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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 <stdbool.h> 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 <stdbool.h> unconditionally: it should be visible to C++11 but do nothing, just as in C23. We already include <stdint.h> without C++ guards in c.h, and that falls under the same C99-compatibility section of the C++11 standard as <stdbool.h>, so let's remove the guards here too. Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/3198438.1731895163%40sss.pgh.pa.us
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‎configure

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@@ -14958,47 +14958,6 @@ if test "$ac_cv_sizeof_off_t" -lt 8; then
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fi
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fi
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# The cast to long int works around a bug in the HP C Compiler
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# version HP92453-01 B.11.11.23709.GP, which incorrectly rejects
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# declarations like `int a3[[(sizeof (unsigned char)) >= 0]];'.
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# This bug is HP SR number 8606223364.
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{ $as_echo "$as_me:${as_lineno-$LINENO}: checking size of bool" >&5
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$as_echo_n "checking size of bool... " >&6; }
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if ${ac_cv_sizeof_bool+:} false; then :
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$as_echo_n "(cached) " >&6
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else
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if ac_fn_c_compute_int "$LINENO" "(long int) (sizeof (bool))" "ac_cv_sizeof_bool" "#include <stdbool.h>
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"; then :
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else
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if test "$ac_cv_type_bool" = yes; then
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{ { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
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$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
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as_fn_err 10000 or 77 "cannot compute sizeof (bool)
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See \`config.log' for more details" "$LINENO" 5; }
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else
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ac_cv_sizeof_bool=0
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fi
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fi
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fi
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{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_sizeof_bool" >&5
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$as_echo "$ac_cv_sizeof_bool" >&6; }
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cat >>confdefs.h <<_ACEOF
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#define SIZEOF_BOOL $ac_cv_sizeof_bool
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_ACEOF
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if test "$ac_cv_sizeof_bool" = 1; then
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$as_echo "#define PG_USE_STDBOOL 1" >>confdefs.h
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fi
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##
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## Functions, global variables

‎configure.ac

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@@ -1691,15 +1691,6 @@ if test "$ac_cv_sizeof_off_t" -lt 8; then
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fi
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fi
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AC_CHECK_SIZEOF([bool], [], [#include <stdbool.h>])
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dnl We use <stdbool.h> if bool has size 1 after including it. Otherwise, c.h
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dnl will fall back to declaring bool as unsigned char.
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if test "$ac_cv_sizeof_bool" = 1; then
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AC_DEFINE([PG_USE_STDBOOL], 1,
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[Define to 1 to use <stdbool.h> to define type bool.])
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fi
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##
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## Functions, global variables

‎meson.build

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@@ -1755,13 +1755,6 @@ if cc.compiles('''
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endif
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# We use <stdbool.h> if bool has size 1 after including it. Otherwise, c.h
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# will fall back to declaring bool as unsigned char.
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if cc.sizeof('bool', prefix: '#include <stdbool.h>', args: test_c_args) == 1
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cdata.set('PG_USE_STDBOOL', 1)
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endif
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# Need to check a call with %m because netbsd supports gnu_printf but emits a
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# warning for each use of %m.
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printf_attributes = ['gnu_printf', '__syslog__', 'printf']

‎src/backend/jit/llvm/llvmjit_types.c

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@@ -117,11 +117,9 @@ ExecEvalBoolSubroutineTemplate(ExprState *state,
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}
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/*
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* Clang represents stdbool.h style booleans that are returned by functions
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* differently (as i1) than stored ones (as i8). Therefore we do not just need
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* TypeBool (above), but also a way to determine the width of a returned
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* integer. This allows us to keep compatible with non-stdbool using
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* architectures.
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* Clang represents bool returned by functions differently (as i1) than stored
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* ones (as i8). Therefore we do not just need TypeStorageBool (above), but
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* also a way to determine the width of a returned integer.
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*/
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extern bool FunctionReturningBool(void);
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bool

