Build of lldb is failing with SWIG 4.1.0

[jplesnik]

I am testing rebuild of SWIG dependencies against version 4.1.0 in Fedora rawhide/38.

The build of lldb-15.0.0 is failing with this version.

/builddir/build/BUILD/lldb-15.0.0.src/redhat-linux-build/bindings/python/LLDBWrapPython.cpp:22100:19: error: non-const lvalue reference to type 'lldb::FileSP' (aka 'shared_ptr<lldb_private::File>') cannot bind to a value of unrelated type 'SwigValueWrapper<std::shared_ptr<lldb_private::File>>'
    lldb::FileSP &sp = result;
                  ^    ~~~~~~
/builddir/build/BUILD/lldb-15.0.0.src/redhat-linux-build/bindings/python/LLDBWrapPython.cpp:22140:19: error: non-const lvalue reference to type 'lldb::FileSP' (aka 'shared_ptr<lldb_private::File>') cannot bind to a value of unrelated type 'SwigValueWrapper<std::shared_ptr<lldb_private::File>>'
    lldb::FileSP &sp = result;
                  ^    ~~~~~~
/builddir/build/BUILD/lldb-15.0.0.src/redhat-linux-build/bindings/python/LLDBWrapPython.cpp:22180:19: error: non-const lvalue reference to type 'lldb::FileSP' (aka 'shared_ptr<lldb_private::File>') cannot bind to a value of unrelated type 'SwigValueWrapper<std::shared_ptr<lldb_private::File>>'
    lldb::FileSP &sp = result;
                  ^    ~~~~~~
/builddir/build/BUILD/lldb-15.0.0.src/redhat-linux-build/bindings/python/LLDBWrapPython.cpp:30742:19: error: non-const lvalue reference to type 'lldb::FileSP' (aka 'shared_ptr<lldb_private::File>') cannot bind to a value of unrelated type 'SwigValueWrapper<std::shared_ptr<lldb_private::File>>'
    lldb::FileSP &sp = result;
                  ^    ~~~~~~
4 errors generated.

Complete build log is here.

[wsfulton]

This is due to a change in SwigValueWraper for C++11 and later for improved move semantics in commit d1055f4, see #999.

A simple patch fixes it for lldb and is backwards compatible with older versions of SWIG.

-- lldb-15.0.0.src/bindings/python/python-typemaps.swig-original	2022-09-20 20:45:33.545145308 +0100
+++ lldb-15.0.0.src/bindings/python/python-typemaps.swig	2022-09-20 20:45:38.952152804 +0100
@@ -435,7 +435,7 @@ template <> bool SetNumberFromPyObject<d
 
 %typemap(out) lldb::FileSP {
   $result = nullptr;
-  lldb::FileSP &sp = $1;
+  const lldb::FileSP &sp = $1;
   if (sp) {
     PythonFile pyfile = unwrapOrSetPythonException(PythonFile::FromFile(*sp));
     if (!pyfile.IsValid())

[jplesnik]

The patch helped. Thank you.