Hello,

while reading the postgres code, occasionally I see a little bit of inconsistency in the comments after #else (and corresponding #endif).

In some places #else/endif's comment expresses condition for else block to be active:
#ifdef HAVE_UUID_OSSP
...
#else                           /* !HAVE_UUID_OSSP */
...
#endif                          /* HAVE_UUID_OSSP */

and in others -- just the opposite:

#ifdef SHA2_UNROLL_TRANSFORM
...
#else                           /* SHA2_UNROLL_TRANSFORM */
...
#endif                          /* SHA2_UNROLL_TRANSFORM */

Also, #endif comment after #else might expresses condition for else block to be active:
#ifdef USE_ICU
...
#else                           /* !USE_ICU */
...
#endif                          /* !USE_ICU */

or it might be just the opposite, like in HAVE_UUID_OSSP and SHA2_UNROLL_TRANSFORM examples above.


I propose making them more consistent. Would the following guidelines be acceptable?


1. #else/#elif/#endif's comment, if present, should reflect the
condition of the #else/#elif block as opposed to always being a copy
of #if/ifdef/ifndef condition.

e.g. prefer this:
#if LLVM_VERSION_MAJOR > 11
...
#else                           /* LLVM_VERSION_MAJOR <= 11 */
...
#endif                          /* LLVM_VERSION_MAJOR <= 11 */

over this:

#if LLVM_VERSION_MAJOR > 11
...
#else                           /* LLVM_VERSION_MAJOR > 11 */
...
#endif                          /* LLVM_VERSION_MAJOR > 11 */


2. In #else/#elif/#endif comments, prefer A to defined(A).

E.g. prefer this:
#endif                          /* DMETAPHONE_MAIN */
over
#endif                          /* defined DMETAPHONE_MAIN */

And this:
#else                           /* !_MSC_VER */
over
#else                           /* !defined(_MSC_VER) */


3. Textual hand-crafted condition comments are perfectly fine.
Like this:
#else                           /* no ppoll(), so use select() */


4. #else/#endif condition comment, if present, should reflect the
*effective* condition, i.e. condition taking into account previous
#if/#elif-s.

E.g. do this:
#if defined(HAVE_INT128)
...
#elif defined(HAS_64_BIT_INTRINSICS)
...
#else                           /* !HAVE_INT128 && !HAS_64_BIT_INTRINSICS */
...
#endif                          /* !HAVE_INT128 && !HAS_64_BIT_INTRINSICS */


5. Comment of the form "!A && !B", if deemed complicated enough, may
also be expressed as "neither A nor B" for easier reading.

Example:
#if (defined(HAVE_LANGINFO_H) && defined(CODESET)) || defined(WIN32)
...
#else /* neither (HAVE_LANGINFO_H && CODESET) nor WIN32 */
...
#endif /* neither (HAVE_LANGINFO_H && CODESET) nor WIN32 */


6. Use "!" as opposed to "not" to be consistent. E.g. do this:
#ifdef LOCK_DEBUG
...
#else                           /* !LOCK_DEBUG */
...
#endif                          /* !LOCK_DEBUG */

as opposed to:

#ifdef LOCK_DEBUG
...
#else                           /* not LOCK_DEBUG */
...
#endif                          /* not LOCK_DEBUG */


The draft of proposed changes is attached as
0001-Make-else-endif-comments-more-consistent.patch
In the patch I've also cleaned up some minor things, like removing
occasional "//" comments within "/* */" ones.

Any thoughts?
--
Anton Voloshin
Postgres Professional, The Russian Postgres Company
https://postgrespro.ru
From a118eb1c4caa1a140cd9a8c4230b91c7bfb91773 Mon Sep 17 00:00:00 2001
From: Anton Voloshin <a.volos...@postgrespro.ru>
Date: Sat, 27 Aug 2022 15:56:11 +0300
Subject: [PATCH] Make else/endif comments more consistent

This only changes condition comments after some preprocessor directives
(mostly else and endif).

1. #else/#elif/#endif's comment, if present, should reflect the condition
of the #else/#elif block as opposed to always being a copy of #if/ifdef/ifndef
condition.

e.g. do this:
#if LLVM_VERSION_MAJOR > 11
...
#else                           /* LLVM_VERSION_MAJOR <= 11 */
...
#endif                          /* LLVM_VERSION_MAJOR <= 11 */

as opposed to

#if LLVM_VERSION_MAJOR > 11
...
#else                           /* LLVM_VERSION_MAJOR > 11 */
...
#endif                          /* LLVM_VERSION_MAJOR > 11 */


2. In #else/#elif/#endif comments, prefer A to defined(A).

E.g. prefer this:
#endif                          /* DMETAPHONE_MAIN */
over
#endif                          /* defined DMETAPHONE_MAIN */

And this:
#else                           /* !_MSC_VER */
over
#else                           /* !defined(_MSC_VER) */


3. Textual hand-crafted condition comments are perfectly fine.
Like this:
#else                           /* no ppoll(), so use select() */


4. #else/#endif condition comment, if present, should reflect the *effective*
condition, i.e. condition taking into account previous #if/#elif-s.

E.g. do this:
#if defined(HAVE_INT128)
...
#elif defined(HAS_64_BIT_INTRINSICS)
...
#else                           /* !HAVE_INT128 && !HAS_64_BIT_INTRINSICS */
...
#endif                          /* !HAVE_INT128 && !HAS_64_BIT_INTRINSICS */


5. Comment of the form "!A && !B", if deemed complicated enough, may also be
expressed as "neither A nor B" for easier reading.

