plperl_system.h | 23 +---------- 11 files changed, 8 insertions(+), 160 deletions(-) diff --git a/configure b/configure index 02b2c2e106..ff59f1422d 100755 --- a/configure +++ b/configure @@ -14958,47 +14958,6 @@ if test "$ac_cv_sizeof_off_t" -lt 8; then fi fi -# The cast to long int works around a bug in the HP C Compiler -# version HP92453-01 B.11.11.23709.GP, which incorrectly rejects -# declarations like `int a3[[(sizeof (unsigned char)) >= 0]];'. -# This bug is HP SR number 8606223364. -{ $as_echo "$as_me:${as_lineno-$LINENO}: checking size of bool" >&5 -$as_echo_n "checking size of bool... " >&6; } -if ${ac_cv_sizeof_bool+:} false; then : - $as_echo_n "(cached) " >&6 -else - if ac_fn_c_compute_int "$LINENO" "(long int) (sizeof (bool))" "ac_cv_sizeof_bool" "#include -"; then : - -else - if test "$ac_cv_type_bool" = yes; then - { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5 -$as_echo "$as_me: error: in \`$ac_pwd':" >&2;} -as_fn_error 77 "cannot compute sizeof (bool) -See \`config.log' for more details" "$LINENO" 5; } - else - ac_cv_sizeof_bool=0 - fi -fi - -fi -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_sizeof_bool" >&5 -$as_echo "$ac_cv_sizeof_bool" >&6; } - - - -cat >>confdefs.h <<_ACEOF -#define SIZEOF_BOOL $ac_cv_sizeof_bool -_ACEOF - - - -if test "$ac_cv_sizeof_bool" = 1; then - -$as_echo "#define PG_USE_STDBOOL 1" >>confdefs.h - -fi - ## ## Functions, global variables diff --git a/configure.ac b/configure.ac index 99a5b1aac6..2181700964 100644 --- a/configure.ac +++ b/configure.ac @@ -1691,15 +1691,6 @@ if test "$ac_cv_sizeof_off_t" -lt 8; then fi fi -AC_CHECK_SIZEOF([bool], [], [#include ]) - -dnl We use if bool has size 1 after including it. Otherwise, c.h -dnl will fall back to declaring bool as unsigned char. -if test "$ac_cv_sizeof_bool" = 1; then - AC_DEFINE([PG_USE_STDBOOL], 1, - [Define to 1 to use to define type bool.]) -fi - ## ## Functions, global variables diff --git a/meson.build b/meson.build index 6bc3bb51dc..451c3f6d85 100644 --- a/meson.build +++ b/meson.build @@ -1755,13 +1755,6 @@ if cc.compiles(''' endif -# We use if bool has size 1 after including it. Otherwise, c.h -# will fall back to declaring bool as unsigned char. -if cc.sizeof('bool', prefix: '#include ', args: test_c_args) == 1 - cdata.set('PG_USE_STDBOOL', 1) -endif - - # Need to check a call with %m because netbsd supports gnu_printf but emits a # warning for each use of %m. printf_attributes = ['gnu_printf', '__syslog__', 'printf'] diff --git a/src/backend/jit/llvm/llvmjit_types.c b/src/backend/jit/llvm/llvmjit_types.c index 4a9e077014..13efe18e6b 100644 --- a/src/backend/jit/llvm/llvmjit_types.c +++ b/src/backend/jit/llvm/llvmjit_types.c @@ -117,11 +117,9 @@ ExecEvalBoolSubroutineTemplate(ExprState *state, } /* - * Clang represents stdbool.h style booleans that are returned by functions - * differently (as i1) than stored ones (as i8). Therefore we do not just need - * TypeBool (above), but also a way to determine the width of a returned - * integer. This allows us to keep compatible with non-stdbool using - * architectures. + * Clang represents bool returned by functions differently (as i1) than stored + * ones (as i8). Therefore we do not just need TypeStorageBool (above), but + * also a way to determine the width of a returned integer. */ extern bool FunctionReturningBool(void); bool diff --git a/src/backend/utils/fmgr/dfmgr.c b/src/backend/utils/fmgr/dfmgr.c index c7aa789b51..8e81ecc749 100644 --- a/src/backend/utils/fmgr/dfmgr.c +++ b/src/backend/utils/fmgr/dfmgr.c @@ -18,16 +18,6 @@ #ifndef WIN32 #include - -/* - * On macOS, insists on including . If we're not - * using stdbool, undef bool to undo the damage. - */ -#ifndef PG_USE_STDBOOL -#ifdef bool -#undef bool -#endif -#endif #endif /* !WIN32 */ #include "fmgr.h" diff --git a/src/include/c.h b/src/include/c.h index fe1ce87882..304dff27e3 100644 --- a/src/include/c.h +++ b/src/include/c.h @@ -450,37 +450,11 @@ typedef void (*pg_funcptr_t) (void); * bool * Boolean value, either true or false. * - * We use stdbool.h if bool has size 1 after including it. That's useful for - * better compiler and debugger output and for compatibility with third-party - * libraries. But PostgreSQL currently cannot deal with bool of other sizes; - * there are static assertions around the code to prevent that. - * - * For C++ compilers, we assume the compiler has a compatible built-in - * definition of bool. - * - * See also the version of this code in