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

1 files changed, 2 insertions, 21 deletions

diff --git a/src/pl/plperl/plperl_system.h b/src/pl/plperl/plperl_system.h
index 48f6575e513..d1b9ea17fca 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
+ * <stdbool.h> 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) ?			   \