Example:
#if (defined(HAVE_LANGINFO_H) && defined(CODESET)) || defined(WIN32)
...
#else                           /* neither (HAVE_LANGINFO_H && CODESET) nor WIN32 */
...
#endif                          /* neither (HAVE_LANGINFO_H && CODESET) nor WIN32 */


6. Use "!" as opposed to "not" to be consistent. E.g. do this:
#ifdef LOCK_DEBUG
...
#else                           /* !LOCK_DEBUG */
...
#endif                          /* !LOCK_DEBUG */

as opposed to:

#ifdef LOCK_DEBUG
...
#else                           /* not LOCK_DEBUG */
...
#endif                          /* not LOCK_DEBUG */
---
 contrib/fuzzystrmatch/dmetaphone.c         |  4 ++--
 contrib/uuid-ossp/uuid-ossp.c              |  2 +-
 contrib/xml2/xslt_proc.c                   |  2 +-
 src/backend/catalog/indexing.c             |  2 +-
 src/backend/executor/execExprInterp.c      |  2 +-
 src/backend/jit/llvm/llvmjit.c             | 16 ++++++++--------
 src/backend/libpq/pqcomm.c                 |  5 +++--
 src/backend/port/posix_sema.c              |  2 +-
 src/backend/postmaster/postmaster.c        |  4 ++--
 src/backend/storage/ipc/procarray.c        |  2 +-
 src/backend/storage/lmgr/lock.c            |  4 ++--
 src/backend/storage/lmgr/lwlock.c          |  4 ++--
 src/backend/storage/lmgr/spin.c            |  2 +-
 src/backend/utils/adt/numeric.c            |  2 +-
 src/backend/utils/adt/pg_locale.c          | 20 ++++++++++----------
 src/backend/utils/adt/varlena.c            |  8 ++++----
 src/backend/utils/adt/xml.c                |  8 ++++----
 src/backend/utils/misc/guc.c               |  4 ++--
 src/bin/pg_basebackup/pg_basebackup.c      |  2 +-
 src/common/d2s.c                           |  5 ++---
 src/common/d2s_intrinsics.h                |  8 ++++----
 src/common/f2s.c                           |  4 ++--
 src/common/file_perm.c                     |  2 +-
 src/common/hashfn.c                        | 12 ++++++------
 src/common/sha2.c                          |  8 ++++----
 src/include/c.h                            |  8 ++++----
 src/include/common/int128.h                |  2 +-
 src/include/port.h                         |  4 ++--
 src/include/port/pg_bitutils.h             |  4 ++--
 src/include/port/pg_bswap.h                |  4 ++--
 src/include/postgres.h                     |  2 +-
 src/include/postmaster/syslogger.h         |  2 +-
 src/include/storage/s_lock.h               |  4 ++--
 src/include/utils/elog.h                   |  2 +-
 src/interfaces/ecpg/pgtypeslib/dt_common.c |  4 ++--
 src/interfaces/ecpg/pgtypeslib/timestamp.c |  4 ++--
 src/interfaces/libpq/fe-auth.c             |  4 ++--
 src/interfaces/libpq/fe-connect.c          |  6 +++---
 src/interfaces/libpq/fe-misc.c             |  2 +-
 src/interfaces/libpq/fe-secure.c           |  2 +-
 src/port/chklocale.c                       |  4 ++--
 src/port/pg_crc32c_sb8.c                   |  2 +-
 src/port/pg_strong_random.c                |  2 +-
 43 files changed, 98 insertions(+), 98 deletions(-)

diff --git a/contrib/fuzzystrmatch/dmetaphone.c b/contrib/fuzzystrmatch/dmetaphone.c
index 6f4d2b730e9..20140ace47d 100644
--- a/contrib/fuzzystrmatch/dmetaphone.c
+++ b/contrib/fuzzystrmatch/dmetaphone.c
@@ -198,7 +198,7 @@ dmetaphone_alt(PG_FUNCTION_ARGS)
  */
 
 #define META_FREE(x) ((void)true)	/* pfree((x)) */
-#else							/* not defined DMETAPHONE_MAIN */
+#else							/* DMETAPHONE_MAIN */
 
 /* use the standard malloc library when not running in PostgreSQL */
 
@@ -209,7 +209,7 @@ dmetaphone_alt(PG_FUNCTION_ARGS)
 					  (v = (t*)realloc((v),((n)*sizeof(t))))
 
 #define META_FREE(x) free((x))
-#endif							/* defined DMETAPHONE_MAIN */
+#endif							/* DMETAPHONE_MAIN */
 
 
 
diff --git a/contrib/uuid-ossp/uuid-ossp.c b/contrib/uuid-ossp/uuid-ossp.c
index b868812358d..07a32d59c9e 100644
--- a/contrib/uuid-ossp/uuid-ossp.c
+++ b/contrib/uuid-ossp/uuid-ossp.c
@@ -401,7 +401,7 @@ uuid_generate_internal(int v, unsigned char *ns, const char *ptr, int len)
 	return DirectFunctionCall1(uuid_in, CStringGetDatum(strbuf));
 }
 
-#endif							/* HAVE_UUID_OSSP */
+#endif							/* !HAVE_UUID_OSSP */
 
 
 Datum
diff --git a/contrib/xml2/xslt_proc.c b/contrib/xml2/xslt_proc.c
index 2189bca86ff..03f8b5874ae 100644
--- a/contrib/xml2/xslt_proc.c
+++ b/contrib/xml2/xslt_proc.c
@@ -189,7 +189,7 @@ xslt_process(PG_FUNCTION_ARGS)
 			(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 			 errmsg("xslt_process() is not available without libxslt")));
 	PG_RETURN_NULL();
-#endif							/* USE_LIBXSLT */
+#endif							/* !USE_LIBXSLT */
 }
 
 #ifdef USE_LIBXSLT
diff --git a/src/backend/catalog/indexing.c b/src/backend/catalog/indexing.c
index 0b920933226..49cdead8d6b 100644
--- a/src/backend/catalog/indexing.c
+++ b/src/backend/catalog/indexing.c
@@ -204,7 +204,7 @@ CatalogTupleCheckConstraints(Relation heapRel, HeapTuple tup)
 
 #define CatalogTupleCheckConstraints(heapRel, tup)  ((void) 0)
 
-#endif							/* USE_ASSERT_CHECKING */
+#endif							/* !USE_ASSERT_CHECKING */
 
 /*
  * CatalogTupleInsert - do heap and indexing work for a new catalog tuple
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 636794ca6f1..e806e4432ea 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -132,7 +132,7 @@ static ExprEvalOpLookup reverse_dispatch_table[EEOP_LAST];
 #define EEO_DISPATCH()		goto starteval
 #define EEO_OPCODE(opcode)	(opcode)
 
-#endif							/* EEO_USE_COMPUTED_GOTO */
+#endif							/* !EEO_USE_COMPUTED_GOTO */
 
