Merge from origin/emacs-26

317b354 ; Add notes about cross-compiling macOS versions
4b176eb Fix macOS run-time feature check
c03574b * etc/NEWS-*: Fix capitalization of "Emacs"

# Conflicts:
#	etc/NEWS

1 files changed, 29 insertions, 0 deletions

diff --git a/nextstep/INSTALL b/nextstep/INSTALL
index 64f8f8fcf70..726a897c371 100644
--- a/nextstep/INSTALL
+++ b/nextstep/INSTALL
@@ -45,6 +45,35 @@ files will be installed under whatever 'prefix' is set to (defaults to
 require 'sudo' for "make install").
 
 
+Targeting different macOS versions
+----------------------------------
+
+The Emacs build process automatically enables or disables macOS
+features according to the version of macOS it is being built on.  It
+is possible to override this automatic configuration if you are
+targeting a different version of macOS, or wish to build one
+executable that is able to enable or disable features at run-time.
+
+To build a version compatible with an older version of macOS use this
+flag:
+
+  -DMAC_OS_X_VERSION_MIN_REQUIRED=x
+
+and to build for a newer version of macOS:
+
+  -DMAC_OS_X_VERSION_MAX_ALLOWED=x
+
+For example, to enable run-time checks for features available between
+macOS 10.6, and 10.12 inclusive:
+
+  ./configure --with-ns CFLAGS="-DMAC_OS_X_VERSION_MIN_REQUIRED=1060 \
+    -DMAC_OS_X_VERSION_MAX_ALLOWED=101200 -g3 -O2"
+
+The macOS version numbers are formatted as 10x0 for macOS up to 10.10,
+and 10xx00 for macOS 10.10 and above.  A full list is provided in
+/usr/include/AvailabilityMacros.h.
+
+
 Installation
 ------------