‎src/backend/utils/fmgr/dfmgr.c

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#ifndef WIN32
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#include <dlfcn.h>
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/*
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* On macOS, <dlfcn.h> insists on including <stdbool.h>. If we're not
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* using stdbool, undef bool to undo the damage.
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*/
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#ifndef PG_USE_STDBOOL
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#ifdef bool
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#undef bool
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#endif
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#endif
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#endif /* !WIN32 */
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#include "fmgr.h"

‎src/include/c.h

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@@ -450,37 +450,11 @@ typedef void (*pg_funcptr_t) (void);
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* bool
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* Boolean value, either true or false.
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*
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* We use stdbool.h if bool has size 1 after including it. That's useful for
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* better compiler and debugger output and for compatibility with third-party
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* libraries. But PostgreSQL currently cannot deal with bool of other sizes;
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* there are static assertions around the code to prevent that.
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*
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* For C++ compilers, we assume the compiler has a compatible built-in
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* definition of bool.
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*
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* See also the version of this code in src/interfaces/ecpg/include/ecpglib.h.
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* PostgreSQL currently cannot deal with bool of size other than 1; there are
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* static assertions around the code to prevent that.
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*/
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#ifndef __cplusplus
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#ifdef PG_USE_STDBOOL
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#include <stdbool.h>
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#else
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#ifndef bool
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typedef unsigned char bool;
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#endif
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#ifndef true
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#define true ((bool) 1)
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#endif
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#ifndef false
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#define false ((bool) 0)
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#endif
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#endif /* not PG_USE_STDBOOL */
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#endif /* not C++ */
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/* ----------------------------------------------------------------

‎src/include/pg_config.h.in

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@@ -597,9 +597,6 @@
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/* Define to best printf format archetype, usually gnu_printf if available. */
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#undef PG_PRINTF_ATTRIBUTE
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/* Define to 1 to use <stdbool.h> to define type bool. */
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#undef PG_USE_STDBOOL
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/* PostgreSQL version as a string */
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#undef PG_VERSION
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RELSEG_SIZE requires an initdb. */
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#undef RELSEG_SIZE
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/* The size of `bool', as computed by sizeof. */
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#undef SIZEOF_BOOL
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/* The size of `long', as computed by sizeof. */
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#undef SIZEOF_LONG
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‎src/interfaces/ecpg/include/ecpg_config.h.in

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@@ -6,6 +6,3 @@
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/* Define to 1 if `long long int' works and is 64 bits. */
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#undef HAVE_LONG_LONG_INT_64
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/* Define to 1 to use <stdbool.h> to define type bool. */
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#undef PG_USE_STDBOOL

‎src/interfaces/ecpg/include/ecpglib.h

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@@ -7,42 +7,14 @@
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#ifndef _ECPGLIB_H
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#define _ECPGLIB_H
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#include <stdbool.h>
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#include <string.h>
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#include "ecpg_config.h"
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#include "ecpgtype.h"
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#include "libpq-fe.h"
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#include "sqlca.h"
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/*
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* This is a small extract from c.h since we don't want to leak all postgres
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* definitions into ecpg programs; but we need to know what bool is.
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*/
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#ifndef __cplusplus
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#ifdef PG_USE_STDBOOL
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#include <stdbool.h>
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#else
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/*
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* We assume bool has been defined if true and false are. This avoids
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* duplicate-typedef errors if this file is included after c.h.
30-
*/
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#if !(defined(true) && defined(false))
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typedef unsigned char bool;
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#endif
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#ifndef true
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#define true ((bool) 1)
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#endif
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#ifndef false
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#define false ((bool) 0)
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#endif
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#endif /* not PG_USE_STDBOOL */
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#endif /* not C++ */
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#ifdef __cplusplus
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extern "C"

‎src/interfaces/ecpg/include/meson.build

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@@ -5,7 +5,6 @@ ecpg_inc = include_directories('.')
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ecpg_conf_keys = [
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'HAVE_LONG_INT_64',
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'HAVE_LONG_LONG_INT_64',
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'PG_USE_STDBOOL',
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]
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ecpg_conf_data = configuration_data()

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