 #define EEO_NEXT() \
 	do { \
diff --git a/src/backend/jit/llvm/llvmjit.c b/src/backend/jit/llvm/llvmjit.c
index 6c72d43beb6..d331d9afad4 100644
--- a/src/backend/jit/llvm/llvmjit.c
+++ b/src/backend/jit/llvm/llvmjit.c
@@ -101,10 +101,10 @@ static LLVMTargetRef llvm_targetref;
 static LLVMOrcThreadSafeContextRef llvm_ts_context;
 static LLVMOrcLLJITRef llvm_opt0_orc;
 static LLVMOrcLLJITRef llvm_opt3_orc;
-#else							/* LLVM_VERSION_MAJOR > 11 */
+#else							/* LLVM_VERSION_MAJOR <= 11 */
 static LLVMOrcJITStackRef llvm_opt0_orc;
 static LLVMOrcJITStackRef llvm_opt3_orc;
-#endif							/* LLVM_VERSION_MAJOR > 11 */
+#endif							/* LLVM_VERSION_MAJOR <= 11 */
 
 
 static void llvm_release_context(JitContext *context);
@@ -211,11 +211,11 @@ llvm_release_context(JitContext *context)
 			sp = LLVMOrcExecutionSessionGetSymbolStringPool(ee);
 			LLVMOrcSymbolStringPoolClearDeadEntries(sp);
 		}
-#else							/* LLVM_VERSION_MAJOR > 11 */
+#else							/* LLVM_VERSION_MAJOR <= 11 */
 		{
 			LLVMOrcRemoveModule(jit_handle->stack, jit_handle->orc_handle);
 		}
-#endif							/* LLVM_VERSION_MAJOR > 11 */
+#endif							/* LLVM_VERSION_MAJOR <= 11 */
 
 		pfree(jit_handle);
 	}
@@ -849,7 +849,7 @@ llvm_session_initialize(void)
 		llvm_opt3_orc = llvm_create_jit_instance(opt3_tm);
 		opt3_tm = 0;
 	}
-#else							/* LLVM_VERSION_MAJOR > 11 */
+#else							/* LLVM_VERSION_MAJOR <= 11 */
 	{
 		llvm_opt0_orc = LLVMOrcCreateInstance(opt0_tm);
 		llvm_opt3_orc = LLVMOrcCreateInstance(opt3_tm);
@@ -873,7 +873,7 @@ llvm_session_initialize(void)
 		}
 #endif
 	}
-#endif							/* LLVM_VERSION_MAJOR > 11 */
+#endif							/* LLVM_VERSION_MAJOR <= 11 */
 
 	on_proc_exit(llvm_shutdown, 0);
 
@@ -917,7 +917,7 @@ llvm_shutdown(int code, Datum arg)
 			llvm_ts_context = NULL;
 		}
 	}
-#else							/* LLVM_VERSION_MAJOR > 11 */
+#else							/* LLVM_VERSION_MAJOR <= 11 */
 	{
 		/* unregister profiling support, needs to be flushed to be useful */
 
@@ -941,7 +941,7 @@ llvm_shutdown(int code, Datum arg)
 			llvm_opt0_orc = NULL;
 		}
 	}
-#endif							/* LLVM_VERSION_MAJOR > 11 */
+#endif							/* LLVM_VERSION_MAJOR <= 11 */
 }
 
 /* helper for llvm_create_types, returning a function's return type */
diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index cba0caced73..65276234838 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -1668,7 +1668,8 @@ pq_setkeepalivesidle(int idle, Port *port)
 #else							/* WIN32 */
 	return pq_setkeepaliveswin32(port, idle, port->keepalives_interval);
 #endif
-#else
+#else							/* neither PG_TCP_KEEPALIVE_IDLE
+								 * nor SIO_KEEPALIVE_VALS */
 	if (idle != 0)
 	{
 		ereport(LOG,
@@ -1752,7 +1753,7 @@ pq_setkeepalivesinterval(int interval, Port *port)
 #else							/* WIN32 */
 	return pq_setkeepaliveswin32(port, port->keepalives_idle, interval);
 #endif
-#else
+#else							/* neither TCP_KEEPINTVL nor SIO_KEEPALIVE_VALS */
 	if (interval != 0)
 	{
 		ereport(LOG,
diff --git a/src/backend/port/posix_sema.c b/src/backend/port/posix_sema.c
index a97a3ed99ee..24f60755c6e 100644
--- a/src/backend/port/posix_sema.c
+++ b/src/backend/port/posix_sema.c
@@ -137,7 +137,7 @@ PosixSemaphoreCreate(sem_t *sem)
 	if (sem_init(sem, 1, 1) < 0)
 		elog(FATAL, "sem_init failed: %m");
 }
-#endif							/* USE_NAMED_POSIX_SEMAPHORES */
+#endif							/* !USE_NAMED_POSIX_SEMAPHORES */
 
 
 /*
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 1664fcee2a7..2c5f6bbd3f8 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -4213,7 +4213,7 @@ BackendStartup(Port *port)
 		/* And run the backend */
 		BackendRun(port);
 	}
-#endif							/* EXEC_BACKEND */
+#endif							/* !EXEC_BACKEND */
 
 	if (pid < 0)
 	{
@@ -5411,7 +5411,7 @@ StartChildProcess(AuxProcType type)
 
 		AuxiliaryProcessMain(type); /* does not return */
 	}
-#endif							/* EXEC_BACKEND */
+#endif							/* !EXEC_BACKEND */
 
 	if (pid < 0)
 	{
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 0555b02a8d9..04728435f38 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -332,7 +332,7 @@ static void DisplayXidCache(void);
 #define xc_by_known_assigned_inc()	((void) 0)
 #define xc_no_overflow_inc()		((void) 0)
 #define xc_slow_answer_inc()		((void) 0)
-#endif							/* XIDCACHE_DEBUG */
+#endif							/* !XIDCACHE_DEBUG */
 
 /* Primitives for KnownAssignedXids array handling for standby */
 static void KnownAssignedXidsCompress(bool force);
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 5f5803f6814..8342a6d18e1 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -360,11 +360,11 @@ PROCLOCK_PRINT(const char *where, const PROCLOCK *proclockP)
 			 PROCLOCK_LOCKMETHOD(*(proclockP)),
 			 proclockP->tag.myProc, (int) proclockP->holdMask);
 }
-#else							/* not LOCK_DEBUG */
+#else							/* !LOCK_DEBUG */
 
 #define LOCK_PRINT(where, lock, type)  ((void) 0)
 #define PROCLOCK_PRINT(where, proclockP)  ((void) 0)
-#endif							/* not LOCK_DEBUG */
+#endif							/* !LOCK_DEBUG */
 
 
 static uint32 proclock_hash(const void *key, Size keysize);
diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 38317edaf96..c8d73da00e5 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -311,10 +311,10 @@ LOG_LWDEBUG(const char *where, LWLock *lock, const char *msg)
 	}
 }
 
