Refer to OS X as "macOS", except for the port name which is still "darwin".

We weren't terribly consistent about whether to call Apple's OS "OS X"
or "Mac OS X", and the former is probably confusing to people who aren't
Apple users.  Now that Apple has rebranded it "macOS", follow their lead
to establish a consistent naming pattern.  Also, avoid the use of the
ancient project name "Darwin", except as the port code name which does not
seem desirable to change.  (In short, this patch touches documentation and
comments, but no actual code.)

I didn't touch contrib/start-scripts/osx/, either.  I suspect those are
obsolete and due for a rewrite, anyway.

I dithered about whether to apply this edit to old release notes, but
those were responsible for quite a lot of the inconsistencies, so I ended
up changing them too.  Anyway, Apple's being ahistorical about this,
so why shouldn't we be?

15 files changed, 25 insertions, 22 deletions

diff --git a/src/Makefile.shlib b/src/Makefile.shlib
index 924d21f443c..de93f416393 100644
--- a/src/Makefile.shlib
+++ b/src/Makefile.shlib
@@ -323,7 +323,7 @@ endif
 endif # shlib_major
 
 # Where possible, restrict the symbols exported by the library to just the
-# official list, so as to avoid unintentional ABI changes.  On recent Darwin
+# official list, so as to avoid unintentional ABI changes.  On recent macOS
 # this also quiets multiply-defined-symbol warnings in programs that use
 # libpgport along with libpq.
 ifneq (,$(SHLIB_EXPORTS))
diff --git a/src/backend/Makefile b/src/backend/Makefile
index 3b08defe2bc..4946d37929c 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -26,8 +26,8 @@ include $(srcdir)/common.mk
 # As of 1/2010:
 # The probes.o file is necessary for dtrace support on Solaris, and on recent
 # versions of systemtap.  (Older systemtap releases just produce an empty
-# file, but that's okay.)  However, OS X's dtrace doesn't use it and doesn't
-# even recognize the -G option.  So, build probes.o except on Darwin.
+# file, but that's okay.)  However, macOS's dtrace doesn't use it and doesn't
+# even recognize the -G option.  So, build probes.o except on macOS.
 # This might need adjustment as other platforms add dtrace support.
 ifneq ($(PORTNAME), darwin)
 ifeq ($(enable_dtrace), yes)
diff --git a/src/backend/port/dynloader/darwin.c b/src/backend/port/dynloader/darwin.c
index a83c614f4f1..7b6b48d14ac 100644
--- a/src/backend/port/dynloader/darwin.c
+++ b/src/backend/port/dynloader/darwin.c
@@ -1,5 +1,5 @@
 /*
- * Dynamic loading support for Darwin
+ * Dynamic loading support for macOS (Darwin)
  *
  * If dlopen() is available (Darwin 10.3 and later), we just use it.
  * Otherwise we emulate it with the older, now deprecated, NSLinkModule API.
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 40995580af3..0c0a609735e 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -1273,7 +1273,7 @@ PostmasterMain(int argc, char *argv[])
 #ifdef HAVE_PTHREAD_IS_THREADED_NP
 
 	/*
-	 * On Darwin, libintl replaces setlocale() with a version that calls
+	 * On macOS, libintl replaces setlocale() with a version that calls
 	 * CFLocaleCopyCurrent() when its second argument is "" and every relevant
 	 * environment variable is unset or empty.  CFLocaleCopyCurrent() makes
 	 * the process multithreaded.  The postmaster calls sigprocmask() and
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 582d3e460b2..260a5aac496 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -1844,8 +1844,8 @@ varstr_sortsupport(SortSupport ssup, Oid collid, bool bpchar)
 	 * Even apart from the risk of broken locales, it's possible that there
 	 * are platforms where the use of abbreviated keys should be disabled at
 	 * compile time.  Having only 4 byte datums could make worst-case
-	 * performance drastically more likely, for example.  Moreover, Darwin's
-	 * strxfrm() implementations is known to not effectively concentrate a
+	 * performance drastically more likely, for example.  Moreover, macOS's
+	 * strxfrm() implementation is known to not effectively concentrate a
 	 * significant amount of entropy from the original string in earlier
 	 * transformed blobs.  It's possible that other supported platforms are
 	 * similarly encumbered.  So, if we ever get past disabling this
diff --git a/src/backend/utils/misc/ps_status.c b/src/backend/utils/misc/ps_status.c
index c50be8aab65..a889b170c83 100644
--- a/src/backend/utils/misc/ps_status.c
+++ b/src/backend/utils/misc/ps_status.c
@@ -223,8 +223,8 @@ save_ps_display_args(int argc, char **argv)
 #if defined(__darwin__)
 
 		/*
-		 * Darwin (and perhaps other NeXT-derived platforms?) has a static
-		 * copy of the argv pointer, which we may fix like so:
+		 * macOS (and perhaps other NeXT-derived platforms?) has a static copy
+		 * of the argv pointer, which we may fix like so:
 		 */
 		*_NSGetArgv() = new_argv;
 #endif
diff --git a/src/backend/utils/probes.d b/src/backend/utils/probes.d
index 976774e795e..2f92dfa9adb 100644
--- a/src/backend/utils/probes.d
+++ b/src/backend/utils/probes.d
@@ -12,7 +12,7 @@
  * Typedefs used in PostgreSQL.
  *
  * NOTE: Do not use system-provided typedefs (e.g. uintptr_t, uint32_t, etc)
- * in probe definitions, as they cause compilation errors on Mac OS X 10.5.
+ * in probe definitions, as they cause compilation errors on macOS 10.5.
  */
 #define LocalTransactionId unsigned int
 #define LWLockMode int
diff --git a/src/bin/psql/input.c b/src/bin/psql/input.c
index 2359b11dcdd..a7d017a2d5a 100644
--- a/src/bin/psql/input.c
+++ b/src/bin/psql/input.c
@@ -411,7 +411,7 @@ saveHistory(char *fname, int max_lines)
 
