Change with shared library compatibility version handling

For ELF binaries (e.g., Linux): default compatible version (SONAME =
`<library-name>.so.<MAJOR>`) can be specialized using additional `cnum`
parameter to `<library-name>.so.<MAJOR>.<MINOR>` or
`<library-name>.so.<MAJOR>.<MINOR>.<PATCH>`.

For Mach-O binaries (e.g., OS X):

- (bugfix) install-name points to compatible version (not absolute path
  to a non-versioned library)
- Default install-name `<install-path>/<library-name>.<MAJOR>.dylib` can
  be specialized using `cnum` parameter to
  `<install-path>/<library-name>.<MAJOR>.<MINOR>.dylib` or
  `<install-path>/<library-name>.<MAJOR>.<MINOR>.<PATCH>.dylib`
- `-Wl,-compatibility_version` and `-Wl,-current_version` flags use
  version from cnum/vnum (default cnum is vnum.split('.')[0])

demos/c++/wscript

@@ -19,6 +19,8 @@ def configure(conf):
 
 def build(bld):
 	bld.shlib(source='a.cpp', target='mylib', vnum='9.8.7')
+	bld.shlib(source='a.cpp', target='mylib2', vnum='9.8.7', cnum='9.8')
+	bld.shlib(source='a.cpp', target='mylib3')
 	bld.program(source='main.cpp', target='app', use='mylib')
 	bld.stlib(target='foo', source='b.cpp')
 

waflib/Tools/ccroot.py

@@ -489,10 +489,19 @@ def apply_vnum(self):
 		def build(bld):
 			bld.shlib(source='a.c', target='foo', vnum='14.15.16')
 
-	In this example, ``libfoo.so`` is installed as ``libfoo.so.1.2.3``, and the following symbolic links are created:
+	In this example on Linux platform, ``libfoo.so`` is installed as ``libfoo.so.14.15.16``, and the following symbolic links are created:
 
-	* ``libfoo.so   → libfoo.so.1.2.3``
-	* ``libfoo.so.1 → libfoo.so.1.2.3``
+	* ``libfoo.so    → libfoo.so.14.15.16``
+	* ``libfoo.so.14 → libfoo.so.14.15.16``
+
+	By default, the library will be assigned SONAME ``libfoo.so.14``, effectively declaring ABI compatibility between all minor and patch releases for the major version of the library.  When necessary, the compatibility can be explicitly defined using `cnum` parameter:
+
+		def build(bld):
+			bld.shlib(source='a.c', target='foo', vnum='14.15.16', cnum='14.15')
+
+	In this case, the assigned SONAME will be ``libfoo.so.14.15`` with ABI compatibility only between path releases for a specific major and minor version of the library.
+
+	On OS X platform, install-name parameter will follow the above logic for SONAME with exception that it also specifies an absolute path (based on install_path) of the library.
 	"""
 	if not getattr(self, 'vnum', '') or os.name != 'posix' or self.env.DEST_BINFMT not in ('elf', 'mac-o'):
 		return
@@ -503,13 +512,18 @@ def apply_vnum(self):
 	nums = self.vnum.split('.')
 	node = link.outputs[0]
 
+	cnum = getattr(self, 'cnum', str(nums[0]))
+	cnums = cnum.split('.')
+	if len(cnums)>len(nums) or nums[0:len(cnums)] != cnums:
+		raise Errors.WafError('invalid compatibility version %s' % cnum)
+
 	libname = node.name
 	if libname.endswith('.dylib'):
 		name3 = libname.replace('.dylib', '.%s.dylib' % self.vnum)
-		name2 = libname.replace('.dylib', '.%s.dylib' % nums[0])
+		name2 = libname.replace('.dylib', '.%s.dylib' % cnum)
 	else:
 		name3 = libname + '.' + self.vnum
-		name2 = libname + '.' + nums[0]
+		name2 = libname + '.' + cnum
 
 	# add the so name for the ld linker - to disable, just unset env.SONAME_ST
 	if self.env.SONAME_ST:
@@ -548,8 +562,10 @@ def apply_vnum(self):
 			inst_to = self.link_task.__class__.inst_to
 		if inst_to:
 			p = Utils.subst_vars(inst_to, self.env)
-			path = os.path.join(p, self.link_task.outputs[0].name)
+			path = os.path.join(p, name2)
 			self.env.append_value('LINKFLAGS', ['-install_name', path])
+			self.env.append_value('LINKFLAGS', '-Wl,-compatibility_version,%s' % cnum)
+			self.env.append_value('LINKFLAGS', '-Wl,-current_version,%s' % self.vnum)
 
 class vnum(Task.Task):
 	"""

waflib/Tools/fc_config.py

@@ -93,7 +93,7 @@ def fortran_modifier_darwin(conf):
 	"""
 	v = conf.env
 	v['FCFLAGS_fcshlib']   = ['-fPIC']
-	v['LINKFLAGS_fcshlib'] = ['-dynamiclib', '-Wl,-compatibility_version,1', '-Wl,-current_version,1']
+	v['LINKFLAGS_fcshlib'] = ['-dynamiclib']
 	v['fcshlib_PATTERN']   = 'lib%s.dylib'
 	v['FRAMEWORKPATH_ST']  = '-F%s'
 	v['FRAMEWORK_ST']      = '-framework %s'

waflib/Tools/gcc.py

@@ -97,7 +97,7 @@ def gcc_modifier_darwin(conf):
 	"""Configuration flags for executing gcc on MacOS"""
 	v = conf.env
 	v['CFLAGS_cshlib']       = ['-fPIC']
-	v['LINKFLAGS_cshlib']    = ['-dynamiclib', '-Wl,-compatibility_version,1', '-Wl,-current_version,1']
+	v['LINKFLAGS_cshlib']    = ['-dynamiclib']
 	v['cshlib_PATTERN']      = 'lib%s.dylib'
 	v['FRAMEWORKPATH_ST']    = '-F%s'
 	v['FRAMEWORK_ST']        = ['-framework']

waflib/Tools/gxx.py

@@ -97,7 +97,7 @@ def gxx_modifier_darwin(conf):
 	"""Configuration flags for executing g++ on MacOS"""
 	v = conf.env
 	v['CXXFLAGS_cxxshlib']   = ['-fPIC']
-	v['LINKFLAGS_cxxshlib']  = ['-dynamiclib', '-Wl,-compatibility_version,1', '-Wl,-current_version,1']
+	v['LINKFLAGS_cxxshlib']  = ['-dynamiclib']
 	v['cxxshlib_PATTERN']    = 'lib%s.dylib'
 	v['FRAMEWORKPATH_ST']    = '-F%s'
 	v['FRAMEWORK_ST']        = ['-framework']