-#else							/* not LOCK_DEBUG */
+#else							/* !LOCK_DEBUG */
 #define PRINT_LWDEBUG(a,b,c) ((void)0)
 #define LOG_LWDEBUG(a,b,c) ((void)0)
-#endif							/* LOCK_DEBUG */
+#endif							/* !LOCK_DEBUG */
 
 #ifdef LWLOCK_STATS
 
diff --git a/src/backend/storage/lmgr/spin.c b/src/backend/storage/lmgr/spin.c
index 2a3ee1084b3..33bace7f03b 100644
--- a/src/backend/storage/lmgr/spin.c
+++ b/src/backend/storage/lmgr/spin.c
@@ -45,7 +45,7 @@ PGSemaphore *SpinlockSemaArray;
 
 #define NUM_EMULATION_SEMAPHORES 0
 
-#endif							/* HAVE_SPINLOCKS */
+#endif							/* !HAVE_SPINLOCKS */
 
 /*
  * Report the amount of shared memory needed to store semaphores for spinlock
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 920a63b0081..bb3d3538363 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -9801,7 +9801,7 @@ sqrt_var(const NumericVar *arg, NumericVar *result, int rscale)
 	int64_to_numericvar(s_int64, &s_var);
 	if (step >= 0)
 		int64_to_numericvar(r_int64, &r_var);
-#endif							/* HAVE_INT128 */
+#endif							/* !HAVE_INT128 */
 
 	/*
 	 * The remaining iterations with src_ndigits > 8 (or 16, if have int128)
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 1a047a97d74..3c71c7f9123 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1120,7 +1120,7 @@ IsoLocaleName(const char *winlocname)
 		return get_iso_localename(winlocname);
 }
 
-#else							/* !defined(_MSC_VER) */
+#else							/* !_MSC_VER */
 
 static char *
 IsoLocaleName(const char *winlocname)
@@ -1128,7 +1128,7 @@ IsoLocaleName(const char *winlocname)
 	return NULL;				/* Not supported on MinGW */
 }
 
-#endif							/* defined(_MSC_VER) */
+#endif							/* !_MSC_VER */
 
 #endif							/* WIN32 && LC_MESSAGES */
 
@@ -1420,12 +1420,12 @@ make_icu_collator(const char *iculocstr,
 	/* We will leak this string if the caller errors later :-( */
 	resultp->info.icu.locale = MemoryContextStrdup(TopMemoryContext, iculocstr);
 	resultp->info.icu.ucol = collator;
-#else							/* not USE_ICU */
+#else							/* !USE_ICU */
 	/* could get here if a collation was created by a build with ICU */
 	ereport(ERROR,
 			(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 			 errmsg("ICU is not supported in this build")));
-#endif							/* not USE_ICU */
+#endif							/* !USE_ICU */
 }
 
 
@@ -1569,12 +1569,12 @@ pg_newlocale_from_collation(Oid collid)
 			}
 
 			result.info.lt = loc;
-#else							/* not HAVE_LOCALE_T */
+#else							/* !HAVE_LOCALE_T */
 			/* platform that doesn't support locale_t */
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("collation provider LIBC is not supported on this platform")));
-#endif							/* not HAVE_LOCALE_T */
+#endif							/* !HAVE_LOCALE_T */
 		}
 		else if (collform->collprovider == COLLPROVIDER_ICU)
 		{
@@ -2036,12 +2036,12 @@ wchar2char(char *to, const wchar_t *from, size_t tolen, pg_locale_t locale)
 		result = wcstombs(to, from, tolen);
 
 		uselocale(save_locale);
-#endif							/* HAVE_WCSTOMBS_L */
+#endif							/* !HAVE_WCSTOMBS_L */
 #else							/* !HAVE_LOCALE_T */
 		/* Can't have locale != 0 without HAVE_LOCALE_T */
 		elog(ERROR, "wcstombs_l is not available");
 		result = 0;				/* keep compiler quiet */
-#endif							/* HAVE_LOCALE_T */
+#endif							/* !HAVE_LOCALE_T */
 	}
 
 	return result;
@@ -2113,12 +2113,12 @@ char2wchar(wchar_t *to, size_t tolen, const char *from, size_t fromlen,
 			result = mbstowcs(to, str, tolen);
 
 			uselocale(save_locale);
-#endif							/* HAVE_MBSTOWCS_L */
+#endif							/* !HAVE_MBSTOWCS_L */
 #else							/* !HAVE_LOCALE_T */
 			/* Can't have locale != 0 without HAVE_LOCALE_T */
 			elog(ERROR, "mbstowcs_l is not available");
 			result = 0;			/* keep compiler quiet */
-#endif							/* HAVE_LOCALE_T */
+#endif							/* !HAVE_LOCALE_T */
 		}
 
 		pfree(str);
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 8539cef0246..5315c073e43 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -1692,10 +1692,10 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 					pfree(uchar1);
 					pfree(uchar2);
 				}
-#else							/* not USE_ICU */
+#else							/* !USE_ICU */
 				/* shouldn't happen */
 				elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
-#endif							/* not USE_ICU */
+#endif							/* !USE_ICU */
 			}
 			else
 			{
@@ -2413,10 +2413,10 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 				pfree(uchar1);
 				pfree(uchar2);
 			}
-#else							/* not USE_ICU */
+#else							/* !USE_ICU */
 			/* shouldn't happen */
 			elog(ERROR, "unsupported collprovider: %c", sss->locale->provider);
-#endif							/* not USE_ICU */
+#endif							/* !USE_ICU */
 		}
 		else
 		{
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index 60a85c46971..937bec61a88 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -922,10 +922,10 @@ xml_is_document(xmltype *arg)
 		xmlFreeDoc(doc);
 
 	return result;
-#else							/* not USE_LIBXML */
+#else							/* !USE_LIBXML */
 	NO_XML_SUPPORT();
 	return false;
-#endif							/* not USE_LIBXML */
+#endif							/* !USE_LIBXML */
 }
 
 
@@ -2077,10 +2077,10 @@ map_sql_identifier_to_xml_name(const char *ident, bool fully_escaped,
 	}
 
 	return buf.data;
-#else							/* not USE_LIBXML */
+#else							/* !USE_LIBXML */
 	NO_XML_SUPPORT();
 	return NULL;
-#endif							/* not USE_LIBXML */
+#endif							/* !USE_LIBXML */
 }
 