src/interfaces/ecpg/include/ecpglib.h. + * PostgreSQL currently cannot deal with bool of size other than 1; there are + * static assertions around the code to prevent that. */ -#ifndef __cplusplus - -#ifdef PG_USE_STDBOOL #include -#else - -#ifndef bool -typedef unsigned char bool; -#endif - -#ifndef true -#define true ((bool) 1) -#endif - -#ifndef false -#define false ((bool) 0) -#endif - -#endif /* not PG_USE_STDBOOL */ -#endif /* not C++ */ /* ---------------------------------------------------------------- diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in index 6e25afc58f..ab0f8cc2b4 100644 --- a/src/include/pg_config.h.in +++ b/src/include/pg_config.h.in @@ -597,9 +597,6 @@ /* Define to best printf format archetype, usually gnu_printf if available. */ #undef PG_PRINTF_ATTRIBUTE -/* Define to 1 to use to define type bool. */ -#undef PG_USE_STDBOOL - /* PostgreSQL version as a string */ #undef PG_VERSION @@ -630,9 +627,6 @@ RELSEG_SIZE requires an initdb. */ #undef RELSEG_SIZE -/* The size of `bool', as computed by sizeof. */ -#undef SIZEOF_BOOL - /* The size of `long', as computed by sizeof. */ #undef SIZEOF_LONG diff --git a/src/interfaces/ecpg/include/ecpg_config.h.in b/src/interfaces/ecpg/include/ecpg_config.h.in index 2b439c1e58..75f542f263 100644 --- a/src/interfaces/ecpg/include/ecpg_config.h.in +++ b/src/interfaces/ecpg/include/ecpg_config.h.in @@ -6,6 +6,3 @@ /* Define to 1 if `long long int' works and is 64 bits. */ #undef HAVE_LONG_LONG_INT_64 - -/* Define to 1 to use to define type bool. */ -#undef PG_USE_STDBOOL diff --git a/src/interfaces/ecpg/include/ecpglib.h b/src/interfaces/ecpg/include/ecpglib.h index 771761ffe4..dbf3cc3a0c 100644 --- a/src/interfaces/ecpg/include/ecpglib.h +++ b/src/interfaces/ecpg/include/ecpglib.h @@ -7,6 +7,7 @@ #ifndef _ECPGLIB_H #define _ECPGLIB_H +#include #include #include "ecpg_config.h" @@ -14,35 +15,6 @@ #include "libpq-fe.h" #include "sqlca.h" -/* - * This is a small extract from c.h since we don't want to leak all postgres - * definitions into ecpg programs; but we need to know what bool is. - */ -#ifndef __cplusplus - -#ifdef PG_USE_STDBOOL -#include -#else - -/* - * We assume bool has been defined if true and false are. This avoids - * duplicate-typedef errors if this file is included after c.h. - */ -#if !(defined(true) && defined(false)) -typedef unsigned char bool; -#endif - -#ifndef true -#define true ((bool) 1) -#endif - -#ifndef false -#define false ((bool) 0) -#endif - -#endif /* not PG_USE_STDBOOL */ -#endif /* not C++ */ - #ifdef __cplusplus extern "C" diff --git a/src/interfaces/ecpg/include/meson.build b/src/interfaces/ecpg/include/meson.build index b4a5aedd51..a3beb3cc7b 100644 --- a/src/interfaces/ecpg/include/meson.build +++ b/src/interfaces/ecpg/include/meson.build @@ -5,7 +5,6 @@ ecpg_inc = include_directories('.') ecpg_conf_keys = [ 'HAVE_LONG_INT_64', 'HAVE_LONG_LONG_INT_64', - 'PG_USE_STDBOOL', ] ecpg_conf_data = configuration_data() diff --git a/src/pl/plperl/plperl_system.h b/src/pl/plperl/plperl_system.h index 48f6575e51..d1b9ea17fc 100644 --- a/src/pl/plperl/plperl_system.h +++ b/src/pl/plperl/plperl_system.h @@ -72,16 +72,10 @@ #endif /* - * Regarding bool, both PostgreSQL and Perl might use stdbool.h or not, - * depending on configuration. If both agree, things are relatively harmless. - * If not, things get tricky. If PostgreSQL does but Perl does not, define - * HAS_BOOL here so that Perl does not redefine bool; this avoids compiler - * warnings. If PostgreSQL does not but Perl does, we need to undefine bool - * after we include the Perl headers; see below. + * Define HAS_BOOL here so that Perl does not redefine bool. We included + * in c.h. */ -#ifdef PG_USE_STDBOOL #define HAS_BOOL 1 -#endif /* * Get the basic Perl API. We use PERL_NO_GET_CONTEXT mode so that our code @@ -180,19 +174,6 @@ /* perl version and platform portability */ #include "ppport.h" -/* - * perl might have included stdbool.h. If we also did that earlier (see c.h), - * then that's fine. If not, we probably rejected it for some reason. In - * that case, undef bool and proceed with our own bool. (Note that stdbool.h - * makes bool a macro, but our own replacement is a typedef, so the undef - * makes ours visible again). - */ -#ifndef PG_USE_STDBOOL -#ifdef bool -#undef bool -#endif -#endif - /* supply HeUTF8 if it's missing - ppport.h doesn't supply it, unfortunately */ #ifndef HeUTF8 #define HeUTF8(he) ((HeKLEN(he) == HEf_SVKEY) ? \ -- 2.39.5