build: Restrict binary compatibility to 2.14

On ELF systems, this bumps the soname from libxml2.so.2 to
libxml2.so.16. For historic reasons, the last component is the sum of
major and minor version.

CMakeLists.txt

@@ -412,7 +412,7 @@ if(CMAKE_C_COMPILER_ID MATCHES "Clang" OR CMAKE_C_COMPILER_ID STREQUAL "GNU")
 -Wno-long-long -Wno-format-extra-args -Wno-array-bounds")
 endif()
 
-set(LIBXML_MINOR_COMPAT 0)
+set(LIBXML_MINOR_COMPAT 14)
 math(EXPR LIBXML_SOVERSION "${LIBXML_MAJOR_VERSION} + ${LIBXML_MINOR_COMPAT}")
 set_target_properties(
     LibXml2

NEWS

@@ -15,6 +15,9 @@ Support for RELAX NG can now be disabled with a new configuration
 option independently of XML Schemas support. It is still enabled by
 default.
 
+Binary compatibility is restricted to versions 2.14 or newer. On ELF
+systems, the soname was bumped from libxml2.so.2 to libxml2.so.16.
+
 ### New features
 
 Input callbacks can now be set on a parser context and an improved API
@@ -48,11 +51,13 @@ Support for the range and point extensions of the xpointer() scheme
 was removed. The rest of the XPointer implementation isn't affected.
 The xpointer() scheme now behaves like the xpath1() scheme.
 
-Several legacy functions were removed from the header files.
+Several legacy symbols and the functions in xmlunicode.h were removed.
 
 The shell was moved from libxml2 to xmllint. Several related functions
 are no longer available.
 
+ELF version information was removed.
+
 ### Planned removals
 
 Support for HTTP is planned to be removed in the 2.15 release.

configure.ac

@@ -17,7 +17,7 @@ LIBXML_MICRO_VERSION=`echo $LIBXML_VERSION | cut -d . -f 3`
 LIBXML_MICRO_VERSION_SUFFIX=
 
 # The oldest minor version we are compatible with.
-LIBXML_MINOR_COMPAT=0
+LIBXML_MINOR_COMPAT=14
 LIBXML_CURRENT=`expr $LIBXML_MAJOR_VERSION + $LIBXML_MINOR_VERSION`
 LIBXML_AGE=`expr $LIBXML_MINOR_VERSION - $LIBXML_MINOR_COMPAT`
 LIBXML_VERSION_INFO=$LIBXML_CURRENT:$LIBXML_MICRO_VERSION:$LIBXML_AGE

meson.build

@@ -481,7 +481,7 @@ foreach file : xml_opt_src
     endif
 endforeach
 
-v_min_compat = 0
+v_min_compat = 14
 xml_lib = library(
     'xml2',
     files(xml_src),