 
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 9fbbfb1be54..608cadf18b3 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -3635,9 +3635,9 @@ static struct config_int ConfigureNamesInt[] =
 		0,
 #endif
 		0, 5,
-#else							/* not DISCARD_CACHES_ENABLED */
+#else							/* !DISCARD_CACHES_ENABLED */
 		0, 0, 0,
-#endif							/* not DISCARD_CACHES_ENABLED */
+#endif							/* !DISCARD_CACHES_ENABLED */
 		NULL, NULL, NULL
 	},
 
diff --git a/src/bin/pg_basebackup/pg_basebackup.c b/src/bin/pg_basebackup/pg_basebackup.c
index 9ce30d43a41..e135ed4497b 100644
--- a/src/bin/pg_basebackup/pg_basebackup.c
+++ b/src/bin/pg_basebackup/pg_basebackup.c
@@ -2180,7 +2180,7 @@ BaseBackup(char *compression_algorithm, char *compression_detail,
 			pg_fatal("child thread exited with error %u",
 					 (unsigned int) status);
 		/* Exited normally, we're happy */
-#endif
+#endif							/* WIN32 */
 	}
 
 	/* Free the configuration file contents */
diff --git a/src/common/d2s.c b/src/common/d2s.c
index e711ea6f85a..52d7fd63e15 100644
--- a/src/common/d2s.c
+++ b/src/common/d2s.c
@@ -213,8 +213,7 @@ mulShiftAll(const uint64 m, const uint64 *const mul, const int32 j,
 	return mulShift(4 * m, mul, j);
 }
 
-#else							/* // !defined(HAVE_INT128) &&
-								 * !defined(HAS_64_BIT_INTRINSICS) */
+#else							/* !HAVE_INT128 && !HAS_64_BIT_INTRINSICS */
 
 static inline uint64
 mulShiftAll(uint64 m, const uint64 *const mul, const int32 j,
@@ -258,7 +257,7 @@ mulShiftAll(uint64 m, const uint64 *const mul, const int32 j,
 	return shiftright128(mid, hi, j - 64 - 1);
 }
 
-#endif							/* // HAS_64_BIT_INTRINSICS */
+#endif							/* !HAVE_INT128 && !HAS_64_BIT_INTRINSICS */
 
 static inline uint32
 decimalLength(const uint64 v)
diff --git a/src/common/d2s_intrinsics.h b/src/common/d2s_intrinsics.h
index a338d0e2e11..e8393ee7677 100644
--- a/src/common/d2s_intrinsics.h
+++ b/src/common/d2s_intrinsics.h
@@ -59,7 +59,7 @@ shiftright128(const uint64 lo, const uint64 hi, const uint32 dist)
 	return __shiftright128(lo, hi, (unsigned char) dist);
 }
 
-#else							/* defined(HAS_64_BIT_INTRINSICS) */
+#else							/* !HAS_64_BIT_INTRINSICS */
 
 static inline uint64
 umul128(const uint64 a, const uint64 b, uint64 *const productHi)
@@ -111,7 +111,7 @@ shiftright128(const uint64 lo, const uint64 hi, const uint32 dist)
 #endif
 }
 
-#endif							/* // defined(HAS_64_BIT_INTRINSICS) */
+#endif							/* !HAS_64_BIT_INTRINSICS */
 
 #ifdef RYU_32_BIT_PLATFORM
 
@@ -171,7 +171,7 @@ div1e8(const uint64 x)
 	return umulh(x, UINT64CONST(0xABCC77118461CEFD)) >> 26;
 }
 
-#else							/* RYU_32_BIT_PLATFORM */
+#else							/* !RYU_32_BIT_PLATFORM */
 
 static inline uint64
 div5(const uint64 x)
@@ -197,6 +197,6 @@ div1e8(const uint64 x)
 	return x / 100000000;
 }
 
-#endif							/* RYU_32_BIT_PLATFORM */
+#endif							/* !RYU_32_BIT_PLATFORM */
 
 #endif							/* RYU_D2S_INTRINSICS_H */
diff --git a/src/common/f2s.c b/src/common/f2s.c
index 39366b65c70..b81c409cdb4 100644
--- a/src/common/f2s.c
+++ b/src/common/f2s.c
@@ -147,7 +147,7 @@ mulShift(const uint32 m, const uint64 factor, const int32 shift)
 
 	return (bits1Hi << (32 - s)) | (bits1Lo >> s);
 
-#else							/* RYU_32_BIT_PLATFORM */
+#else							/* !RYU_32_BIT_PLATFORM */
 
 	const uint64 sum = (bits0 >> 32) + bits1;
 	const uint64 shiftedSum = sum >> (shift - 32);
@@ -155,7 +155,7 @@ mulShift(const uint32 m, const uint64 factor, const int32 shift)
 	Assert(shiftedSum <= PG_UINT32_MAX);
 	return (uint32) shiftedSum;
 
-#endif							/* RYU_32_BIT_PLATFORM */
+#endif							/* !RYU_32_BIT_PLATFORM */
 }
 
 static inline uint32
diff --git a/src/common/file_perm.c b/src/common/file_perm.c
index 9597f9d4015..ae612692f42 100644
--- a/src/common/file_perm.c
+++ b/src/common/file_perm.c
@@ -78,7 +78,7 @@ GetDataDirectoryCreatePerm(const char *dataDir)
 	/* Set permissions */
 	SetDataDirectoryCreatePerm(statBuf.st_mode);
 	return true;
-#else							/* !defined(WIN32) && !defined(__CYGWIN__) */
+#else							/* WIN32 || __CYGWIN__ */
 	/*
 	 * On Windows, we don't have anything to do here since they don't have
 	 * Unix-y permissions.
diff --git a/src/common/hashfn.c b/src/common/hashfn.c
index 8779575b991..04b02bbbb7a 100644
--- a/src/common/hashfn.c
+++ b/src/common/hashfn.c
@@ -251,7 +251,7 @@ hash_bytes(const unsigned char *k, int keylen)
 				a += k[0];
 				/* case 0: nothing left to add */
 		}
-#endif							/* WORDS_BIGENDIAN */
+#endif							/* !WORDS_BIGENDIAN */
 	}
 	else
 	{
@@ -268,7 +268,7 @@ hash_bytes(const unsigned char *k, int keylen)
 			a += (k[0] + ((uint32) k[1] << 8) + ((uint32) k[2] << 16) + ((uint32) k[3] << 24));
 			b += (k[4] + ((uint32) k[5] << 8) + ((uint32) k[6] << 16) + ((uint32) k[7] << 24));
 			c += (k[8] + ((uint32) k[9] << 8) + ((uint32) k[10] << 16) + ((uint32) k[11] << 24));
-#endif							/* WORDS_BIGENDIAN */
+#endif							/* !WORDS_BIGENDIAN */
 			mix(a, b, c);
 			k += 12;
 			len -= 12;
@@ -351,7 +351,7 @@ hash_bytes(const unsigned char *k, int keylen)
 				a += k[0];
 				/* case 0: nothing left to add */
 		}
-#endif							/* WORDS_BIGENDIAN */
+#endif							/* !WORDS_BIGENDIAN */
 	}
 
