Author:     Noah Misch <noah@leadboat.com>
Commit:     Noah Misch <noah@leadboat.com>

    AIX: Fix missing libpq symbols by respecting SHLIB_EXPORTS.
    
    We make each AIX shared library export all globals found in .o files
    that originate in the library.  That doesn't include symbols acquired by
    -lpgcommon_shlib.  That is good on average, but it became a problem for
    libpq when commit e6afa8918c461c1dd80c5063a950518fa4e950cd moved five
    official libpq API symbols into src/common.  Fix this by implementing
    the SHLIB_EXPORTS mechanism for AIX, so affected libraries export the
    same symbols that they export on Linux.  This reintroduces symbols
    pg_encoding_to_char, pg_utf_mblen, pg_char_to_encoding,
    pg_valid_server_encoding, and pg_valid_server_encoding_id.  Back-patch
    to v13, where the aforementioned commit first appeared.  While a minor
    release is usually the wrong time to add or remove symbol exports in
    libpq or libecpg, we should expect users to want each documented symbol.
    
    Tony Reix
    
    Discussion: https://postgr.es/m/PR3PR02MB6396742E2FC3E77D37A920BC86C79@PR3PR02MB6396.eurprd02.prod.outlook.com

diff --git a/src/Makefile.shlib b/src/Makefile.shlib
index 29a7f6d..6b79db1 100644
--- a/src/Makefile.shlib
+++ b/src/Makefile.shlib
@@ -329,7 +329,11 @@ $(shlib): $(OBJS) | $(SHLIB_PREREQS)
 	rm -f $(stlib)
 	$(LINK.static) $(stlib) $^
 	$(RANLIB) $(stlib)
+ifeq (,$(SHLIB_EXPORTS))
 	$(MKLDEXPORT) $(stlib) $(shlib) >$(exports_file)
+else
+	( echo '#! $(shlib)'; $(AWK) '/^[^#]/ {printf "%s\n",$$1}' $(SHLIB_EXPORTS) ) >$(exports_file)
+endif
 	$(COMPILER) -o $(shlib) $(stlib) -Wl,-bE:$(exports_file) $(LDFLAGS) $(LDFLAGS_SL) $(SHLIB_LINK)
 	rm -f $(stlib)
 	$(AR) $(AROPT) $(stlib) $(shlib)
diff --git a/src/port/README b/src/port/README
index c446b46..97f18a6 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.  Windows, Linux, and macOS use an export list to
-control the symbols exported by libpq.
+dependency is a problem.  Windows, Linux, AIX, and macOS use an export
+list to control the symbols exported by libpq.