 	/*
 	 * Suppressing the write attempt when HISTFILE is set to /dev/null may
-	 * look like a negligible optimization, but it's necessary on e.g. Darwin,
+	 * look like a negligible optimization, but it's necessary on e.g. macOS,
 	 * where write_history will fail because it tries to chmod the target
 	 * file.
 	 */
diff --git a/src/include/port/darwin.h b/src/include/port/darwin.h
index 29c4b91d8ce..15fb69d6dbb 100644
--- a/src/include/port/darwin.h
+++ b/src/include/port/darwin.h
@@ -2,7 +2,7 @@
 
 #define __darwin__	1
 
-#if HAVE_DECL_F_FULLFSYNC		/* not present before OS X 10.3 */
+#if HAVE_DECL_F_FULLFSYNC		/* not present before macOS 10.3 */
 #define HAVE_FSYNC_WRITETHROUGH
 
 #endif
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 9668b52103f..f3a9e5a83fe 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -1252,7 +1252,7 @@ setKeepalivesIdle(PGconn *conn)
 	}
 #else
 #ifdef TCP_KEEPALIVE
-	/* Darwin uses TCP_KEEPALIVE rather than TCP_KEEPIDLE */
+	/* macOS uses TCP_KEEPALIVE rather than TCP_KEEPIDLE */
 	if (setsockopt(conn->sock, IPPROTO_TCP, TCP_KEEPALIVE,
 				   (char *) &idle, sizeof(idle)) < 0)
 	{
diff --git a/src/port/README b/src/port/README
index 58fb32d9f94..4ae96da0158 100644
--- a/src/port/README
+++ b/src/port/README
@@ -28,5 +28,5 @@ applications.
 from libpgport are linked first.  This avoids having applications
 dependent on symbols that are _used_ by libpq, but not intended to be
 exported by libpq.  libpq's libpgport usage changes over time, so such a
-dependency is a problem.  Win32, Linux, and Darwin use an export list to
+dependency is a problem.  Windows, Linux, and macOS use an export list to
 control the symbols exported by libpq.
diff --git a/src/port/chklocale.c b/src/port/chklocale.c
index 3c0ef6a2530..915821a4e91 100644
--- a/src/port/chklocale.c
+++ b/src/port/chklocale.c
@@ -395,7 +395,7 @@ pg_get_encoding_from_locale(const char *ctype, bool write_message)
 #ifdef __darwin__
 
 	/*
-	 * Current OS X has many locales that report an empty string for CODESET,
+	 * Current macOS has many locales that report an empty string for CODESET,
 	 * but they all seem to actually use UTF-8.
 	 */
 	if (strlen(sys) == 0)
diff --git a/src/template/darwin b/src/template/darwin
index 542f706b0fa..ea6d3b0b042 100644
--- a/src/template/darwin
+++ b/src/template/darwin
@@ -1,9 +1,12 @@
 # src/template/darwin
 
-# Select appropriate semaphore support.  Darwin 6.0 (Mac OS X 10.2) and up
-# support System V semaphores; before that we have to use POSIX semaphores,
-# which are less good for our purposes because they eat a file descriptor
-# per backend per max_connection slot.
+# Note: Darwin is the original code name for macOS, also known as OS X.
+# We still use "darwin" as the port name, partly because config.guess does.
+
+# Select appropriate semaphore support.  Darwin 6.0 (macOS 10.2) and up
+# support System V semaphores; before that we have to use named POSIX
+# semaphores, which are less good for our purposes because they eat a
+# file descriptor per backend per max_connection slot.
 case $host_os in
   darwin[015].*)
     USE_NAMED_POSIX_SEMAPHORES=1
diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
index 1154d4c300e..b28cb0b1e1e 100644
--- a/src/test/regress/pg_regress.c
+++ b/src/test/regress/pg_regress.c
@@ -738,9 +738,9 @@ initialize_environment(void)
 		/*
 		 * Most platforms have adopted the POSIX locale as their
 		 * implementation-defined default locale.  Exceptions include native
-		 * Windows, Darwin with --enable-nls, and Cygwin with --enable-nls.
+		 * Windows, macOS with --enable-nls, and Cygwin with --enable-nls.
 		 * (Use of --enable-nls matters because libintl replaces setlocale().)
-		 * Also, PostgreSQL does not support Darwin with locale environment
+		 * Also, PostgreSQL does not support macOS with locale environment
 		 * variables unset; see PostmasterMain().
 		 */
 #if defined(WIN32) || defined(__CYGWIN__) || defined(__darwin__)
diff --git a/src/tools/find_typedef b/src/tools/find_typedef
index fee0fb5152d..24e9b76651d 100755
--- a/src/tools/find_typedef
+++ b/src/tools/find_typedef
@@ -13,7 +13,7 @@
 # find both .o files and executables.  Therefore, ignore error messages about
 # unsuitable files being fed to objdump.
 #
-# This is known to work on Linux and on some BSDen, including Mac OS X.
+# This is known to work on Linux and on some BSDen, including macOS.
 #
 # Caution: on the platforms we use, this only prints typedefs that are used
 # to declare at least one variable or struct field.  If you have say