 	final(a, b, c);
@@ -490,7 +490,7 @@ hash_bytes_extended(const unsigned char *k, int keylen, uint64 seed)
 				a += k[0];
 				/* case 0: nothing left to add */
 		}
-#endif							/* WORDS_BIGENDIAN */
+#endif							/* !WORDS_BIGENDIAN */
 	}
 	else
 	{
@@ -507,7 +507,7 @@ hash_bytes_extended(const unsigned char *k, int keylen, uint64 seed)
 			a += (k[0] + ((uint32) k[1] << 8) + ((uint32) k[2] << 16) + ((uint32) k[3] << 24));
 			b += (k[4] + ((uint32) k[5] << 8) + ((uint32) k[6] << 16) + ((uint32) k[7] << 24));
 			c += (k[8] + ((uint32) k[9] << 8) + ((uint32) k[10] << 16) + ((uint32) k[11] << 24));
-#endif							/* WORDS_BIGENDIAN */
+#endif							/* !WORDS_BIGENDIAN */
 			mix(a, b, c);
 			k += 12;
 			len -= 12;
@@ -590,7 +590,7 @@ hash_bytes_extended(const unsigned char *k, int keylen, uint64 seed)
 				a += k[0];
 				/* case 0: nothing left to add */
 		}
-#endif							/* WORDS_BIGENDIAN */
+#endif							/* !WORDS_BIGENDIAN */
 	}
 
 	final(a, b, c);
diff --git a/src/common/sha2.c b/src/common/sha2.c
index f1dcd330457..6e99375b41b 100644
--- a/src/common/sha2.c
+++ b/src/common/sha2.c
@@ -380,7 +380,7 @@ SHA256_Transform(pg_sha256_ctx *context, const uint8 *data)
 	/* Clean up */
 	a = b = c = d = e = f = g = h = T1 = 0;
 }
-#else							/* SHA2_UNROLL_TRANSFORM */
+#else							/* !SHA2_UNROLL_TRANSFORM */
 
 static void
 SHA256_Transform(pg_sha256_ctx *context, const uint8 *data)
@@ -470,7 +470,7 @@ SHA256_Transform(pg_sha256_ctx *context, const uint8 *data)
 	/* Clean up */
 	a = b = c = d = e = f = g = h = T1 = T2 = 0;
 }
-#endif							/* SHA2_UNROLL_TRANSFORM */
+#endif							/* !SHA2_UNROLL_TRANSFORM */
 
 void
 pg_sha256_update(pg_sha256_ctx *context, const uint8 *data, size_t len)
@@ -706,7 +706,7 @@ SHA512_Transform(pg_sha512_ctx *context, const uint8 *data)
 	/* Clean up */
 	a = b = c = d = e = f = g = h = T1 = 0;
 }
-#else							/* SHA2_UNROLL_TRANSFORM */
+#else							/* !SHA2_UNROLL_TRANSFORM */
 
 static void
 SHA512_Transform(pg_sha512_ctx *context, const uint8 *data)
@@ -796,7 +796,7 @@ SHA512_Transform(pg_sha512_ctx *context, const uint8 *data)
 	/* Clean up */
 	a = b = c = d = e = f = g = h = T1 = T2 = 0;
 }
-#endif							/* SHA2_UNROLL_TRANSFORM */
+#endif							/* !SHA2_UNROLL_TRANSFORM */
 
 void
 pg_sha512_update(pg_sha512_ctx *context, const uint8 *data, size_t len)
diff --git a/src/include/c.h b/src/include/c.h
index 101ba41331e..9f591c0e958 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -900,7 +900,7 @@ extern void ExceptionalCondition(const char *conditionName,
 	StaticAssertStmt(condition, errmessage)
 #define StaticAssertDecl(condition, errmessage) \
 	extern void static_assert_func(int static_assert_failure[(condition) ? 1 : -1])
-#endif							/* HAVE__STATIC_ASSERT */
+#endif							/* !HAVE__STATIC_ASSERT */
 #else							/* C++ */
 #if defined(__cpp_static_assert) && __cpp_static_assert >= 200410
 #define StaticAssertStmt(condition, errmessage) \
@@ -916,7 +916,7 @@ extern void ExceptionalCondition(const char *conditionName,
 	((void) ({ StaticAssertStmt(condition, errmessage); }))
 #define StaticAssertDecl(condition, errmessage) \
 	extern void static_assert_func(int static_assert_failure[(condition) ? 1 : -1])
-#endif							/* __cpp_static_assert */
+#endif							/* !__cpp_static_assert */
 #endif							/* C++ */
 
 
@@ -945,7 +945,7 @@ extern void ExceptionalCondition(const char *conditionName,
 #define AssertVariableIsOfTypeMacro(varname, typename) \
 	(StaticAssertExpr(sizeof(varname) == sizeof(typename), \
 	 CppAsString(varname) " does not have type " CppAsString(typename)))
-#endif							/* HAVE__BUILTIN_TYPES_COMPATIBLE_P */
+#endif							/* !HAVE__BUILTIN_TYPES_COMPATIBLE_P */
 
 
 /* ----------------------------------------------------------------
@@ -1324,7 +1324,7 @@ typedef intptr_t sigjmp_buf[5];
 #define sigjmp_buf jmp_buf
 #define sigsetjmp(x,y) setjmp(x)
 #define siglongjmp longjmp
-#endif							/* __MINGW64__ */
+#endif							/* !__MINGW64__ */
 #endif							/* WIN32 */
 
