Below are the changes for the current release.
See the CHANGES file for changes in older releases.
See the RELEASENOTES file for a summary of changes in each release.
Issue # numbers mentioned below can be found on Github. For more details, add
the issue number to the end of the URL: https://github.com/swig/swig/issues/

Version 4.0.1 (21 Aug 2019)
===========================

2019-08-20: TekuConcept
            [Javascript] #1535 Add %native support to Javascript.

2019-08-20: bkotzz
            [Java] #1616 Add SWIG_JavaIllegalStateException to support throwing
            java.lang.IllegalStateException from JNI code.

2019-08-19: sjml
            [Lua] #1596 tostring output changes to show the underlying C/C++ pointer.

2019-08-08: rokups
            [C#, Java] #1601 Fix invalid code generated for "%constant enum EnumType.

2019-08-07: wsfulton
            [Python] Fix method overloading of methods that take STL containers of different
            types. The following usage (using std::vector) would fail when using -builtin:

              %include <std_string.i>
              %include <std_vector.i>

              %inline %{
              struct X {};
              %}

              %template(VectorX) std::vector<X>;
              %template(VectorInt) std::vector<int>;

              %inline %{
              using namespace std;
              string VectorOverload(vector<X> v);
              string VectorOverload(vector<int> v);
              %}

            The following would incorrectly fail:

              s = VectorOverload([1, 2, 3])

            With:

              Traceback (most recent call last):
                File "runme3.py", line 20, in <module>
                  ret = VectorOverload([1, 2, 3])
              TypeError: Wrong number or type of arguments for overloaded function 'VectorOverload'.
                Possible C/C++ prototypes are:
                  VectorOverload(std::vector< Number,std::allocator< Number > >)
                  VectorOverload(std::vector< int,std::allocator< int > >)

            The problem was due to some error handling that was not cleared during typehecking.
            In this case an error was not cleared when the elements in the list failed the
            typecheck for converting to X. Only occurs in Python 3+.

            In some combinations of overloaded methods, the following type of error message would
            occur:

              RuntimeError: in sequence element 0

              The above exception was the direct cause of the following exception:

              Traceback (most recent call last):
                File "runme3.py", line 23, in <module>
                  check(VectorOverload(v), "vector<X>")
              SystemError: <built-in function VectorOverload> returned a result with an error set

2019-08-01: wsfulton
            #1602 Fix regression in 4.0.0 where a template function containing a parameter
            with the same name as the function name led to the parameter name used in the
            target language being incorrectly modified.

2019-07-29: wsfulton
            Remove all generated files on error. Previously generated files were not removed,
            potentially breaking Makefiles using file dependencies, especially when -Werror
            (warnings as errors) was used.

2019-07-23: smithx
            [C#] #1530 #1532 Fix marshalling of std::wstring to C#.

2019-07-18: gicmo
            [Python] #1587 Python 3.8 support - remove use of deprecated PyObject_GC_UnTrack.

2019-07-18: cher-nov
            [Python] #1573 Generated Python code uses consistent string quoting style - double
            quotes.

2019-07-16: geefr
            [C#] #616 #1576 Fix C# bool INPUT[], bool OUTPUT[], bool INOUT[] typemaps to marshall
            as 1-byte.

2019-07-12: vadz
            [C#, Java] #1568 #1583 Fix std::set<> typemaps for primitive types.

2019-07-12: vadz
            #1566 #1584 Regression in 4.0.0 - fix missing value for first item of enums with
            trailing comma.

2019-07-11: mcfarljm
            #1548 #1578 Fix segfault in Doxygen parser parsing empty lines in some commands like
            \code.

2019-07-09: IsaacPascual
            [C#, Java] #1570 Fix name of generated C#/Java classes for %interface macros
            in swiginterface.i when wrapping nested C++ classes.

2019-07-05: wsfulton
            [Python] #1547 Whitespace fixes in Doxygen translated comments into pydoc comments
            for Sphinx compatibility.

2019-06-28: wsfulton
            [MzScheme, OCaml] #1559 $arg and $input were incorrectly substituted in the
            argout typemap when two or more arguments were present.

2019-06-24: wsfulton
            [Python, Ruby] #1538 Remove the UnknownExceptionHandler class in order to be
            C++17 compliant as it uses std::unexpected_handler which was removed in C++17.
            This class was intended for director exception handling but was never used by
            SWIG and was never documented.

            *** POTENTIAL INCOMPATIBILITY ***

2019-06-06: bkotzz
            [Java] #1552 Improve performance in Java std::vector constructor wrapper that takes
            a native Java array as input.

2019-06-03: olly
	    [Python] Fix regression in implicit_conv handling of tuples,
	    introduced in SWIG 4.0.0.  Fixes #1553, reported by Alexandre
	    Duret-Lutz.

2019-05-24: wsfulton
            [Octave] Fix detection of Octave on MacOS.

2019-05-24: opoplawski
            [Octave] #1522 Adapt OCTAVE_LDFLAGS for Octave 5.1.

2019-05-22: ferdynator
	    [PHP] #1528 Don't add a closing '?>' PHP tag to generated files.
	    PSR-2 says it MUST be omitted for files containing only PHP.