 /* /port compatibility functions */
diff --git a/src/include/common/int128.h b/src/include/common/int128.h
index 8f035cf4cb2..140ba45dc98 100644
--- a/src/include/common/int128.h
+++ b/src/include/common/int128.h
@@ -271,6 +271,6 @@ int128_to_int64(INT128 val)
 	return (int64) val.lo;
 }
 
-#endif							/* USE_NATIVE_INT128 */
+#endif							/* !USE_NATIVE_INT128 */
 
 #endif							/* INT128_H */
diff --git a/src/include/port.h b/src/include/port.h
index cec41eae713..a349f6aed76 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -327,14 +327,14 @@ extern FILE *pgwin32_popen(const char *command, const char *type);
 #define popen(a,b) pgwin32_popen(a,b)
 #define pclose(a) _pclose(a)
 
-#else							/* !WIN32 */
+#else							/* !WIN32 || __CYGWIN__ */
 
 /*
  *	Win32 requires a special close for sockets and pipes, while on Unix
  *	close() does them all.
  */
 #define closesocket close
-#endif							/* WIN32 */
+#endif							/* !WIN32 || __CYGWIN__ */
 
 /*
  * On Windows, setvbuf() does not support _IOLBF mode, and interprets that
diff --git a/src/include/port/pg_bitutils.h b/src/include/port/pg_bitutils.h
index 814e0b2dba0..0e821bb8ca0 100644
--- a/src/include/port/pg_bitutils.h
+++ b/src/include/port/pg_bitutils.h
@@ -67,7 +67,7 @@ pg_leftmost_one_pos64(uint64 word)
 		shift -= 8;
 
 	return shift + pg_leftmost_one_pos[(word >> shift) & 255];
-#endif							/* HAVE__BUILTIN_CLZ */
+#endif							/* !HAVE__BUILTIN_CLZ */
 }
 
 /*
@@ -126,7 +126,7 @@ pg_rightmost_one_pos64(uint64 word)
 	}
 	result += pg_rightmost_one_pos[word & 255];
 	return result;
-#endif							/* HAVE__BUILTIN_CTZ */
+#endif							/* !HAVE__BUILTIN_CTZ */
 }
 
 /*
diff --git a/src/include/port/pg_bswap.h b/src/include/port/pg_bswap.h
index 4033d2bf399..70dff5ba807 100644
--- a/src/include/port/pg_bswap.h
+++ b/src/include/port/pg_bswap.h
@@ -154,8 +154,8 @@ pg_bswap64(uint64 x)
 #define		DatumBigEndianToNative(x)	pg_bswap64(x)
 #else							/* SIZEOF_DATUM != 8 */
 #define		DatumBigEndianToNative(x)	pg_bswap32(x)
-#endif							/* SIZEOF_DATUM == 8 */
-#endif							/* WORDS_BIGENDIAN */
+#endif							/* SIZEOF_DATUM != 8 */
+#endif							/* !WORDS_BIGENDIAN */
 #endif							/* SIZEOF_DATUM */
 
 #endif							/* PG_BSWAP_H */
diff --git a/src/include/postgres.h b/src/include/postgres.h
index 13903fa022a..0d21ba0f7a5 100644
--- a/src/include/postgres.h
+++ b/src/include/postgres.h
@@ -277,7 +277,7 @@ typedef struct
 	(((varattrib_1b_e *) (PTR))->va_header = 0x01, \
 	 ((varattrib_1b_e *) (PTR))->va_tag = (tag))
 
-#endif							/* WORDS_BIGENDIAN */
+#endif							/* !WORDS_BIGENDIAN */
 
 #define VARDATA_4B(PTR)		(((varattrib_4b *) (PTR))->va_4byte.va_data)
 #define VARDATA_4B_C(PTR)	(((varattrib_4b *) (PTR))->va_compressed.va_data)
diff --git a/src/include/postmaster/syslogger.h b/src/include/postmaster/syslogger.h
index 6436724f3db..b89d74d7761 100644
--- a/src/include/postmaster/syslogger.h
+++ b/src/include/postmaster/syslogger.h
@@ -36,7 +36,7 @@
 #else
 #define PIPE_CHUNK_SIZE  ((int) PIPE_BUF)
 #endif
-#else							/* not defined */
+#else							/* !PIPE_BUF */
 /* POSIX says the value of PIPE_BUF must be at least 512, so use that */
 #define PIPE_CHUNK_SIZE  512
 #endif
diff --git a/src/include/storage/s_lock.h b/src/include/storage/s_lock.h
index 65aa66c5984..76fb08aa372 100644
--- a/src/include/storage/s_lock.h
+++ b/src/include/storage/s_lock.h
@@ -710,7 +710,7 @@ spin_delay(void)
 #define S_UNLOCK(lock)	\
 	do { _ReadWriteBarrier(); (*(lock)) = 0; } while (0)
 
-#endif
+#endif	/* _MSC_VER */
 
 
 #endif	/* !defined(HAS_TEST_AND_SET) */
@@ -743,7 +743,7 @@ extern int	tas_sema(volatile slock_t *lock);
 #define TAS(lock)	tas_sema(lock)
 
 
-#endif	/* HAVE_SPINLOCKS */
+#endif	/* !HAVE_SPINLOCKS */
 
 
 /*
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index 56398176901..0e41e62e39b 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -154,7 +154,7 @@
 		if (elevel_ >= ERROR) \
 			pg_unreachable(); \
 	} while(0)
-#endif							/* HAVE__BUILTIN_CONSTANT_P */
+#endif							/* !HAVE__BUILTIN_CONSTANT_P */
 
 #define ereport(elevel, ...)	\
 	ereport_domain(elevel, TEXTDOMAIN, __VA_ARGS__)
diff --git a/src/interfaces/ecpg/pgtypeslib/dt_common.c b/src/interfaces/ecpg/pgtypeslib/dt_common.c
index e0fae3d5f1d..f8c90f040b0 100644
--- a/src/interfaces/ecpg/pgtypeslib/dt_common.c
+++ b/src/interfaces/ecpg/pgtypeslib/dt_common.c
@@ -1040,8 +1040,8 @@ abstime2tm(AbsoluteTime _time, int *tzp, struct tm *tm, char **tzn)
 	}
 	else
 		tm->tm_isdst = -1;
-#else							/* not (HAVE_STRUCT_TM_TM_ZONE ||
-								 * HAVE_INT_TIMEZONE) */
+#else							/* neither HAVE_STRUCT_TM_TM_ZONE
+								 * nor HAVE_INT_TIMEZONE */
 	if (tzp != NULL)
 	{
 		/* default to UTC */
diff --git a/src/interfaces/ecpg/pgtypeslib/timestamp.c b/src/interfaces/ecpg/pgtypeslib/timestamp.c
index 54cc04addd2..61f68b21b06 100644
--- a/src/interfaces/ecpg/pgtypeslib/timestamp.c
+++ b/src/interfaces/ecpg/pgtypeslib/timestamp.c
@@ -158,8 +158,8 @@ timestamp2tm(timestamp dt, int *tzp, struct tm *tm, fsec_t *fsec, const char **t
 			if (tzn != NULL)
 				*tzn = TZNAME_GLOBAL[(tm->tm_isdst > 0)];
 #endif
-#else							/* not (HAVE_STRUCT_TM_TM_ZONE ||
-								 * HAVE_INT_TIMEZONE) */
+#else							/* neither HAVE_STRUCT_TM_TM_ZONE
+								 * nor HAVE_INT_TIMEZONE */
 			*tzp = 0;
 			/* Mark this as *no* time zone available */
 			tm->tm_isdst = -1;
diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c
index 49a1c626f64..29490160ac6 100644
--- a/src/interfaces/libpq/fe-auth.c
+++ b/src/interfaces/libpq/fe-auth.c
@@ -971,14 +971,14 @@ pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn)
 				pgunlock_thread();
 			}
 			break;
-#else							/* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
+#else							/* !ENABLE_GSS || !ENABLE_SSPI */
 			/* No GSSAPI *or* SSPI support */
 		case AUTH_REQ_GSS:
 		case AUTH_REQ_GSS_CONT:
 			appendPQExpBufferStr(&conn->errorMessage,
 								 libpq_gettext("GSSAPI authentication not supported\n"));
 			return STATUS_ERROR;
-#endif							/* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
+#endif							/* !ENABLE_GSS || !ENABLE_SSPI */
 
 #ifdef ENABLE_SSPI
 		case AUTH_REQ_SSPI:
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 917b19e0e9d..417ad2ae50d 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -3111,7 +3111,7 @@ keep_going:						/* We will come back to here until there is
 #else							/* !USE_SSL */
 				/* can't get here */
 				goto error_return;
-#endif							/* USE_SSL */
+#endif							/* !USE_SSL */
 			}
 
 		case CONNECTION_GSS_STARTUP:
@@ -3215,7 +3215,7 @@ keep_going:						/* We will come back to here until there is
 #else							/* !ENABLE_GSS */
 				/* unreachable */
 				goto error_return;
-#endif							/* ENABLE_GSS */
+#endif							/* !ENABLE_GSS */
 			}
 
 			/*
@@ -4930,7 +4930,7 @@ ldapServiceLookup(const char *purl, PQconninfoOption *options,
 		ldap_unbind(ld);
 		return 3;
 	}
-#endif							/* WIN32 */
+#endif							/* !WIN32 */
 
 	/* search */
 	res = NULL;
diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index 795500c5935..d2c0b693005 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -1161,7 +1161,7 @@ pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time)
 
 	return select(sock + 1, &input_mask, &output_mask,
 				  &except_mask, ptr_timeout);
-#endif							/* HAVE_POLL */
+#endif							/* !HAVE_POLL */
 }
 
 
diff --git a/src/interfaces/libpq/fe-secure.c b/src/interfaces/libpq/fe-secure.c
index 3df4a97f2e9..d7c011499ac 100644
--- a/src/interfaces/libpq/fe-secure.c
+++ b/src/interfaces/libpq/fe-secure.c
@@ -107,7 +107,7 @@ struct sigpipe_info
 		if (!SIGPIPE_MASKED(conn)) \
 			pqsignal(SIGPIPE, spinfo); \
 	} while (0)
-#endif							/* ENABLE_THREAD_SAFETY */
+#endif							/* !ENABLE_THREAD_SAFETY */
 #else							/* WIN32 */
 
 #define DECLARE_SIGPIPE_INFO(spinfo)
diff --git a/src/port/chklocale.c b/src/port/chklocale.c
index 2aaf2ae8c04..d1b6df7baa1 100644
--- a/src/port/chklocale.c
+++ b/src/port/chklocale.c
@@ -415,7 +415,7 @@ pg_get_encoding_from_locale(const char *ctype, bool write_message)
 	free(sys);
 	return -1;
 }
-#else							/* (HAVE_LANGINFO_H && CODESET) || WIN32 */
+#else							/* neither (HAVE_LANGINFO_H && CODESET) nor WIN32 */
 
 /*
  * stub if no multi-language platform support
@@ -430,4 +430,4 @@ pg_get_encoding_from_locale(const char *ctype, bool write_message)
 	return PG_SQL_ASCII;
 }
 
-#endif							/* (HAVE_LANGINFO_H && CODESET) || WIN32 */
+#endif							/* neither (HAVE_LANGINFO_H && CODESET) nor WIN32 */
diff --git a/src/port/pg_crc32c_sb8.c b/src/port/pg_crc32c_sb8.c
index b3f579fcd6f..67ea7010c56 100644
--- a/src/port/pg_crc32c_sb8.c
+++ b/src/port/pg_crc32c_sb8.c
@@ -636,7 +636,7 @@ static const uint32 pg_crc32c_table[8][256] = {
 		0xE54C35A1, 0xAC704886, 0x7734CFEF, 0x3E08B2C8,
 		0xC451B7CC, 0x8D6DCAEB, 0x56294D82, 0x1F1530A5
 	}
-#else							/* !WORDS_BIGENDIAN */
+#else							/* WORDS_BIGENDIAN */
 	{
 		0x00000000, 0x03836BF2, 0xF7703BE1, 0xF4F35013,
 		0x1F979AC7, 0x1C14F135, 0xE8E7A126, 0xEB64CAD4,
diff --git a/src/port/pg_strong_random.c b/src/port/pg_strong_random.c
index be589c9d0bd..3bb79cc69c9 100644
--- a/src/port/pg_strong_random.c
+++ b/src/port/pg_strong_random.c
@@ -137,7 +137,7 @@ pg_strong_random(void *buf, size_t len)
 	return false;
 }
 
-#else							/* not USE_OPENSSL or WIN32 */
+#else							/* neither USE_OPENSSL nor WIN32 */
 
 /*
  * Without OpenSSL or Win32 support, just read /dev/urandom ourselves.
-- 
2.37.2

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